Report of concrete pavement evaluation : project 105 C-4181-01 Donahoo Road, Wyandotte County : [technical summary].

DOT National Transportation Integrated Search

2013-12-01

The physical properties of hardened concrete cores and fresh concrete test results were compared with aggregate gradation workability differences. The concrete cores were taken from a rural two-lane concrete road in northeastern Kansas constructed in...

Composition and leaching of construction and demolition waste: inorganic elements and organic compounds.

PubMed

Butera, Stefania; Christensen, Thomas H; Astrup, Thomas F

2014-07-15

Thirty-three samples of construction and demolition waste collected at 11 recycling facilities in Denmark were characterised in terms of total content and leaching of inorganic elements and presence of the persistent organic pollutants PCBs and PAHs. Samples included (i) "clean" (i.e. unmixed) concrete waste, (ii) mixed masonry and concrete, (iii) asphalt and (iv) freshly cast concrete cores; both old and newly generated construction and demolition waste was included. PCBs and PAHs were detected in all samples, generally in non-critical concentrations. Overall, PAHs were comparable to background levels in urban environments. "Old" and "new" concrete samples indicated different PCB congener profiles and the presence of PCB even in new concrete suggested that background levels in raw materials may be an issue. Significant variability in total content of trace elements, even more pronounced for leaching, was observed indicating that the number of analysed samples may be critical in relation to decisions regarding management and utilisation of the materials. Higher leaching of chromium, sulphate and chloride were observed for masonry-containing and partly carbonated samples, indicating that source segregation and management practices may be important. Generally, leaching was in compliance with available leaching limits, except for selenium, and in some cases chromium, sulphate and antimony. Copyright © 2014 Elsevier B.V. All rights reserved.

Magnetic anisotropy of Silurian organic-rich shale rocks and calcareous concretions from Northern Poland

NASA Astrophysics Data System (ADS)

Niezabitowska, Dominika; Szaniawski, Rafał

2017-04-01

The research has been performed on Wenlockian shales of Pelplin formation from the Pomerania region located in Northern Poland. These organic-rich marine shales were deposited on the western shelf of the Baltica paleo-continent and currently they constitute the cover of East European Platform. The studied shales lie almost completely flat without signs of tectonic deformations. Rock magnetic studies were carried out with the aim of recognizing ferro- and paramagnetic minerals in shales and thus fully understanding the origin of the magnetic anisotropy. The typical dark shales and spherical calcareous concretions from two boreholes were sampled. Based on deflection of shales beds bordered with a concretions, we deduce that such concretions were formed in the early stage of diagenesis, before the final compaction and lithification of surrounding shales. We obtained similar rockmagnetic results for both of rock types. The results of thermal variation of magnetic susceptibility and hysteresis loops show that the magnetic susceptibility is mainly controlled by paramagnetic minerals, due to domination of phyllosilicate minerals, with a smaller impact of ferromagnetic phase. The results of the hysteresis studies documented the domination of low coercivity ferromagnetic minerals, that is magnetite and pyrrhotite. The deposition alignment of flocculated phyllosilicates and further compaction determine distinct bedding parallel foliation of the AMS (Anisotropy of Magnetic Susceptibility) in the both drill cores. In one of the drill core the maximal AMS axes are almost randomly distributed in the bedding plane and show only a weak tendency for grouping. In the second drill core the magnetic lineation is better defined. In the case of concretions the bedding parallel magnetic foliation is also evident but it is much weaker than in shales. In turn, the magnetic lineation in the both drill cores is well developed and the maximal AMS axes are well grouped. In both of the cores the orientation of lineation from concretions complies with site mean lineation from shale rocks. To summarize, the results imply that the phyllosilicate minerals from shales are typically well aligned in the bedding plane by compaction processes. In the case of calcareous concretions the foliation is less developed due to their earlier cementation of flocculated phyllosicates in the calcareous matrix, which occurred before the end of sediments compaction. A good grouping of the maximal AMS axes within the early cemented concretions suggest that the magnetic lineation is rather sedimentary than tectonic in origin. We suggest that the magnetic lineation is probably related to the orientation of flocculated phyllosilicates due to transportation. This work has been funded by the Polish National Centre for Research and Development within the Blue Gas project (No BG2/SHALEMECH/14). Samples were provided by the PGNiG SA.

Braided reinforced composite rods for the internal reinforcement of concrete

NASA Astrophysics Data System (ADS)

Gonilho Pereira, C.; Fangueiro, R.; Jalali, S.; Araujo, M.; Marques, P.

2008-05-01

This paper reports on the development of braided reinforced composite rods as a substitute for the steel reinforcement in concrete. The research work aims at understanding the mechanical behaviour of core-reinforced braided fabrics and braided reinforced composite rods, namely concerning the influence of the braiding angle, the type of core reinforcement fibre, and preloading and postloading conditions. The core-reinforced braided fabrics were made from polyester fibres for producing braided structures, and E-glass, carbon, HT polyethylene, and sisal fibres were used for the core reinforcement. The braided reinforced composite rods were obtained by impregnating the core-reinforced braided fabric with a vinyl ester resin. The preloading of the core-reinforced braided fabrics and the postloading of the braided reinforced composite rods were performed in three and two stages, respectively. The results of tensile tests carried out on different samples of core-reinforced braided fabrics are presented and discussed. The tensile and bending properties of the braided reinforced composite rods have been evaluated, and the results obtained are presented, discussed, and compared with those of conventional materials, such as steel.

Gas-cooled nuclear reactor

DOEpatents

Peinado, Charles O.; Koutz, Stanley L.

1985-01-01

A gas-cooled nuclear reactor includes a central core located in the lower portion of a prestressed concrete reactor vessel. Primary coolant gas flows upward through the core and into four overlying heat-exchangers wherein stream is generated. During normal operation, the return flow of coolant is between the core and the vessel sidewall to a pair of motor-driven circulators located at about the bottom of the concrete pressure vessel. The circulators repressurize the gas coolant and return it back to the core through passageways in the underlying core structure. If during emergency conditions the primary circulators are no longer functioning, the decay heat is effectively removed from the core by means of natural convection circulation. The hot gas rising through the core exits the top of the shroud of the heat-exchangers and flows radially outward to the sidewall of the concrete pressure vessel. A metal liner covers the entire inside concrete surfaces of the concrete pressure vessel, and cooling tubes are welded to the exterior or concrete side of the metal liner. The gas coolant is in direct contact with the interior surface of the metal liner and transfers its heat through the metal liner to the liquid coolant flowing through the cooling tubes. The cooler gas is more dense and creates a downward convection flow in the region between the core and the sidewall until it reaches the bottom of the concrete pressure vessel when it flows radially inward and up into the core for another pass. Water is forced to flow through the cooling tubes to absorb heat from the core at a sufficient rate to remove enough of the decay heat created in the core to prevent overheating of the core or the vessel.

Neutron and X-ray Tomography (NeXT) system for simultaneous, dual modality tomography.

PubMed

LaManna, J M; Hussey, D S; Baltic, E; Jacobson, D L

2017-11-01

Dual mode tomography using neutrons and X-rays offers the potential of improved estimation of the composition of a sample from the complementary interaction of the two probes with the sample. We have developed a simultaneous neutron and 90 keV X-ray tomography system that is well suited to the study of porous media systems such as fuel cells, concrete, unconventional reservoir geologies, limestones, and other geological media. We present the characteristic performance of both the neutron and X-ray modalities. We illustrate the use of the simultaneous acquisition through improved phase identification in a concrete core.

Neutron and X-ray Tomography (NeXT) system for simultaneous, dual modality tomography

NASA Astrophysics Data System (ADS)

LaManna, J. M.; Hussey, D. S.; Baltic, E.; Jacobson, D. L.

2017-11-01

Dual mode tomography using neutrons and X-rays offers the potential of improved estimation of the composition of a sample from the complementary interaction of the two probes with the sample. We have developed a simultaneous neutron and 90 keV X-ray tomography system that is well suited to the study of porous media systems such as fuel cells, concrete, unconventional reservoir geologies, limestones, and other geological media. We present the characteristic performance of both the neutron and X-ray modalities. We illustrate the use of the simultaneous acquisition through improved phase identification in a concrete core.

Results of detailed analyses performed on boring cores extracted from the concrete floors of the Fukushima Daiichi nuclear power plant reactor buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maeda, Koji; Sasaki, S.; Kumai, M.

Due to the massive earthquake and tsunami on March 11, 2011, and the following severe accident at the Fukushima Daiichi Nuclear Power Plant, concrete surfaces within the reactor buildings were exposed to radioactive liquid and vapor phase contaminants. In order to clarify the situation of this contamination in the reactor buildings of Units 1, 2 and 3, selected samples were transported to the Fuels Monitoring Facility in the Oarai Engineering Center of JAEA where they were subjected to analyses to determine the surface radionuclide concentrations and to characterize the radionuclide distributions in the samples. In particular, penetration of radiocesium inmore » the surface coatings layer and sub-surface concrete was evaluated. The analysis results indicate that the situation of contamination in the building of Unit 2 was different from others, and the protective surface coatings on the concrete floors provided significant protection against radionuclide penetration. The localized penetration of contamination in the concrete floors was found to be confined within a millimeter of the surface of the coating layer of some millimeters. (authors)« less

Hollow-core FRP-concrete-steel bridge columns under extreme loading.

DOT National Transportation Integrated Search

2015-04-01

This report presents the behavior of hollow-core fiber reinforced polymer concrete - steel columns (HC-FCS) under : combined axial-flexural as well as vehicle collision loads. The HC-FCS column consists of a concrete wall sandwiched between an ou...

Dominance of debonding defect of CFST on PZT sensor response considering the meso-scale structure of concrete with multi-scale simulation

NASA Astrophysics Data System (ADS)

Xu, Bin; Chen, Hongbing; Mo, Y.-L.; Zhou, Tianmin

2018-07-01

Piezoelectric-lead-zirconate-titanate(PZT)-based interface debonding defects detection for concrete filled steel tubulars (CFSTs) has been proposed and validated through experiments, and numerical study on its mechanism has been carried out recently by assuming that concrete material is homogenous. However, concrete is composed of coarse and fine aggregates, mortar and interface transition zones (ITZs) and even initial defects and is a typical nonhomogeneous material and its mesoscale structure might affect the wave propagation in the concrete core of CFST members. Therefore, it is significantly important to further investigate the influence of mesoscale structure of concrete on the stress wave propagation and the response of embedded PZT sensor for the interface debonding detection. In this study, multi-physical numerical simulation on the wave propagation and embedded PZT sensor response of rectangular CFST members with numerical concrete core considering the randomness in circular aggregate distribution, and coupled with surface-mounted PZT actuator and embedded PZT sensor is carried out. The effect of randomness in the circular aggregates distribution and the existence of ITZs are discussed. Both a local stress wave propagation behavior including transmission, reflection, and diffraction at the interface between concrete core and steel tube under a pulse signal excitation and a global wave field in the cross-section of the rectangular CFST models without and with interface debonding defects under sweep frequency excitation are simulated. The sensitivity of an evaluation index based on wavelet packet analysis on the embedded PZT sensor response on the variation of mesoscale parameters of concrete core without and with different interface debonding defects under sweep frequency voltage signal is investigated in details. The results show that the effect of the interface debondings on the embedded PZT measurement is dominant when compared to the meso-scale structures of concrete core. This study verified the feasibility of the PZT based debonding detection for rectangular CFST members even the meso-scale structure of concrete core is considered.

Effect of core geometry and size on concrete compressive strength.

DOT National Transportation Integrated Search

2016-07-01

To evaluate the in-place concrete strength for acceptance for a structural member with : potentially substandard strength, the compressive strength of cores may be required for : assessment. Depending on the geometry and size of the core specimen, th...

Wireless Concrete Strength Monitoring of Wind Turbine Foundations.

PubMed

Perry, Marcus; Fusiek, Grzegorz; Niewczas, Pawel; Rubert, Tim; McAlorum, Jack

2017-12-16

Wind turbine foundations are typically cast in place, leaving the concrete to mature under environmental conditions that vary in time and space. As a result, there is uncertainty around the concrete's initial performance, and this can encourage both costly over-design and inaccurate prognoses of structural health. Here, we demonstrate the field application of a dense, wireless thermocouple network to monitor the strength development of an onshore, reinforced-concrete wind turbine foundation. Up-to-date methods in fly ash concrete strength and maturity modelling are used to estimate the distribution and evolution of foundation strength over 29 days of curing. Strength estimates are verified by core samples, extracted from the foundation base. In addition, an artificial neural network, trained using temperature data, is exploited to demonstrate that distributed concrete strengths can be estimated for foundations using only sparse thermocouple data. Our techniques provide a practical alternative to computational models, and could assist site operators in making more informed decisions about foundation design, construction, operation and maintenance.

Quantitative analysis of concrete using portable x-ray fluorescence: Method development and validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Washington, Aaron L.; Narrows, William; Christian, Jonathan H.

During Decommissioning and Demolition (D&D) activities at SRS, it is important that the building be screened for radionuclides and heavy metals to ensure that the proper safety and disposal metrics are in place. A major source of contamination at DOE facilities is the accumulation of mercury contamination, from nuclear material processing and Liquid Waste System (LWS). This buildup of mercury could possibly cause harm to any demolition crew or the environment should this material be released. The current standard method is to take core samples in various places in the facility and use X-ray fluorescence (XRF) to detect the contamination.more » This standard method comes with a high financial value due to the security levels of these sample facilities with unknown contamination levels. Here in we propose the use of portable XRF units to detect for this contamination on-site. To validate this method, the instrument has to be calibrated to detect the heavy metal contamination, be both precise with the known elemental concentrations and consistent with its actual results of a sample concrete and pristine contaminant, and be able to detect changes in the sample concrete’s composition. After receiving the various concrete samples with their compositions found by a XRF wave-dispersive method, the calibration factor’s linear regressions were adjusted to give the baseline concentration of the concrete with no contamination. Samples of both concrete and concrete/flyash were evaluated; their standard deviations revealed that the measurements were consistent with the known composition. Finally, the samples were contaminated with different concentrations of sodium tungsten dihydrate, allowed to air dry, and measured. When the contaminated samples were analyzed, the heavy metal contamination was seen within the spectrum of the instrument, but there was not a trend of quantification based on the concentration of the solution.« less

Investigation and Rehabilitation to Extend Service Life of DSS-13 Antenna Concrete Foundation

NASA Technical Reports Server (NTRS)

Riewe, A. A., Jr.

1984-01-01

An investigation to establish the cause and, devise a repair technique to maintain the serviceability of the DSS-13 26 meter antenna is described. Core samples are obtained from the concrete and various laboratory tests conducted. In-place nondestructive type tests are also performed. The tests established that the concrete is deteriorating because of alkali aggregate reactivity. This is a phenomenon wherein certain siliceous constituents present in some aggregates react with alkalies in the portland cement to produce a silica gel which, in turn, imbibes water, swells, and cracks the concrete. The scheme consists of a supplemental steel frame friction pile anchored grade beam encircling the existing foundation. This system provides adequate bracing against base shear and overturning due to seismic loading. Larger cracks are sealed using a pressure injected two-component epoxy.

Posttest analysis of a laboratory-cast monolith of salt-saturated concrete. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wakeley, L.D.; Poole, T.S.

A salt-saturated concrete was formulated for laboratory testing of cementitious mixtures with potential for use in disposal of radioactive wastes in a geologic repository in halite rock. Cores were taken from a laboratory-cast concrete monolith on completion of tests of permeability, strain, and stress. The cores were analyzed for physical and chemical evidence of brine migration through the concrete, and other features with potential impact on installation of crete plugs at the Waste Isolation Pilot Plant (WIPP) in New Mexico. The posttest analyses of the cores provided evidence of brine movement along the interface between concrete and pipe, and littlemore » indication of permeability through the monolith itself. There may also have been diffusion of chloride into the monolith without actual brine flow.« less

Evaluation of subsurface damage in concrete deck joints using impact echo method

DOE PAGES

Rickard, Larry; Choi, Wonchang

2016-01-01

Many factors can affect the overall performance and longevity of highway bridges, including the integrity of their deck joints. This study focuses on the evaluation of subsurface damage in deteriorated concrete deck joints, which includes the delamination and corrosion of the reinforcement. Impact echo and surface wave technology, mainly a portable seismic property analyzer (PSPA), were employed to evaluate the structural deficiency of concrete joints. Laboratory tests of core samples were conducted to verify the nondestructive test results. As a result, the primary advantage of the PSPA as a bridge assessment tool lies in its ability to assess the concrete’smore » modulus and to detect subsurface defects at a particular point simultaneously.« less

Wireless Concrete Strength Monitoring of Wind Turbine Foundations

PubMed Central

Niewczas, Pawel; Rubert, Tim

2017-01-01

Wind turbine foundations are typically cast in place, leaving the concrete to mature under environmental conditions that vary in time and space. As a result, there is uncertainty around the concrete’s initial performance, and this can encourage both costly over-design and inaccurate prognoses of structural health. Here, we demonstrate the field application of a dense, wireless thermocouple network to monitor the strength development of an onshore, reinforced-concrete wind turbine foundation. Up-to-date methods in fly ash concrete strength and maturity modelling are used to estimate the distribution and evolution of foundation strength over 29 days of curing. Strength estimates are verified by core samples, extracted from the foundation base. In addition, an artificial neural network, trained using temperature data, is exploited to demonstrate that distributed concrete strengths can be estimated for foundations using only sparse thermocouple data. Our techniques provide a practical alternative to computational models, and could assist site operators in making more informed decisions about foundation design, construction, operation and maintenance. PMID:29258176

Application of Nonlinear Elastic Resonance Spectroscopy For Damage Detection In Concrete: An Interesting Story

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byers, Loren W.; Ten Cate, James A.; Johnson, Paul A.

2012-06-28

Nonlinear resonance ultrasound spectroscopy experiments conducted on concrete cores, one chemically and mechanically damaged by alkali-silica reactivity, and one undamaged, show that this material displays highly nonlinear wave behavior, similar to many other damaged materials. They find that the damaged sample responds more nonlinearly, manifested by a larger resonant peak and modulus shift as a function of strain amplitude. The nonlinear response indicates that there is a hysteretic influence in the stress-strain equation of state. Further, as in some other materials, slow dynamics are present. The nonlinear response they observe in concrete is an extremely sensitive indicator of damage. Ultimately,more » nonlinear wave methods applied to concrete may be used to guide mixing, curing, or other production techniques, in order to develop materials with particular desired qualities such as enhanced strength or chemical resistance, and to be used for damage inspection.« less

OECD 2-D Core Concrete Interaction (CCI) tests : CCI-2 test plan, Rev. 0 January 31, 2004.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmer, M. T.; Kilsdonk, D. J.; Lomperski, S.

The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1)more » resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of two long-term 2-D Core-Concrete Interaction (CCI) experiments designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. The first of these two tests, CCI-1, was conducted on December 19, 2003. This test investigated the interaction of a fully oxidized 400 kg PWR core melt, initially containing 8 wt % calcined siliceous concrete, with a specially designed two-dimensional siliceous concrete test section with an initial cross-sectional area of 50 cm x 50 cm. The second of these two planned tests, CCI-2, will be conducted with a nearly identical test facility and experiment boundary conditions, but with a Limestone/Common Sand (LCS) concrete test section to investigate the effect of concrete type on the two-dimensional core-concrete interaction and debris cooling behavior. The objective of this report is to provide the overall test plan for CCI-2 to enable pretest calculations to be carried out. The report begins by providing a summary description of the CCI-2 test apparatus, followed by a description of the planned test operating procedure. Overall specifications for CCI-2 are provided in Table 1-1.« less

EVALUATION OF THE DURABILITY OF THE STRUCTURAL CONCRETE OF REACTOR BUILDINGS AT SRS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, A.; Reigel, M.

2011-02-28

The Department of Energy (DOE) intends to close 100-150 facilities in the DOE complex using an in situ decommissioning (ISD) strategy that calls for grouting the below-grade interior volume of the structure and leaving the above-grade interior open or demolishing it and disposing of it in the slit trenches in E Area. These closures are expected to persist and remain stable for centuries, but there are neither facility-specific monitoring approaches nor studies on the rate of deterioration of the materials used in the original construction or on the ISD components added during closure (caps, sloped roofs, etc). This report willmore » focus on the evaluation of the actual aging/degradation of the materials of construction used in the ISD structures at Savannah River Site (SRS) above grade, specifically P & R reactor buildings. Concrete blocks (six 2 to 5 ton blocks) removed from the outer wall of the P Reactor Building were turned over to SRNL as the first source for concrete cores. Larger cores were received as a result of grouting activities in P and R reactor facilities. The cores were sectioned and evaluated using microscopy, x-ray diffraction (XRD), ion chromatography (IC) and thermal analysis. Scanning electron microscopy shows that the aggregate and cement phases present in the concrete are consistent with the mix design and no degradation mechanisms are evident at the aggregate-cement interfaces. Samples of the cores were digested and analyzed for chloride ingress as well as sulfate attack. The concentrations of chloride and sulfate ions did not exceed the limits of the mix design and there is no indication of any degradation due to these mechanisms. Thermal analysis on samples taken along the longitudinal axis of the cores show that there is a 1 inch carbonation layer (i.e., no portlandite) present in the interior wall of the reactor building and a negligible carbonation layer in the exterior wall. A mixed layer of carbonate and portlandite extends deeper into the interior (2-3 inches) and exterior (1-2 inches) walls. This is more extensive than measured in previous SRS structures. Once the completely carbonated layer reaches the rebar that is approximately 2-3 inches into the concrete wall, the steel is susceptible to corrosion. The growth rate of the carbonated layer was estimated from current observations and previous studies. Based on the estimated carbonation rate, the steel rebar should be protected from carbonation induced corrosion for at least another 100 years. If degradation of these structures is dominated by the carbonation mechanism, the length of time before water intrusion is expected into the process room of P-reactor is estimated to be between 425-675 years.« less

Petrographic Analysis of Portland Cement Concrete Cores from Pease Air National Guard Base, New Hampshire

DTIC Science & Technology

2016-11-01

by a white deposit. Carbon- ation staining was observed within the top 2 mm of the sample. The aggre- gates were angular to sub-round ( granitic to...was observed within the top 2 mm of the sample and down surface cracks. The aggre- gates were angular to sub-round ( granitic to gneissic in...Carbona- tion staining was observed within the top 2 mm of the sample. The aggregates were angular to sub-round ( granitic to gneissic in

Detecting alkali-silica reaction in thick concrete structures using linear array ultrasound

NASA Astrophysics Data System (ADS)

Bull Ezell, N. Dianne; Albright, Austin; Clayton, Dwight; Santos-Villalobos, Hector

2018-03-01

Commercial nuclear power plants (NPPs) depend heavily on concrete structures, making the long-term performance of these structures crucial for safe operation, especially with license period extensions to 60 years and possibly beyond. Alkali-silica reaction (ASR) is a reaction that occurs over time in concrete between alkaline cement paste and reactive, noncrystalline silica (aggregates). In the presence of water, an expansive gel is formed within the aggregates, which results in microcracks in aggregates and adjacent cement paste. ASR can potentially affect concrete properties and performance characteristics such as compressive strength, modulus of elasticity, flexural stiffness, shear strength, and tensile strength. Currently, no nondestructive evaluation methods have proven effective in identifying ASR before surface cracks form. ASR is identified visibly or by petrographic analysis. Although ASR definitely impacts concrete material properties, the performance of concrete structures exhibiting ASR depends on whether or not the concrete is unconfined or confined with reinforcing bars. Confinement by reinforcing bars restrainsthe expansion of ASR-affected concrete, similar to prestressing, thus improving the performance of a structure. Additionally, there is no direct correlation between the mechanical properties of concrete sample cores and the in-situ properties of the concrete. The University of Tennessee-Knoxville, Oak Ridge National Laboratory, and a consortium of universities have developed an accelerated ASR experiment. Three large concrete specimens, representative of NPP infrastructure, were constructed containing both embedded and surface instruments. This paper presents preliminary analysis of these specimens using a frequency-banded synthetic aperture focusing technique.

Us army corps of engineers - Engineering research and development center - Petrographic analysis of section 3 personnel tunnel concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, J. M.

The Concrete and Materials Branch (CMB) of the Geotechnical and Structures Laboratory was requested to perform an analysis on concrete cores collected from the north and south walls of the H-Canyon Section 3 Personnel Tunel, Savannah River Site, Aiken, South Carolina to determine the cause of the lower than expected compressive strength. This study examined five cores provided to the ERDC by the Department of Energy. The cores were logged in as CMB No. 170051-1 to 170051-5 and subjected to petrographic examination, air void analysis, chemical sprays, scanning electron microscopy, and x-ray diffraction.

Hydrophobization of Concrete Using Granular Nanostructured Aggregate

NASA Astrophysics Data System (ADS)

Ogurtsova, Y. N.; Strokova, V. V.; Labuzova, M. V.

2017-11-01

The possibility of giving hydrophobical properties to the fine-grained concrete matrix by using a granular nanostructured aggregate (GNA) with a hydrophobizing additive is investigated in this work. GNA is obtained by granulating the silica raw material with an alkaline component. The introduction of a hydrophobizing additive into the raw mix of GNA allows to encapsulate it reducing the negative effect on hydration processes, the intensity of migration of moisture and efflorescence in concrete and, consequently, improving the performance characteristics of fine-grained concrete products. The hydrophobizing ability of a solution of sodium polysilicates formed in the core of GNA during concrete heat and moisture treatment is proved. The analysis of IR spectra after the impregnation of cement stone samples with a solution of sodium polysilicates showed an increase in the degree of hydration and the formation of framework water aluminosilicates. Atmospheric processes modelling showed that the use of GNA on the basis of gaize with calcium stearate and on the basis of fly ash with GKZh-11 makes it possible to increase the resistance of fine-grained concrete to the atmospheric effect of the medium, namely, the outwashing of readily soluble compounds.

Concrete probe-strength study : final report.

DOT National Transportation Integrated Search

1969-12-01

The Windsor probe - test system was evaluated for determining compressive strength of concrete by comparing probe strengths against cylinder and core strengths from both laboratory and field-poured concrete. Advantages and disadvantages of this syste...

Bearing capacity and rigidity of short plastic-concrete-tubal vertical columns under transverse load

NASA Astrophysics Data System (ADS)

Dolzhenko, A. V.; Naumov, A. E.; Shevchenko, A. E.

2018-03-01

The results of mathematical modeling in determining strain-stress distribution parameters of a short plastic-concrete-tubal vertical column under horizontal load as those in vertical constructions are described. Quantitative parameters of strain-stress distribution during vertical and horizontal loads and horizontal stiffness were determined by finite element modeling. The internal stress in the concrete column core was analyzed according to equivalent stress in Mohr theory of failure. It was determined that the bearing capacity of a short plastic- concrete-tubal vertical column is 25% higher in resistibility and 15% higher in rigidness than those of the caseless concrete columns equal in size. Cracks formation in the core of a short plastic-concrete-tubal vertical column happens under significantly bigger horizontal loads with less amount of concrete spent than that in caseless concrete columns. The significant increase of bearing capacity and cracking resistance of a short plastic-concrete-tubal vertical column under vertical and horizontal loads allows recommending them as highly effective and highly reliable structural wall elements in civil engineering.

Analysis of laboratory compaction methods of roller compacted concrete

NASA Astrophysics Data System (ADS)

Trtík, Tomáš; Chylík, Roman; Bílý, Petr; Fládr, Josef

2017-09-01

Roller-Compacted Concrete (RCC) is an ordinary concrete poured and compacted with machines typically used for laying of asphalt road layers. One of the problems connected with this technology is preparation of representative samples in the laboratory. The aim of this work was to analyse two methods of preparation of RCC laboratory samples with bulk density as the comparative parameter. The first method used dynamic compaction by pneumatic hammer. The second method of compaction had a static character. The specimens were loaded by precisely defined force in laboratory loading machine to create the same conditions as during static rolling (in the Czech Republic, only static rolling is commonly used). Bulk densities obtained by the two compaction methods were compared with core drills extracted from real RCC structure. The results have shown that the samples produced by pneumatic hammer tend to overestimate the bulk density of the material. For both compaction methods, immediate bearing index test was performed to verify the quality of compaction. A fundamental difference between static and dynamic compaction was identified. In static compaction, initial resistance to penetration of the mandrel was higher, after exceeding certain limit the resistance was constant. This means that the samples were well compacted just on the surface. Specimens made by pneumatic hammer actively resisted throughout the test, the whole volume was uniformly compacted.

Use of ground penetrating radar for construction quality assurance of concrete pavement.

DOT National Transportation Integrated Search

2009-11-01

Extracting concrete cores is the most common method for measuring the thickness of concrete pavement for construction : quality control. Although this method provides a relatively accurate thickness measurement, it is destructive, labor : intensive, ...

Numerical analysis on seismic behavior of reinforced concrete beam to concrete filled steel tubular column connections with ring-beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Yi., E-mail: zhaoyi091218@163.com; Xu, Li. Hua.

This paper presents numerical study of the seismic behavior of reinforced concrete beam to concrete filled steel tube column connections with ring-beam. The material stress-strain relations, element type and boundary condition are selected, which are consistent with actual situation. Then the seismic behavior of this type of joint are researched by ABAQUS, and finite element analyses are conducted under cyclic loading. Its parameters are discussed including thickness of steel tubular column wall, sectional dimension of the ring-beam and strength of the core concrete. The results show that the ultimate capacity of the connections is improved with sectional dimension of themore » ring-beam increased. In the meanwhile, the influence on skeleton curve of the joints is slight of which included thickness of steel tubular column wall and strength of the core concrete.« less

Effect of water on the triaxial response under monotonic loading of asphalt concrete used in dams

NASA Astrophysics Data System (ADS)

Gaxiola Hernández, Alberto; Ossa López, Alexandra

2018-01-01

Embankment dams with asphalt concrete cores have been constructed on practically all continents with satisfactory results. Nowadays many advantages, such as the mechanical strength, are known that makes asphalt concrete a competitive alternative for the construction of the impervious elements of dams. However, the current available information does not describe the effect of prolonged contact between asphalt concrete and water on the structure of an embankment dam. In this research cylindrical asphalt concrete specimens with a void content similar to that used in impervious barriers of dams were fabricated and submerged in water for a prolonged period to simulate the conditions experienced by asphalt concrete placed inside an embankment dam as its core material. Subsequently, triaxial compression tests were conducted on the specimens. The results indicated that the asphalt concrete exhibited a reduction in strength because of the saturation process to which the material was subjected. However, no changes were observed in the mechanical response to prolonged contact with water for periods of up to 12 months.

Comparison of the performance of concrete-filled steel tubular and hollow steel diagrid buildings

NASA Astrophysics Data System (ADS)

Peter, Minu Ann; S, Sajith A.; Nagarajan, Praveen

2018-03-01

In the recent construction scenario, diagrid structures are becoming a popular high-rise building structural system. Diagrid structures consist of diagonals in the perimeter and an interior core. The corner and interior vertical columns are not required due to the structural efficiency of diagrid structural systems. Steel and concrete are commonly used material for diagrid. An alternate material for diagrid is concrete-filled steel tube (CFST). CFST incorporates the advantages of both steel and concrete. In CFST, the inward buckling of the steel tube is effectively prevented by the filled concrete. The compressive strength of concrete increases due to the tri-axial state of stress in concrete induced by the steel tube. The longitudinal as well as lateral reinforcement to the concrete core is also provided by the steel tube. This paper compares the performance of CFST and steel diagrid buildings using linear static analysis. For this purpose, a 12 storey and 36 storey building are analysed using finite element method and CFST diagrid building is found to perform better.

OECD MCCI 2-D Core Concrete Interaction (CCI) tests : CCI-2 test data report-thermalhydraulic results, Rev. 0 October 15, 2004.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmer, M. T.; Lomperski, S.; Kilsdonk, D. J.

The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1)more » resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of two long-term 2-D Core-Concrete Interaction (CCI) experiments designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. This data report provides thermal hydraulic test results from the CCI-2 experiment, which was conducted on August 24, 2004. Test specifications for CCI-2 are provided in Table 1-1. This experiment investigated the interaction of a fully oxidized 400 kg PWR core melt, initially containing 8 wt % Limestone/Common Sand (LCS) concrete, with a specially designed two-dimensional LCS concrete test section with an initial cross-sectional area of 50 cm x 50 cm. The report begins by providing a summary description of the CCI-2 test apparatus and operating procedures, followed by presentation of the thermal-hydraulic results. Detailed posttest debris examination results will be provided in a subsequent publication. Observations drawn within this report regarding the overall cavity erosion behavior may be subject to revision once the posttest examinations are completed, since these examinations will fully reveal the final cavity shape.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmer, M. T.

The overall objective of the current work is to carry out a scoping analysis to determine the impact of ATF on late phase accident progression; in particular, the molten core-concrete interaction portion of the sequence that occurs after the core debris fails the reactor vessel and relocates into containment. This additional study augments previous work by including kinetic effects that govern chemical reaction rates during core-concrete interaction. The specific ATF considered as part of this study is SiC-clad UO 2.

Post-construction monitoring of a Core-Loc™ breakwater using tripod-based LiDAR

USGS Publications Warehouse

Podoski, Jessica H.; Bawden, Gerald W.; Bond, Sandra; Smith, Thomas D.; Foster, James

2010-01-01

The goal of the technology application described herein is to determine whether breakwater monitoring data collected using Tripod (or Terrestrial) Light Detection and Ranging (T-LiDAR) can give insight into processes such as how Core-Loc™ concrete armour units nest following construction, and in turn how settlement affects armour layer stability, concrete cap performance, and armour unit breakage.  A further objective is that this information can then be incorporated into the design of future projects using concrete armour units.  The results of this application of T-LiDAR, including the challenges encountered and the conclusions drawn regarding initial concrete armour unit movement will be presented in this paper.

OECD MCCI project 2-D Core Concrete Interaction (CCI) tests : CCI-3 test data report-thermalhydraulic results. Rev. 0 October 15, 2005.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmer, M. T.; Lomperski, S.; Kilsdonk, D. J.

The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1)more » resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of a third long-term 2-D Core-Concrete Interaction (CCI) experiment designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. This data report provides thermal hydraulic test results from the CCI-3 experiment, which was conducted on September 22, 2005. Test specifications for CCI-3 are provided in Table 1-1. This experiment investigated the interaction of a fully oxidized 375 kg PWR core melt, initially containing 15 wt% siliceous concrete, with a specially designed two-dimensional siliceous concrete test section with an initial cross-sectional area of 50 cm x 50 cm. The sand and aggregate constituents for this particular siliceous concrete were provided by CEA as an in-kind contribution to the program. The report begins by providing a summary description of the CCI-3 test apparatus and operating procedures, followed by presentation of the thermal-hydraulic results. Detailed posttest debris examination results will be provided in a subsequent publication. Observations drawn within this report regarding the overall cavity erosion behavior may be subject to revision once the posttest examinations are completed, since these examinations will fully reveal the final cavity shape.« less

Key findings and remaining questions in the areas of core-concrete interaction and debris coolability

DOE PAGES

Farmer, M. T.; Gerardi, C.; Bremer, N.; ...

2016-10-31

The reactor accidents at Fukushima-Dai-ichi have rekindled interest in late phase severe accident behavior involving reactor pressure vessel breach and discharge of molten core melt into the containment. Two technical issues of interest in this area include core-concrete interaction and the extent to which the core debris may be quenched and rendered coolable by top flooding. The OECD-sponsored Melt Coolability and Concrete Interaction (MCCI) programs at Argonne National Laboratory included the conduct of large scale reactor material experiments and associated analysis with the objectives of resolving the ex-vessel debris coolability issue, and to address remaining uncertainties related to long-term two-dimensionalmore » molten core-concrete interactions under both wet and dry cavity conditions. These tests provided a broad database to support accident management planning, as well as the development and validation of models and codes that can be used to extrapolate the experiment results to plant conditions. This paper provides a high level overview of the key experiment results obtained during the program. Finally, a discussion is also provided that describes technical gaps that remain in this area, several of which have arisen based on the sequence of events and operator actions during Fukushima.« less

Key findings and remaining questions in the areas of core-concrete interaction and debris coolability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmer, M. T.; Gerardi, C.; Bremer, N.

The reactor accidents at Fukushima-Dai-ichi have rekindled interest in late phase severe accident behavior involving reactor pressure vessel breach and discharge of molten core melt into the containment. Two technical issues of interest in this area include core-concrete interaction and the extent to which the core debris may be quenched and rendered coolable by top flooding. The OECD-sponsored Melt Coolability and Concrete Interaction (MCCI) programs at Argonne National Laboratory included the conduct of large scale reactor material experiments and associated analysis with the objectives of resolving the ex-vessel debris coolability issue, and to address remaining uncertainties related to long-term two-dimensionalmore » molten core-concrete interactions under both wet and dry cavity conditions. These tests provided a broad database to support accident management planning, as well as the development and validation of models and codes that can be used to extrapolate the experiment results to plant conditions. This paper provides a high level overview of the key experiment results obtained during the program. Finally, a discussion is also provided that describes technical gaps that remain in this area, several of which have arisen based on the sequence of events and operator actions during Fukushima.« less

Exclusion Area Radiation Release during the MIT Reactor Design Basis Accident.

DTIC Science & Technology

1983-05-06

Concrete Wall 116 6.2 Concrete Albedo Dose 121 6.3 Steel Door Scattering Dose 124 7.1 Total Dose Results 133 A.1 Values of N /NO for Neutron -Capture...plate fuel elements arranged in x a compact hexagonal core. This core design maximizes the neutron flux in the DO2 reflector region where numerous...sec) V = Volume of the fuel (cm 3 f Ef = Macroscopic fission cross section (cm ) = Thermal neutron flux ( neutrons /cm2 - sec) = Core-averaged value Yi

Lessons to be learned from rehabilitation of concrete structures in bleach plants in pulp and paper mills

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nixon, R.

The deterioration of concrete structures due to chloride induced reinforcing steel corrosion such as in elevated concrete floor slabs, columns, and beams in bleach plants is a constant and growing problem within the pulp and paper industry. In general, the condition analysis methods used for assessing the extent of bleach plant concrete degradation include physical testing of drilled concrete core samples, chloride ion concentration testing, half-cell potential measurements, and physical sounding of concrete surfaces, i.e. chain drag for topside surfaces and hammer sounding of soffit surfaces. While this paper does not promote any vastly different evaluative methods, it does sharemore » learnings relative to interpreting the data provided by these typical test methods. It further offers some recommendations on how to improve the use of these typical evaluation techniques and offers some other test methods which should be considered as valuable additions for such evaluations. One of the most common methods which has been used in the past for large scale bleach plant concrete restoration has been the application of site dry mixed shotcrete for rebuilding the soffits of floor slabs and the faces of columns and beams. More often than not, bulk mixed dry shotcrete repairs have not been cost-effective because they prematurely failed due to excessive hydration related shrinkage cracking, lack of sufficient adhesion to the parent concrete substrate or other problems related to poor durability or construction practice.« less

A PVDF-Based Sensor for Internal Stress Monitoring of a Concrete-Filled Steel Tubular (CFST) Column Subject to Impact Loads.

PubMed

Du, Guofeng; Li, Zhao; Song, Gangbing

2018-05-23

Impact loads can have major adverse effects on the safety of civil engineering structures, such as concrete-filled steel tubular (CFST) columns. The study of mechanical behavior and stress analysis of CFST columns under impact loads is very important to ensure their safety against such loads. At present, the internal stress monitoring of the concrete cores CFST columns under impact loads is still a very challenging subject. In this paper, a PVDF (Polyvinylidene Fluoride) piezoelectric smart sensor was developed and successfully applied to the monitoring of the internal stress of the concrete core of a CFST column under impact loads. The smart sensor consists of a PVDF piezoelectric film sandwiched between two thin steel plates through epoxy. The protection not only prevents the PVDF film from impact damages but also ensures insulation and waterproofing. The smart sensors were embedded into the circular concrete-filled steel tube specimen during concrete pouring. The specimen was tested against impact loads, and testing data were collected. The time history of the stress obtained from the PVDF smart sensor revealed the evolution of core concrete internal stress under impact loads when compared with the impact force⁻time curve of the hammer. Nonlinear finite element simulations of the impact process were also carried out. The results of FEM simulations had good agreement with the test results. The results showed that the proposed PVDF piezoelectric smart sensors can effectively monitor the internal stress of concrete-filled steel tubular columns under impact loads.

Quantitative determination of sulfur content in concrete with laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Weritz, F.; Ryahi, S.; Schaurich, D.; Taffe, A.; Wilsch, G.

2005-08-01

Laser-induced breakdown spectroscopy has been employed for the investigation of the sulfur content of concrete. Sulfur compounds are a natural but minor component in building materials. The ingress of sulfates or sulfuric acid constitutes a major risk of chemical aggression for concrete. There is a need for a fast method, which can be used on-site and is able to investigate a wide range of different measuring points, so that damages can be characterized. For quantitative determination the sulfur spectral line at 921.3 nm is used. The optimum ambient atmosphere has been determined by comparison of measurements accomplished under air, argon and helium atmosphere. Reference samples have been produced and calibration curves have been determined, the results of LIBS measurements are compared with results from chemical analysis. Defining a limit for the intensity ratio of a calcium and a oxygen spectral line can reduce the influence of the heterogeneity of the material, so that only spectra with a high amount of cementitious material are evaluated. Depth profiles and spatial resolved sulfur distributions are presented measured on concrete cores originating from a highly sulfate contaminated clarifier.

Petrographic examination of concrete cores taken from the Ohio strategic highway research program (SHRP) specific pavement studies test road.

DOT National Transportation Integrated Search

2003-08-26

The 3-mile long SHRP pavement project is located on US 23, 25-miles north of Columbus, Ohio, : in Delaware County. Northbound lanes were constructed of portland cement concrete (PCC), : while southbound lanes were constructed of asphalt concrete (AC)...

Mineralogical and chemical assessment of concrete damaged by the oxidation of sulfide-bearing aggregates: Importance of thaumasite formation on reaction mechanisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodrigues, A.; Duchesne, J., E-mail: josee.duchesne@ggl.ulaval.ca; Fournier, B.

Damages in concrete containing sulfide-bearing aggregates were recently observed in the Trois-Rivieres area (Quebec, Canada), characterized by rapid deterioration within 3 to 5 years after construction. A petrographic examination of concrete core samples was carried out using a combination of tools including: stereomicroscopic evaluation, polarized light microscopy, scanning electron microscopy, X-ray diffraction and electron microprobe analysis. The aggregate used to produce concrete was an intrusive igneous rock with different metamorphism degrees and various proportions of sulfide minerals. In the rock, sulfide minerals were often surrounded by a thin layer of carbonate minerals (siderite). Secondary reaction products observed in the damagedmore » concrete include 'rust' mineral forms (e.g. ferric oxyhydroxides such as goethite, limonite (FeO (OH) nH{sub 2}O) and ferrihydrite), gypsum, ettringite and thaumasite. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste/aggregate and provokes the formation of sulfate minerals. Understanding both mechanisms, oxidation and internal sulfate attack, is important to be able to duplicate the damaging reaction in laboratory conditions, thus allowing the development of a performance test for evaluating the potential for deleterious expansion in concrete associated with sulfide-bearing aggregates.« less

Performance of Zinc Anodes for Cathodic Protection of Reinforced Concrete Bridges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Covino, Bernard S. Jr.; Cramer, Stephen D.; Bullard, Sophie J.

2002-03-01

Operation of thermal spray zinc (Zn) anodes for cathodic protection (CP) of reinforced concrete structures was investigated in laboratory and field studies conducted by the Albany Research Center (ARC) in collaboration with the Oregon Department of Transportation. The purposes of the research presented in this report were: evaluate the need for preheating concrete to improve the adhesion of the anode; estimate the service life of thermal spray Zn CP anodes; determine the optimum thickness for Zn CP anodes; characterize the anode-concrete interfacial chemistry; and correlate field and laboratory results. Laboratory studies involved accelerated electrochemical aging of thermal sprayed Zn anodesmore » on concrete slabs, some of which were periodically wetted while others were unwetted. Concrete used in the slabs contained either 1.2 or 3 kg NaCl /m3 (2 or 5 lbs NaCl /yd3) as part of the concrete mix design. The Zn anodes were applied to the slabs using the twin wire arc-spray technique. Half of the slabs were preheated to 120-160 C (250-320 F) to improve the initial Zn anode bond strength and the other half were not. Accelerated aging was done at a current density of 0.032 A/m2 (3 mA/ft2), 15 times that used on Oregon DOT Coastal bridges, i.e, . 0.0022 A/m2 (0.2 mA/ft2) Cores from the Cape Creek Bridge (OR), the Richmond San Rafael Bridge (CA), and the East Camino Underpass (CA) were used to study the anode-concrete interfacial chemistry, to relate the chemistry to electrochemical age at the time of sampling, and to compare the chemistry of the field anodes to the chemistry of anodes from the laboratory studies. Cores from a CALTRANS study of a silane sealant used prior to the application of the Zn anodes and cores with galvanized rebar from the Longbird Bridge (Bermuda) were also studied. Aged laboratory and field anodes were characterized by measuring some or all of the following parameters: thickness, bond strength, anode-concrete interfacial chemistry, bulk chemistry, anode resistance, circuit resistance, electrochemical age, and air and water permeability. Models are presented for the operation of periodically-wetted and unwetted thermal spray Zn anodes from the initial energizing of the anode to the end of its service life. The models were developed in terms of bond strength, circuit resistance, anode-concrete interfacial chemistry, electrochemical age, and anode condition. The most significant results of the research are: (1) preheating concrete surfaces prior to coating with Zn is unnecessary; (2) anodes generally fail due to loss of bond strength rather than Zn consumption; (3) Unwetted anodes fail more quickly than periodically-wetted anodes; (4) 0.47-0.60 mm (12-15 mil) anode thickness is adequate for most Oregon DOT coastal impressed current CP (ICCP) installations; (5) based on bond strength, thermal spray Zn ICCP anode service life is approximately 27 years at 0.0022 A/m2 (0.2 mA/ft2); (6) anode reaction products alter the anode-concrete interface by rejecting Ca from the cement paste, by replacing it with Zn, and by the accumulation of a Zn mineral layer that includes chloride and sulfur compounds; (7) CP system circuit resistance provides an effective means for monitoring the condition of Zn ICCP anodes as they age.« less

The foundation mass concrete construction technology of Hongyun Building B tower raft

NASA Astrophysics Data System (ADS)

Liu, Yu; Yin, Suhua; Wu, Yanli; Zhao, Ying

2017-08-01

The foundation of Hongyun building B tower is made of raft board foundation which is 3300mm in the thickness and 2800mm beside side of the core tube. It is researched that the raft foundation mass concrete construction technology is expatiated from temperature and cracks of the raft foundation and the temperature control and monitoring of the concrete base slab construction and concrete curing.

Alkali-aggregate reaction under the influence of deicing salts in the Hokuriku district, Japan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katayama, Tetsuya; Tagami, Masahiko; Sarai, Yoshinori

2004-11-15

Concrete cores taken from highway bridges and culverts undergoing alkali-silica reaction (ASR) were investigated petrographically by means of core scanning, point counting, polarizing microscopy, scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), electron-probe microanalysis with energy-dispersive spectrometry, in conjunction with wet chemical analyses and expansion tests. Field damage was roughly proportional to the content of andesite in the gravel aggregates due to the presence of highly reactive cristobalite and tridymite. Electron-probe microanalyzer analysis of unhydrated cement phases in the concrete revealed that the cement used had contained at least 0.5% to 1.0% alkali (Na{sub 2}Oeq) and that both the aggregatesmore » and the deicing salts had supplied part of the water-soluble alkali to concrete toward the threshold of producing ASR (Na{sub 2}O{sub eq} 3.0 kg/m{sup 3}). An accelerated concrete core expansion test (1 M NaOH, 80 deg. C) of the damaged structures mostly gave core expansions of >0.10% at 21 days (or >0.05% at 14 days), nearly comparable to those of a slow expansion test with saturated NaCl solution (50 deg. C, 91 days) which produced Cl-containing ASR gel.« less

National Program for Inspection of Non-Federal Dams. Shoe Pond Dam (MA 00183) Danvers River Basin, Beverly, Massachusetts. Phase I Inspection Report.

DTIC Science & Technology

1979-09-01

2%𔃾 foot long earth embankment with a concrete core wall. The dam is in fair condition. The dam has been classified in the "small" size and in the...The dam at Shoe Pond is a 17 foot high, 250 foot long earth embankment with a concrete core wall. The dam, which was originally constructed in 190I...elevation (EL) 20.5. Discharge flows down a concrete -lined chute and into a lower pond. The difference in elevation between the ""’"_".-..o upper and

OECD MMCI 2-D Core Concrete Interaction (CCI) tests : CCCI-1 test data report-thermalhydraulic results. Rev 0 January 31, 2004.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmer, M. T.; Lomperski, S.; Aeschlimann, R. W.

The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1)more » resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten coreconcrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of two long-term 2-D Core-Concrete Interaction (CCI) experiments designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. This data report provides thermal hydraulic test results from the CCI-1 experiment, which was conducted on December 19, 2003. Test specifications for CCI-1 are provided in Table 1-1. This experiment investigated the interaction of a fully oxidized 400 kg PWR core melt, initially containing 8 wt % calcined siliceous concrete, with a specially designed two-dimensional siliceous concrete test section with an initial cross-sectional area of 50 cm x 50 cm. The report begins by providing a summary description of the CCI-1 test apparatus and operating procedures, followed by presentation of the thermal-hydraulic results. The posttest debris examination results will be provided in a subsequent publication. Observations drawn within this report regarding the overall cavity erosion behavior may be subject to revision once the posttest examinations are completed, since these examinations will fully reveal the final cavity shape.« less

Asphalt concrete properties and performance in Alaska : final report

DOT National Transportation Integrated Search

1981-07-01

This report examines asphalt pavement properties of 117 older highway sections within the State of Alaska. Principal research objectives included: 1) documentation of commonly measured physical properties of the asphalt concrete cores and extracted a...

Cyclic performance of concrete-filled steel batten built-up columns

NASA Astrophysics Data System (ADS)

Razzaghi, M. S.; Khalkhaliha, M.; Aziminejad, A.

2016-03-01

Steel built-up batten columns are common types of columns in Iran and some other parts of the world. They are economic and have acceptable performance due to gravity loads. Although several researches have been conducted on the behavior of the batten columns under axial loads, there are few available articles about their seismic performance. Experience of the past earthquakes, particularly the 2003 Bam earthquake in Iran, revealed that these structural members are seismically vulnerable. Thus, investigation on seismic performance of steel batten columns due to seismic loads and providing a method for retrofitting them are important task in seismic-prone areas. This study aims to investigate the behavior of concrete-filled batten columns due to combined axial and lateral loads. To this end, nonlinear static analyses were performed using ANSYS software. Herein, the behaviors of the steel batten columns with and without concrete core were compared. The results of this study showed that concrete-filled steel batten columns, particularly those filled with high-strength concrete, may cause significant increases in energy absorption and capacity of the columns. Furthermore, concrete core may improve post-buckling behavior of steel batten columns.

Effect of verification cores on tip capacity of drilled shafts.

DOT National Transportation Integrated Search

2009-02-01

This research addressed two key issues: : 1) Will verification cores holes fill during concrete backfilling? If so, what are the mechanical properties of the : filling material? In dry conditions, verification core holes always completely fill with c...

Dataset of producing and curing concrete using domestic treated wastewater

PubMed Central

Asadollahfardi, Gholamreza; Delnavaz, Mohammad; Rashnoiee, Vahid; Fazeli, Alireza; Gonabadi, Navid

2015-01-01

We tested the setting time of cement, slump and compressive and tensile strength of 54 triplicate cubic samples and 9 cylindrical samples of concrete with and without a Super plasticizer admixture. We produced concrete samples made with drinking water and treated domestic wastewater containing 300, 400 kg/m3 of cement before chlorination and then cured concrete samples made with drinking water and treated wastewater. Second, concrete samples made with 350 kg/m3 of cement with a Superplasticizer admixture made with drinking water and treated wastewater and then cured with treated wastewater. The compressive strength of all the concrete samples made with treated wastewater had a high coefficient of determination with the control concrete samples. A 28-day tensile strength of all the samples was 96–100% of the tensile strength of the control samples and the setting time was reduced by 30 min which was consistent with a ASTMC191 standard. All samples produced and cured with treated waste water did not have a significant effect on water absorption, slump and surface electrical resistivity tests. However, compressive strength at 21 days of concrete samples using 300 kg/m3 of cement in rapid freezing and thawing conditions was about 11% lower than concrete samples made with drinking water. PMID:26862577

Dataset of producing and curing concrete using domestic treated wastewater.

PubMed

Asadollahfardi, Gholamreza; Delnavaz, Mohammad; Rashnoiee, Vahid; Fazeli, Alireza; Gonabadi, Navid

2016-03-01

We tested the setting time of cement, slump and compressive and tensile strength of 54 triplicate cubic samples and 9 cylindrical samples of concrete with and without a Super plasticizer admixture. We produced concrete samples made with drinking water and treated domestic wastewater containing 300, 400 kg/m(3) of cement before chlorination and then cured concrete samples made with drinking water and treated wastewater. Second, concrete samples made with 350 kg/m(3) of cement with a Superplasticizer admixture made with drinking water and treated wastewater and then cured with treated wastewater. The compressive strength of all the concrete samples made with treated wastewater had a high coefficient of determination with the control concrete samples. A 28-day tensile strength of all the samples was 96-100% of the tensile strength of the control samples and the setting time was reduced by 30 min which was consistent with a ASTMC191 standard. All samples produced and cured with treated waste water did not have a significant effect on water absorption, slump and surface electrical resistivity tests. However, compressive strength at 21 days of concrete samples using 300 kg/m(3) of cement in rapid freezing and thawing conditions was about 11% lower than concrete samples made with drinking water.

Non-traditional shape GFRP rebars for concrete reinforcement

NASA Astrophysics Data System (ADS)

Claure, Guillermo G.

The use of glass-fiber-reinforced-polymer (GFRP) composites as internal reinforcement (rebars) for concrete structures has proven to be an alternative to traditional steel reinforcement due to significant advantages such as magnetic transparency and, most importantly, corrosion resistance equating to durability and structural life extension. In recent years, the number of projects specifying GFRP reinforcement has increased dramatically leading the construction industry towards more sustainable practices. Typically, GFRP rebars are similar to their steel counterparts having external deformations or surface enhancements designed to develop bond to concrete, as well as having solid circular cross-sections; but lately, the worldwide composites industry has taken advantage of the pultrusion process developing GFRP rebars with non-traditional cross-sectional shapes destined to optimize their mechanical, physical, and environmental attributes. Recently, circular GFRP rebars with a hollow-core have also become available. They offer advantages such as a larger surface area for improved bond, and the use of the effective cross-sectional area that is engaged to carry load since fibers at the center of a solid cross-section are generally not fully engaged. For a complete understanding of GFRP rebar physical properties, a study on material characterization regarding a quantitative cross-sectional area analysis of different GFRP rebars was undertaken with a sample population of 190 GFRP specimens with rebar denomination ranging from #2 to #6 and with different cross-sectional shapes and surface deformations manufactured by five pultruders from around the world. The water displacement method was applied as a feasible and reliable way to conduct the investigation. In addition to developing a repeatable protocol for measuring cross-sectional area, the objectives of establishing critical statistical information related to the test methodology and recommending improvements to existing provisions and standards allowing for a consistent universal norm for all GFRP rebars were reached. This dissertation also presents an evaluation of the structural behavior of reinforced concrete (RC) beams and slabs using the new type of GFRP rebar consisting of a non-traditional hollow-core shape compared to "traditional" solid round rebars with equivalent cross-sectional areas within the framework of two studies, respectively. To validate the design assumptions following ACI 440.1R design guidelines, two conditions were investigated: under-reinforced (failure controlled by rupture of GFRP rebar); and, over-reinforced (failure controlled by crushing of concrete). For comparison, a cyclic three-point bending load test matrix was developed: for beams, 3 under-reinforced and 3 over-reinforced with hollow-core and solid GFRP rebars, respectively, making a total of 12 RC specimens; for slabs, 3 under-reinforced and 3 over-reinforced with hollow-core and 2 types of solid GFRP rebars, respectively, making a total of 18 RC slabs. The studies on GFRP RC beams and slabs concluded that the hollow-core GFRP rebars were as effective as their solid counterpart and ACI 440.1R design guidelines were applicable to predict their performance. It was shown that final design may be controlled by the permissible deflections as governing parameter for elements under service conditions. Also, a final study with a test matrix containing six extra specimens was generated for post-fire residual strength evaluation of fire-exposed GFRP RC slabs along with temperature gradient in the slabs and dynamic mechanical analysis (DMA) investigation on GFRP samples extracted from the fire-exposed slabs. In this study, the ability of GFRP RC slabs to retain structural integrity during a standards fire exposure as well as determining the residual structural capacity were investigated. The residual strength evaluation of the fire-exposed slabs showed a range of results varying between +/- 10%, of the virgin slabs. And, 19 mm (0.75 in.) cover with normal weight concrete was shown to be adequate to provide the necessary fire protection to the GFRP rebars preventing irreversible damage for two-hour fire rated GFRP RC slabs subjected to service loads; also, from the DMA and glass transition temperature of samples extracted from the GFRP rebars, it is inferred that the resin had undergone a post curing phase.

Combining Mineral Identification Techniques to Help Homeowners of Northeastern Connecticut Diagnose Pyrrhotite Laced Concrete Foundations

NASA Astrophysics Data System (ADS)

Gourley, J. R.; Geiss, C. E.

2017-12-01

Crumbling concrete linked to the mineral pyrrhotite is an emerging home owner crisis in northeastern Connecticut as new home foundations are failing within only several years. Potentially thousands of homes that have been built between the mid 1980's and 2016 are affected. Homes have been rendered worthless as basement concrete is crumbling and the cost of repair often exceeds the value of the home. In all of the failing concrete cases the presence of pyrrhotite from a local quarry is the common denominator. Testing for pyrrhotite, until now, has been costly and often invasive, with large core samples required. In working with a local advocacy group, The Connecticut Coalition Against Crumbling Basements (CCACB), we have developed a rapid analysis method that uses a combination of magnetic susceptibility and high resolution X-ray diffraction to identify both the mineral pyrrhotite and/or its expansive product mineral, ettringite. The goal of this method to give homeowners a reliable diagnosis that could help in mitigation decisions and/or the determination of the resale value of their homes. The partnership of Trinity College's Environmental Science Program with the CCACB has built a rewarding bridge between education and the community. Faculty, students and local advocates are collaborating to solve a problem that will help homeowners diagnose a potentially devastating non-natural "geo" hazard that can adversely affect home values where concrete is of an unknown provenance.

Evaluation of in-place concrete strength by core testing.

DOT National Transportation Integrated Search

2016-11-01

The overall objective of the work contained in this report is to develop an ALDOT procedure to evaluate core strength results obtained under various conditions. Since there are many factors that influence the apparent strength of cores, strength corr...

Forensic Investigation of AC and PCC Pavements with Extended Service Life : Volume 3 : Petrographic Examination of Blast Furnace Slag Aggregate Concrete Cores taken from PCC Pavements in Cuyahoga County , Ohio : Executive Summary Report

DOT National Transportation Integrated Search

2010-09-01

Air-cooled blast furnace slag has been used as a coarse : aggregate in portland cement-based pavement concretes : since at least the early 1900s. Many of these concretes : have performed satisfactorily. In recent times a number : of PCC slag aggre...

Evaluation of Girder Cores from the US 90 Bayou Ramos Bridge

DOT National Transportation Integrated Search

2012-05-01

This technical assistance report documents the investigation conducted by the Louisiana Transportation Research Center (LTRC) of the cored concrete from girders of the US 90 Bayou Ramos Bridge near Morgan City, LA. The unit weights of the cores were ...

Validation of the CoRE Questionnaire for a Medical Journal Peer Review.

PubMed

Doi, Suhail A R; Salzman-Scott, Sherry A; Onitilo, Adedayo A

2016-01-01

If a peer review instrument asks concrete questions (defined as items that can only generate disagreement if reviewers have different degrees of expertise), then questionnaires could become more meaningful in terms of resolving subjectivity thus leading to more reviewer agreement. A concrete item questionnaire with well-chosen questions can also help resolve disagreement when reviewers have the same level of expertise. We have recently created the core-item reviewer evaluation (CoRE) questionnaire for which decision-threshold score levels have been created, but which have not been validated. This prospective validation of these thresholds for the CoRE questionnaire demonstrated strong agreement between reviewer recommendations and their reported score levels when tested prospectively at Clinical Medicine and Research. We conclude that using the CoRE questionnaire will help reduce peer reviewer disagreement. More importantly, when reviewer expertise varies, editors can more easily detect this and decide which opinion reflects the greater expertise.

Thermodynamic evaluation of the solidification phase of molten core-concrete under estimated Fukushima Daiichi nuclear power plant accident conditions

NASA Astrophysics Data System (ADS)

Kitagaki, Toru; Yano, Kimihiko; Ogino, Hideki; Washiya, Tadahiro

2017-04-01

The solidification phases of molten core-concrete under the estimated molten core-concrete interaction (MCCI) conditions in the Fukushima Daiichi Nuclear Power Plant Unit 1 were predicted using the thermodynamic equilibrium calculation tool, FactSage 6.2, and the NUCLEA database in order to contribute toward the 1F decommissioning work and to understand the accident progression via the analytical results for the 1F MCCI products. We showed that most of the U and Zr in the molten core-concrete forms (U,Zr)O2 and (Zr,U)SiO4, and the formation of other phases with these elements is limited. However, the formation of (Zr,U)SiO4 requires a relatively long time because it involves a change in the crystal structure from fcc-(U,Zr)O2 to tet-(U,Zr)O2, followed by the formation of (Zr,U)SiO4 by reaction with SiO2. Therefore, the formation of (Zr,U)SiO4 is limited under quenching conditions. Other common phases are the oxide phases, CaAl2Si2O8, SiO2, and CaSiO3, and the metallic phases of the Fe-Si and Fe-Ni alloys. The solidification phenomenon of the crust under quenching conditions and that of the molten pool under thermodynamic equilibrium conditions in the 1F MCCI progression are discussed.

Behavior of hollow-core FRP-concrete-steel columns subjected to cyclic axial compression.

DOT National Transportation Integrated Search

2014-08-01

This report presents the results of an experimental study that was conducted to investigate the effects of key parameters on the compressive behavior of fiber reinforced polymer (FRP)-concrete-steel double-skin tubular columns (FSDT). Hybrid FSDT col...

Rigid and Flexible Pavement Aircraft Tie-Downs

DTIC Science & Technology

2010-05-01

Concrete Pier, Prior to PCC Placement Neenah anchors are equipped with two ½-in-diameter cored holes to allow insertion of a section of rebar through...facilitate this process, a Hilti drill was utilized to perform the concrete drilling process. The drill bit diameter exceeded the rebar diameter by...aggregate particles not become lodged against the rebar sections inside the dowel sleeves, impeding the flow of concrete and possibly creating air voids

Unidirectional Core-Shell Hybrids for Concrete Reinforcement - A preliminary Study

DTIC Science & Technology

1994-02-01

angle with respect to the rebar longitudinal axis. 14. SUBJECT TERMS 115. WNUMER OF PAGES FRP, rebar , concrete , fibers, carbon fibers, glass fibers...structures. The main cause of deterioration is concrete cracking and corrosion of steel reinforcement exposed to the marine environment and aggressive...agents such as deicing salts for bridges and pavements . To prevent this corrosion , galvanized and epoxy-coated steel reinforcing bars are currently being

76 FR 4097 - Erie Boulevard Hydropower, L.P.; Notice of Application Tendered for Filing With the Commission...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-24

... Oswegatchie River and consists of: (1) A 941-foot-long dam with a 192-foot-long, 69-foot-high concrete gravity... consists of: (1) A 568-foot-long dam and a 120-foot-long earthen embankment with a concrete core wall, and a 229- foot-long, 70-foot-high concrete gravity spillway with a crest elevation of 1,080.0 feet msl...

A case study : early cracking of unreinforced concrete pavement.

DOT National Transportation Integrated Search

1973-01-01

A study of cores from both the concrete and subbase of the cracked pavement, along with an examination of the in-place subgrade and subbase, suggested that there was no structural damage to the pavement except for the cracking. The situation was aggr...

Ex-Vessel Core Melt Modeling Comparison between MELTSPREAD-CORQUENCH and MELCOR 2.1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robb, Kevin R.; Farmer, Mitchell; Francis, Matthew W.

System-level code analyses by both United States and international researchers predict major core melting, bottom head failure, and corium-concrete interaction for Fukushima Daiichi Unit 1 (1F1). Although system codes such as MELCOR and MAAP are capable of capturing a wide range of accident phenomena, they currently do not contain detailed models for evaluating some ex-vessel core melt behavior. However, specialized codes containing more detailed modeling are available for melt spreading such as MELTSPREAD as well as long-term molten corium-concrete interaction (MCCI) and debris coolability such as CORQUENCH. In a preceding study, Enhanced Ex-Vessel Analysis for Fukushima Daiichi Unit 1: Meltmore » Spreading and Core-Concrete Interaction Analyses with MELTSPREAD and CORQUENCH, the MELTSPREAD-CORQUENCH codes predicted the 1F1 core melt readily cooled in contrast to predictions by MELCOR. The user community has taken notice and is in the process of updating their systems codes; specifically MAAP and MELCOR, to improve and reduce conservatism in their ex-vessel core melt models. This report investigates why the MELCOR v2.1 code, compared to the MELTSPREAD and CORQUENCH 3.03 codes, yield differing predictions of ex-vessel melt progression. To accomplish this, the differences in the treatment of the ex-vessel melt with respect to melt spreading and long-term coolability are examined. The differences in modeling approaches are summarized, and a comparison of example code predictions is provided.« less

Physical-durable performance of concrete incorporating high loss on ignition-fly ash

NASA Astrophysics Data System (ADS)

Huynh, Trong-Phuoc; Ngo, Si-Huy; Hwang, Chao-Lung

2018-04-01

This study investigates the feasibility of using raw fly ash with a high loss on ignition in concrete. The fly ash-free concrete samples were prepared with different water-to-binder (w/b) ratios of 0.35, 0.40, and 0.45, whereas the fly ash concrete samples were prepared with a constant w/b of 0.40 and with various fly ash contents (10%, 20%, and 30%) as a cement substitution. The physical properties and durability performance of the concretes were evaluated through fresh concrete properties, compressive strength, strength efficiency of cement, ultrasonic pulse velocity, and resistance to sulfate attack. Test results show that the w/b ratio affected the concrete properties significantly. The incorporation of fly ash increased the workability and reduced the unit weight of fresh concrete. In addition, the fly ash concrete samples containing up to 20% fly ash exhibited an improved strength at long-term ages. Further, all of the fly ash concrete samples showed a good durability performance with ultrasonic pulse velocity value of greater than 4100 m/s and a comparable sulfate resistance to the no-fly ash concrete.

Void parameters of 24 cores of concrete removed from a consolidation test study section of I-64.

DOT National Transportation Integrated Search

1972-01-01

During the construction of I-64 near Charlottesville, Virginia, the Ballenger Paving Company chose to set up a limited experiment to investigate various factors affecting the consolidation of concrete by vibration. The test design varied the speed of...

An evaluation of the performance of concretes containing fly ash and ground slag in bridge decks.

DOT National Transportation Integrated Search

2006-01-01

Cores from 36 bridge decks were evaluated to assess the condition and quality of the concrete by petrographic methods and direct and indirect measures of the transport properties. Transport properties were measured by a rate of absorption test (ASTM ...

Dynamic responses of concrete-filled steel tubular member under axial compression considering creep effect

NASA Astrophysics Data System (ADS)

Jiang, X. T.; Wang, Y. D.; Dai, C. H.; Ding, M.

2017-08-01

The finite element model of concrete-filled steel tubular member was established by the numerical analysis software considering material nonlinearity to analyze concrete creep effect on the dynamic responses of the member under axial compression and lateral impact. In the model, the constitutive model of core concrete is the plastic damage model, that of steel is the Von Mises yield criterion and kinematic hardening model, and the creep effect at different ages is equivalent to the change of concrete elastic modulus. Then the dynamic responses of concrete-filled steel tubular member considering creep effects was simulated, and the effects of creep on contact time, impact load, deflection, stress and strain were discussed. The fruits provide a scientific basis for the design of the impact resistance of concrete filled steel tubular members.

Measurement of the pore size distribution of limestone aggregates in concrete pavement cores : phase I.

DOT National Transportation Integrated Search

2012-04-01

Freeze-thaw damage is one of the common forms of distress for concrete pavements in Kansas. D-Cracking is a form of : freeze-thaw damage caused by aggregates with poor freeze-thaw durability. It is believed that pores in the aggregates below : 10 m...

DISTRIBUTION COEFICIENTS (KD) GENERATED FROM A CORE SAMPLE COLLECTED FROM THE SALTSTONE DISPOSAL FACILITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Almond, P.; Kaplan, D.

Core samples originating from Vault 4, Cell E of the Saltstone Disposal Facility (SDF) were collected in September of 2008 (Hansen and Crawford 2009, Smith 2008) and sent to SRNL to measure chemical and physical properties of the material including visual uniformity, mineralogy, microstructure, density, porosity, distribution coefficients (K{sub d}), and chemical composition. Some data from these experiments have been reported (Cozzi and Duncan 2010). In this study, leaching experiments were conducted with a single core sample under conditions that are representative of saltstone performance. In separate experiments, reducing and oxidizing environments were targeted to obtain solubility and Kd valuesmore » from the measurable species identified in the solid and aqueous leachate. This study was designed to provide insight into how readily species immobilized in saltstone will leach from the saltstone under oxidizing conditions simulating the edge of a saltstone monolith and under reducing conditions, targeting conditions within the saltstone monolith. Core samples were taken from saltstone poured in December of 2007 giving a cure time of nine months in the cell and a total of thirty months before leaching experiments began in June 2010. The saltstone from Vault 4, Cell E is comprised of blast furnace slag, class F fly ash, portland cement, and Deliquification, Dissolution, and Adjustment (DDA) Batch 2 salt solution. The salt solution was previously analyzed from a sample of Tank 50 salt solution and characterized in the 4QCY07 Waste Acceptance Criteria (WAC) report (Zeigler and Bibler 2009). Subsequent to Tank 50 analysis, additional solution was added to the tank solution from the Effluent Treatment Project as well as from inleakage from Tank 50 pump bearings (Cozzi and Duncan 2010). Core samples were taken from three locations and at three depths at each location using a two-inch diameter concrete coring bit (1-1, 1-2, 1-3; 2-1, 2-2, 2-3; 3-1, 3-2, 3-3) (Hansen and Crawford 2009). Leaching experiments were conducted with a section of core sample 3-2. All cores from location 3 were drilled without using water. Core sample 3-2 was drilled from approximately six inches to a depth of approximately 13 inches. Approximately six inches of the core was removed but it broke into two pieces during removal from the bit. At the time of drilling, core material appeared olive green in color (Smith 2008). The fact that the samples were cored as olive green and were received after storage with a gray outer layer is indicative that some oxidation had occurred prior to leaching studies.« less

Numerical Investigation on Detection of Prestress Losses in a Prestressed Concrete Slab by Modal Analysis

NASA Astrophysics Data System (ADS)

Kovalovs, A.; Rucevskis, S.; Akishin, P.; Kolupajevs, J.

2017-10-01

The paper presents numerical results of loss of prestress in the reinforced prestressed precast hollow core slabs by modal analysis. Loss of prestress is investigated by the 3D finite element method, using ANSYS software. In the numerical examples, variables initial stresses were introduced into seven-wire stress-relieved strands of the concrete slabs. The effects of span and material properties of concrete on the modal frequencies of the concrete structure under initial stress were studied. Modal parameters computed from the finite element models were compared. Applicability and effectiveness of the proposed method was investigated.

RADON GENERATION AND TRANSPORT IN AGED CONCRETE

EPA Science Inventory

The report gives results of a characterization of radon generation and transport in Florida concretes sampled from 12- to 45-year-old residential slabs. It also compares measurements from old concrete samples to previous measurements on newly poured Florida residential concretes....

Behavior of Concrete Cylinders Strengthened with a Basalt-FRP and Subjected to Mechanical Loads and Elevated Temperatures

NASA Astrophysics Data System (ADS)

Tulendinov, T.; Zesers, A.; Tamužs, V.

2017-09-01

Concrete samples were manufactured and strengthened with a basalt FRP (BFRP) using two kinds of winding patterns (spiral and tight). The efficiency of common and temperature-resistant epoxy binders were studied. Some of the samples were encased in an external concrete shell for an additional protection of the FRP reinforcement during heating. Both plain and polypropylene-microfiber-reinforced concretes were used for the external casing. Stress-strain relations of the samples before and after heating were obtained. The effects of high temperatures on the integrity of concrete samples with a BFRP reinforcement was investigated.

Construction at Turn Basin

NASA Image and Video Library

2017-06-14

Modifications are underway at the Launch Complex 39 turn basin wharf at NASA's Kennedy Space Center in Florida to prepare for the arrival of the agency's massive Space Launch System (SLS) core stage aboard the barge Pegasus. Precast concrete poles are being driven to a depth of about 70 feet into the bedrock below the water around the turn basin; later filled with concrete. The upgrades are necessary to accommodate the increased weight of the core stage along with ground support and transportation equipment aboard the modified barge Pegasus. The Ground Systems Development and Operations Program is overseeing the upgrades to the turn basin wharf.

Seismic assessment of WSDOT bridges with prestressed hollow core piles : part II.

DOT National Transportation Integrated Search

2009-12-01

This report investigates the seismic performance of a reinforced concrete : bridge with prestressed hollow core piles. Both nonlinear static and nonlinear dynamic : analyses were carried out. A three-dimensional spine model of the bridge was : ...

Influence of Steel Reinforcement on In-Situ Stress Evaluation in Concrete Structures by the Core-Drilling Method

NASA Astrophysics Data System (ADS)

McGinnis, M. J.; Pessiki, S.

2006-03-01

The core-drilling method is an emerging technique for evaluating in-situ stress in a concrete structure. A small hole is drilled into the structure, and the deformations in the vicinity of the hole are measured and related via elasticity theory to the stress. The method is similar to the ASTM hole-drilling strain-gauge method excepting that displacements rather than strains are the measured quantities. The technique may be considered nondestructive since the ability of the structure to perform its function is unaffected, and the hole is easily repaired. Displacement measurements in the current work are performed using 3D digital image correlation and industrial photogrammetry. The current paper addresses perturbations in the method caused by steel reinforcement within the concrete. The reinforcement is significantly stiffer than the surrounding concrete, altering the expected displacement field. A numerical investigation performed indicates an under-prediction of stress by as much as 18 percent in a heavily reinforced structure, although the effect is significantly smaller for more common amounts of reinforcement.

Influence of Steel Reinforcement on In-Situ Stress Evaluation in Concrete Structures by the Core-Drilling Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGinnis, M. J.; Pessiki, S.

2006-03-06

The core-drilling method is an emerging technique for evaluating in-situ stress in a concrete structure. A small hole is drilled into the structure, and the deformations in the vicinity of the hole are measured and related via elasticity theory to the stress. The method is similar to the ASTM hole-drilling strain-gauge method excepting that displacements rather than strains are the measured quantities. The technique may be considered nondestructive since the ability of the structure to perform its function is unaffected, and the hole is easily repaired. Displacement measurements in the current work are performed using 3D digital image correlation andmore » industrial photogrammetry. The current paper addresses perturbations in the method caused by steel reinforcement within the concrete. The reinforcement is significantly stiffer than the surrounding concrete, altering the expected displacement field. A numerical investigation performed indicates an under-prediction of stress by as much as 18 percent in a heavily reinforced structure, although the effect is significantly smaller for more common amounts of reinforcement.« less

Corrosion Propagation of Rebar Embedded in High Performance Concrete

NASA Astrophysics Data System (ADS)

Nazim, Manzurul

The FDOT has been using supplementary cementitious materials while constructing steel reinforced concrete marine bridge structures for over 3 decades. Previous findings indicated that such additions in concrete mix make the concrete more durable. To better understand corrosion propagation of rebar in high performance concrete: mature concrete samples that were made (2008/2009) with Portland cement, a binary mix, a ternary mix and recently prepared (April 2016 with 50% OPC + 50% slag and 80% OPC + 20% Fly ash) concrete samples were considered. None of these concretes had any admixed chloride to start with. An accelerated chloride transport process was used to drive chloride ions into the concrete so that chlorides reach and exceed the chloride threshold at the rebar surface and initiate corrosion. Electrochemical measurements were taken at regular intervals (during and after the electro-migration process) to observe the corrosion propagation in each sample.

Binary effect of fly ash and palm oil fuel ash on heat of hydration aerated concrete.

PubMed

Mehmannavaz, Taha; Ismail, Mohammad; Radin Sumadi, Salihuddin; Rafique Bhutta, Muhammad Aamer; Samadi, Mostafa; Sajjadi, Seyed Mahdi

2014-01-01

The binary effect of pulverized fuel ash (PFA) and palm oil fuel ash (POFA) on heat of hydration of aerated concrete was studied. Three aerated concrete mixes were prepared, namely, concrete containing 100% ordinary Portland cement (control sample or Type I), binary concrete made from 50% POFA (Type II), and ternary concrete containing 30% POFA and 20% PFA (Type III). It is found that the temperature increases due to heat of hydration through all the concrete specimens especially in the control sample. However, the total temperature rises caused by the heat of hydration through both of the new binary and ternary concrete were significantly lower than the control sample. The obtained results reveal that the replacement of Portland cement with binary and ternary materials is beneficial, particularly for mass concrete where thermal cracking due to extreme heat rise is of great concern.

Binary Effect of Fly Ash and Palm Oil Fuel Ash on Heat of Hydration Aerated Concrete

PubMed Central

Mehmannavaz, Taha; Ismail, Mohammad; Radin Sumadi, Salihuddin; Rafique Bhutta, Muhammad Aamer; Samadi, Mostafa

2014-01-01

The binary effect of pulverized fuel ash (PFA) and palm oil fuel ash (POFA) on heat of hydration of aerated concrete was studied. Three aerated concrete mixes were prepared, namely, concrete containing 100% ordinary Portland cement (control sample or Type I), binary concrete made from 50% POFA (Type II), and ternary concrete containing 30% POFA and 20% PFA (Type III). It is found that the temperature increases due to heat of hydration through all the concrete specimens especially in the control sample. However, the total temperature rises caused by the heat of hydration through both of the new binary and ternary concrete were significantly lower than the control sample. The obtained results reveal that the replacement of Portland cement with binary and ternary materials is beneficial, particularly for mass concrete where thermal cracking due to extreme heat rise is of great concern. PMID:24696646

An alternative potentiometric method for determining chloride content in concrete samples from reinforced-concrete bridges.

DOT National Transportation Integrated Search

2002-01-01

Analysis of chloride contents in ground concrete samples collected from reinforced concrete bridges and other structures exposed to deicing salts or seawater has become an important part of the inspection for such structures. Such an analysis provide...

EVALUATIONS ON ASR DAMAGE OF CONCRETE STRUCTURE AND ITS STRUCTURAL PERFORMANCE

NASA Astrophysics Data System (ADS)

Ueda, Naoshi; Nakamura, Hikaru; Kunieda, Minoru; Maeno, Hirofumi; Morishit, Noriaki; Asai, Hiroshi

In this paper, experiments and finite element analyses were conducted in order to evaluate effects of ASR on structural performance of RC and PC structures. From the experimental results, it was confirmed that the ASR expansion was affected by the restraint of reinforcement and the magnitude of prestress. The material properties of concrete damaged by ASR had anisotropic characteristics depending on the degree of ASR expansion. Therefore, when the structural performance of RC and PC structures were evaluated by using the material properties of core concrete, the direction and place where cylinder specimens were cored should be considered. On the other hand, by means of proposed analytical method, ASR expansion behaviors of RC and PC beams and changing of their structural performance were evaluated. As the results, it was confirmed that PC structure had much advantage comparing with RC structure regarding the structural performance under ASR damage because of restraint by prestress against the ASR.

Comparative testing of nondestructive examination techniques for concrete structures

NASA Astrophysics Data System (ADS)

Clayton, Dwight A.; Smith, Cyrus M.

2014-03-01

A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide foundation, support, shielding, and containment functions. Concrete has been used in the construction of nuclear power plants (NPPs) because of three primary properties, its inexpensiveness, its structural strength, and its ability to shield radiation. Examples of concrete structures important to the safety of LWR plants include containment building, spent fuel pool, and cooling towers. Comparative testing of the various NDE concrete measurement techniques requires concrete samples with known material properties, voids, internal microstructure flaws, and reinforcement locations. These samples can be artificially created under laboratory conditions where the various properties can be controlled. Other than NPPs, there are not many applications where critical concrete structures are as thick and reinforced. Therefore, there are not many industries other than the nuclear power plant or power plant industry that are interested in performing NDE on thick and reinforced concrete structures. This leads to the lack of readily available samples of thick and heavily reinforced concrete for performing NDE evaluations, research, and training. The industry that typically performs the most NDE on concrete structures is the bridge and roadway industry. While bridge and roadway structures are thinner and less reinforced, they have a good base of NDE research to support their field NDE programs to detect, identify, and repair concrete failures. This paper will summarize the initial comparative testing of two concrete samples with an emphasis on how these techniques could perform on NPP concrete structures.

Teaching Subtraction and Multiplication with Regrouping Using the Concrete-Representational-Abstract Sequence and Strategic Instruction Model

ERIC Educational Resources Information Center

Flores, Margaret M.; Hinton, Vanessa; Strozier, Shaunita D.

2014-01-01

Based on Common Core Standards (2010), mathematics interventions should emphasize conceptual understanding of numbers and operations as well as fluency. For students at risk for failure, the concrete-representational-abstract (CRA) sequence and the Strategic Instruction Model (SIM) have been shown effective in teaching computation with an emphasis…

Evaluation of cores from Jefferson Highway near Airline Highway : technical assistance report 16-03TA-C.

DOT National Transportation Integrated Search

2016-09-01

This technical assistance report documents the investigation conducted by the Louisiana Transportation Research Center (LTRC) of the cored concrete from Westbound Jefferson Highway near Airline Highway in Baton Rouge, LA. The petrographic analysis sh...

5. DETAIL OF SOUTHERN ARCH. PIER AND ABUTMENTS HAVE BEEN ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. DETAIL OF SOUTHERN ARCH. PIER AND ABUTMENTS HAVE BEEN REINFORCED WITH CONCRETE. INTRADOS HAS BEEN PARGED WITH MORTAR. - Core Creek County Bridge, Spanning Core Creek, approximately 1 mile South of State Route 332 (Newtown Bypass), Newtown, Bucks County, PA

Measurement of energy muons in EAS at energy region larger thean 10(17) eV

NASA Technical Reports Server (NTRS)

Matsubara, Y.; Hara, T.; Hayashida, N.; Kamata, K.; Nagano, M.; Ohoka, H.; Tanahasni, G.; Teshima, T.

1985-01-01

A measurement of low energy muons in extensive air showers (EAS) (threshold energies are 0.25, 0.5, 0.75 and 1.38 GeV) was carried out. The density under the concrete shielding equivalent to 0.25 GeV at core distance less than 500 m and 0.5 GeV less than 150 m suffers contamination of electromagnetic components. Therefore the thickness of concrete shielding for muon detectors for the giant air shower array is determined to be 0.5 GeV equivalence. Effects of photoproduced muons are found to be negligible in the examined ranges of shower sizes and core distances. The fluctuation of the muon density in 90 sq m is at most 25% between 200 m and 600 m from the core around 10 to the 17th power eV.

Stiffening of short small-size circular composite steel–concrete columns with shear connectors

PubMed Central

Younes, Sherif M.; Ramadan, Hazem M.; Mourad, Sherif A.

2015-01-01

An experimental program was conducted to investigate the effect of shear connectors’ distribution and method of load application on load–displacement relationship and behavior of thin-walled short concrete-filled steel tube (CFT) columns when subjected to axial load. The study focused on the compressive strength of the CFT columns and the efficiency of the shear stud in distribution of the load between the concrete core and steel tube. The study showed that the use of shear connectors enhanced slightly the axial capacity of CFT columns. It is also shown that shear connectors have a great effect on load distribution between the concrete and steel tubes. PMID:27222757

Discovery of novel per- and polyfluoroalkyl substances (PFASs) at a fire fighting training ground and preliminary investigation of their fate and mobility.

PubMed

Baduel, Christine; Mueller, Jochen F; Rotander, Anna; Corfield, John; Gomez-Ramos, Maria-José

2017-10-01

Aqueous film forming foams (AFFFs) have been released at fire training facilities for several decades resulting in the contamination of soil and groundwater by per- and polyfluoroalkyl substances (PFASs). AFFF compositions are proprietary and may contain a broad range of PFASs for which the chemical structures and degradation products are not known. In this study, high resolution quadrupole-time-of-flight tandem mass spectrometry (LC-QTOF-MS/MS) in combination with data processing using filtering strategies was applied to characterize and elucidate the PFASs present in concrete extracts collected at a fire training ground after the historical use of various AFFF formulations. Twelve different fluorochemical classes, representing more than 60 chemicals, were detected and identified in the concrete extracts. Novel PFASs homologues, unmonitored before in environmental samples such as chlorinated PFSAs, ketone PFSAs, dichlorinated PFSAs and perfluoroalkane sulphonamides (FASAs) were detected in soil samples collected in the vicinity of the fire training ground. Their detection in the soil cores (from 0 to 2 m) give an insight on the potential mobility of these newly identified PFASs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nondestructive corrosion detection in concrete through integrated heat induction and IR thermography

NASA Astrophysics Data System (ADS)

Kwon, Seung-Jun; Xue, Henry; Feng, Maria Q.; Baek, Seunghoon

2011-04-01

Steel corrosion in concrete is a main cause of deterioration and early failure of concrete structures. A novel integration of electromagnetic heat induction and infrared (IR) thermography is proposed for nondestructive detection of steel corrosion in concrete, by taking advantage of the difference in thermal characteristics of corroded and non-corroded steel. This paper focuses on experimental investigation of the concept. An inductive heater is developed to remotely heat the steel rebar from concrete surface, which is integrated with an IR camera. Bare rebar and concrete samples with different cover depths are prepared. Each concrete sample is embedded with a single steel rebar in the middle, resulting an identical cover depth from the front and the back surfaces, which enables heat induction from one surface and IR thermogrphay from the other simultaneously. The impressed current method is adopted to induce accelerated corrosion on the rebar. IR video images are recorded during both heating and cooling periods. The test results demonstrate a clear difference in thermal characteristics between corroded and non-corroded samples. The corroded samples show higher rates of heating and cooling as well as a higher peak IR intensity than those of the non-corroded samples. This study demonstrates a potential for nondestructive detection of rebar corrosion in concrete.

Earthquake Resilient Tall Reinforced Concrete Buildings at Near-Fault Sites Using Base Isolation and Rocking Core Walls

NASA Astrophysics Data System (ADS)

Calugaru, Vladimir

This dissertation pursues three main objectives: (1) to investigate the seismic response of tall reinforced concrete core wall buildings, designed following current building codes, subjected to pulse type near-fault ground motion, with special focus on the relation between the characteristics of the ground motion and the higher-modes of response; (2) to determine the characteristics of a base isolation system that results in nominally elastic response of the superstructure of a tall reinforced concrete core wall building at the maximum considered earthquake level of shaking; and (3) to demonstrate that the seismic performance, cost, and constructability of a base-isolated tall reinforced concrete core wall building can be significantly improved by incorporating a rocking core-wall in the design. First, this dissertation investigates the seismic response of tall cantilever wall buildings subjected to pulse type ground motion, with special focus on the relation between the characteristics of ground motion and the higher-modes of response. Buildings 10, 20, and 40 stories high were designed such that inelastic deformation was concentrated at a single flexural plastic hinge at their base. Using nonlinear response history analysis, the buildings were subjected to near-fault seismic ground motions as well as simple close-form pulses, which represented distinct pulses within the ground motions. Euler-Bernoulli beam models with lumped mass and lumped plasticity were used to model the buildings. Next, this dissertation investigates numerically the seismic response of six seismically base-isolated (BI) 20-story reinforced concrete buildings and compares their response to that of a fixed-base (FB) building with a similar structural system above ground. Located in Berkeley, California, 2 km from the Hayward fault, the buildings are designed with a core wall that provides most of the lateral force resistance above ground. For the BI buildings, the following are investigated: two isolation systems (both implemented below a three-story basement), isolation periods equal to 4, 5, and 6 s, and two levels of flexural strength of the wall. The first isolation system combines tension-resistant friction pendulum bearings and nonlinear fluid viscous dampers (NFVDs); the second combines low-friction tension-resistant cross-linear bearings, lead-rubber bearings, and NFVDs. Finally, this dissertation investigates the seismic response of four 20-story buildings hypothetically located in the San Francisco Bay Area, 0.5 km from the San Andreas fault. One of the four studied buildings is fixed-base (FB), two are base-isolated (BI), and one uses a combination of base isolation and a rocking core wall (BIRW). Above the ground level, a reinforced concrete core wall provides the majority of the lateral force resistance in all four buildings. The FB and BI buildings satisfy requirements of ASCE 7-10. The BI and BIRW buildings use the same isolation system, which combines tension-resistant friction pendulum bearings and nonlinear fluid viscous dampers. The rocking core-wall includes post-tensioning steel, buckling-restrained devices, and at its base is encased in a steel shell to maximize confinement of the concrete core. The total amount of longitudinal steel in the wall of the BIRW building is 0.71 to 0.87 times that used in the BI buildings. Response history two-dimensional analysis is performed, including the vertical components of excitation, for a set of ground motions scaled to the design earthquake and to the maximum considered earthquake (MCE). While the FB building at MCE level of shaking develops inelastic deformations and shear stresses in the wall that may correspond to irreparable damage, the BI and the BIRW buildings experience nominally elastic response of the wall, with floor accelerations and shear forces which are 0.36 to 0.55 times those experienced by the FB building. The response of the four buildings to two historical and two simulated near-fault ground motions is also studied, demonstrating that the BIRW building has the largest deformation capacity at the onset of structural damage. (Abstract shortened by UMI.).

Electromagnetic Metrology on Concrete and Corrosion.

PubMed

Kim, Sung; Surek, Jack; Baker-Jarvis, James

2011-01-01

To augment current methods for the evaluation of reinforcing bar (rebar) corrosion within concrete, we are exploring unique features in the dielectric and magnetic spectra of pure iron oxides and corrosion samples. Any signature needs to be both prominent and consistent in order to identify corrosion within concrete bridge deck or other structures. In order to measure the permittivity and propagation loss through concrete as a function of temperature and humidity, we cut and carefully fitted samples from residential concrete into three different waveguides. We also poured and cured a mortar sample within a waveguide that was later measured after curing 30 days. These measurements were performed from 45 MHz to 12 GHz. Our concrete measurements showed that the coarse granite aggregate that occupied about half the sample volume reduced the electromagnetic propagation loss in comparison to mortar. We also packed ground corrosion samples and commercially available iron-oxide powders into a transmission-line waveguide and found that magnetite and corrosion sample spectra are similar, with a feature between 0.5 GHz and 2 GHz that may prove useful for quantifying corrosion. We also performed reflection (S 11) measurements at various corrosion surfaces and in loose powders from 45 MHz to 50 GHz. These results are a first step towards quantifying rebar corrosion in concrete.

Electromagnetic Metrology on Concrete and Corrosion*

PubMed Central

Kim, Sung; Surek, Jack; Baker-Jarvis, James

2011-01-01

To augment current methods for the evaluation of reinforcing bar (rebar) corrosion within concrete, we are exploring unique features in the dielectric and magnetic spectra of pure iron oxides and corrosion samples. Any signature needs to be both prominent and consistent in order to identify corrosion within concrete bridge deck or other structures. In order to measure the permittivity and propagation loss through concrete as a function of temperature and humidity, we cut and carefully fitted samples from residential concrete into three different waveguides. We also poured and cured a mortar sample within a waveguide that was later measured after curing 30 days. These measurements were performed from 45 MHz to 12 GHz. Our concrete measurements showed that the coarse granite aggregate that occupied about half the sample volume reduced the electromagnetic propagation loss in comparison to mortar. We also packed ground corrosion samples and commercially available iron-oxide powders into a transmission-line waveguide and found that magnetite and corrosion sample spectra are similar, with a feature between 0.5 GHz and 2 GHz that may prove useful for quantifying corrosion. We also performed reflection (S11) measurements at various corrosion surfaces and in loose powders from 45 MHz to 50 GHz. These results are a first step towards quantifying rebar corrosion in concrete. PMID:26989590

Monitoring, Modeling, and Diagnosis of Alkali-Silica Reaction in Small Concrete Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agarwal, Vivek; Cai, Guowei; Gribok, Andrei V.

Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. This report describes alkali-silica reaction (ASR) degradation mechanisms and factors influencing the ASR. A fully coupled thermo-hydro-mechanical-chemical model developed by Saouma and Perotti by taking into consideration the effects of stress on the reaction kinetics and anisotropic volumetric expansion is presentedmore » in this report. This model is implemented in the GRIZZLY code based on the Multiphysics Object Oriented Simulation Environment. The implemented model in the GRIZZLY code is randomly used to initiate ASR in a 2D and 3D lattice to study the percolation aspects of concrete. The percolation aspects help determine the transport properties of the material and therefore the durability and service life of concrete. This report summarizes the effort to develop small-size concrete samples with embedded glass to mimic ASR. The concrete samples were treated in water and sodium hydroxide solution at elevated temperature to study how ingress of sodium ions and hydroxide ions at elevated temperature impacts concrete samples embedded with glass. Thermal camera was used to monitor the changes in the concrete sample and results are summarized.« less

Elasto-plastic bond mechanics of embedded fiber optic sensors in concrete under uniaxial tension with strain localization

NASA Astrophysics Data System (ADS)

Li, Qingbin; Li, Guang; Wang, Guanglun

2003-12-01

Brittleness of the glass core inside fiber optic sensors limits their practical usage, and therefore they are coated with low-modulus softer protective materials. Protective coatings absorb a portion of the strain, and hence part of the structural strain is sensed. The study reported here corrects for this error through development of a theoretical model to account for the loss of strain in the protective coating of optical fibers. The model considers the coating as an elasto-plastic material and formulates strain transfer coefficients for elastic, elasto-plastic and strain localization phases of coating deformations in strain localization in concrete. The theoretical findings were verified through laboratory experimentation. The experimental program involved fabrication of interferometric optical fiber sensors, embedding within mortar samples and tensile tests in a closed-loop servo-hydraulic testing machine. The elasto-plastic strain transfer coefficients were employed for correction of optical fiber sensor data and results were compared with those of conventional extensometers.

Preliminary engineering design of sodium-cooled CANDLE core

NASA Astrophysics Data System (ADS)

Takaki, Naoyuki; Namekawa, Azuma; Yoda, Tomoyuki; Mizutani, Akihiko; Sekimoto, Hiroshi

2012-06-01

The CANDLE burning process is characterized by the autonomous shifting of burning region with constant reactivity and constant spacial power distribution. Evaluations of such critical burning process by using widely used neutron diffusion and burning codes under some realistic engineering constraints are valuable to confirm the technical feasibility of the CANDLE concept and to put the idea into concrete core design. In the first part of this paper, it is discussed that whether the sustainable and stable CANDLE burning process can be reproduced even by using conventional core analysis tools such as SLAROM and CITATION-FBR. As a result, it is certainly possible to demonstrate it if the proper core configuration and initial fuel composition required as CANDLE core are applied to the analysis. In the latter part, an example of a concrete image of sodium cooled, metal fuel, 2000MWt rating CANDLE core has been presented by assuming an emerging inevitable technology of recladding. The core satisfies engineering design criteria including cladding temperature, pressure drop, linear heat rate, and cumulative damage fraction (CDF) of cladding, fast neutron fluence and sodium void reactivity which are defined in the Japanese FBR design project. It can be concluded that it is feasible to design CADLE core by using conventional codes while satisfying some realistic engineering design constraints assuming that recladding at certain time interval is technically feasible.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogel, R.E.

This document is in two parts: the first is the data package entitled ``Concrete Samples for Organic Samples`` and the second is entitled ``Concrete Samples for Organic Samples -- Addendum 1A`` which is the 222-S validation summary report.

Axial compression behavior and partial composite action of SC walls in safety-related nuclear facilities

NASA Astrophysics Data System (ADS)

Zhang, Kai

Steel-plate reinforced concrete (SC) composite walls typically consist of thick concrete walls with two exterior steel faceplates. The concrete core is sandwiched between the two steel faceplates, and the faceplates are attached to the concrete core using shear connectors, for example, ASTM A108 steel headed shear studs. The shear connectors and the concrete infill enhance the stability of the steel faceplates, and the faceplates serve as permanent formwork for concrete placement. SC composite walls were first introduced in the 1980's in Japan for nuclear power plant (NPP) structures. They are used in the new generation of nuclear power plants (GIII+) and being considered for small modular reactors (SMR) due to their structural efficiency, economy, safety, and construction speed. Steel faceplates can potentially undergo local buckling at certain locations of NPP structures where compressive forces are significant. The steel faceplates are usually thin (0.25 to 1.50 inches in Customary units, or 6.5 to 38 mm in SI units) to maintain economical and constructional efficiency, the geometric imperfections and locked-in stresses induced during construction make them more vulnerable to local buckling. Accidental thermal loading may also reduce the compressive strength and exacerbate the local buckling potential of SC composite walls. This dissertation presents the results from experimental and numerical investigations of the compressive behavior of SC composite walls at ambient and elevated temperatures. The results are used to establish a slenderness limit to prevent local buckling before yielding of the steel faceplates and to develop a design approach for calculating the compressive strength of SC composite walls with non-slender and slender steel faceplates at ambient and elevated temperatures. Composite action in SC walls is achieved by the embedment of shear connectors into the concrete core. The strength and stiffness of shear connectors govern the level of composite action. This level of partial composite action can influence the behavior and stiffness of SC composite walls. This dissertation presents numerical investigations of the level of partial composite action and its influence on the flexural stiffness of SC walls. The results are used to propose design criteria for steel headed shear studs, such as their size, spacing, and strength.

Respirable concrete dust--silicosis hazard in the construction industry.

PubMed

Linch, Kenneth D

2002-03-01

Concrete is an extremely important part of the infrastructure of modern life and must be replaced as it ages. Many of the methods of removing, repairing, or altering existing concrete structures have the potential for producing vast quantities of respirable dust. Since crystalline silica in the form of quartz is a major component of concrete, airborne respirable quartz dust may be produced during construction work involving the disturbance of concrete, thereby producing a silicosis hazard for exposed workers. Silicosis is a debilitating and sometimes fatal lung disease resulting from breathing microscopic particles of crystalline silica. Between 1992 and 1998, the National Institute for Occupational Safety and Health (NIOSH) made visits to construction projects where concrete was being mechanically disturbed in order to obtain data concerning respirable crystalline silica dust exposures. The construction activities studied included: abrasive blasting, concrete pavement sawing and drilling, and asphalt/concrete milling. Air samples of respirable dust were obtained using 10-mm nylon cyclone pre-separators, 37-mm polyvinyl chloride (PVC) filters, and constant-flow pumps calibrated at 1.7 L/min. In addition, high-volume respirable dust samples were obtained on 37-mm PVC filters using 1/2" metal cyclones (Sensidyne model 18) and constant-flow pumps calibrated at 9.0 L/min. Air sample analysis included total weight gain by gravimetric analysis according to NIOSH Analytical Method 600 and respirable crystalline silica (quartz and cristobalite) using x-ray diffraction, as per NIOSH Analytical Method 7500. For abrasive blasting of concrete structures, the respirable crystalline silica (quartz) concentration ranged up to 14.0 mg/m3 for a 96-minute sample resulting in an eight-hour time-weighted average (TWA) of 2.8 mg/m3. For drilling concrete highway pavement the respirable quartz concentrations ranged up to 4.4 mg/m3 for a 358-minute sample, resulting in an eight-hour TWA of 3.3 mg/m3. For concrete wall grinding during new building construction the respirable quartz measurements ranged up to 0.66 mg/m3 for a 191-minute sample, resulting in an eight-hour TWA of 0.26 mg/m3. The air sampling results for concrete sawing ranged up to 14.0 mg/m3 for a 350-minute sample resulting in an eight-hour TWA of 10.0 mg/m3. During the milling of asphalt from concrete highway pavement, the sampling indicated a respirable quartz concentration ranging up to 0.34 mg/m3 for a 504-minute sample, resulting in an eight-hour TWA of 0.36 mg/m3. The results of this work indicate the potential for respirable quartz concentrations involving disturbance of concrete to range up to 280 times the NIOSH Recommended Exposure Limit (REL) of 0.05 mg/m3 assuming exposure for an eight- to ten-hour workday. Considering the aging of the concrete infrastructure in the United States, these results pose a challenge to all who have an interest in preventing silica exposures and the associated disease silicosis.

Design of SC walls and slabs for impulsive loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varma, Amit H.

2015-11-11

Reinforced concrete (RC) structures have historically been the preferred choice for blast resistant structures because of their mass and the ductility provided by steel reinforcement. Steel-plate composite (SC) walls are a viable alternative to RC for protecting the infrastructure against explosive threats. SC structures consist of two steel faceplates with a plain concrete core between them. The steel faceplates are anchored to the concrete using stud anchors and connected to each other using tie bars. SC structures provide mass from the concrete infill and ductility from the continuous external steel faceplates. This dissertation presents findings and recommendations from experimental andmore » analytical investigations of the performance of SC walls subjected to far-field blast loads.« less

The analysis of mechanical properties of non autoclaved aerated concrete with the substitution of fly ash and bottom ash

NASA Astrophysics Data System (ADS)

Karolina, R.; Muhammad, F.

2018-02-01

Based on PP. No.85 of 1999 on the management of hazardous and toxic (B3), fly ash and bottom ash wastes are categorized into B3 waste because there are heavy metal oxide contents that can pollute the environment. One form of environmental rescue that can be applied is to utilize waste fly ash and bottom ash in the manufacture of concrete. In this research, fly ash and bottom ash waste are used as substitution of cement and fine aggregate to make lightweight concrete. The purpose of this research is to know the mechanical properties of non-autoclaved aerated lightweight concrete (NAAC) with FA and BA substitution to cement and fine aggregate which is expected to improve the quality of concrete. The NAAC lightweight concrete in this study is divided into 4 categories: normal NAAC lightweight concrete, NAAC lightweight NAAC substituted concrete with FA, NAAC lightweight concrete substituted with BA, and NAAC combined light weight from FA and BA with variations of 10%, 20% And 30%. The test specimen used in cylindrical shape, which was tested at the age of 28 days, amounted to 90 pieces and consisted of 10 variations. Each variation amounted to 9 samples. Based on the test results with FA and BA substitutions of 10%, 20%, and 30%, the highest compressive strength was achieved in samples with FA 30% of 12.687 MPa, maximum tensile strength achieved in samples with FA 30% of 1,540 MPa, The highest absorption was achieved in normal NAAC of 5.66%. Based on the weight of the contents of all samples, samples can be categorized in lightweight concrete, since the weight of the contents is less than 1900 kg / m3.

Benefits of aggregates surface modification in concrete production

NASA Astrophysics Data System (ADS)

Junak, J.; Sicakova, A.

2017-10-01

In our study, recycled concrete aggregates (RCA), which surfaces had been modified by geopolymer material based on coal fly ash, were used to produce the concrete samples. In these samples, fraction 4/8 mm was replaced by recycled concrete aggregate with a range of 100%. To modify the surface of RCA was “Solo” and “Triple stage” modification used. On these samples real density, total water absorption and compressive strength were examined after 28, 90, 180 and 365 days of hardening. The highest compressive strength 56.8 MPa, after 365 days hardening, reached sample which had improved RCA surface by “Triple stage mixing”.

Prediction of reinforced concrete strength by ultrasonic velocities

NASA Astrophysics Data System (ADS)

Sabbağ, Nevbahar; Uyanık, Osman

2017-06-01

This study was aimed to determine the strength of the reinforced concrete and to reveal the reinforcement effect on the concrete strength by Ultrasonic P and S wave velocities. Studies were conducted with prepared 9 different concrete designs of showing low, medium and high strength features. 4 kinds of cubic samples which unreinforced and including 10, 14 or 20 mm diameter reinforcement were prepared for these designs. Studies were carried out on total 324 samples including 9 samples for each design of these 4 kinds. The prepared samples of these designs were subjected to water curing. On some days of the 90-day period, P and S wave measurements were repeated to reveal the changes in seismic velocities of samples depending on whether reinforced or unreinforced of samples and diameter of reinforcement. Besides, comparisons were done by performing uniaxial compressive strength test with crushing of 3 samples on 7th, 28th and 90th days. As a result of studies and evaluations, it was seen that values of seismic velocities and uniaxial compressive strength increased depending on reinforcement and diameter of reinforcement in low strength concretes. However, while the seismic velocities were not markedly affected from reinforcement or reinforcement diameter in high strength concrete, uniaxial compressive strength values were negatively affected.

Preliminary study of neutron absorption by concrete with boron carbide addition

NASA Astrophysics Data System (ADS)

Abdullah, Yusof; Ariffin, Fatin Nabilah Tajul; Hamid, Roszilah; Yusof, Mohd Reusmaazran; Zali, Nurazila Mat; Ahmad, Megat Harun Al Rashid Megat; Yazid, Hafizal; Ahmad, Sahrim; Mohamed, Abdul Aziz

2014-02-01

Concrete has become a conventional material in construction of nuclear reactor due to its properties like safety and low cost. Boron carbide was added as additives in the concrete construction as it has a good neutron absorption property. The sample preparation for concrete was produced with different weight percent of boron carbide powder content. The neutron absorption rate of these samples was determined by using a fast neutron source of Americium-241/Be (Am-Be 241) and detection with a portable backscattering neutron detector. Concrete with 20 wt % of boron carbide shows the lowest count of neutron transmitted and this indicates the most neutrons have been absorbed by the concrete. Higher boron carbide content may affect the concrete strength and other properties.

Quantitative estimation of carbonation and chloride penetration in reinforced concrete by laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Eto, Shuzo; Matsuo, Toyofumi; Matsumura, Takuro; Fujii, Takashi; Tanaka, Masayoshi Y.

2014-11-01

The penetration profile of chlorine in a reinforced concrete (RC) specimen was determined by laser-induced breakdown spectroscopy (LIBS). The concrete core was prepared from RC beams with cracking damage induced by bending load and salt water spraying. LIBS was performed using a specimen that was obtained by splitting the concrete core, and the line scan of laser pulses gave the two-dimensional emission intensity profiles of 100 × 80 mm2 within one hour. The two-dimensional profile of the emission intensity suggests that the presence of the crack had less effect on the emission intensity when the measurement interval was larger than the crack width. The chlorine emission spectrum was measured without using the buffer gas, which is usually used for chlorine measurement, by collinear double-pulse LIBS. The apparent diffusion coefficient, which is one of the most important parameters for chloride penetration in concrete, was estimated using the depth profile of chlorine emission intensity and Fick's law. The carbonation depth was estimated on the basis of the relationship between carbon and calcium emission intensities. When the carbon emission intensity was statistically higher than the calcium emission intensity at the measurement point, we determined that the point was carbonated. The estimation results were consistent with the spraying test results using phenolphthalein solution. These results suggest that the quantitative estimation by LIBS of carbonation depth and chloride penetration can be performed simultaneously.

Nonlinear Ultrasonic Diagnosis and Prognosis of ASR Damage in Dry Cask Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qu, Jianmin; Bazant, Zdenek; Jacobs, Laurence

Alkali-silica reaction (ASR) is a deleterious chemical process that may occur in cement-based materials such as mortars and concretes, where the hydroxyl ions in the highly alkaline pore solution attack the siloxane groups in the siliceous minerals in the aggregates. The reaction produces a cross-linked alkali-silica gel. The ASR gel swells in the presence of water. Expansion of the gel results in cracking when the swelling-induced stress exceeds the fracture toughness of the concrete. As the ASR continues, cracks may grow and eventually coalesce, which results in reduced service life and a decrease safety of concrete structures. Since concrete ismore » widely used as a critical structural component in dry cask storage of used nuclear fuels, ASR damage poses a significant threat to the sustainability of long term dry cask storage systems. Therefore, techniques for effectively detecting, managing and mitigating ASR damage are needed. Currently, there are no nondestructive methods to accurately detect ASR damage in existing concrete structures. The only current way of accurately assessing ASR damage is to drill a core from an existing structure, and conduct microscopy on this drilled cylindrical core. Clearly, such a practice is not applicable to dry cask storage systems. To meet these needs, this research is aimed at developing (1) a suite of nonlinear ultrasonic quantitative nondestructive evaluation (QNDE) techniques to characterize ASR damage, and (2) a physics-based model for ASR damage evolution using the QNDE data. Outcomes of this research will provide a nondestructive diagnostic tool to evaluate the extent of the ASR damage, and a prognostic tool to estimate the future reliability and safety of the concrete structures in dry cask storage systems« less

Performance of fly ash based geopolymer incorporating palm kernel shell for lightweight concrete

NASA Astrophysics Data System (ADS)

Razak, Rafiza Abd; Abdullah, Mohd Mustafa Al Bakri; Yahya, Zarina; Jian, Ang Zhi; Nasri, Armia

2017-09-01

A concrete which cement is totally replaced by source material such as fly ash and activated by highly alkaline solutions is known as geopolymer concrete. Fly ash is the most common source material for geopolymer because it is a by-product material, so it can get easily from all around the world. An investigation has been carried out to select the most suitable ingredients of geopolymer concrete so that the geopolymer concrete can achieve the desire compressive strength. The samples were prepared to determine the suitable percentage of palm kernel shell used in geopolymer concrete and cured for 7 days in oven. After that, other samples were prepared by using the suitable percentage of palm kernel shell and cured for 3, 14, 21 and 28 days in oven. The control sample consisting of ordinary Portland cement and palm kernel shell and cured for 28 days were prepared too. The NaOH concentration of 12M, ratio Na2SiO3 to NaOH of 2.5, ratio fly ash to alkaline activator solution of 2.0 and ratio water to geopolymer of 0.35 were fixed throughout the research. The density obtained for the samples were 1.78 kg/m3, water absorption of 20.41% and the compressive strength of 14.20 MPa. The compressive strength of geopolymer concrete is still acceptable as lightweight concrete although the compressive strength is lower than OPC concrete. Therefore, the proposed method by using fly ash mixed with 10% of palm kernel shell can be used to design geopolymer concrete.

Rapid method to determine 89Sr/ 90Sr in large concrete samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.

Here, a new rapid method has been developed that provides high quality low-level measurements of 89,90Sr in concrete samples with an MDA (Minimum Detectable Activity) of <1 mBq g -1. The new method is fast, meets new decommissioning regulatory limits and is robust even if refractory particles are present. The method utilizes a rapid fusion to ensure total dissolution of samples and rapid preconcentration and separation of 89,90Sr from 5-10 g concrete samples. When, the 89Sr/ 90Sr ratio is high, Sr can be isolated from up to 5g concrete samples, total 89/90Sr measured, and then 90Sr determined via 90Y separatedmore » after a period of ingrowth. Another approach allows the immediate determination of 90Sr in 10 g concrete aliquots without waiting for 90Y ingrowth, in instances where the shorter lived 89Sr is unlikely to be encountered.« less

Rapid method to determine 89Sr/ 90Sr in large concrete samples

DOE PAGES

Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.; ...

2016-03-24

Here, a new rapid method has been developed that provides high quality low-level measurements of 89,90Sr in concrete samples with an MDA (Minimum Detectable Activity) of <1 mBq g -1. The new method is fast, meets new decommissioning regulatory limits and is robust even if refractory particles are present. The method utilizes a rapid fusion to ensure total dissolution of samples and rapid preconcentration and separation of 89,90Sr from 5-10 g concrete samples. When, the 89Sr/ 90Sr ratio is high, Sr can be isolated from up to 5g concrete samples, total 89/90Sr measured, and then 90Sr determined via 90Y separatedmore » after a period of ingrowth. Another approach allows the immediate determination of 90Sr in 10 g concrete aliquots without waiting for 90Y ingrowth, in instances where the shorter lived 89Sr is unlikely to be encountered.« less

The effect of zeolite and diatomite on the corrosion of reinforcement steel in 1 M HCl solution

NASA Astrophysics Data System (ADS)

Gerengi, Husnu; Kurtay, Mine; Durgun, Hatice

The greatest disadvantage of reinforced concrete structures is the corrosion occurring in the reinforcement which, over time, causes a reduction in the reinforcement-concrete adherence and eventual sectional loss. The purpose of this study was to reveal the corrosion mechanism of ribbed reinforcement inside additive-free (reference), 20% zeolite-doped and 20% diatomite-doped concrete samples after exposure to 1 M HCl over 240 days. Electrochemical impedance spectroscopy (EIS) measurements were made every 10 days. Consequently, it was determined that the 20% zeolite-doped concrete samples had higher concrete and reinforcement resistance compared to the 20% diatomite-doped and the reference concrete, i.e. they exhibited less corrosion.

Preliminary study of neutron absorption by concrete with boron carbide addition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdullah, Yusof, E-mail: yusofabd@nuclearmalaysia.gov.my; Yusof, Mohd Reusmaazran; Zali, Nurazila Mat

2014-02-12

Concrete has become a conventional material in construction of nuclear reactor due to its properties like safety and low cost. Boron carbide was added as additives in the concrete construction as it has a good neutron absorption property. The sample preparation for concrete was produced with different weight percent of boron carbide powder content. The neutron absorption rate of these samples was determined by using a fast neutron source of Americium-241/Be (Am-Be 241) and detection with a portable backscattering neutron detector. Concrete with 20 wt % of boron carbide shows the lowest count of neutron transmitted and this indicates themore » most neutrons have been absorbed by the concrete. Higher boron carbide content may affect the concrete strength and other properties.« less

Mechanical Properties of Lightweight Concrete Using Recycled Cement-Sand Brick as Coarse Aggregates Replacement

NASA Astrophysics Data System (ADS)

Joohari, Ilya; Farhani Ishak, Nor; Amin, Norliyati Mohd

2018-03-01

This paper presents the result of replacing natural course aggregate with recycled cement-sand brick (CSB) towards the mechanical properties of concrete. Natural aggregates were used in this study as a control sample to compare with recycled coarse aggregates. This study was also carried to determine the optimum proportion of coarse aggregates replacement to produce lightweight concrete. Besides, this study was conducted to observe the crack and its behaviour development during the mechanical testing. Through this study, four types of concrete mixed were prepared, which were the control sample, 25%, 50% and 75% replacement of CSB. The test conducted to determine the effectiveness of recycled CSB as coarse aggregates replacement in this study were slump test, density measurement, compression test, and flexural test and. The strength of concrete was tested at 7 days and 28 days of curing. From the results obtained, the optimum proportion which produced the highest strength is 25% replacement of recycled CSB. The compressive and flexural strength has decreased by 10%-12% and 4%-34% respectively compared to the control sample. The presence of recycled coarse aggregates in sample has decreased the density of concrete by 0.8%-3% compared to the control sample.

Physical and mechanical properties of self-compacting concrete containing superplasticizer and metakaolin

NASA Astrophysics Data System (ADS)

Shahidan, Shahiron; Tayeh, Bassam A.; Jamaludin, A. A.; Bahari, N. A. A. S.; Mohd, S. S.; Zuki Ali, N.; Khalid, F. S.

2017-11-01

The development of concrete technology shows a variety of admixtures in concrete to produce special concrete. This includes the production of self-compacting concrete which is able to fill up all spaces, take formwork shapes and pass through congested reinforcement bars without vibrating or needing any external energy. In this study, the main objective is to compare the physical and mechanical properties of self-compacting concrete containing metakaolin with normal concrete. Four types of samples were produced to study the effect of metakaolin towards the physical and mechanical properties of self-compacting concrete where 0%, 5%, 10% and 15% of metakaolin were used as cement replacement. The physical properties were investigated using slump test for normal concrete and slump flow test for self-compacting concrete. The mechanical properties were tested for compressive strength and tensile strength. The findings of this study show that the inclusion of metakaolin as cement replacement can increase both compressive and tensile strength compared to normal concrete. The highest compressive strength was found in self-compacting concrete with 15% metakaolin replacement at 53.3 MPa while self-compacting concrete with 10% metakaolin replacement showed the highest tensile strength at 3.6 MPa. On top of that, the finishing or concrete surface of both cube and cylinder samples made of self-compacting concrete produced a smooth surface with the appearance of less honeycombs compared to normal concrete.

Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete

PubMed Central

López-Uceda, Antonio; Ayuso, Jesús; Jiménez, José Ramón; Agrela, Francisco; Barbudo, Auxiliadora; De Brito, Jorge

2016-01-01

This research aims to produce non-structural concrete with mixed recycled aggregates (MRA) in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%), using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results) from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors’ knowledge, there have not been any upscaled applications of concrete with MRA and low cement content. PMID:28787892

Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete.

PubMed

López-Uceda, Antonio; Ayuso, Jesús; Jiménez, José Ramón; Agrela, Francisco; Barbudo, Auxiliadora; De Brito, Jorge

2016-02-02

This research aims to produce non-structural concrete with mixed recycled aggregates (MRA) in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%), using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results) from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors' knowledge, there have not been any upscaled applications of concrete with MRA and low cement content.

Contribution a la caracterisation des betons endommages par des methodes de l'acoustique non lineaire. Application a la reaction alcalis-silice

NASA Astrophysics Data System (ADS)

Kodjo, Apedovi

The aim of this thesis is to contribute to the non-destructive characterization of concrete materials damaged by alkali-silica reaction (ASR). For this purpose, some nonlinear characterization techniques have been developed, as well as a nonlinear resonance test device. In order to optimize the sensitivity of the test device, the excitation module and signal processing have been improved. The nonlinear tests were conducted on seven samples of concrete damaged by ASR, three samples of concrete damaged by heat, three concrete samples damaged mechanically and three sound concrete samples. Since, nonlinear behaviour of the material is often attribute to its micro-defects hysteretic behaviour, it was shown at first that concrete damaged by ASR exhibits an hysteresis behaviour. To conduct this study, an acoustoelastic test was set, and then nonlinear resonance test device was used for characterizing sound concrete and concrete damaged by ASR. It was shown that the nonlinear technique can be used for characterizing the material without knowing its initial state, and also for detecting early damage in the reactive material. Studies were also carried out on the effect of moisture regarding the nonlinear parameters; they allowed understanding the low values of nonlinear parameters measured on concrete samples that were kept in high moisture conditions. In order to find a specific characteristic of damage caused by ASR, the viscosity of ASR gel was used. An approach, based on static creep analysis, performed on the material, while applying the nonlinear resonance technique. The spring-damping model of Maxwell was used for the interpretation of the results. Then, the creep time was analysed on samples damaged by ASR. It appears that the ASR gel increases the creep time. Finally, the limitations of the nonlinear resonance technique for in situ application have been explained and a new applicable nonlinear technique was initiated. This technique use an external source such as a mass for making non-linearity behaviour in the material, while an ultrasound wave is investigating the medium. Keywords. Concrete, Alkali-silica reaction, Nonlinear acoustics, Nonlinearity, Hysteresis, Damage diagnostics.

BNL program in support of LWR degraded-core accident analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ginsberg, T.; Greene, G.A.

1982-01-01

Two major sources of loading on dry watr reactor containments are steam generatin from core debris water thermal interactions and molten core-concrete interactions. Experiments are in progress at BNL in support of analytical model development related to aspects of the above containment loading mechanisms. The work supports development and evaluation of the CORCON (Muir, 1981) and MARCH (Wooton, 1980) computer codes. Progress in the two programs is described in this paper. 8 figures.

Diffuse ultrasound monitoring of stress and damage development on a 15-ton concrete beam.

PubMed

Zhang, Yuxiang; Planès, Thomas; Larose, Eric; Obermann, Anne; Rospars, Claude; Moreau, Gautier

2016-04-01

This paper describes the use of an ultrasonic imaging technique (Locadiff) for the Non-Destructive Testing & Evaluation of a concrete structure. By combining coda wave interferometry and a sensitivity kernel for diffuse waves, Locadiff can monitor the elastic and structural properties of a heterogeneous material with a high sensitivity, and can map changes of these properties over time when a perturbation occurs in the bulk of the material. The applicability of the technique to life-size concrete structures is demonstrated through the monitoring of a 15-ton reinforced concrete beam subject to a four-point bending test causing cracking. The experimental results show that Locadiff achieved to (1) detect and locate the cracking zones in the core of the concrete beam at an early stage by mapping the changes in the concrete's micro-structure; (2) monitor the internal stress level in both temporal and spatial domains by mapping the variation in velocity caused by the acousto-elastic effect. The mechanical behavior of the concrete structure is also studied using conventional techniques such as acoustic emission, vibrating wire extensometers, and digital image correlation. The performances of the Locadiff technique in the detection of early stage cracking are assessed and discussed.

Acoustic emission of retrofitted fiber-wrapped columns

NASA Astrophysics Data System (ADS)

El Echary, Hazem; Mirmiran, Amir

1998-03-01

In recent years, fiber-wrapping technique has become increasingly popular for retrofitting of existing bridge pier columns in seismic zones. By the way of confinement, the external jacket enhances strength, ductility and shear performance of the column. However, since state of the concrete core is not visible from outside of the jacket, it is of great necessity to develop proper non-destructive methods to evaluate structural integrity of the column. Extensive research on FRP-confined concrete at the University of Central Florida has shown that failure of such hybrid columns is often accompanied by considerable audible and sub-audible noise, making acoustic emission (AE) a viable NDE technique for retrofitted columns. Acoustic emission from fiber-wrapped concrete specimens were monitored. A total of 24 concrete specimens with two types of construction (bonded and unbonded) and four different number of layers (1, 3, 5 and 7) were tested under uniaxial compression. All specimens were made of S-glass fabric and polyester resin with a core diameter of 6' and a length of 12'. Some of the specimens were subjected to cycles of loading and unloading to examine the presence of the Kaiser and the Felicity effects. A 4-channel AEDSP-32/16 (Mistras-2001) machine from Physical Acoustics Corp. was used for the experiments. Results indicate that AE energy and the number of AE counts can both be good representatives for the response of confined concrete. Further, plots of AE energy versus load follows the same bilinear trend that has been observed in the stress-strain response of such specimens. Finally, Felicity effect was observed in all composite specimens.

Compression Strength of Sulfur Concrete Subjected to Extreme Cold

NASA Technical Reports Server (NTRS)

Grugel, Richard N.

2008-01-01

Sulfur concrete cubes were cycled between liquid nitrogen and room temperature to simulate extreme exposure conditions. Subsequent compression testing showed the strength of cycled samples to be roughly five times less than those non-cycled. Fracture surface examination showed de-bonding of the sulfur from the aggregate material in the cycled samples but not in those non-cycled. The large discrepancy found, between the samples is attributed to the relative thermal properties of the materials constituting the concrete.

Infrared spectroscopy of the mineralogy of coprolites from Brean Down: evidence of past human activities and animal husbandry

NASA Astrophysics Data System (ADS)

Allen, Samantha D. M.; Almond, Matthew J.; Bell, Martin G.; Hollins, Peter; Marks, Sonja; Mortimore, Joanne L.

2002-03-01

The mineralogy of 11 concretions from the Bronze Age settlement horizons at Brean Down near Weston-super-Mare, Somerset, UK, has been examined by infrared spectroscopy. The concretions are found to contain calcite and apatite and, in some cases, quartz. Four further concretions from the later Iron Age Meare Village, soil samples from Brean Down and mineralised samples of known faecal origin from a cesspit within the Tudor Merchant's house in Tenby have been similarly examined. It is found that all samples contain calcite, but only the concretions and the Tenby cesspit samples contain apatite. None of the soil samples contain apatite, although these are relatively high in quartz. This suggests that the concretions are coprolites and that the apatite has a biological origin in small bone fragments. The infrared study is backed up by scanning electron microscopy which confirms the presence of phosphorus in the coprolite samples and shows a morphology suggestive of the presence of bone fragments; it is likely, therefore, that the coprolites result from a carnivore—most probably from dogs. The findings show the usefulness of infrared spectroscopy for the rapid identification of mineralised coprolitic material from archaeological sites.

Thermodiffusion in concrete slab as a driving force of indoor radon entry.

PubMed

Minkin, L

2001-02-01

The core of the hypotheses considered is that there is an additional strong driving force-the thermodiffusion of radon and soil air in concrete and soils, which can cause an intensive indoor radon entry. A vertical thermogradient in the slab causes thermodiffusion air flux through concrete into the house. The proof of this concept is based on consideration of concrete slab as a micro-porous system having a pore-size distribution that mostly pertains to Knudsen's region and a transition zone of pore sizes. The Knudsen's theory for a transition zone is developed, which is consistent with the known experimental data of thermodiffusion. Calculated thermodiffusion air flux across a concrete slab under thermogradient 80 K m(-1) approximately ranges 1 x 10(-7)-1 x 10(-6) kg x m(-2) x s(-1). The calculated typical radon-bearing advective air velocity in soil due to thermogradient in the slab is about 1 x 10(-6) m x s(-1).

Strength and deformability of compressed concrete elements with various types of non-metallic fiber and rods reinforcement under static loading

NASA Astrophysics Data System (ADS)

Nevskii, A. V.; Baldin, I. V.; Kudyakov, K. L.

2015-01-01

Adoption of modern building materials based on non-metallic fibers and their application in concrete structures represent one of the important issues in construction industry. This paper presents results of investigation of several types of raw materials selected: basalt fiber, carbon fiber and composite fiber rods based on glass and carbon. Preliminary testing has shown the possibility of raw materials to be effectively used in compressed concrete elements. Experimental program to define strength and deformability of compressed concrete elements with non-metallic fiber reinforcement and rod composite reinforcement included design, manufacture and testing of several types of concrete samples with different types of fiber and longitudinal rod reinforcement. The samples were tested under compressive static load. The results demonstrated that fiber reinforcement of concrete allows increasing carrying capacity of compressed concrete elements and reducing their deformability. Using composite longitudinal reinforcement instead of steel longitudinal reinforcement in compressed concrete elements insignificantly influences bearing capacity. Combined use of composite rod reinforcement and fiber reinforcement in compressed concrete elements enables to achieve maximum strength and minimum deformability.

BNL severe-accident sequence experiments and analysis program. [PWR; BWR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greene, G.A.; Ginsberg, T.; Tutu, N.K.

1983-01-01

In the analysis of degraded core accidents, the two major sources of pressure loading on light water reactor containments are: steam generation from core debris-water thermal interactions; and molten core-concrete interactions. Experiments are in progress at BNL in support of analytical model development related to aspects of the above containment loading mechanisms. The work supports development and evaluation of the CORCON (Muir, 1981) and MARCH (Wooton, 1980) computer codes. Progress in the two programs is described.

Development of New Generation of Ceramics for Environmentally Focused Chemical Separations

NASA Astrophysics Data System (ADS)

Ramakrishnan, Girish

This dissertation focuses on the use of composite materials for environmental applications. For the first time, applications of both fresh and aged concrete as inexpensive adsorbents for nitrogen dioxide (NO2) removal is demonstrated. Concrete is the most widely used composite material of the modern era. Cement manufacturing (a major component of concrete) is considered to be one of the leading contributors to air pollution, resulting in 7% of the global carbon dioxide emissions along with a number of other harmful pollutants such as oxides, mercury and particulates. These emissions aide in the formation of acid rain, smog, and toxic ground level ozone, causing detrimental effects such as respiratory illnesses, visibility reduction, eutrification and global warming. This thesis offers a novel and sustainable solution in mitigating NOX emissions, by introducing the significant adsorption potential of recycled concrete. The work is based on both commercially available cement paste and already aged concrete samples, providing truly scalable solutions. The concrete samples aged for different periods of time were exposed to NO2 to measure their adsorption capacity. The results show that all of the concrete samples (fresh and aged) exhibited excellent NO2 adsorption capacity, with the fresh concrete samples removing almost 100% of the NO2. Furthermore, to compare the effects of long term aging, 12 year-old recently demolished concrete samples were obtained and its NOX removal was shown to be almost 60%. The experimental results provide evidence of nitrate and nitrite species formation from chemical reactions occurring between NO2 and surface alkaline species. This important discovery can be utilized for NO2 removal and subsequent NOX sequestered demolished concrete (NSDC) recycling in new concrete, either as a set accelerating admixture or as a corrosion inhibitor, a big leap towards better sustainability and longevity of the new reinforced concrete structures. The rest of this thesis focuses on development of a new generation of ceramic membranes utilizing thermal spray techniques to produce highly scalable and extremely cost effective filtration membranes. Thermal spray method of membrane manufacturing has the advantage of economic scalability (up to tens of square meters) along with performance enhancement as compared to conventional wet casting process. In addition to developing a proof of concept for this approach, several strategies on how to improve ceramic membranes' performance via spraying process optimization are also described. Specifically, several thermal sprayed Alumina membrane samples were prepared by varying different process parameters. These samples were characterized using known techniques and subjected to permeability and size exclusion tests to correlate spraying parameters with membranes' performance. The membrane samples showed excellent clean water flux comparable to commercially available membranes and had rejection rates up to 96%. These results show that the membranes produced in this research achieve outstanding performance at a fraction of the cost of commercially produced membrane, enabling the use of membrane filtrations units in developing countries.

Neutron attenuation characteristics of polyethylene, polyvinyl chloride, and heavy aggregate concrete and mortars.

PubMed

Abdul-Majid, S; Othman, F

1994-03-01

Polyethylene and polyvinyl chloride pellets were introduced into concrete to improve its neutron attenuation characteristics while several types of heavy coarse aggregates were used to improve its gamma ray attenuation properties. Neutron and gamma ray attenuation were studied in concrete samples containing coarse aggregates of barite, pyrite, basalt, hematite, and marble as well as polyethylene and polyvinyl chloride pellets in narrow-beam geometry. The highest neutron attenuation was shown by polyethylene mortar, followed by polyvinyl chloride mortar; barite and pyrite concrete showed higher gamma ray attenuation than ordinary concrete. Broad-beam and continuous (infinite) medium geometries were used to study the neutron attenuation of samples containing polymers at different concentrations with and without heavy aggregates, the fitting equations were established, and from these the neutron removal coefficients were deduced. In a radiation field of neutrons and gamma rays, the appropriate concentration of polymer and heavy aggregate can be selected to give the optimum total dose attenuation depending on the relative intensities of each type of radiation. This would give much better design flexibility over ordinary concrete. The compressive strength tests performed on mortar and concrete samples showed that their value, in general, decreases as polymer concentration increases and that the polyvinyl chloride mortar showed higher values than the polyethylene mortar. For general construction purposes, the compression strength was considered acceptable in these samples.

Parameters of Concrete Modified with Glass Meal and Chalcedonite Dust

NASA Astrophysics Data System (ADS)

Kotwa, Anna

2017-10-01

Additives used for production of concrete mixtures affect the rheological properties and parameters of hardened concrete, including compressive strength, water resistance, durability and shrinkage of hardened concrete. By their application, the use of cement and production costs may be reduced. The scheduled program of laboratory tests included preparation of six batches of concrete mixtures with addition of glass meal and / or chalcedonite dust. Mineral dust is a waste product obtained from crushed aggregate mining, with grain size below 0,063μm. The main ingredient of chalcedonite dust is silica. Glass meal used in the study is a material with very fine grain size, less than 65μm. This particle size is present in 60% - 90% of the sample. Additives were used to replace cement in concrete mixes in an amount of 15% and 25%. The amount of aggregate was left unchanged. The study used Portland cement CEM I 42.5R. Concrete mixes were prepared with a constant rate w / s = 0.4. The aim of the study was to identify the effect of the addition of chalcedonite dust and / or glass meal on the parameters of hardened concrete, i.e. compressive strength, water absorption and capillarity. Additives used in the laboratory tests significantly affect the compressive strength. The largest decrease in compressive strength of concrete samples was recorded for samples with 50% substitutes of cement additives. This decrease is 34.35%. The smallest decrease in compressive strength was noted in concrete with the addition of 15% of chalcedonite dust or 15% glass meal, it amounts to an average of 15%. The study of absorption shows that all concrete with the addition of chalcedonite dust and glass meal gained a percentage weight increase between 2.7 ÷ 3.1% for the test batches. This is a very good result, which is probably due to grout sealing. In capillary action for the test batches, the percentage weight gains of samples ranges from 4.6% to 5.1%. However, the reference concrete obtained the lowest water absorption as compared to other batches.

TOPAZ-2 reactor distribution during descent in the atmosphere and at the impact with the Earth surface

NASA Astrophysics Data System (ADS)

Grinberg, Eduard I.; Nikolaev, Vadim S.; Sokolov, Nikolai A.; Doschatov, Vitaly V.; Usov, Veniamin A.; Gulidov, Aleksander I.

1995-01-01

The paper presents results of more accurate computational analysis of the TOPAZ-2 system reactor core aerodynamic disruption at an inadvertent reentry. Given are preliminary results on the pattern of disruption of the core partially burnt during its descent in the atmosphere at its impact on the surface of water and sandstone (medium density concrete).

Review of Repair Materials for Fire-Damaged Reinforced Concrete Structures

NASA Astrophysics Data System (ADS)

Zahid, MZA Mohd; Abu Bakar, BH; Nazri, FM; Ahmad, MM; Muhamad, K.

2018-03-01

Reinforced concrete (RC) structures perform well during fire and may be repaired after the fire incident because their low heat conductivity prevents the loss or degradation of mechanical strength of the concrete core and internal reinforcing steel. When an RC structure is heated to more than 500 °C, mechanical properties such as compressive strength, stiffness, and tensile strength start to degrade and deformations occur. Although the fire-exposed RC structure shows no visible damage, its residual strength decreases compared with that in the pre-fire state. Upon thorough assessment, the fire-damaged RC structure can be repaired or strengthened, instead of subjecting to partial or total demolition followed by reconstruction. The structure can be repaired using several materials, such as carbon fiber-reinforced polymer, glass fiber-reinforced polymer, normal strength concrete, fiber-reinforced concrete, ferrocement, epoxy resin mortar, and high-performance concrete. Selecting an appropriate repair material that must be compatible with the substrate or base material is a vital step to ensure successful repair. This paper reviews existing repair materials and factors affecting their performance. Of the materials considered, ultra-high-performance fiber-reinforced concrete (UHPFRC) exhibits huge potential for repairing fire-damaged RC structures but lack of information available. Hence, further studies must be performed to assess the potential of UHPFRC in rehabilitating fire-damaged RC structures.

Non destructive multi elemental analysis using prompt gamma neutron activation analysis techniques: Preliminary results for concrete sample

NASA Astrophysics Data System (ADS)

Dahing, Lahasen@Normanshah; Yahya, Redzuan; Yahya, Roslan; Hassan, Hearie

2014-09-01

In this study, principle of prompt gamma neutron activation analysis has been used as a technique to determine the elements in the sample. The system consists of collimated isotopic neutron source, Cf-252 with HPGe detector and Multichannel Analysis (MCA). Concrete with size of 10×10×10 cm3 and 15×15×15 cm3 were analysed as sample. When neutrons enter and interact with elements in the concrete, the neutron capture reaction will occur and produce characteristic prompt gamma ray of the elements. The preliminary result of this study demonstrate the major element in the concrete was determined such as Si, Mg, Ca, Al, Fe and H as well as others element, such as Cl by analysis the gamma ray lines respectively. The results obtained were compared with NAA and XRF techniques as a part of reference and validation. The potential and the capability of neutron induced prompt gamma as tool for multi elemental analysis qualitatively to identify the elements present in the concrete sample discussed.

Performance of Waterless Concrete

NASA Technical Reports Server (NTRS)

Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

2010-01-01

The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.

Influence of Silicon-Containing Additives on Concrete Waterproofness Property

NASA Astrophysics Data System (ADS)

Butakova, M. D.; Saribekyan, S. S.; Mikhaylov, A. V.

2017-11-01

The article studies the influence of silicon-containing additives on the property of the water resistance of concrete samples. It provides a review of the literature on common approaches and technologies improving concrete waterproofness and reinforced concrete structures. Normal hardening samples were obtained on the basis of concretes containing microsilica, aerosil or ash, or the combinations thereof. This research is aimed at the study of the complex modifier effect r on the basis of metakaolin, superplasticizer and silicon containing additives on the property of concrete water resistance. The need to use a superplasticizer to reduce the water-cement ratio and metakaolin as a hardening accelerator along with the set of strength is substantiated. This article describes a part of the results of the experiment conducted to find alternative options for colmatizing expensive additives used in the concreting foundations of private house-building. The implementation of the scientific work will not only clarify this area but will also broaden the knowledge of such additive as aerosol.

Applicability of recycled aggregates in concrete piles for soft soil improvement.

PubMed

Medeiros-Junior, Ronaldo A; Balestra, Carlos Et; Lima, Maryangela G

2017-01-01

The expressive generation of construction and demolition waste is stimulating several studies for reusing this material. The improvement of soft soils by concrete compaction piles has been widely applied for 40 years in some Brazilian cities. This technique is used to improve the bearing capacity of soft soils, allowing executing shallow foundations instead of deep foundations. The compaction piles use a high volume of material. This article explored the possibility of using recycled aggregates from construction waste to replace the natural aggregates in order to improve the bearing capacity of the soft soil, regarding its compressive strength. Construction wastes from different stages of a construction were used in order to make samples of concrete with recycled aggregates. The strength of concretes with natural aggregates was compared with the strength of concretes with recycled (fine and coarse) aggregates. Results show that all samples met the minimum compressive strength specified for compaction piles used to improve the bearing capacity of soft soils. The concrete with recycled aggregate from the structural stage had even higher resistances than the concrete with natural aggregates. This behaviour was attributed to the large amount of cementitious materials in the composition of this type of concrete. It was also observed that concrete with recycled fine aggregate has a superior resistance to concrete with recycled coarse aggregate.

Investigation on Wall Panel Sandwiched With Lightweight Concrete

NASA Astrophysics Data System (ADS)

Lakshmikandhan, K. N.; Harshavardhan, B. S.; Prabakar, J.; Saibabu, S.

2017-08-01

The rapid population growth and urbanization have made a massive demand for the shelter and construction materials. Masonry walls are the major component in the housing sector and it has brittle characteristics and exhibit poor performance against the uncertain loads. Further, the structure requires heavier sections for carrying the dead weight of masonry walls. The present investigations are carried out to develop a simple, lightweight and cost effective technology for replacing the existing wall systems. The lightweight concrete is developed for the construction of sandwich wall panel. The EPS (Expanded Polystyrene) beads of 3 mm diameter size are mixed with concrete and developed a lightweight concrete with a density 9 kN/m3. The lightweight sandwich panel is cast with a lightweight concrete inner core and ferrocement outer skins. This lightweight wall panel is tested for in-plane compression loading. A nonlinear finite element analysis with damaged plasticity model is carried out with both material and geometrical nonlinearities. The experimental and analytical results were compared. The finite element study predicted the ultimate load carrying capacity of the sandwich panel with reasonable accuracy. The present study showed that the lightweight concrete is well suitable for the lightweight sandwich wall panels.

Precast concrete unit assessment through GPR survey and FDTD modelling

NASA Astrophysics Data System (ADS)

Campo, Davide

2017-04-01

Precast concrete elements are widely used within United Kingdom house building offering ease in assembly and added values as structural integrity, sound and thermal insulation; most common concrete components include walls, beams, floors, panels, lintels, stairs, etc. The lack of respect of the manufacturer instruction during assembling, however, may induce cracking and short/long term loss of bearing capacity. GPR is a well-established not destructive technique employed in the assessment of structural elements because of real-time imaging, quickness of data collecting and ability to discriminate finest structural details. In this work, GPR has been used to investigate two different precast elements: precast reinforced concrete planks constituting the roof slab of a school and precast wood-cement blocks with insulation material pre-fitted used to build a perimeter wall of a private building. Visible cracks affected both constructions. For the assessment surveys, a GSSI 2.0 GHz GPR antenna has been used because of the high resolution required and the small size of the antenna case (155 by 90 by 105mm) enabling scanning up to 45mm from any obstruction. Finite Difference Time Domain (FDTD) numerical modelling was also performed to build a scenario of the expected GPR signal response for a preliminary real-time interpretation and to help solve uncertainties due to complex reflection patterns: simulated radargrams were built using Reflex Software v. 8.2, reproducing the same GPR pulse used for the surveys in terms of wavelet, nominal frequency, sample frequency and time window. Model geometries were derived from the design projects available both for the planks and the blocks; the electromagnetic properties of the materials (concrete, reinforcing bars, air-filled void, insulation and wooden concrete) were inferred from both values reported in literature and a preliminary interpretation of radargrams where internal layer interfaces were clearly recognizable and univocally interpretable. Simulated and real radargrams comparison demonstrated that, in both cases, manufacturer instructions were not fully respected and confirmed GPR as a fast and effective structural assessment technique with the support of FDTD modelling as data interpretation validating method when complex reflection patterns are observed. GPR findings will be then used to address the intrusive coring necessary to evaluate the compressive strength of the concrete and, in synergy with the intrusive survey results, to plan properly corrective actions to ensure the stability of the structures and guarantee the usability.

Sampling and testing for chloride ion in concrete

DOT National Transportation Integrated Search

1977-08-01

One of the most severe problems facing the highway community is chloride ion-induced reinforcing steel corrosion and the subsequent deterioration of concrete bridge decks and marine structures. This report presents recommended methods for sampling an...

Comparison of Hexavalent Chromium Leaching Levels of Zeoliteand Slag-based Concretes

NASA Astrophysics Data System (ADS)

Oravec, Jozef; Eštoková, Adriana

2017-06-01

In this experiment, the reference concrete samples containing Portland cement as binder and the concrete samples with the addition of ground granulated blast furnace slag (85% and 95%, respectively as replacement of Portland cement) and other samples containing ground zeolite (8% and 13%, respectively as replacement of Portland cement) were analyzed regarding the leachability of chromium. The prepared concrete samples were subjected to long-term leaching test for 300 days in three different leaching agents (distilled water, rainwater and Britton-Robinson buffer). Subsequently, the concentration of hexavalent chromium in the various leachates spectrophotometrically was measured. The leaching parameters as values of the pH and the conductivity were also studied. This experiment clearly shows the need for the regulation and control of the waste addition to the construction materials and the need for long-term study in relation to the leaching of heavy metals into the environment.

Contribution a l'auscultation des chaussees mixtes par methodes GPR et electrique

NASA Astrophysics Data System (ADS)

Kaouane, Carole

Quebec's infrastructures are ageing. A reliable, quick and economical assessment of the state of urban roads would help to plan civil engineering. This M.Sc. thesis aims to investigate and develop the potential of Ground Penetrating Radar (GPR) and electrical methods to assess pavement condition subject to wetting, freezing and drying cycles. The objectives are to display defects and estimate water content in the materials used for the mixed pavement construction; these consist in layers of asphalt (top), concrete (middle) and grade and sub-grade (bottom). Prior studies showed a valuable potential of joint application of GPR and electrical resistivity to assess mixed pavement condition. These studies were mainly based on numerical modeling and some site tests using both methods. It was concluded that a better evaluation of the potential of the coupled methods would come from the assessment of physical properties and validation from geotechnical evidences. At first, we characterized the context. Structural defects and water content implied modification of physical properties of road materials. After running numerical modeling, we carried out an experiment in one of the streets in Montreal (Canada) where pavement needed complete rehabilitation. GPR surveys were carried out before the pavement was destroyed and removed, and subsequently a resistivity imaging was carried out on the subgrade layer. We also sampled blocks of asphalt and concrete along the street from the demolition rubble in order to study their physical properties in the lab. Soil samples were taken from trenches to measure water content. The grade and sub-grade were mainly a mix of clayey-silt and gravel, as the embedding ground is grey clay. We measured the complex dielectric constants of asphalt and concrete in the range 50 MHz-900 MHz with a recently developed dielectric probe sampling a volume of 30 cm3. Resistivity measurements were also performed on large cores of asphalt and concrete using an inhouse system. Measurements were carried out on dry and wet samples, which provided a range of values encompassing the climatic conditions for the whole year. Finally the physical property and geotechnical data were used as input to numerical modeling and the modeled responses compared to the survey data. The predicted data fit nicely with the observed data. This work aims to provide further information for a better calibration of geophysical devices in pavement condition assessment. Moreover, it gives a wide range of information, which could become a base for further and more specific works.

Sedimentology of cores recovered from the Canada Basin of the Arctic Ocean

NASA Astrophysics Data System (ADS)

Edwards, B. D.; Saint-Ange, F.; Pohlman, J.; Higgins, J.; Mosher, D. C.; Lorenson, T. D.; Hart, P.

2011-12-01

Researchers from the United States and Canada are collaborating to understand the tectonic and sedimentary history of the Arctic Ocean between Canada and Alaska. As part of this on-going study, a joint US-Canadian ice breaker expedition operated in parts of the Canada Basin during August 2010. Occasional interruptions of the seismic data acquisition provided the ship time to collect gravity and piston cores at five sites-of-opportunity throughout the basin. High-resolution multibeam bathymetry and chirp sub-bottom profiler data collected immediately prior to coring reveal the fine-scale morphology of each site. Core photographs, X-ray radiographs, and physical property data support the following descriptions. Two piston cores were collected from the Beaufort Sea continental margin in a region of known bottom simulating reflectors (BSRs). Site 1 (2538 m water depth): This core recovered 5.72 m of gas-charged, gray sticky clay and silty-clay from an approximately 1100 m diameter, 130 m high conical mound overlying the crest of a buried anticline. Gas hydrate recovered in the core catcher combined with cracks and voids, methane and other hydrocarbon gasses, pyrite concretions, chemosynthetic clams, carbonate nodules, and soft carbonate masses indicate the likely upward migration of deep-seated fluids. Site 2 (1157 m water depth): This core, positioned 40 km upslope from the gas hydrate core, recovered 3 m of gray sticky silty clay and clayey silt near the base of an erosional scarp. Some voids and fracturing are apparent but carbonate masses and pyrite concretions are absent. Site 3 (3070 m water depth): This core from the top of a seamount discovered in 2009 in the north-central part of the Canada Basin recovered 4.94 m of sediment. More than 3 m of dark brown to yellowish brown, massive interbedded silty clays with sands and matrix-supported gravels (ice rafted debris [IRD]) occur in abrupt contact with underlying reddish yellow to brownish yellow silty clay and gravelly sandy clay interpreted to be altered hydrothermally. Successions of IRD layers create a thinly- to medium-bedded sequence throughout the lower section. Site 4 (3700 m water depth; central Canada Basin): This core recovered 3.4 m of sediment typified by decimeter-thick sequences of stacked graded beds with erosional basal contacts (Bouma sequences) characteristic of turbidite deposition. Site 5 (2081 m water depth; continental slope west of the Canadian archipelago): This core recovered 4.96 m of sediment of which the upper 2 m is silty clay to clayey silt with dispersed sand and granules. This upper section has an irregular, sharp basal contact with an underlying 16-cm-thick clast-supported massive gravel. The gravel has a scoured basal contact and overlies a monotonous gray clayey silt containing dispersed granules of IRD. Sparse and poorly preserved fauna throughout all the cores make age determination difficult; however, given the paucity of sediment cores in the Arctic Ocean, these samples provide vital geophysical groundtruth and sedimentological information about the basin.

Pattern recognition of concrete surface cracks and defects using integrated image processing algorithms

NASA Astrophysics Data System (ADS)

Balbin, Jessie R.; Hortinela, Carlos C.; Garcia, Ramon G.; Baylon, Sunnycille; Ignacio, Alexander Joshua; Rivera, Marco Antonio; Sebastian, Jaimie

2017-06-01

Pattern recognition of concrete surface crack defects is very important in determining stability of structure like building, roads or bridges. Surface crack is one of the subjects in inspection, diagnosis, and maintenance as well as life prediction for the safety of the structures. Traditionally determining defects and cracks on concrete surfaces are done manually by inspection. Moreover, any internal defects on the concrete would require destructive testing for detection. The researchers created an automated surface crack detection for concrete using image processing techniques including Hough transform, LoG weighted, Dilation, Grayscale, Canny Edge Detection and Haar Wavelet Transform. An automatic surface crack detection robot is designed to capture the concrete surface by sectoring method. Surface crack classification was done with the use of Haar trained cascade object detector that uses both positive samples and negative samples which proved that it is possible to effectively identify the surface crack defects.

Durability of visitable concrete sewer gallery under the effect of domestic wastewater

NASA Astrophysics Data System (ADS)

Salhi, Aimed; Kriker, Abdelouahed; Tioua, Tahar; Abimiloud, Youcef; Barluenga, Gonzalo

2016-07-01

The durability of concrete structures for the disposal of wastewater depends on their behavior when faced to different aggressions such as mechanics, chemical and biological, causing a deterioration often cementing matrix. The deterioration of recent evacuations wastewater infrastructure, made of reinforced concrete less than 15 years ago, has become an important concern. The aim of this study was to investigate the degradation and the factors responsible for the deterioration of the concrete visitable gallery of sewage from the town of Touggourt (south-east of Algeria). Thus, samples from different parts of the gallery were extracted and unaltered samples were selected as a reference. A degraded sample exposed to H2S gas and another sample of the gallery submerged into wastewater were analyzed to characterize the internal and external damage to the gallery as well as the chemical and mineralogical changes. These tests were complemented by a physical and mechanical characterization of the samples. The experimental results showed the strong anisotropy of both internal and external damage.

A contactless ultrasonic surface wave approach to characterize distributed cracking damage in concrete.

PubMed

Ham, Suyun; Song, Homin; Oelze, Michael L; Popovics, John S

2017-03-01

We describe an approach that utilizes ultrasonic surface wave backscatter measurements to characterize the volume content of relatively small distributed defects (microcrack networks) in concrete. A simplified weak scattering model is used to demonstrate that the scattered wave field projected in the direction of the surface wave propagation is relatively insensitive to scatterers that are smaller than the propagating wavelength, while the scattered field projected in the opposite direction is more sensitive to sub-wavelength scatterers. Distributed microcracks in the concrete serve as the small scatterers that interact with a propagating surface wave. Data from a finite element simulation were used to demonstrate the viability of the proposed approach, and also to optimize a testing configuration to collect data. Simulations were validated through experimental measurements of ultrasonic backscattered surface waves from test samples of concrete constructed with different concentrations of fiber filler (0.0, 0.3 and 0.6%) to mimic increasing microcrack volume density and then samples with actual cracking induced by controlled thermal cycles. A surface wave was induced in the concrete samples by a 50kHz ultrasonic source operating 10mm above the surface at an angle of incidence of 9°. Silicon-based miniature MEMS acoustic sensors located a few millimeters above the concrete surface both behind and in front of the sender were used to detect leaky ultrasonic surface waves emanating from concrete. A normalized backscattered energy parameter was calculated from the signals. Statistically significant differences in the normalized backscattered energy were observed between concrete samples with varying levels of simulated and actual cracking damage volume. Copyright © 2016 Elsevier B.V. All rights reserved.

Numerical study on the mechanism of active interfacial debonding detection for rectangular CFSTs based on wavelet packet analysis with piezoceramics

NASA Astrophysics Data System (ADS)

Xu, Bin; Chen, Hongbing; Xia, Song

2017-03-01

In recent years, Piezoelectric Lead Zirconate Titanate (PZT) based active interfacial debonding defect detection approach for concrete-filled steel tubular (CFST) columns has been proposed and validated experimentally. In order to investigate the mechanism of the PZT based interfacial debonding detection approach, a multi-physics coupling finite element model (FEM) composed of surface-mounted PZT actuator, embedded PZT sensor and a rectangular CFST column is constructed to numerically simulate the stress wave propagation induced by the surface-mounted PZT actuator under different excitation signals with different frequency and amplitude. The measurements of the embedded PZT sensor in concrete core of the CFST columns with different interfacial debonding defect lengths and depths are determined numerically with transient dynamic analysis. The linearity between the PZT response and the input amplitude, the effect of different frequency and measurement distance are discussed and the stress wave fields of CFST members without and with interface debonding defects are compared. Then, the response of the embedded PZT in concrete core is analyzed with wavelet packet analysis. The root mean square deviation (RMSD) of wavelet packet energy spectrum of the PZT measurement is employed as an evaluation index for the interfacial debonding detection. The results showed that the defined index under continuous sinusoidal and sweep frequency signals changes with the interfacial defects length and depth and is capable of effectively identifying the interfacial debonding defect between the concrete core and the steel tubular. Moreover, the index under sweep frequency signal is more sensitive to the interfacial debonding. The simulation results indicate that the interfacial debonding defect leads to the changes in the propagation path, travel time and the magnitude of stress waves. The simulation results meet the findings from the previous experimental study by the authors and help understand the mechanism of interfacial debonding defect detection for CFSTs using PZT technology.

The mechanical and physical properties of concrete containing polystyrene beads as aggregate and palm oil fuel ash as cement replacement material

NASA Astrophysics Data System (ADS)

Adnan, Suraya Hani; Abadalla, Musab Alfatih Salim; Jamellodin, Zalipah

2017-10-01

One of the disadvantages of normal concrete is the high self-weight of the concrete. Density of the normal concrete is in the range of 2200 kg/m3 to 2600 kg/ m3. This heavy self-weight make it as an uneconomical structural material. Advantages of expended polystyrene beads in lightweight concrete is its low in density which can reduce the dead load (self-weight) Improper disposal of the large quantity of palm oil fuel ash which has been produced may contribute to environmental problem in future. In this study, an alternative of using palm oil fuel ash as a cement replacement material is to improve the properties of lightweight concrete. The tests conducted in this study were slump test, compression strength, splitting tensile and water absorption test. These samples were cured under water curing condition for 7, 28 and 56 days before testing. Eight types of mixtures were cast based on percentage (25%, 50%) of polystyrene beads replacement for control samples and (25%, 50%) of polystyrene beads by different ratio 10%, 15%, and 20% replacement of palm oil fuel ash, respectively. Samples with 25% polystyrene beads and 10% palm oil fuel ash obtained the highest compressive strength which is 16.8 MPa, and the splitting tensile strength is 1.57 MPa. The water absorption for samples 25%, 50% polystyrene and 20% palm oil fuel ash is 3.89% and 4.67%, respectively which is lower compared to control samples.

Experimental Research of FRP Composite Tube Confined Steel-reinforced Concrete Stub Columns Under Axial Compression

NASA Astrophysics Data System (ADS)

Wang, Ji Zhong; Cheng, Lu; Wang, Xin Pei

2018-06-01

A new column of FRP composite tube confined steel-reinforced concrete (FTCSRC) column was proposed. This paper elaborates on laboratorial and analytical studies on the behavior of FCTSRC columns subjected to axial compressive load. Eight circular FTCSRC stub columns and one circular steel tube confined concrete (STCC) stub column were tested to investigate the failure mode and axial compression performance of circular FTCRSC columns. Parametric analysis was implemented to inquire the influence of confinement material (CFRP-steel tube or CFRP-GFRP tube), internal steel and CFRP layers on the ultimate load capacity. CFRP-steel composite tube was composed of steel tube and CFRP layer which was wrapped outside the steel tube, while CFRP-GFRP composite tube was composite of GFRP tube and CFRP layer. The test results indicate that the confinement effect of CFRP-steel tube is greatly superior to CFRP-GFRP tube. The ductility performance of steel tube confined high-strength concrete column can be improved obviously by encasing steel in the core concrete. Furthermore, with the increase in the layers of FRP wraps, the axial load capacity increases greatly.

Effect of Fiber Orientation on Dynamic Compressive Properties of an Ultra-High Performance Concrete

DTIC Science & Technology

2017-08-01

measurements for LSFfiberOrient function for multiple cores. Elapsed time is the total time taken to run ; CPU time is the number of cores times the...Superscripts Maximum value during a test Measured value from a calibration run ...movement left or right. Before cutting, the Cor-Tuf Baseline beam was placed on the table and squared with the blade . The blade was then moved into

Assessment of highway condition using combined geophysical surveys

NASA Astrophysics Data System (ADS)

Dera, Abdallah Alhadi

Four pavement sections were investigated using ground penetrating radar (GPR) and Ultrasonic Surface Wave (USW). The objective of this research was to compare the effectiveness of two non-destructive geophysical tools, GPR and the PSPA, in assessing the condition of the pavements, composed of different construction materials. The GPR data were acquired using a 1.5 GHz antenna along five traverses spaced at two ft. intervals approximately 1000 ft. long. On the other hand, the PSPA data were acquired at the stations spaced at 1000 ft. along the five GPR traverses. Core samples were collected at each site to constrain the interpretation of the acquired geophysical data. The sites include section US 63 about three miles north of Rolla, US 54 in Camdenton County, MO 179 in Jefferson City, and HWY U in Dent County. The types of pavement in these sites were, asphalt concrete overlaying portland cement concrete (AC/PCC), and full-depth asphalt concrete (AC) pavements or full depth bituminous mix (BM). Based on the acquired and analyzed data of the GPR and PSPA, the data of both tools correlated reasonably well. The PSPA technique successfully measured the elastic modulus and the thickness of pavement and detected horizontal flaws (e.g. debonding and delaminations). Similarly, the GPR technique successfully measured the thickness of pavement and detected horizontal flaws (e.g. debonding and delaminations) within the pavement. The research demonstrated that both non-destructive geophysical tools (GPR and PSPA) are effective in assessing the condition of different types of pavement.

Study of mass attenuation coefficients and effective atomic numbers of bismuth-ground granulated blast furnace slag concretes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Sandeep, E-mail: sandeep0078monu@gmail.com; Singh, Sukhpal, E-mail: sukhpal-78@rediffmail.com

2016-05-06

Five samples of Bismuth-Ground granulated blast furnace slag (Bi-GGBFS) concretes were prepared using composition (0.6 cement + x Bi{sub 2}O{sub 3} + (0.4-x) GGBFS, x = 0.05, 0.10, 0.15, 0.20 and 0.25) by keeping constant water (W) cement (C) ratio. Mass attenuation coefficients (μ{sub m}) of these prepared samples were calculated using a computer program winXCOM at different gamma ray energies, whereas effective atomic numbers (Z{sub eff}) is calculated using mathematical formulas. The radiation shielding properties of Bi-GGBFS concrete has been compared with standard radiation shielding concretes.

Stabilometer "S" value study on asphalt concrete samples.

DOT National Transportation Integrated Search

1985-07-01

During the late fall of 1969 a study was made to determine the precision when testing asphalt concrete specimens for the Hveem stabilometer ("S") value (AASHTO T 246). Fifty samples, using Chevron 85-100 asphalt cement and aggregate from Walling Sand...

Water absorption tests for measuring permeability of field concrete.

DOT National Transportation Integrated Search

2013-09-01

The research results from CFIRE Project 04-06 were communicated to engineers and researchers in this project. : Specifically, the water absorption of concrete samples (i.e., 2-in. thick, 4-in. diameter discs cut from concrete : cylinders) was found s...

Self-stressed sandwich bridge decks.

DOT National Transportation Integrated Search

1971-01-01

Proposed is an entirely new type of bridge deck, consisting of an unreinforced lightweight concrete slab made of expanding cement sandwiched between two thin plates of steel. The expanding core serves to prestress the panel. Laboratory tests were con...

The Effect of Various Waste Materials' Contents on the Attenuation Level of Anti-Radiation Shielding Concrete.

PubMed

Azeez, Ali Basheer; Mohammed, Kahtan S; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Sandu, Andrei Victor; Razak, Rafiza Abdul

2013-10-23

Samples of concrete contain various waste materials, such as iron particulates, steel balls of used ball bearings and slags from steel industry were assessed for their anti-radiation attenuation coefficient properties. The attenuation measurements were performed using gamma spectrometer of NaI (Tl) detector. The utilized radiation sources comprised 137 Cs and ⁶⁰Co radioactive elements with photon energies of 0.662 MeV for 137 Cs and two energy levels of 1.17 and 1.33 MeV for the ⁶⁰Co. Likewise the mean free paths for the tested samples were obtained. The aim of this work is to investigate the effect of the waste loading rates and the particulate dispersive manner within the concrete matrix on the attenuation coefficients. The maximum linear attenuation coefficient (μ) was attained for concrete incorporates iron filling wastes of 30 wt %. They were of 1.12 ± 1.31×10 -3 for 137 Cs and 0.92 ± 1.57 × 10 -3 for ⁶⁰Co. Substantial improvement in attenuation performance by 20%-25% was achieved for concrete samples incorporate iron fillings as opposed to that of steel ball samples at different (5%-30%) loading rates. The steel balls and the steel slags gave much inferior values. The microstructure, concrete-metal composite density, the homogeneity and particulate dispersion were examined and evaluated using different metallographic, microscopic and measurement facilities.

Nondestructive Handheld Fourier Transform Infrared (FT-IR) Analysis of Spectroscopic Changes and Multivariate Modeling of Thermally Degraded Plain Portland Cement Concrete and its Slag and Fly Ash-Based Analogs.

PubMed

Leung Tang, Pik; Alqassim, Mohammad; Nic Daéid, Niamh; Berlouis, Leonard; Seelenbinder, John

2016-05-01

Concrete is by far the world's most common construction material. Modern concrete is a mixture of industrial pozzolanic cement formulations and aggregate fillers. The former acts as the glue or binder in the final inorganic composite; however, when exposed to a fire the degree of concrete damage is often difficult to evaluate nondestructively. Fourier transform infrared (FT-IR) spectroscopy through techniques such as transmission, attenuated total reflectance, and diffuse reflectance have been rarely used to evaluate thermally damaged concrete. In this paper, we report on a study assessing the thermal damage of concrete via the use of a nondestructive handheld FT-IR with a diffuse reflectance sample interface. In situ measurements can be made on actual damaged areas, without the need for sample preparation. Separate multivariate models were developed to determine the equivalent maximal temperature endured for three common industrial concrete formulations. The concrete mixtures were successfully modeled displaying high predictive power as well as good specificity. This has potential uses in forensic investigation and remediation services particularly for fires in buildings. © The Author(s) 2016.

A 1055 ft/sec impact test of a two foot diameter model nuclear reactor containment system without fracture

NASA Technical Reports Server (NTRS)

Puthoff, R. L.

1972-01-01

A study to determine the feasibility of containing the fission products of a mobile reactor in the event of an impact is presented. The model simulated the reactor core, energy absorbing gamma shielding, neutron shielding and the containment vessel. It was impacted against an 18,000 pound reinforced concrete block at 1055 ft/sec. The model was significantly deformed and the concrete block demolished. No leaks were detected nor were any cracks observed in the model after impact.

Boron carbide nanostructures: A prospective material as an additive in concrete

NASA Astrophysics Data System (ADS)

Singh, Paviter; Kaur, Gurpreet; Kumar, Rohit; Kumar, Umesh; Singh, Kulwinder; Kumar, Manjeet; Bala, Rajni; Meena, Ramovatar; Kumar, Akshay

2018-05-01

In recent decades, manufacture and ingestion of concrete have increased particularly in developing countries. Due to its low cost, safety and strength, concrete have become an economical choice for protection of radiation shielding material in nuclear reactors. As boron carbide has been known as a neutron absorber material makes it a great candidate as an additive in concrete for shielding radiation. This paper presents the synthesis of boron carbide nanostructures by using ball milling method. The X-ray diffraction pattern, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope analysis confirms the formation of boron carbide nanostructures. The effect of boron carbide nanostructures on the strength of concrete samples was demonstrated. The compressive strength tests of concrete cube B4C powder additives for 0 % and 5 % of total weight of cement was compared for different curing time period such as 7, 14, 21 and 28 days. The high compressive strength was observed when 5 wt % boron carbide nanostructures were used as an additive in concrete samples after 28 days curing time and showed significant improvement in strength.

Guidelines for Sampling, Assessing, and Restoring Defective Grout in Prestressed Concrete Bridge Post-Tensioning Ducts

DOT National Transportation Integrated Search

2013-05-01

This document is a technical summary of the Federal Highway Administration report, "Guidelines for Sampling, Assessing, and Restoring Defective Grout in Prestressed Concrete Bridge Post-Tensioning Ducts" (FHWA-HRT-13-028). The objectives of this stud...

Functional characterization of two concrete biofilms using pyrosequencing data

EPA Science Inventory

Phylogenetic studies of concrete biofilms using 16SrRNA-based approaches have demonstrated that concrete surfaces harbor a diverse microbial community. These approaches can provide information on the general taxonomical groups present in a sample but cannot shed light on the func...

Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete

PubMed Central

Long, Wu-Jian; Khayat, Kamal Henri; Lemieux, Guillaume; Hwang, Soo-Duck; Xing, Feng

2014-01-01

With the extensive use of self-consolidating concrete (SCC) worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC) of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration. PMID:28788223

Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete.

PubMed

Long, Wu-Jian; Khayat, Kamal Henri; Lemieux, Guillaume; Hwang, Soo-Duck; Xing, Feng

2014-10-10

With the extensive use of self-consolidating concrete (SCC) worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC) of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration.

The Science of Inaccurate Temperatures: Explaining How the Bahamas Did Not Form in a Jacuzzi

NASA Astrophysics Data System (ADS)

Murray, S.; Swart, P. K.; McNeill, D. F.

2016-12-01

The Bahamas archipelago is a carbonate platform that formed in the warm waters of the Gulf Stream current. Using clumped isotope paleothermometry, it has been shown that carbonates extending back through the Miocene taken from cores throughout the Bahamas have all precipitated from fluids at temperatures similar to what is found in the Bahamas in the present day (15 to 35°C). However, in a single core, (Clino), collected off the western edge of Great Bahama Bank, Δ47 values have been measured which suggest formation at significantly warmer temperatures (42 to 53°C). These values are present in spite of the fact that the sediments have never been deeply buried. In a parallel study, these same cores were measured for their carbonate associated sulfate (CAS). The only core that presented evidence of elevated CAS, indicative of bacterial sulfate reduction (BSR), was the Clino core. In this core the clumped isotope temperatures are correlated with changes in the δ34S of the CAS. This finding suggests that BSR can have a significant effect on the Δ47 value producing erroneous temperatures. This is further supported by examining a carbonate concretion with extreme negative δ13C values (-30‰) taken as evidence of BSR. The clumped isotope temperatures in this nodule are elevated relative to its burial history with an increase of 15 °C from the outer edge of the concretion to the center. The increase in temperature correlates well with the decreasing δ13C suggesting increasing fractionation associated with BSR is directly impacting the clumped isotope measurements.

Thermal stress control using waste steel fibers in massive concretes

NASA Astrophysics Data System (ADS)

Sarabi, Sahar; Bakhshi, Hossein; Sarkardeh, Hamed; Nikoo, Hamed Safaye

2017-11-01

One of the important subjects in massive concrete structures is the control of the generated heat of hydration and consequently the potential of cracking due to the thermal stress expansion. In the present study, using the waste turnery steel fibers in the massive concretes, the amount of used cement was reduced without changing the compressive strength. By substituting a part of the cement with waste steel fibers, the costs and the generated hydration heat were reduced and the tensile strength was increased. The results showed that by using 0.5% turnery waste steel fibers and consequently, reducing to 32% the cement content, the hydration heat reduced to 23.4% without changing the compressive strength. Moreover, the maximum heat gradient reduced from 18.5% in the plain concrete sample to 12% in the fiber-reinforced concrete sample.

Repeatability of testing procedures for resilient modulus and fatigue.

DOT National Transportation Integrated Search

1989-04-01

Extensive use of diametral resilient modulus and fatigue testing is made by the Oregon State Highway Division to evaluate asphaltic concrete materials. Test results on similar materials (e.g., adjacent field cores), however, often indicate a poor lev...

Assessment of optimum threshold and particle shape parameter for the image analysis of aggregate size distribution of concrete sections

NASA Astrophysics Data System (ADS)

Ozen, Murat; Guler, Murat

2014-02-01

Aggregate gradation is one of the key design parameters affecting the workability and strength properties of concrete mixtures. Estimating aggregate gradation from hardened concrete samples can offer valuable insights into the quality of mixtures in terms of the degree of segregation and the amount of deviation from the specified gradation limits. In this study, a methodology is introduced to determine the particle size distribution of aggregates from 2D cross sectional images of concrete samples. The samples used in the study were fabricated from six mix designs by varying the aggregate gradation, aggregate source and maximum aggregate size with five replicates of each design combination. Each sample was cut into three pieces using a diamond saw and then scanned to obtain the cross sectional images using a desktop flatbed scanner. An algorithm is proposed to determine the optimum threshold for the image analysis of the cross sections. A procedure was also suggested to determine a suitable particle shape parameter to be used in the analysis of aggregate size distribution within each cross section. Results of analyses indicated that the optimum threshold hence the pixel distribution functions may be different even for the cross sections of an identical concrete sample. Besides, the maximum ferret diameter is the most suitable shape parameter to estimate the size distribution of aggregates when computed based on the diagonal sieve opening. The outcome of this study can be of practical value for the practitioners to evaluate concrete in terms of the degree of segregation and the bounds of mixture's gradation achieved during manufacturing.

Influences of cement source and sample of cement source on compressive strength variability of gravel aggregate concrete.

DOT National Transportation Integrated Search

2013-06-01

The strength of concrete is influenced by each constituent material used in the concrete : mixture and the proportions of each ingredient. Water-cementitious ratio, cementitious materials, air : content, chemical admixtures, and type of coarse aggreg...

Reuse of municipal solid wastes incineration fly ashes in concrete mixtures.

PubMed

Collivignarelli, Carlo; Sorlini, Sabrina

2002-01-01

This study is aimed at assessing the feasibility of concrete production using stabilized m.s.w. (municipal solid waste) incineration fly ashes in addition to natural aggregates. The tested fly ashes were washed and milled, then stabilized by a cement-lime process and finally were reused as a "recycled aggregate" for cement mixture production, in substitution of a natural aggregate (with dosage of 200-400 kg m(-3)). These mixtures, after curing, were characterized with conventional physical-mechanical tests (compression, traction, flexure, modulus of elasticity, shrinkage). In samples containing 200 kg(waste) m(-3)(concrete), a good compressive strength was achieved after 28 days of curing. Furthermore, concrete leaching behavior was evaluated by means of different leaching tests, both on milled and on monolithic samples. Experimental results showed a remarkable reduction of metal leaching in comparison with raw waste. In some cases, similar behavior was observed in "natural" concrete (produced with natural aggregates) and in "waste containing" concrete.

Correlation between Wavelength Dispersive X-ray Fluorescence (WDXRF) analysis of hardened concrete for chlorides vs. Atomic Absorption (AA) analysis in accordance with AASHTO T- 260; sampling and testing for chloride ion in concrete and concrete raw mater

DOT National Transportation Integrated Search

2014-04-01

A correlation between Wavelength Dispersive X-ray Fluorescence(WDXRF) analysis of Hardened : Concrete for Chlorides and Atomic Absorption (AA) analysis (current method AASHTO T-260, procedure B) has been : found and a new method of analysis has been ...

University of TX Bureau of Economic Geology's Core Research Centers: The Time is Right for Registering Physical Samples and Assigning IGSN's - Workflows, Stumbling Blocks, and Successes.

NASA Astrophysics Data System (ADS)

Averett, A.; DeJarnett, B. B.

2016-12-01

The University Of Texas Bureau Of Economic Geology (BEG) serves as the geological survey for Texas and operates three geological sample repositories that house well over 2 million boxes of geological samples (cores and cuttings) and an abundant amount of geoscience data (geophysical logs, thin sections, geochemical analyses, etc.). Material is accessible and searchable online, and it is publically available to the geological community for research and education. Patrons access information about our collection by using our online core and log database (SQL format). BEG is currently undertaking a large project to: 1) improve the internal accuracy of metadata associated with the collection; 2) enhance the capabilities of the database for both BEG curators and researchers as well as our external patrons; and 3) ensure easy and efficient navigation for patrons through our online portal. As BEG undertakes this project, BEG is in the early stages of planning to export the metadata for its collection into SESAR (System for Earth Sample Registration) and have IGSN's (International GeoSample Numbers) assigned to its samples. Education regarding the value of IGSN's and an external registry (SESAR) has been crucial to receiving management support for the project because the concept and potential benefits of registering samples in a registry outside of the institution were not well-known prior to this project. Potential benefits such as increases in discoverability, repository recognition in publications, and interoperability were presented. The project was well-received by management, and BEG fully supports the effort to register our physical samples with SESAR. Since BEG is only in the initial phase of this project, any stumbling blocks, workflow issues, successes/failures, etc. can only be predicted at this point, but by mid-December, BEG expects to have several concrete issues to present in the session. Currently, our most pressing issue involves establishing the most efficient workflow for exporting of large amounts of metadata in a format that SESAR can easily ingest, and how this can be best accomplished with very few BEG staff assigned to the project.

Seismic performance of interior precast concrete beam-column connections with T-section steel inserts under cyclic loading

NASA Astrophysics Data System (ADS)

Ketiyot, Rattapon; Hansapinyo, Chayanon

2018-04-01

An experimental investigation was conducted to study the performance of precast beam-column concrete connections using T-section steel inserts into the concrete beam and joint core, under reversed cyclic loading. Six 2/3-scale interior beam-column subassemblies, one monolithic concrete specimen and five precast concrete specimens were tested. One precast specimen was a simple connection for a gravity load resistant design. Other precast specimens were developed with different attributes to improve their seismic performance. The test results showed that the performance of the monolithic specimen M1 represented ductile seismic behavior. Failure of columns and joints could be prevented, and the failure of the frame occurred at the flexural plastic hinge formation at the beam ends, close to the column faces. For the precast specimens, the splitting crack along the longitudinal lapped splice was a major failure. The precast P5 specimen with double steel T-section inserts showed better seismic performance compared to the other precast models. However, the dowel bars connected to the steel inserts were too short to develop a bond. The design of the precast concrete beams with lap splice is needed for longer lap lengths and should be done at the beam mid span or at the low flexural stress region.

On stress-state optimization in steel-concrete composite structures

NASA Astrophysics Data System (ADS)

Brauns, J.; Skadins, U.

2017-10-01

The plastic resistance of a concrete-filled column commonly is given as a sum of the components and taking into account the effect of confinement. The stress state in a composite column is determined by taking into account the non-linear relationship of modulus of elasticity and Poisson’s ratio on the stress level in the concrete core. The effect of confinement occurs at a high stress level when structural steel acts in tension and concrete in lateral compression. The stress state of a composite beam is determined taking into account non-linear dependence on the position of neutral axis. In order to improve the stress state of a composite element and increase the safety of the construction the appropriate strength of steel and concrete has to be applied. The safety of high-stressed composite structures can be achieved by using high-performance concrete (HPC). In this study stress analysis of the composite column and beam is performed with the purpose of obtaining the maximum load-bearing capacity and enhance the safety of the structure by using components with the appropriate strength and by taking into account the composite action. The effect of HPC on the stress state and load carrying capacity of composite elements is analysed.

Sinabung Volcanic Ash Utilization As The Additive for Paving Block Quality A and B

NASA Astrophysics Data System (ADS)

Sembiring, I. S.; Hastuty, I. P.

2017-03-01

Paving block is one of the building materials used as the top layer of the road structure besides asphalt and concrete. Paving block is made of mixed materials such as portland cement or other adhesive materials, water and aggregate. In this research, the material used as the additive of cement and concrete is volcanic ash from Mount Sinabung, it is based on the results of the material testing, Sinabung ash contains 74.3% silica (SiO2). The purpose of this research aims to analyze the behavior of the paving blocks quality A and B with and without a mixture of Sinabung ash, to analyze the workability of fresh concrete using Sinabung ash as an additive in concrete, and to compare the test results of paving blocks with and without using Sinabung ash. The samples that we made consist of four variations of the concrete mix to experiment a mixture of normal sample without additive, samples which are mixed with the addition of Sinabung ash 5%, 10%, 15%, 20% and 25% of the volume of concrete/m3. Each variation consists of 10 samples of the concrete with 28 days curing time period. We will do the compressive strength and water absorption test to the samples to determine whether the samples are in accordance with the type needed. According to the test result, paving blocks with Sinabung ash and curing time reach quality A at 0%, 5% and 10% mixture with the compressive strength of each 50.14 MPa, 46.20 MPa and 1.49Mpa, and reach quality B at 15%, 20 %,25% mixture with curing time and 0%, 5%, 10%, 15%, 20% and 25% mixture without curing time. According to the absorption values we got from the test which are 6.66%, 6.73%, 6.88%, 7.03%, 7.09% and 7.16%, the entire sample have average absorption exceeding SNI standardization which is above 6% and reach quality C. Based on compressive strength and absorption data obtained Sinabung ash can’t fully replace cement as the binder because of the low CaO content.

Concrete with onyx waste aggregate as aesthetically valued structural concrete

NASA Astrophysics Data System (ADS)

Setyowati E., W.; Soehardjono, A.; Wisnumurti

2017-09-01

The utillization of Tulungagung onyx stone waste as an aggregate of concrete mixture will improve the economic value of the concrete due to the brighter color and high aesthetic level of the products. We conducted the research of 75 samples as a test objects to measure the compression stress, splits tensile stress, flexural tensile stress, elasticity modulus, porosity modulus and also studied 15 test objects to identify the concrete micro structures using XRD test, EDAX test and SEM test. The test objects were made from mix designed concrete, having ratio cement : fine aggregate : coarse aggregate ratio = 1 : 1.5 : 2.1, and W/C ratio = 0.4. The 28 days examination results showed that the micro structure of Tulungagung onyx waste concrete is similar with normal concrete. Moreover, the mechanical test results proved that Tulungagung onyx waste concretes also have a qualified level of strength to be used as a structural concrete with higher aesthetic level.

Preliminary investigation on the suitablity of using fiber reinforced concrete in the construction of a hazardous waste disposal vessel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramey, M.R.; Daie-e, G.

1988-07-01

There are certain hazardous wastes that must be contained in an extremely secure vessel for transportation and disposal. The vessel, among other things, must be able to withstand relatively large impacts without rupturing. Such containment vessels therefore must be able to absorb substantial amounts of energy during an impact and still perform their function. One of the impacts that the vessel must withstand is a 30-foot fall onto an unyielding surface. For some disposal scenarios it is proposed to encase the waste in a steel enclosure which is to be surrounded by a thick layer of concrete which, in turn,more » is encased by a relatively thin steel shell. Tests on concrete in compression and flexure, including static, dynamic and impact tests, have shown that low modulus concretes tend to behave in a less brittle manner than higher modulus concretes. Tests also show that fiber reinforced concretes have significantly greater ductility, crack propagation resistance and toughness than conventional concretes. Since it is known that concrete is a reasonably brittle material, it is necessary to do impact tests on sample containment structures consisting of thin-walled metal containers having closed ends which are filled with concrete, grout, or fiber reinforced concrete. This report presents the results of simple tests aimed at observing the behavior of sample containment structures subjected to impacts due to a fall from 30 feet. 8 figs., 4 tabs.« less

The Effect of Various Waste Materials’ Contents on the Attenuation Level of Anti-Radiation Shielding Concrete

PubMed Central

Azeez, Ali Basheer; Mohammed, Kahtan S.; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Sandu, Andrei Victor; Razak, Rafiza Abdul

2013-01-01

Samples of concrete contain various waste materials, such as iron particulates, steel balls of used ball bearings and slags from steel industry were assessed for their anti-radiation attenuation coefficient properties. The attenuation measurements were performed using gamma spectrometer of NaI (Tl) detector. The utilized radiation sources comprised 137Cs and 60Co radioactive elements with photon energies of 0.662 MeV for 137Cs and two energy levels of 1.17 and 1.33 MeV for the 60Co. Likewise the mean free paths for the tested samples were obtained. The aim of this work is to investigate the effect of the waste loading rates and the particulate dispersive manner within the concrete matrix on the attenuation coefficients. The maximum linear attenuation coefficient (μ) was attained for concrete incorporates iron filling wastes of 30 wt %. They were of 1.12 ± 1.31×10−3 for 137Cs and 0.92 ± 1.57 × 10−3 for 60Co. Substantial improvement in attenuation performance by 20%–25% was achieved for concrete samples incorporate iron fillings as opposed to that of steel ball samples at different (5%–30%) loading rates. The steel balls and the steel slags gave much inferior values. The microstructure, concrete-metal composite density, the homogeneity and particulate dispersion were examined and evaluated using different metallographic, microscopic and measurement facilities. PMID:28788363

Building the Core Architecture of a Multiagent System Product Line: With an example from a future NASA Mission

NASA Technical Reports Server (NTRS)

Pena, Joaquin; Hinchey, Michael G.; Ruiz-Cortes, Antonio

2006-01-01

The field of Software Product Lines (SPL) emphasizes building a core architecture for a family of software products from which concrete products can be derived rapidly. This helps to reduce time-to-market, costs, etc., and can result in improved software quality and safety. Current AOSE methodologies are concerned with developing a single Multiagent System. We propose an initial approach to developing the core architecture of a Multiagent Systems Product Line (MAS-PL), exemplifying our approach with reference to a concept NASA mission based on multiagent technology.

Thermal behavior of cylindrical buckling restrained braces at elevated temperatures.

PubMed

Talebi, Elnaz; Tahir, Mahmood Md; Zahmatkesh, Farshad; Yasreen, Airil; Mirza, Jahangir

2014-01-01

The primary focus of this investigation was to analyze sequentially coupled nonlinear thermal stress, using a three-dimensional model. It was meant to shed light on the behavior of Buckling Restraint Brace (BRB) elements with circular cross section, at elevated temperature. Such bracing systems were comprised of a cylindrical steel core encased in a strong concrete-filled steel hollow casing. A debonding agent was rubbed on the core's surface to avoid shear stress transition to the restraining system. The numerical model was verified by the analytical solutions developed by the other researchers. Performance of BRB system under seismic loading at ambient temperature has been well documented. However, its performance in case of fire has yet to be explored. This study showed that the failure of brace may be attributed to material strength reduction and high compressive forces, both due to temperature rise. Furthermore, limiting temperatures in the linear behavior of steel casing and concrete in BRB element for both numerical and analytical simulations were about 196°C and 225°C, respectively. Finally it is concluded that the performance of BRB at elevated temperatures was the same as that seen at room temperature; that is, the steel core yields prior to the restraining system.

The Media Agenda-Setting Effect of Concrete versus Abstract Issues.

ERIC Educational Resources Information Center

Yagade, Aileen; Dozier, David M.

1990-01-01

Matches a content analysis sample of "Time" magazine coverage of two "concrete" issues (drug abuse, energy) and two "abstract" issues (nuclear arms race, federal budget deficit) with Gallup poll data over a lengthy period of time. Finds that concreteness increases news media agenda-setting power whereas abstractness…

Development of a robust field technique to quantify the air-void distribution in fresh concrete.

DOT National Transportation Integrated Search

2013-07-01

In order to make concrete frost durable it is common to provide a small and well distributed air void system. Current measuring techniques require weeks to complete on hardened and polished samples of concrete. This report presents the results of a n...

Use of scanning electron microscopy and microanalysis to determine chloride content of concrete and raw materials.

DOT National Transportation Integrated Search

2013-02-01

Standard sample sets of cement and mortar formulations with known levels of Cl as well as concrete samples subject to Cl diffusion were all prepared for and analyzed with scanning electron microscopy (SEM) and electron microprobe (EPMA). Using x-ray ...

Application of ground-penetrating radar technique to evaluate the waterfront location in hardened concrete

NASA Astrophysics Data System (ADS)

Rodríguez-Abad, Isabel; Klysz, Gilles; Martínez-Sala, Rosa; Balayssac, Jean Paul; Mené-Aparicio, Jesús

2016-12-01

The long-term performance of concrete structures is directly tied to two factors: concrete durability and strength. When assessing the durability of concrete structures, the study of the water penetration is paramount, because almost all reactions like corrosion, alkali-silica, sulfate, etc., which produce their deterioration, require the presence of water. Ground-penetrating radar (GPR) has shown to be very sensitive to water variations. On this basis, the objective of this experimental study is, firstly, to analyze the correlation between the water penetration depth in concrete samples and the GPR wave parameters. To do this, the samples were immersed into water for different time intervals and the wave parameters were obtained from signals registered when the antenna was placed on the immersed surface of the samples. Secondly, a procedure has been developed to be able to determine, from those signals, the reliability in the detection and location of waterfront depths. The results have revealed that GPR may have an enormous potential in this field, because excellent agreements were found between the correlated variables. In addition, when comparing the waterfront depths calculated from GPR measurements and those visually registered after breaking the samples, we observed that they totally agreed when the waterfront was more than 4 cm depth.

Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

NASA Astrophysics Data System (ADS)

Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

2015-01-01

Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

Research and Development in the U.S. Army Corps of Engineers: Improving the Common Stock of Knowledge

DTIC Science & Technology

2011-08-01

instrumentation researchers such as Eugene Woodman, Francis Hanes, L.H. Daniels, and Leo F. Ingram developed instru- ments ranging from high-speed cameras to...dredging involved computer modeling of various prob- lems, and CERC helped in the development of technologies such as breakwater designs, CORE- LOC ...of hydraulic engineering and modeling, bridge scour analysis, development of the CORE- LOC Concrete Armoring and Samoa Stone products for coastal

A 640 foot per second impact test of a two foot diameter model nuclear reactor containment system without fracture

NASA Technical Reports Server (NTRS)

Puthoff, R. L.

1971-01-01

An impact test was conducted on an 1142 pound 2 foot diameter sphere model. The purpose of this test was to determine the feasibility of containing the fission products of a mobile reactor in an impact. The model simulated the reactor core, energy absorbing gamma shielding, neutron shielding and the containment vessel. It was impacted against an 18,000 pound reinforced concrete block. The model was significantly deformed and the concrete block demolished. No leaks were detected nor cracks observed in the model after impact.

Teaching Multiplication with Regrouping to Students with Learning Disabilities

ERIC Educational Resources Information Center

Flores, Margaret M.; Hinton, Vanessa M.; Schweck, Kelly B.

2014-01-01

The Common Core Standards require demonstration of conceptual knowledge of numbers, operations, and relations between mathematical concepts. Supplemental instruction should explicitly guide students with specific learning disabilities (SLD) in these skills. In this article, we illustrate implementation of the concrete-representational-abstract…

Factors affecting the performance of bridge decks in Virginia.

DOT National Transportation Integrated Search

1991-01-01

A detailed examination was made of 34 bridge decks, 11 to 30 years old, containing uncoated reinforcing steel. These bridges are located throughout Virginia. Cores were taken from each to evaluate the quality of the concrete with the objective of det...

Precast alternative for flat slab bridges : final report.

DOT National Transportation Integrated Search

2013-10-26

The cast-in-place (CIP) concrete slab bridge and the hollow core flat slab bridge are two very common bridge types utilized by the : South Carolina Department of Transportation (SCDOT). The CIP bridge is durable but has a long construction time while...

Soil architecture relationships with dynamic soil physical processes: a conceptual study using natural, artificial, and 3D-printed soil cores

NASA Astrophysics Data System (ADS)

Lamandé, Mathieu; Schjønning, Per; Dal Ferro, Nicola; Morari, Francesco

2017-04-01

Pore system architecture is a key feature for understanding physical, biological and chemical processes in soils. Development of visualisation technics, especially x-ray CT, during recent years has been useful in describing the complex relationships between soil architecture and soil functions. We believe that combining visualization with physical models is a step further towards a better understanding of these relationships. We conducted a concept study using natural, artificial and 3D-printed soil cores. Eight natural soil cores (100 cm3) were sampled in a cultivated stagnic Luvisol at two depths (topsoil and subsoil), representing contrasting soil pore systems. Cylinders (100 cm3) were produced from plastic or from autoclaved aerated concrete. Holes of diameters 1.5 and 3 mm were drilled in the cylinder direction for the plastic cylinder and for one of the AAC cylinders. All natural and artificial cores were scanned in a micro x-ray CT scanner at a resolution of 35 µm. The reconstructed image of each soil core was printed with 3D multijet printing technology at a resolution of 29 µm. In some reconstructed digital volumes of the natural soil cores, pores of different sizes (equivalent diameter of 35, 70, 100, and 200 µm) were removed before additional 3D printing. Effective air-filled porosity, Darcian air permeability, and oxygen diffusion were measured on all natural, artificial and printed cores. The comparison of the natural and the artificial cores emphasized the difference in pore architecture between topsoil (sponge like) and subsoil (dominated by large vertical macropores). This study showed the high potential of using printed soil cores for understanding soil pore functions. The results confirm the suitability of the Ball model partitioning the pore system into arterial, marginal and remote pores to describe effects of soil structure on gas transport.

An Investigation of Concrete Deterioration at South Florida Water Management District Structure S65E

DTIC Science & Technology

2014-02-01

24 Figure 19. SEM micrographs of deterioration observed on fracture surface including borehole near exposed surface and transition between...photomicrographs of repaired concrete surface. ........................................ 36 Figure A6. Supplemental photomicrographs of fractured sample...38 Figure B1. Supplemental SEM micrographs of inner non-deteriorated concrete fracture surface

Experimental data on compressive strength and durability of sulfur concrete modified by styrene and bitumen.

PubMed

Dehestani, M; Teimortashlu, E; Molaei, M; Ghomian, M; Firoozi, S; Aghili, S

2017-08-01

In this data article experimental data on the compressive strength, and the durability of styrene and bitumen modified sulfur concrete against acidic water and ignition are presented. The percent of the sulfur cement and the gradation of the aggregates used are according to the ACI 548.2R-93 and ASTM 3515 respectively. For the styrene modified sulfur concrete different percentages of styrene are used. Also for the bitumen modified sulfur concrete, different percentages of bitumen and the emulsifying agent (triton X-100) are utilized. From each batch three 10×10×10 cm cubic samples were casted. One of the samples was used for the compressive strength on the second day of casting, and one on the twenty-eighth day. Then the two samples were put under the high pressure flame of the burning liquid gas for thirty seconds and their ignition resistances were observed. The third sample was put into the acidic water and after twenty eight days immersion in water was dried in the ambient temperature. After drying its compressive strength has been evaluated.

Comparison of Static and Dynamic Elastic Modules of Different Strength Concretes

NASA Astrophysics Data System (ADS)

Uyanık, Osman; Sabbaǧ, Nevbahar

2016-04-01

In this study, the static and dynamic elastic (Young) modules of concrete with different strength was intended to compare. For this purpose 150mm dimensions 9 for each design cubic samples prepared and they were subjected to water cure during 28 days. After Seismic Ultrasonic P and S wave travel time measurements of samples, P and S wave velocities and taking advantage of elasticity theory the dynamic elastic modules were calculated. Concrete strength was obtained from the uniaxial compression tests in order to calculate the static elastic modules of the samples. The static elastic modulus is calculated by using the empirical relationships used in international standards. The obtained static and dynamic elastic modules have been associated. A curve was obtained from this association result that approximately similar to the stress-strain curve of obtaining at failure criterion of the sample. This study was supported with OYP05277-DR-14 Project No. by SDU and State Hydraulic Works 13th Regional/2012-01 Project No. Keywords: Concrete Strength, P and S wave Velocities, Static, Dynamic, Young Modules

Structure formation control of foam concrete

NASA Astrophysics Data System (ADS)

Steshenko, Aleksei; Kudyakov, Aleksander; Konusheva, Viktoriya; Syrkin, Oleg

2017-01-01

The process of predetermined foam concrete structure formation is considered to be a crucial issue from the point of process control and it is currently understudied thus defining the need for additional research. One of the effective ways of structure formation control in naturally hardening foam concrete is reinforcement with dispersed fibers or introduction of plasticizers. The paper aims at studying the patterns of influence of microreinforcing and plasticizing additives on the structure and performance properties of foam concrete. Preparation of foam concrete mix has been conducted using one-step technology. The structure of modified foam concrete has been studied by means of electron microscopy. The cellular structure of foam concrete samples with the additives is homogeneous; the pores are uniformly distributed over the total volume. It has been revealed that introduction of the Neolas 5.2 plasticizer and microreinforcing fibers in the foam concrete mixture in the amount of 0.4 - 0.1 % by weight of cement leads to reduction of the average pore diameter in the range of 45.3 to 30.2 microns and the standard deviation of the pore average diameter from 23.6 to 9.2 in comparison with the sample without additive. Introduction of modifying additives has stimulated formation of a large number of closed pores. Thus porosity of conditionally closed pores has increased from 16.06 % to 34.48 %, which has lead to increase of frost resistance brand of foam concrete from F15 to F50 and to reduction of its water absorption by weight by 20 %.

Study of Rust Effect on the Corrosion Behavior of Reinforcement Steel Using Impedance Spectroscopy

NASA Astrophysics Data System (ADS)

Bensabra, Hakim; Azzouz, Noureddine

2013-12-01

Most studies on corrosion of steel reinforcement in concrete are conducted on steel samples with polished surface (free of all oxides) in order to reproduce the same experimental conditions. However, before embedding in concrete, the steel bars are often covered with natural oxides (rust), which are formed during exposure to the atmosphere. The presence of this rust may affect the electrochemical behavior of steel rebar in concrete. In order to understand the effect of rust on the corrosion behavior of reinforcement steel, potentiodynamic and electrochemical impedance spectroscopy (EIS) tests were carried out in a simulated concrete pore solution using steel samples with two different surface conditions: polished and rusted samples. The obtained results have shown that the presence of rust on the steel bar has a negative effect on its corrosion behavior, with or without the presence of chlorides. This detrimental effect can be explained by the fact that the rust provokes a decrease of the electrolyte resistance at the metal-concrete interface and reduces the repassivating ability. In addition, the rust layer acts as a barrier against the hydroxyl ion diffusion, which prevents the realkalinization phenomenon.

Rare earth elements in the phosphatic-enriched sediment of the Peru shelf

USGS Publications Warehouse

Piper, D.Z.; Baedecker, P.A.; Crock, J.G.; Burnett, W.C.; Loebner, B.J.

1988-01-01

Apatite-enriched materials from the Peru shelf have been analyzed for their major oxide and rare earth element (REE) concentrations. The samples consist of (1) the fine fraction of sediment, mostly clay material, (2) phosphatic pellets and fish debris, which are dispersed throughout the fine-grained sediment, (3) tabular-shaped phosphatic crusts, which occur within the uppermost few centimeters of sediment, and (4) phosphatic nodules, which occur on the seafloor. The bulk REE concentrations of the concretions suggest that these elements are partitioned between the enclosed detrital material and the apatite fraction. Analysis of the fine-grained sediment with which the samples are associated suggested that this detrital fraction in the concretions should have shale REE values; the analysis of the fish debris suggested that the apatite fraction might have seawater values. The seawater contribution of REE's is negligible in the nodules and crust, in which the apatite occurs as a fine-grained interstitial cement. That is, the concentration of REE's and the REE patterns are predominantly a function of the amount of enclosed fine-grained sediment. By contrast, the REE pattern of the pelletal apatite suggests a seawater source and the absolute REE concentrations are relatively high. The REE P2O5 ratios of the apatite fraction of these samples thus vary from approximately zero (in the case of the crust and nodules) to as much as approximately 1.2 ?? 10-3 (in the case of the pellets). The range of this ratio suggests that rather subtle variations in the depositional environment might cause a significant variation in the REE content of this authigenic fraction of the sediment. Pelletal glauconite was also recovered from one sediment core. Its REE concentrations closely resemble those of the fish debris. ?? 1988.

Fukushima Daiichi Unit 1 Ex-Vessel Prediction: Core Concrete Interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robb, Kevin R; Farmer, Mitchell; Francis, Matthew W

Lower head failure and corium concrete interaction were predicted to occur at Fukushima Daiichi Unit 1 (1F1) by several different system-level code analyses, including MELCOR v2.1 and MAAP5. Although these codes capture a wide range of accident phenomena, they do not contain detailed models for ex-vessel core melt behavior. However, specialized codes exist for analysis of ex-vessel melt spreading (e.g., MELTSPREAD) and long-term debris coolability (e.g., CORQUENCH). On this basis, an analysis was carried out to further evaluate ex-vessel behavior for 1F1 using MELTSPREAD and CORQUENCH. Best-estimate melt pour conditions predicted by MELCOR v2.1 and MAAP5 were used as input.more » MELTSPREAD was then used to predict the spatially dependent melt conditions and extent of spreading during relocation from the vessel. The results of the MELTSPREAD analysis are reported in a companion paper. This information was used as input for the long-term debris coolability analysis with CORQUENCH.« less

Corrosion products of carbonation induced corrosion in existing reinforced concrete facades

DOE Office of Scientific and Technical Information (OSTI.GOV)

Köliö, Arto; Honkanen, Mari; Lahdensivu, Jukka

Active corrosion in reinforced concrete structures is controlled by environmental conditions and material properties. These factors determine the corrosion rate and type of corrosion products which govern the total achieved service life. The type and critical amount of corrosion products were studied by electron microscopy and X-ray diffractometry on concrete and reinforcement samples from existing concrete facades on visually damaged locations. The corrosion products in outdoor environment exposed concrete facades are mostly hydroxides (Feroxyhite, Goethite and Lepidocrocite) with a volume ratio to Fe of approximately 3. The results can be used to calibrate calculation of the critical corrosion penetration ofmore » concrete facade panels.« less

Behaviour of Recycled Coarse Aggregate Concrete: Age and Successive Recycling

NASA Astrophysics Data System (ADS)

Sahoo, Kirtikanta; Pathappilly, Robin Davis; Sarkar, Pradip

2016-06-01

Recycled Coarse Aggregate (RCA) concrete construction technique can be called as `green concrete', as it minimizes the environmental hazard of the concrete waste disposal. Indian standard recommends target mean compressive strength of the conventional concrete in terms of water cement ratio ( w/ c). The present work is an attempt to study the behaviour of RCA concrete from two samples of parent concrete having different age group with regard to the relationship of compressive strength with water cement ratios. Number of recycling may influence the mechanical properties of RCA concrete. The influence of age and successive recycling on the properties such as capillary water absorption, drying shrinkage strain, air content, flexural strength and tensile splitting strength of the RCA concrete are examined. The relationship between compressive strength at different w/ c ratios obtained experimentally is investigated for the two parameters such as age of parent concrete and successive recycling. The recycled concrete using older recycled aggregate shows poor quality. While the compressive strength reduces with successive recycling gradually, the capillary water absorption increases abruptly, which leads to the conclusion that further recycling may not be advisable.

Carbon analysis for inspecting carbonation of concrete using a TEA CO2 laser-induced plasma.

PubMed

Kagawa, Kiichiro; Idris, Nasrullah; Wada, Munehide; Kurniawan, Hendrik; Tsuyuki, Kenichiro; Miura, Satoru

2004-08-01

It has been demonstrated that a spectrochemical analysis of carbon using the laser plasma method can be successfully applied to inspect the carbonation of concrete by detecting carbon produced in aged concrete by a chemical reaction of Ca(OH)2 with CO2 gas in environmental air, turning into CaCO3, which induces degradation of the quality of building concrete. A comparative study has been made using a TEA CO2 laser (500-1000 mJ) and a Q-switched Nd-YAG laser (50-200 mJ) to search for the optimum conditions for carbon analysis, proving the advantage of the TEA CO2 laser for this purpose. Also, it was clarified that laser irradiation with suitable defocusing conditions is a crucial point for obtaining high sensitivity in the detection of carbon. Practical experiments on the inspection of carbonation were carried out using both a concrete sample that had been intentionally carbonated by exposure to high concentrations of CO2 gas and a naturally carbonated concrete sample. As a result, good coincidence was observed between the laser method and the ordinary method, which uses the chemical indicator phenolphthalein, implying that this laser technique is applicable as an in situ quantitative method of inspection for carbonation of concrete.

Physio-chemical reactions in recycle aggregate concrete.

PubMed

Tam, Vivian W Y; Gao, X F; Tam, C M; Ng, K M

2009-04-30

Concrete waste constitutes the major proportion of construction waste at about 50% of the total waste generated. An effective way to reduce concrete waste is to reuse it as recycled aggregate (RA) for the production of recycled aggregate concrete (RAC). This paper studies the physio-chemical reactions of cement paste around aggregate for normal aggregate concrete (NAC) and RAC mixed with normal mixing approach (NMA) and two-stage mixing approach (TSMA) by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Four kinds of physio-chemical reactions have been recorded from the concrete samples, including the dehydration of C(3)S(2)H(3), iron-substituted ettringite, dehydroxylation of CH and development of C(6)S(3)H at about 90 degrees C, 135 degrees C, 441 degrees C and 570 degrees C, respectively. From the DSC results, it is confirmed that the concrete samples with RA substitution have generated less amount of strength enhancement chemical products when compared to those without RA substitution. However, the results from the TSMA are found improving the RAC quality. The pre-mix procedure of the TSMA can effectively develop some strength enhancing chemical products including, C(3)S(2)H(3), ettringite, CH and C(6)S(3)H, which shows that RAC made from the TSMA can improve the hydration processes.

Behavior of reinforcement SCC beams under elevated temperatures

NASA Astrophysics Data System (ADS)

Fathi, Hamoon; Farhang, Kianoosh

2015-09-01

This experimental study focuses on the behavior of heated reinforced concrete beams. Four types of concrete mixtures were used for the tested self-compacting concrete beams. A total of 72 reinforced concrete beams and 72 standard cylindrical specimens were tested. The compressive strength under uniaxial loading at 23 °C ranged from 30 to 45 MPa. The specimens were exposed to different temperatures. The test parameters of interest were the compressive strength and the temperature of the specimens. The effect of changes in the parameters was examined so as to control the behavior of the tested concrete and that of the reinforced concrete beam. The results indicated that flexibility and compressive strength of the reinforced concrete beams decreased at higher temperatures. Furthermore, heating beyond 400 °C produced greater variations in the structural behavior of the materials in both the cylindrical samples and the reinforced concrete beams.

An embedded stress sensor for concrete SHM based on amorphous ferromagnetic microwires.

PubMed

Olivera, Jesús; González, Margarita; Fuente, José Vicente; Varga, Rastislav; Zhukov, Arkady; Anaya, José Javier

2014-10-24

A new smart concrete aggregate design as a candidate for applications in structural health monitoring (SHM) of critical elements in civil infrastructure is proposed. The cement-based stress/strain sensor was developed by utilizing the stress/strain sensing properties of a magnetic microwire embedded in cement-based composite (MMCC). This is a contact-less type sensor that measures variations of magnetic properties resulting from stress variations. Sensors made of these materials can be designed to satisfy the specific demand for an economic way to monitor concrete infrastructure health. For this purpose, we embedded a thin magnetic microwire in the core of a cement-based cylinder, which was inserted into the concrete specimen under study as an extra aggregate. The experimental results show that the embedded MMCC sensor is capable of measuring internal compressive stress around the range of 1-30 MPa. Two stress sensing properties of the embedded sensor under uniaxial compression were studied: the peak amplitude and peak position of magnetic switching field. The sensitivity values for the amplitude and position within the measured range were 5 mV/MPa and 2.5 µs/MPa, respectively.

Global Warming Implications of the Use of By-Products and Recycled Materials in Western Australia’s Housing Sector

PubMed Central

Lawania, Krishna; Sarker, Prabir; Biswas, Wahidul

2015-01-01

Western Australia’s housing sector is growing rapidly and around half a million houses are expected to be built by 2030, which not only will result in increased energy and resources demand but will have socio-economic impacts. Majority of Western Australians live in detached houses made of energy intensive clay bricks, which have a high potential to generate construction and demolition (C&D) waste. Therefore, there is a need to look into the use of alternative materials and construction methods. Due to Western Australia’s temperate climate, concrete could not only offer a comfortable living space but an operational energy saving also can be achieved. This paper has assessed the global warming implications of cast in-situ concrete sandwich wall system as an alternative to clay brick walls (CBW) with partial replacement of cement in concrete with by-products such as fly ash (FA) and ground granulated blast furnace slag (GGBFS), natural aggregate (NA) with recycled crushed aggregate (RCA), natural sand (NS) with manufactured sand (MS) and, polyethylene terephthalate (PET) foam core as a replacement to polystyrene core for construction of a typical 4 × 2 × 2 detached house in Perth. Life cycle management (LCM) approach has been used to determine global warming reduction benefits due to the use of available by-products and recycled materials in Western Australian houses.

Dynamic Eigenvalue Problem of Concrete Slab Road Surface

NASA Astrophysics Data System (ADS)

Pawlak, Urszula; Szczecina, Michał

2017-10-01

The paper presents an analysis of the dynamic eigenvalue problem of concrete slab road surface. A sample concrete slab was modelled using Autodesk Robot Structural Analysis software and calculated with Finite Element Method. The slab was set on a one-parameter elastic subsoil, for which the modulus of elasticity was separately calculated. The eigen frequencies and eigenvectors (as maximal vertical nodal displacements) were presented. On the basis of the results of calculations, some basic recommendations for designers of concrete road surfaces were offered.

Studying the Variation in Gas Permeability of Porous Building Substrates

NASA Astrophysics Data System (ADS)

Townsend, L.; Savidge, C. R.; Hu, L.; Rizzo, D. M.; Hayden, N. J.; Dewoolkar, M.

2009-12-01

Understanding permeability of building materials is important for problems involving studies of contaminant transport. Examples include contamination from fire, acid rain, and chemical and biological weapons. Our research investigates the gas permeability of porous building substrates such as concretes, limestones, sandstones, and bricks. Each sample was cored to produce 70 mm (2.75”) diameter cores approximately 75-130 mm (3-5”) tall. The surface gas permeability was measured on the top surface of these specimens using the AutoScan II device manufactured by New England Research, Inc. The measurements were taken along a 3 mm grid producing a map of surface gas permeability. An example map is shown in Figure 1. The macroscopic measurements were performed along the entire cored specimen. A second set of measurements were made on a 5 mm thick slice cut from the top of each specimen to examine whether these measurements compare better with the surface measurements. The macroscopic gas permeability was measured for all specimens using ASTM D 4525. The results are summarized in Table 1. In general, the surface and macroscopic gas permeability measurements (Table 1) compare reasonably well (within one order of magnitude). The permeability of the 5 mm slices is not significantly different from the entire core for the specimens tested. Figure 1. Results of surface permeability mappingof Ohio Sandstone using the AutoScan II device. a) Map of gas permeability b) Range of gas permeability c) Density function of permeability. Table 1. Gas permeability values (mD)

Acoustic Signal Processing for Pipe Condition Assessment (WaterRF Report 4360)

EPA Science Inventory

Unique to prestressed concrete cylinder pipe (PCCP), individual wire breaks create an excitation in the pipe wall that may vary in response to the remaining compression of the pipe core. This project was designed to improve acoustic signal processing for pipe condition assessment...

Nuclear reactor cavity floor passive heat removal system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, Tyler A.; Neeley, Gary W.; Inman, James B.

A nuclear reactor includes a reactor core disposed in a reactor pressure vessel. A radiological containment contains the nuclear reactor and includes a concrete floor located underneath the nuclear reactor. An ex vessel corium retention system includes flow channels embedded in the concrete floor located underneath the nuclear reactor, an inlet in fluid communication with first ends of the flow channels, and an outlet in fluid communication with second ends of the flow channels. In some embodiments the inlet is in fluid communication with the interior of the radiological containment at a first elevation and the outlet is in fluidmore » communication with the interior of the radiological containment at a second elevation higher than the first elevation. The radiological containment may include a reactor cavity containing a lower portion of the pressure vessel, wherein the concrete floor located underneath the nuclear reactor is the reactor cavity floor.« less

Thermal Behavior of Cylindrical Buckling Restrained Braces at Elevated Temperatures

PubMed Central

Talebi, Elnaz; Tahir, Mahmood Md.; Yasreen, Airil

2014-01-01

The primary focus of this investigation was to analyze sequentially coupled nonlinear thermal stress, using a three-dimensional model. It was meant to shed light on the behavior of Buckling Restraint Brace (BRB) elements with circular cross section, at elevated temperature. Such bracing systems were comprised of a cylindrical steel core encased in a strong concrete-filled steel hollow casing. A debonding agent was rubbed on the core's surface to avoid shear stress transition to the restraining system. The numerical model was verified by the analytical solutions developed by the other researchers. Performance of BRB system under seismic loading at ambient temperature has been well documented. However, its performance in case of fire has yet to be explored. This study showed that the failure of brace may be attributed to material strength reduction and high compressive forces, both due to temperature rise. Furthermore, limiting temperatures in the linear behavior of steel casing and concrete in BRB element for both numerical and analytical simulations were about 196°C and 225°C, respectively. Finally it is concluded that the performance of BRB at elevated temperatures was the same as that seen at room temperature; that is, the steel core yields prior to the restraining system. PMID:24526915

A mechanism for the production of ultrafine particles from concrete fracture.

PubMed

Jabbour, Nassib; Rohan Jayaratne, E; Johnson, Graham R; Alroe, Joel; Uhde, Erik; Salthammer, Tunga; Cravigan, Luke; Faghihi, Ehsan Majd; Kumar, Prashant; Morawska, Lidia

2017-03-01

While the crushing of concrete gives rise to large quantities of coarse dust, it is not widely recognized that this process also emits significant quantities of ultrafine particles. These particles impact not just the environments within construction activities but those in entire urban areas. The origin of these ultrafine particles is uncertain, as existing theories do not support their production by mechanical processes. We propose a hypothesis for this observation based on the volatilisation of materials at the concrete fracture interface. The results from this study confirm that mechanical methods can produce ultrafine particles (UFP) from concrete, and that the particles are volatile. The ultrafine mode was only observed during concrete fracture, producing particle size distributions with average count median diameters of 27, 39 and 49 nm for the three tested concrete samples. Further volatility measurements found that the particles were highly volatile, showing between 60 and 95% reduction in the volume fraction remaining by 125 °C. An analysis of the volatile fraction remaining found that different volatile material is responsible for the production of particles between the samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Non-destructive testing of concrete.

DOT National Transportation Integrated Search

1979-11-01

This research project was initiated to evaluate the performance of an ultrasonic testing device device in predicting compressive strengths from tests performed on samples of fresh concrete. : The initial phase of this study involved laboratory perora...

The Usability of Rock-Like Materials for Numerical Studies on Rocks

NASA Astrophysics Data System (ADS)

Zengin, Enes; Abiddin Erguler, Zeynal

2017-04-01

The approaches of synthetic rock material and mass are widely used by many researchers for understanding the failure behavior of different rocks. In order to model the failure behavior of rock material, researchers take advantageous of different techniques and software. But, the majority of all these instruments are based on distinct element method (DEM). For modeling the failure behavior of rocks, and so to create a fundamental synthetic rock material model, it is required to perform related laboratory experiments for providing strength parameters. In modelling studies, model calibration processes are performed by using parameters of intact rocks such as porosity, grain size, modulus of elasticity and Poisson ratio. In some cases, it can be difficult or even impossible to acquire representative rock samples for laboratory experiments from heavily jointed rock masses and vuggy rocks. Considering this limitation, in this study, it was aimed to investigate the applicability of rock-like material (e.g. concrete) to understand and model the failure behavior of rock materials having complex inherent structures. For this purpose, concrete samples having a mixture of %65 cement dust and %35 water were utilized. Accordingly, intact concrete samples representing rocks were prepared in laboratory conditions and their physical properties such as porosity, pore size and density etc. were determined. In addition, to acquire the mechanical parameters of concrete samples, uniaxial compressive strength (UCS) tests were also performed by simultaneously measuring strain during testing. The measured physical and mechanical properties of these extracted concrete samples were used to create synthetic material and then uniaxial compressive tests were modeled and performed by using two dimensional discontinuum program known as Particle Flow Code (PFC2D). After modeling studies in PFC2D, approximately similar failure mechanism and testing results were achieved from both experimental and artificial simulations. The results obtained from these laboratory tests and modelling studies were compared with the other researcher's studies in respect to failure mechanism of different type of rocks. It can be concluded that there is similar failure mechanism between concrete and rock materials. Therefore, the results obtained from concrete samples that would be prepared at different porosity and pore sizes can be used in future studies in selection micro-mechanical and physical properties to constitute synthetic rock materials for understanding failure mechanism of rocks having complex inherent structures such as vuggy rocks or heavily jointed rock masses.

Long-term Metal Performance of Three Permeable Pavements ...

EPA Pesticide Factsheets

EPA constructed a 4,000-m2 parking lot surfaced with three permeable pavements (permeable interlocking concrete pavers, pervious concrete, and porous asphalt) on the Edison Environmental Center in Edison, NJ in 2009. Samples from each permeable pavement infiltrate were collected for six years beginning in January 2010 and analyzed for twenty-two metals. Although the infiltrate metals concentrations varied by surface, metal concentrations in more than 99% of the permeable pavement infiltrate samples met both the groundwater effluent limitations and maximum contaminant levels in national primary drinking water regulations for barium, chromium, copper, manganese, nickel and zinc. Arsenic, cadmium, lead and antimony met those standards in 60% to 98% of the samples with no measurable difference found among pavements. Aluminum and iron in pervious concrete and porous asphalt infiltrates met standards at more than 90%, however permeable interlocking concrete paver infiltrates have 50% and 93% samples exceeds standards, respectively. Concentrations of arsenic, iron, potassium, lithium, magnesium, antimony, tin, manganese, and zinc in all permeable pavement infiltrates decreased with time, whereas, aluminum, barium, calcium, chromium and strontium in porous asphalt infiltrates increased. Most metal concentrations in permeable pavement infiltrates either exhibited no significant difference between snow/no-snow seasons or showed statistically larger concentrations

Crumb Rubber-Concrete Panels Under Blast Loads

DTIC Science & Technology

2010-05-01

and the samples were labeled. Samples were picked up with an overhead crane and a form spreader connected to two points on the sample, each outside...uniform loading. Shortly after test started 8 to 9 cracks developed within quarter points and 2 cracks developed through pick points where form spreader ...dynamic behaviour of recycled tyre rubber-filled concrete.” Cem. Concr. Res., 32, 1587–1596. Huang, B., Li, G., Pang, S. S., and Eggers, J. (2004

Repair of heat damaged reinforced concrete slab with High Strength Fibre Reinforced Concrete materials

NASA Astrophysics Data System (ADS)

Ain Hamiruddin, Nur; Razak, Rafiza Abd; Muhammad, Khairunnisa; Zahid, Muhd Zulham Affendi Mohd

2018-04-01

The purpose of this study is to investigate the flexural behaviour of heat damaged reinforced concrete (RC) slab by using High Strength Fibre Reinforced Concrete (HSFRC) as repair materials. The slab samples consist of twelve one-way columns heated at 200 ° C, 400 ° C and 600 ° C for 120 minutes. The thickness of the HSFRC layer used to heat damaged slab samples is 40 mm thick. Two distinct curing methods were implement during this study: i.e. normal curing (standard room temperature 26°C) and heat curing (temperature of 90°C for 48 hours). The center-point loading flexural strength test based on ASTM C 293 were referred to examine the flexural strength of the slab samples other than evaluated the mechanical properties of repaired samples (i.e. flexural strength, secant stiffness, toughness and ductility). The HSFRC's results showed that compressive strength at 28 days was 88.66 MPa. Whereas the flexural strength of heat damage repaired samples that exposed to 200°C (R200), 400°C (RNC400) and 400°C (RHC400) were gained by about 3.06% (34.93 MPa), 14.47% (38.79 MPa) and 30.95% (44.38 MPa) respectively, contrasted to the control sample (CS) which is 33.89 MPa. However, heat damage for non-repaired samples that exposed to 200 ° C (NR200) and 400°C (NR400) decline by about 0.77% (33.63 MPa) and 8.13% (31.14 MPa) respectively. Therefore, the utilized of HSFRC as repair materials can improve the flexural strength than control sample (CS). This is clearly indicate that HSFRC can enhance the mechanical properties of heat damaged reinforced concrete (RC) slab which can illustrate that the results of flexural behaviour reflected the superiority by using HSFRC as repair materials.

Radiological and material characterization of high volume fly ash concrete.

PubMed

Ignjatović, I; Sas, Z; Dragaš, J; Somlai, J; Kovács, T

2017-03-01

The main goal of research presented in this paper was the material and radiological characterization of high volume fly ash concrete (HVFAC) in terms of determination of natural radionuclide content and radon emanation and exhalation coefficients. All concrete samples were made with a fly ash content between 50% and 70% of the total amount of cementitious materials from one coal burning power plant in Serbia. Physical (fresh and hardened concrete density) and mechanical properties (compressive strength, splitting tensile strength and modulus of elasticity) of concrete were tested. The radionuclide content ( 226 Ra, 232 Th and 40 K) and radon massic exhalation of HVFAC samples were determined using gamma spectrometry. Determination of massic exhalation rates of HVFAC and its components using radon accumulation chamber techniques combined with a radon monitor was performed. The results show a beneficial effect of pozzolanic activity since the increase in fly ash content resulted in an increase in compressive strength of HVFAC by approximately 20% for the same mass of cement used in the mixtures. On the basis of the obtained radionuclide content of concrete components the I -indices of different HVFAC samples were calculated and compared with measured values (0.27-0.32), which were significantly below the recommended 1.0 index value. The prediction was relatively close to the measured values as the ratio between the calculated and measured I-index ranged between 0.89 and 1.14. Collected results of mechanical and radiological properties and performed calculations clearly prove that all 10 designed concretes with a certain type of fly ash are suitable for structural and non-structural applications both from a material and radiological point of view. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cognitive Metaphor Theory and the Metaphysics of Immediacy

ERIC Educational Resources Information Center

Madsen, Mathias W.

2016-01-01

One of the core tenets of cognitive metaphor theory is the claim that metaphors ground abstract knowledge in concrete, first-hand experience. In this paper, I argue that this grounding hypothesis contains some problematic conceptual ambiguities and, under many reasonable interpretations, empirical difficulties. I present evidence that there are…

Effects Of Desensitization Treatment On Core-Condition Training

ERIC Educational Resources Information Center

Fry, P. S.

1973-01-01

Pre- and posttest ratings on measures of helping skills such as empathy, respect, concreteness, and genuineness were obtained in the preliminary and advanced training. A significant training effect was obtained for both groups. Desensitization treatment was a significant source of variance for the experimental subjects in training. (Author/LA)

10 CFR 52.47 - Contents of applications; technical information.

Code of Federal Regulations, 2013 CFR

2013-01-01

... accidents, e.g., challenges to containment integrity caused by core-concrete interaction, steam explosion... such as the service water intake structure and the ultimate heat sink; (2) An application for... design except for site-specific elements such as the service water intake structure and the ultimate heat...

10 CFR 52.47 - Contents of applications; technical information.

Code of Federal Regulations, 2010 CFR

2010-01-01

... accidents, e.g., challenges to containment integrity caused by core-concrete interaction, steam explosion... such as the service water intake structure and the ultimate heat sink; (2) An application for... design except for site-specific elements such as the service water intake structure and the ultimate heat...

10 CFR 52.47 - Contents of applications; technical information.

Code of Federal Regulations, 2011 CFR

2011-01-01

... accidents, e.g., challenges to containment integrity caused by core-concrete interaction, steam explosion... such as the service water intake structure and the ultimate heat sink; (2) An application for... design except for site-specific elements such as the service water intake structure and the ultimate heat...

10 CFR 52.47 - Contents of applications; technical information.

Code of Federal Regulations, 2014 CFR

2014-01-01

... accidents, e.g., challenges to containment integrity caused by core-concrete interaction, steam explosion... such as the service water intake structure and the ultimate heat sink; (2) An application for... design except for site-specific elements such as the service water intake structure and the ultimate heat...

10 CFR 52.47 - Contents of applications; technical information.

Code of Federal Regulations, 2012 CFR

2012-01-01

... accidents, e.g., challenges to containment integrity caused by core-concrete interaction, steam explosion... such as the service water intake structure and the ultimate heat sink; (2) An application for... design except for site-specific elements such as the service water intake structure and the ultimate heat...

Properties and Leachability of Self-Compacting Concrete Incorporated with Fly Ash and Bottom Ash

NASA Astrophysics Data System (ADS)

Kadir, Aeslina Abdul; Ikhmal Haqeem Hassan, Mohd; Jamaluddin, Norwati; Bakri Abdullah, Mohd Mustafa Al

2016-06-01

The process of combustion in coal-fired power plant generates ashes, namely fly ash and bottom ash. Besides, coal ash produced from coal combustion contains heavy metals within their compositions. These metals are toxic to the environment as well as to human health. Fortunately, treatment methods are available for these ashes, and the use of fly ash and bottom ash in the concrete mix is one of the few. Therefore, an experimental program was carried out to study the properties and determine the leachability of selfcompacting concrete incorporated with fly ash and bottom ash. For experimental study, self-compacting concrete was produced with fly ash as a replacement for Ordinary Portland Cement and bottom ash as a replacement for sand with the ratios of 10%, 20%, and 30% respectively. The fresh properties tests conducted were slump flow, t500, sieve segregation and J-ring. Meanwhile for the hardened properties, density, compressive strength and water absorption test were performed. The samples were then crushed to be extracted using Toxicity Characteristic Leaching Procedure and heavy metals content within the samples were identified accordingly using Atomic Absorption Spectrometry. The results demonstrated that both fresh and hardened properties were qualified to categorize as self-compacting concrete. Improvements in compressive strength were observed, and densities for all the samples were identified as a normal weight concrete with ranges between 2000 kg/m3 to 2600 kg/m3. Other than that, it was found that incorporation up to 30% of the ashes was safe as the leached heavy metals concentration did not exceed the regulatory levels, except for arsenic. In conclusion, this study will serve as a reference which suggests that fly ash and bottom ash are widely applicable in concrete technology, and its incorporation in self-compacting concrete constitutes a potential means of adding value to appropriate mix and design.

Development of Vegetation-Pervious Concrete in Grid Beam System for Soil Slope Protection.

PubMed

Bao, Xiaohua; Liao, Wenyu; Dong, Zhijun; Wang, Shanyong; Tang, Waiching

2017-01-24

One of the most efficient and environmentally friendly methods for preventing a landslide on a slope is to vegetate it. Vegetation-pervious concretes have a promising potential for soil protection. In this study, the vegetation-pervious concrete with low alkalinity was developed and studied. Combined with a grid beam structure system, the stability and strength between the vegetation-pervious concrete and base soil are believed to be enhanced effectively. For improving plant adaptability, the alkalinity of concrete can be decreased innovatively by adding a self-designed admixture into the cement paste. The effects of the admixture content on alkalinity and compressive strength of the hardened pervious concrete were investigated using X-ray diffraction (XRD) and compression test, respectively. Meanwhile, the permeability of the vegetation-pervious concrete was studied as well. Through comparing with ordinary pervious concrete, the effect of low alkaline pervious concrete on vegetation growth was investigated in a small-scale field for ten weeks. The test results indicated that the alkalinity of the cement samples decreased with the increase of admixture content, and the vegetation grew successfully on previous concrete. By increasing the admixture content to approximately 3.6%, the compressive strength of pervious concrete was more than 25 MPa.

Development of a Failure Theory for Concrete

DOT National Transportation Integrated Search

2012-07-31

The failure behavior of concrete materials is not completely understood because conventional test methods fail to assess the : material response independent of the sample size and shape. : To study the influence of strength affecting test conditions,...

Organic compounds in concrete from demolition works.

PubMed

Van Praagh, M; Modin, H; Trygg, J

2015-11-01

This study aims to verify the effect of physically removing the outer surface of contaminated concrete on total contents and on potential mobility of pollutants by means of leaching tests. Reclaimed concrete from 3 industrial sites in Sweden were included: A tar impregnated military storage, a military tar track-depot, as well as concrete constructions used for disposing of pesticide production surplus and residues. Solid materials and leachates from batch and column leaching tests were analysed for metals, Cl, F, SO4, DOC and contents of suspected organic compounds (polycyclic aromatic hydrocarbons, PAH, and pesticides/substances for pesticide production such as phenoxy acids, chlorophenols and chlorocresols, respectively). In case of PAH contaminated concrete, results indicate that removing 1 or 5 mm of the surface lead to total concentrations below the Swedish guidelines for recycling of aggregates and soil in groundwork constructions. 3 out of 4 concrete samples contaminated with pesticides fulfilled Swedish guidelines for contaminated soil. Results from batch and column leaching tests indicated, however, that concentrations above environmental quality standards for certain PAH and phenoxy acids, respectively, might occur at site when the crushed concrete is recycled in groundwork constructions. As leaching tests engaged in the study deviated from leaching test standards with a limited number of samples, the potential impact of the leaching tests' equipment on measured PAH and pesticide leachate concentrations has to be evaluated in future work. Copyright © 2015. Published by Elsevier Ltd.

The Latent Structure of Dictionaries.

PubMed

Vincent-Lamarre, Philippe; Massé, Alexandre Blondin; Lopes, Marcos; Lord, Mélanie; Marcotte, Odile; Harnad, Stevan

2016-07-01

How many words-and which ones-are sufficient to define all other words? When dictionaries are analyzed as directed graphs with links from defining words to defined words, they reveal a latent structure. Recursively removing all words that are reachable by definition but that do not define any further words reduces the dictionary to a Kernel of about 10% of its size. This is still not the smallest number of words that can define all the rest. About 75% of the Kernel turns out to be its Core, a "Strongly Connected Subset" of words with a definitional path to and from any pair of its words and no word's definition depending on a word outside the set. But the Core cannot define all the rest of the dictionary. The 25% of the Kernel surrounding the Core consists of small strongly connected subsets of words: the Satellites. The size of the smallest set of words that can define all the rest-the graph's "minimum feedback vertex set" or MinSet-is about 1% of the dictionary, about 15% of the Kernel, and part-Core/part-Satellite. But every dictionary has a huge number of MinSets. The Core words are learned earlier, more frequent, and less concrete than the Satellites, which are in turn learned earlier, more frequent, but more concrete than the rest of the Dictionary. In principle, only one MinSet's words would need to be grounded through the sensorimotor capacity to recognize and categorize their referents. In a dual-code sensorimotor/symbolic model of the mental lexicon, the symbolic code could do all the rest through recombinatory definition. Copyright © 2016 Cognitive Science Society, Inc.

CBP [TASK 12] experimental study of the concrete salstone two-layer system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samson, Eric; Protiere, Yannick

This report presents the results of a study which intended to study the behavior of concrete samples placed in contact with a wasteform mixture bearing high level of sulfate in its pore solution. A setup was prepared which consisted in a wasteform poured on top of vault concrete mixes (identified as Vault 1/4 and Vault 2 mixes) cured for approximately 6 months.

Ultrasonic Evaluation of the Pull-Off Adhesion between Added Repair Layer and a Concrete Substrate

NASA Astrophysics Data System (ADS)

Czarnecki, Slawomir

2017-10-01

This paper concerns the evaluation of the pull-off adhesion between a concrete added repair layer with variable thickness and a concrete substrate, based on parameters assessed using ultrasonic pulse velocity (UPV) method. In construction practice, the experimental determination of pull-off adhesion f b, between added repair layer and a concrete substrate is necessary to assess the quality of repair. This is usually carried out with the use of pull-off method which results in local damage of the added concrete layer in all the testing areas. Bearing this in mind, it is important to describe the method without these disadvantages. The prediction of the pull-off adhesion of the two-layer concrete elements with variable thickness of each layer might be provided by means of UPV method with two-sided access to the investigated element. For this purpose, two-layered cylindrical specimens were obtained by drilling the borehole from a large size specially prepared concrete element. Those two-layer elements were made out of concrete substrate layer and Polymer Cement Concrete (PCC) mortar as an added repair layer. The values of pull-off adhesion f b of the elements were determined before obtaining the samples by using the semi-destructive pull-off method. The ultrasonic wave velocity was determined in samples with variable thickness of each layer and was then compared to theoretical ultrasonic wave velocity predicted for those specimens. The regression curve for the dependence of velocity and pull-off adhesion, determined by the pulloff method, was made. It has been proved that together with an increase of ratio of investigated ultrasonic wave velocity divided by theoretical ultrasonic wave velocity, the pull-off adhesion value f b between added repair layer with variable thickness and a substrate layer also increases.

Production of Dioxins and Furans from the Burning of Excess Gun Propellant

DTIC Science & Technology

2011-01-01

This is done by positioning the charges on the surface of the ground, in a shallow trench, on a concrete slab or in metal trays and igniting them from...environment are not fully understood. Burning, whether on snow cover, the ground or a combustion plate ( concrete or steel), does not lead to complete...the values for the background samples. The results for the samples taken from under the burnt pads (at a soil depth of 0 to 1 cm, samples BOP-12

Effect of notch position on fracture energy for foamed concrete

NASA Astrophysics Data System (ADS)

Naqiuddin Zamri, Mohd; Rahman, Norashidah Abd; Jaini, Zainorizuan Mohd; Shamila Bahador, Nurul

2017-11-01

Foamed concrete is one of the lightweight concrete used to replace normal concrete. Foamed concrete has potential as a building construction material in Malaysia due to low density range. However, the behavior of fracture energy on foamed concrete still under investigation. Therefore, a study to determine the fracture energy of foamed concrete was conducted. In this study, foamed concrete fracture energy was obtained using the three-point bending test methods develop by RILEM and Hillerborg. A total of 12 beams with different types of notch and positions of notch were tested on the load-deflection condition. In addition, a total of 9 cube samples were cast to support the result of fracture energy by using model from Bazant and Becq-Giraudon and Comite Euro-International du Beton (CEB). Results showed the far the position of the notch from midpoint, the higher the value of fracture energy. In this study, the value of fracture energy ranges between 15 N/m and 40 N/m.

A Study on the Reuse of Plastic Concrete Using Extended Set-Retarding Admixtures.

PubMed

Lobo, Colin; Guthrie, William F; Kacker, Raghu

1995-01-01

The disposal of ready mixed concrete truck wash water and returned plastic concrete is a growing concern for the ready mixed concrete industry. Recently, extended set-retarding admixtures, or stabilizers, which slow or stop the hydration of portland cement have been introduced to the market. Treating truck wash-water or returned plastic concrete with stabilizing admixtures delays its setting and hardening, thereby facilitating the incorporation of these typically wasted materials in subsequent concrete batches. In a statistically designed experiment, the properties of blended concrete containing stabilized plastic concrete were evaluated. The variables in the study included (1) concrete age when stabilized, (2) stabilizer dosage, (3) holding period of the treated (stabilized) concrete prior to blending with fresh ingredients, and (4) amount of treated concrete in the blended batch. The setting time, strength, and drying shrinkage of the blended concretes were evaluated. For the conditions tested, batching 5 % treated concrete with fresh material did not have a significant effect on the setting time, strength, or drying shrinkage of the resulting blended concrete. Batching 50 % treated concrete with fresh materials had a significant effect on the setting characteristics of the blended cocnrete, which in turn affected the water demand to maintain slump. The data suggests that for a known set of conditions, the stabilizer dosage can be optimized within a relatively narrow range to produce desired setting characteristics. The strength and drying shrinkage of the blended concretes were essentially a function of the water content at different sampling ages and the relationship followed the general trend of control concrete.

A Study on the Reuse of Plastic Concrete Using Extended Set-Retarding Admixtures

PubMed Central

Lobo, Colin; Guthrie, William F.; Kacker, Raghu

1995-01-01

The disposal of ready mixed concrete truck wash water and returned plastic concrete is a growing concern for the ready mixed concrete industry. Recently, extended set-retarding admixtures, or stabilizers, which slow or stop the hydration of portland cement have been introduced to the market. Treating truck wash-water or returned plastic concrete with stabilizing admixtures delays its setting and hardening, thereby facilitating the incorporation of these typically wasted materials in subsequent concrete batches. In a statistically designed experiment, the properties of blended concrete containing stabilized plastic concrete were evaluated. The variables in the study included (1) concrete age when stabilized, (2) stabilizer dosage, (3) holding period of the treated (stabilized) concrete prior to blending with fresh ingredients, and (4) amount of treated concrete in the blended batch. The setting time, strength, and drying shrinkage of the blended concretes were evaluated. For the conditions tested, batching 5 % treated concrete with fresh material did not have a significant effect on the setting time, strength, or drying shrinkage of the resulting blended concrete. Batching 50 % treated concrete with fresh materials had a significant effect on the setting characteristics of the blended cocnrete, which in turn affected the water demand to maintain slump. The data suggests that for a known set of conditions, the stabilizer dosage can be optimized within a relatively narrow range to produce desired setting characteristics. The strength and drying shrinkage of the blended concretes were essentially a function of the water content at different sampling ages and the relationship followed the general trend of control concrete. PMID:29151762

Maintenance Resources by Building Use for U.S. Army Installations. Volume 3. Appendices I through P

DTIC Science & Technology

1991-05-01

floor I____ ______ __ Solid core (safety 0423230 10 2.78 glass ) painted exterior door Drinking fountain 081 1HOO _______6 1.77 Wood, finished 0415FI0...Concrete, finished 062B200 25 1.15 flooring Solid core wood 0423230 26 1.12 (safety glass ) paint exterior door Safety switch, 1122100 27 1.07 enclosed...exterior, 1st floor Steel frame 0431210 26 1.04 (painted) operable window, 1st floor Steel (w/safety 0421220 27 1.04 glass ) painted exterior door Pipe

Carbon Nanofiber Cement Sensors to Detect Strain and Damage of Concrete Specimens Under Compression

PubMed Central

Baeza, F. Javier; Garcés, Pedro

2017-01-01

Cement composites with nano-additions have been vastly studied for their functional applications, such as strain and damage sensing. The capacity of a carbon nanofiber (CNF) cement paste has already been tested. However, this study is focused on the use of CNF cement composites as sensors in regular concrete samples. Different measuring techniques and humidity conditions of CNF samples were tested to optimize the strain and damage sensing of this material. In the strain sensing tests (for compressive stresses up to 10 MPa), the response depends on the maximum stress applied. The material was more sensitive at higher loads. Furthermore, the actual load time history did not influence the electrical response, and similar curves were obtained for different test configurations. On the other hand, damage sensing tests proved the capability of CNF cement composites to measure the strain level of concrete samples, even for loads close to the material’s strength. Some problems were detected in the strain transmission between sensor and concrete specimens, which will require specific calibration of each sensor one attached to the structure. PMID:29186797

Carbon Nanofiber Cement Sensors to Detect Strain and Damage of Concrete Specimens Under Compression.

PubMed

Galao, Oscar; Baeza, F Javier; Zornoza, Emilio; Garcés, Pedro

2017-11-24

Cement composites with nano-additions have been vastly studied for their functional applications, such as strain and damage sensing. The capacity of a carbon nanofiber (CNF) cement paste has already been tested. However, this study is focused on the use of CNF cement composites as sensors in regular concrete samples. Different measuring techniques and humidity conditions of CNF samples were tested to optimize the strain and damage sensing of this material. In the strain sensing tests (for compressive stresses up to 10 MPa), the response depends on the maximum stress applied. The material was more sensitive at higher loads. Furthermore, the actual load time history did not influence the electrical response, and similar curves were obtained for different test configurations. On the other hand, damage sensing tests proved the capability of CNF cement composites to measure the strain level of concrete samples, even for loads close to the material's strength. Some problems were detected in the strain transmission between sensor and concrete specimens, which will require specific calibration of each sensor one attached to the structure.

[Damage of modern building materials by microscopic fungi].

PubMed

Chuenko, A I; Karpenko, Iu V

2011-01-01

Resistance of three materials, produced on the basis of concrete compounds to the action of microscopic fungi, isolated from damaged living buildings, has been first investigated. It has been shown that samples of froth-block and thermoeffective block had low fungal resistance, in contrast to samples of cellular polystyrene concrete, which were resistant to fungal action, that can be associated with peculiarities of their component composition.

Evaluation of performance based concrete for bridge decks.

DOT National Transportation Integrated Search

2015-06-01

The Washington State Department of Transportation (WSDOT) revised the concrete : specification for bridge decks in 2011 to be more performance based with the desired effect of : having less early-age shrinkage cracking. This report evaluates a sample...

Identification of concrete deteriorating minerals by polarizing and scanning electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gregerova, Miroslava, E-mail: mirka@sci.muni.cz; Vsiansky, Dalibor, E-mail: daliborv@centrum.cz

2009-07-15

The deterioration of concrete represents one of the most serious problems of civil engineering worldwide. Besides other processes, deterioration of concrete consists of sulfate attack and carbonation. Sulfate attack results in the formation of gypsum, ettringite and thaumasite in hardened concrete. Products of sulfate attack may cause a loss of material strength and a risk of collapse of the concrete constructions. The authors focused especially on the microscopical research of sulfate attack. Concrete samples were taken from the Charles Bridge in Prague, Czech Republic. A succession of degrading mineral formation was suggested. Microscope methods represent a new approach to solvingmore » the deterioration problems. They enable evaluation of the state of concrete constructions and in cooperation with hydro-geochemistry, mathematics and statistics permit prediction of the durability of a structure. Considering the number of concrete constructions and their age, research of concrete deterioration has an increasing importance. The results obtained can also be useful for future construction, because they identify the risk factors associated with formation of minerals known to degrade structures.« less

Experimental investigation of steel fiber-reinforced concrete beams under cyclic loading

NASA Astrophysics Data System (ADS)

Ranjbaran, Fariman; Rezayfar, Omid; Mirzababai, Rahmatollah

2018-03-01

An experimental study has been conducted to study the cyclic behavior of reinforced concrete beams in which steel fibers were added to the concrete mix. Seven similar geometrically specimens in full scale were studied under four- point bending test in the form of slow cyclic loading. One sample as a control specimen was made without steel fibers or 0% volume fraction (vf) and six other samples with 1, 2 and 4% vf of steel fibers in twin models. The maximum and ultimate resistance, ductility, degradation of loading and unloading stiffness, absorption and dissipation of energy and equivalent viscous damping were studied in this investigation and the effect of steel fibers on the cyclic behavior was compared with each other. Generally, the addition of steel fibers up to a certain limit value (vf = 2%) improves the cyclic behavior of reinforced concrete beams and results in the increase of maximum strength and ultimate displacement.

Potential Impacts from Using Photoactive Roads as AN Air Quality Mitigation Strategy

NASA Astrophysics Data System (ADS)

Toro, C.; Jobson, B. T.; Shen, S.; Chung, S. H.; Haselbach, L.

2013-12-01

Mobile sources are major contributors to photochemical air pollution in urban areas. It has been proposed that the use of TiO2 coated roadways ('photoactive roads') could be an effective approach to reduce mobile source emissions by oxidizing NOx and VOC emissions at the roadway surface. However, studies have shown that formation of HONO and aldehydes can occur from some TiO2 treated surfaces during the photocatalytic oxidation of NOx and VOC, respectively. By changing the NOx-to-VOC ratio and generating photolabile HOx radical precursors, photoactive roads may enhance ozone formation rates in urban areas. In this work we present results that quantify NOx and VOC loss rates onto TiO2 treated asphalt and concrete samples, as well as HONO and aldehydes yields that result from the photocatalytic process. The treatment used a commercially available product. These objectives are relevant considering that the quantification of pollutant loss rates and yields of byproducts have not been determined for asphalt and that in the US more than 90% of the roadway surface is made of this material. Surface reaction probabilities (γ) and byproduct yields were determined using a CSTR photochemical chamber under varying conditions of water vapor and UV-A light intensity. Our results indicate that asphalt surfaces have a significantly higher molar yield of HONO compared to concrete surfaces with similar TiO2 loading. Concrete surfaces have reaction probabilities with NO one order of magnitude higher than asphalt samples. Fresh asphalt samples showed negligible photocatalytic activity, presumably due to absorption of TiO2 into the bitumen substrate. Laboratory-prepared asphalt samples with a higher degree of exposed aggregates showed increased HONO molar yields when compared to real-road asphalt samples, whose HONO molar yield was ~1%. Preliminary results for aldehydes formation showed similar molar yields between aged asphalt and concrete, even though aged asphalt samples had twice the TiO2 loading than concrete samples.

Calcium Carbonate Precipitation by Bacillus and Sporosarcina Strains Isolated from Concrete and Analysis of the Bacterial Community of Concrete.

PubMed

Kim, Hyun Jung; Eom, Hyo Jung; Park, Chulwoo; Jung, Jaejoon; Shin, Bora; Kim, Wook; Chung, Namhyun; Choi, In-Geol; Park, Woojun

2016-03-01

Microbially induced calcium carbonate precipitation (CCP) is a long-standing but re-emerging environmental engineering process for production of self-healing concrete, bioremediation, and long-term storage of CO2. CCP-capable bacteria, two Bacillus strains (JH3 and JH7) and one Sporosarcina strain (HYO08), were isolated from two samples of concrete and characterized phylogenetically. Calcium carbonate crystals precipitated by the three strains were morphologically distinct according to field emission scanning electron microscopy. Energy dispersive X-ray spectrometry mapping confirmed biomineralization via extracellular calcium carbonate production. The three strains differed in their physiological characteristics: growth at alkali pH and high NaCl concentrations, and urease activity. Sporosarcina sp. HYO08 and Bacillus sp. JH7 were more alkali- and halotolerant, respectively. Analysis of the community from the same concrete samples using barcoded pyrosequencing revealed that the relative abundance of Bacillus and Sporosarcina species was low, which indicated low culturability of other dominant bacteria. This study suggests that calcium carbonate crystals with different properties can be produced by various CCP-capable strains, and other novel isolates await discovery.

Ultrastructural study of iron oxide precipitates: implications for the search for biosignatures in the Meridiani hematite concretions, Mars.

PubMed

Souza-Egipsy, Virginia; Ormö, Jens; Beitler Bowen, Brenda; Chan, Marjorie A; Komatsu, Goro

2006-08-01

Two terrestrial environments that have been proposed as analogs for the iron oxide precipitation in the Meridiani Planum region of Mars include the Rio Tinto precipitates and southern Utah marble concretions. Samples of two typical Utah iron oxide concretions and iron oxide precipitates in contact with biofilms from Rio Tinto have been studied to determine whether evidence could be found for biomediation in the precipitation process and to identify likely locations for fossil microorganisms. Scanning electron microscopy, energy dispersive X-ray, and gas chromatography-mass spectrometry (GC-MS) were used to search for biosignatures in the Utah marbles. The precipitation of iron oxides resembles known biosignatures, though organic compounds could not be confirmed with GC-MS analysis. In contrast, textural variations induced by biological activity are abundant in the modern Rio Tinto samples. Although no compelling evidence of direct or indirect biomediation was found in the Utah marbles, the ultrastructure of the iron oxide cement in the concretion suggests an inward growth during concretion precipitation from an initially spherical redox front. No indication for growth from a physical nucleus was found.

Influence of metakaolin on chemical resistance of concrete

NASA Astrophysics Data System (ADS)

Mlinárik, L.; Kopecskó, K.

2013-12-01

Nowadays the most suitable and widely used construction material is concrete. We could develop concrete for every request in connection with the properties of fresh concrete and the quality of hardened concrete, too. The demand is rising in application of special concretes, like high performance and ultra high performance concretes (HPC, UHPC). These are usable in extreme natural circumstances or in very corrosive surroundings (for example: sewage farm, sewer, cooling tower, biogas factories). The pH value of the commercial sewage is between 7-8, but this value is often around 4 or less. The concrete pipes, which transport the sewage, are under corrosion, because above the liquid level sulphuric acid occurs due to microbes. Acidic surroundings could start the corrosion of concrete. When the pH value reduces, the influence of the acids will increase. The most significant influence has the sulphuric acid. The pH value of sulphuric acid is about 1, or less. Earlier in the cooling towers of coal thermal power stations used special coating on the concrete wall. Recently application of high performance concrete without polymeric coating is more general. Cementitious supplementary materials are widely used to protect the concrete from these corrosive surroundings. Usually used cementitious supplementary materials are ground granulated blastfurnace slag (GGBS), flying ash (FA) or silica fume (SF). In the last years there has been a growing interest in the application of metakaolin. Metakaolin is made by heat treatment, calcinations of a natural clay mineral, kaolinite. In our present research the chemical resistance of mortars in different corrosive surroundings (pH=1 sulphuric acid; pH=3 acetic acid) and the chloride ion migration were studied on series of mortar samples using rapid chloride migration test. Cement paste and mortar samples were made with 17% metakaolin replacement or without metakaolin. The following cements were used: CEM II/A-S 42.5 N, CEM I 42.5 N-S. We concluded that the replacement of cement by metakaolin results in significant increases in compressive and tensile strengths and it prevents the infiltration of harmful substances.

Carbonate concretions as a significant component of ancient marine carbon cycles: Insights from paired organic and inorganic carbon isotope analyses of a Cretaceous shale

NASA Astrophysics Data System (ADS)

Loyd, S. J.

2014-12-01

Carbonate concretions often occur within fine-grained, organic-rich sedimentary rocks. This association reflects the common production of diagenetic minerals through biologic cycling of organic matter. Chemical analysis of carbonate concretions provides the rare opportunity to explore ancient shallow diagenetic environments, which are inherently transient due to progressive burial but are an integral component of the marine carbon cycle. The late Cretaceous Holz Shale (~80 Ma) contains abundant calcite concretions that exhibit textural and geochemical characteristics indicative of relatively shallow formation (i.e., near the sediment-water interface). Sampled concretions contain between 5.4 and 9.8 wt.% total inorganic carbon (TIC), or ~45 and 82 wt.% CaCO3, compared to host shale values which average ~1.5 wt.% TIC. Organic carbon isotope compositions (δ13Corg) are relatively constant in host and concretion samples ranging from ­-26.3 to -24.0‰ (VPDB). Carbonate carbon isotope compositions (δ13Ccarb) range from -22.5 to -3.4‰, indicating a significant but not entirely organic source of carbon. Concretions of the lower Holz Shale exhibit considerably elevated δ13Ccarb values averaging -4.8‰, whereas upper Holz Shale concretions express an average δ13Ccarb value of -17.0‰. If the remaining carbonate for lower Holz Shale concretions is sourced from marine fluids and/or dissolved marine carbonate minerals (e.g., shells), a simple mass balance indicates that ~28% of concretion carbon was sourced from organic matter and ~72% from late Cretaceous marine inorganic carbon (with δ13C ~ +2.5‰). Upper Holz Shale calculations indicate a ~73% contribution from organic matter and a ~27% contribution from inorganic carbon. When normalized for carbonate, organic contents within the concretions are ~2-13 wt.% enriched compared to host contents. This potentially reflects the protective nature of cementation that acts to limit permeability and chemical destruction of organic material. These data imply that concretion growth in shallow sediments can act as a significant and long-term sink for both marine inorganic and organic carbon.

Interaction processes at the concrete-bentonite interface after 13 years of FEBEX-Plug operation. Part II: Bentonite contact

NASA Astrophysics Data System (ADS)

Fernández, Raúl; Torres, Elena; Ruiz, Ana I.; Cuevas, Jaime; Alonso, María Cruz; García Calvo, José Luis; Rodríguez, Enrique; Turrero, María Jesús

2017-06-01

The in situ FEBEX experiment performed at the URL in Grimsel (Swizerland) was dismantled after 18 years of operation. Interface samples between bentonite and a shotcreted concrete plug that was constructed in a second operational phase have been studied after 13 years of interaction. Mineralogical and geochemical characterization of samples have been performed by XRD, SEM-EDX, TG and FTIR techniques in addition to determinations of major ions by chemical analysis of aqueous extracts, δ18O and δ13C stable isotopes both in concrete paste and bentonite, and exchangeable cations in bentonite. Low mineralogical alteration impact was observed in bentonite that is only affected by a few millimeters. A large accumulation of Mg was observed at the bentonite side of the interface precipitating as silicates in various forms. In addition, heterogeneous carbonation was observed at the interface, but mostly affecting the concrete side. Migration of aqueous species occurred, being the most relevant the diffusion of chloride and sulfate from bentonite to concrete, in agreement with Part I of this study. Chloride advanced more into the concrete, while sulfates reacted to form ettringite, which has an evident alteration impact at the very interface (<0.5 mm rim) within the concrete. The ionic mobility has also redistributed the exchangeable cations in bentonite, increasing the content in Ca2+ and Na+, compensated by a decrease in Mg2+. The results presented in this paper complement those presented in Part I, focusing on the alteration of concrete by the bentonite and the granite groundwater.

Gaseous mercury from curing concretes that contain fly ash: laboratory measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Danold W. Golightly; Ping Sun; Chin-Min Cheng

2005-08-01

Total gaseous mercury in headspace air was measured for enclosed concretes dry curing at 40 C for intervals of 2, 28, and 56 days. Release of mercury was confirmed for ordinary Portland cement concrete (OPC) and three concretes in which class F fly ash from coal-combustion substituted for a fraction of the cement: (a) 33% fly ash (FA33), (b) 55% fly ash (FA55), and (c) 33% fly ash plus 0.5% mercury-loaded powdered activated carbon (HgPAC). Mean rates of mercury release (0.10-0.43 ng/day per kg of concrete) over the standard first 28 days of curing followed the order OPC {lt} FA33more » {approximately} FA55 {lt} HgPAC. The mercury flux from exposed surfaces of these concretes ranged from 1.9 {+-} 0.5 to 8.1 {+-} 2.0 ng/m{sup 2}/h, values similar to the average flux for multiple natural substrates in Nevada, 4.2 {+-} 1.4 ng/m{sup 2}/h, recently published by others. Air sampling extending for 28 days beyond the initial 28-day maturation for OPC, FA55, and HgPAC suggested that the average Hg release rate by OPC is constant over 56 days and that mercury release rates for FA55 and HgPAC may ultimately diminish to levels exhibited by OPC concrete. The release of mercury from all samples was less than 0.1% of total mercury content over the initial curing period, implying that nearly all of the mercury was retained in the concrete. 20 refs., 3 figs., 3 tabs.« less

Characterization of Laboratory Prepared Concrete Pastes Exposed to High Alkaline and High Sodium Salt Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Langton, C. A.

The objective of this study was to identify potential chemical degradation mechanisms for the Saltstone Disposal Unit (SDU) concretes, which over the performance life of the structures may be exposed to highly alkaline sodium salt solutions containing sulfate, hydroxide, and other potentially corrosive chemicals in salt solution and saltstone flush water, drain water, leachate and / or pore solution. The samples analyzed in this study were cement pastes prepared in the SIMCO Technologies, Inc. concrete laboratory. They were based on the paste fractions of the concretes used to construct the Saltstone Disposal Units (SDUs). SDU 1 and 4 concrete pastesmore » were represented by the PV1 test specimens. The paste in the SDU 2, 3, 5, and 6 concrete was represented by the PV2 test specimens. SIMCO Technologies, Inc. selected the chemicals and proportions in the aggressive solutions to approximate proportions in the saltstone pore solution [2, 3, 5, and 6]. These test specimens were cured for 56 days in curing chamber before being immersed in aggressive solutions. After exposure, the samples were frozen to prevent additional chemical transport and reaction. Selected archived (retrieved from the freezer) samples were sent to the Savannah River National Laboratory (SRNL) for additional characterization using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray (EDX) spectroscopy. Characterization results are summarized in this report. In addition, a correlation between the oxide composition of the pastes and their chemical durability in the alkaline salt solutions is provided.« less

Experimental thermal characterization of concrete to be used in CP5.2 packaging system

NASA Astrophysics Data System (ADS)

Lo Frano, R.; Maggini, A.; Aquaro, D.

2017-01-01

This work deals with the experimental evaluation of the thermal conductivity of a concrete matrix to be used for embedding LILW bituminised Wastes into the packaging system. Such a type of packaging, identified with the acronym CP5.2, has been also qualified by executing at the Lab. Scalbatraio of Dep. of Civil and Industrial Engineering of the University of Pisa, an experimental test campaign accordingly to the IAEA regulations. In particular, the knowledge of the thermal conductivity is important because of the fire or furnace test to carry out in oven at 800 °C for 30 minutes. These data allowed to simulate pre-test conditions and to set up safety and operational fire test procedures. The concrete thermal conductivity was obtained by performing hot wire tests on cylindrical concrete samples for temperatures ranging from 100° to about 800°C. Thermal conductivity is determined at steady state condition. Results indicate a monotonically reduction of the thermal conductivity as the temperature increases. The comparison with concrete thermal conductivity data available in literature indicates a quite good agreement. Finally, visual and X-ray inspection of sample did not highlight the presence of micro/macro damages that would have affected the thermal performance of the concrete under study.

Fukushima Daiichi Unit 1 Ex-Vessel Prediction: Core-Concrete Interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robb, Kevin R.; Farmer, Mitchell T.; Francis, Matthew W.

Lower head failure and corium-concrete interaction were predicted to occur at Fukushima Daiichi Unit 1 (1F1) by several different system-level code analyses, including MELCOR v2.1 and MAAP5. Although these codes capture a wide range of accident phenomena, they do not contain detailed models for ex-vessel core melt behavior. However, specialized codes exist for the analysis of ex-vessel melt spreading (e.g., MELTSPREAD) and long-term debris coolability (e.g., CORQUENCH). On this basis, in this paper an analysis was carried out to further evaluate ex-vessel behavior for 1F1 using MELTSPREAD and CORQUENCH. Best-estimate melt pour conditions predicted by MELCOR v2.1 and MAAP5 weremore » used as input. MELTSPREAD was then used to predict the spatially dependent melt conditions and extent of spreading during relocation from the vessel. The results of the MELTSPREAD analysis are reported in a companion paper. This information was used as input for the long-term debris coolability analysis with CORQUENCH. For the MELCOR-based melt pour scenario, CORQUENCH predicted the melt would readily cool within 2.5 h after the pour, and the sumps would experience limited ablation (approximately 18 cm) under water-flooded conditions. Finally, for the MAAP-based melt pour scenarios, CORQUENCH predicted that the melt would cool in approximately 22.5 h, and the sumps would experience approximately 65 cm of concrete ablation under water-flooded conditions.« less

Fukushima Daiichi Unit 1 Ex-Vessel Prediction: Core-Concrete Interaction

DOE PAGES

Robb, Kevin R.; Farmer, Mitchell T.; Francis, Matthew W.

2016-10-31

Lower head failure and corium-concrete interaction were predicted to occur at Fukushima Daiichi Unit 1 (1F1) by several different system-level code analyses, including MELCOR v2.1 and MAAP5. Although these codes capture a wide range of accident phenomena, they do not contain detailed models for ex-vessel core melt behavior. However, specialized codes exist for the analysis of ex-vessel melt spreading (e.g., MELTSPREAD) and long-term debris coolability (e.g., CORQUENCH). On this basis, in this paper an analysis was carried out to further evaluate ex-vessel behavior for 1F1 using MELTSPREAD and CORQUENCH. Best-estimate melt pour conditions predicted by MELCOR v2.1 and MAAP5 weremore » used as input. MELTSPREAD was then used to predict the spatially dependent melt conditions and extent of spreading during relocation from the vessel. The results of the MELTSPREAD analysis are reported in a companion paper. This information was used as input for the long-term debris coolability analysis with CORQUENCH. For the MELCOR-based melt pour scenario, CORQUENCH predicted the melt would readily cool within 2.5 h after the pour, and the sumps would experience limited ablation (approximately 18 cm) under water-flooded conditions. Finally, for the MAAP-based melt pour scenarios, CORQUENCH predicted that the melt would cool in approximately 22.5 h, and the sumps would experience approximately 65 cm of concrete ablation under water-flooded conditions.« less

Comparative study of procedures for the analysis of chloride in hardened concrete.

DOT National Transportation Integrated Search

1976-01-01

In the widely used potentiometric titration procedure for the analysis of chloride in powdered hardened concrete samples, difficulties have often been encountered when determining the endpoint. These difficulties have been eliminated through the use ...

Characterization and mediation of microbial deterioration of concrete bridge structures.

DOT National Transportation Integrated Search

2013-04-01

Samples obtained from deteriorated bridge structures in Texas were cultured in growth medium containing thiosulfate as an energy source and investigated for acid production, type of acid produced by microbes and the bio-deterioration of concrete cyli...

Detection and Analysis of the Magnetic Field Component of Electromagnetic Radiation Emission from Macroscopic Fracturing of Cement-Bound Granular Material

NASA Astrophysics Data System (ADS)

Maquiling, J. T.; Ceralde, P. I. B.

2016-12-01

Countries most prone to earthquake damage have been in pursuit of a possible earthquake precursor. This study aims to detect and measure the magnetic field component of the Electromagnetic Radiation (EMR) emitted by quasi-brittle materials that undergo macroscopic fracturing. Cement-Bound Granular Materials (CBGM) were prepared by mixing cement, sand and gravel in a beam mold. Additional aggregates in the form of saw dust were added to produce variable CBGM samples. A concrete beam holder was designed and fabricated such that induced cracks from impact loading would form at the center of the beam. Six Vernier software magnetic field sensors were used to detect the magnetic field (MF) component of the EMR emission. Initial calibration was done to minimize noise in the laboratory. The magnetic field sensors were set at a low amplification range (±6.4x10-3 T) setting with 0.0002 mT precision at 20-50 Hz. Sensor locations and orientations were specified and fixed throughout the experiment. The impact loading process was repeated until concrete failure. The time of drop was determined through the occurrence of peak sound levels (dB) induced by the collision noise using a sound level meter at fast time weighting. Magnetic field fluctuations manifesting near the occurrence of sound level impulses were recorded. Peak magnetic field values within ±200ms from the recorded time of impact were considered to be originating from the concrete fracture. Concrete samples consisting of cement, sand and gravel produced magnetic field emissions measuring 0.58-1.07 μT while the same concrete mixture added with dispersed fine sawdust released 0.55-1.28 μT. A more dispersed set of values of magnetic field emissions were observed for concrete with sawdust. Comparison between the average number of drops done before failure occurs between the two concrete mixtures also indicated that the addition of dispersed sawdust resulted to weaker CBGM samples. Upon increasing input energy from weight drop by 150%, magnetic field emissions from samples of the same concrete mixture showed significant increase with maximum magnitude of emission measured at 1.06 μT. A model of the magnetic field magnitudes with respect to sensor position was generated by non-linear data-fitting method using Microsoft Excel and SciLab.

The Empower Program, K-2: Concrete Strategies for Positive Behavioral Support

ERIC Educational Resources Information Center

Baker, Rachel

2016-01-01

Let's face it--teaching can be stressful. In this generation of Common Core Standards and highstakes testing, educators are often left without the time to plan positive behavioral supports or the sanity to cultivate compassionate relationships with their students. Even though they understand the critical relationship between behavior and…

"But What Can I Do?": Three Necessary Tensions in Teaching Teachers about Race

ERIC Educational Resources Information Center

Pollock, Mica; Deckman, Sherry; Mira, Meredith; Shalaby, Carla

2010-01-01

A core question of teacher education--"What can I do?"--plagues courses on race in particular ways. Teachers struggle for "concrete" applications of "theoretical" ideas about race, question the potential for "everyday" activity to dismantle inequality "structures," and wrestle with the need for both professional and personal development on racial…

Using Indigenous Materials for Construction

DTIC Science & Technology

2015-07-01

Theoretical models were devised for prediction of the structural attributes of indigenous ferrocement sheets and sandwich composite panels comprising the...indigenous ferrocement skins and aerated concrete core. Structural designs were developed for these indigenous sandwich composite panels in typical...indigenous materials and building systems developed in the project were evaluated. Numerical modeling capabilities were developed for structural

68. VIEW OF WOOD STAVE PIPE TAKEN FROM THE TOP ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

68. VIEW OF WOOD STAVE PIPE TAKEN FROM THE TOP OF THE PENSTOCK LINE, LOOKING SOUTH. PORTION OF PIPE BETWEEN THE FOREBAY AND RAILROAD TRACK WILL BE COVERED WITH CONCRETE CORE WALL AND EARTH EMBANKMENT OF RESERVOIR, Print No. 185, November 1903 - Electron Hydroelectric Project, Along Puyallup River, Electron, Pierce County, WA

Unit: Model for Matter, Inspection Pack, National Trial Print.

ERIC Educational Resources Information Center

Australian Science Education Project, Toorak, Victoria.

Mental and physical models are treated in the Australian Science Education Project trial unit prepared for students in a transitional stage between concrete and abstract reasoning. Students are introduced to the particle model of matter through a series of core activities, including a combination game using nuts and bolts, culminating in a…

Unit: Energy for Life, Inspection Pack, National Trial Print.

ERIC Educational Resources Information Center

Australian Science Education Project, Toorak, Victoria.

This unit, providing information about human nutrition and energy use, has been prepared for students whose level of thinking is transitional between concrete and formal stages. The unit is based upon an analogy between combustion and respiration and upon the molecular structure of food components. The core portion of the unit presents activities…

Self-immunity microcapsules for corrosion protection of steel bar in reinforced concrete

NASA Astrophysics Data System (ADS)

Wang, Yanshuai; Fang, Guohao; Ding, Weijian; Han, Ningxu; Xing, Feng; Dong, Biqin

2015-12-01

A novel microcapsule-based self-immunity system for reinforced concrete is proposed. Its feasibility for hindering the corrosion of steel rebar by means of lifting the threshold value of [Cl-]/[OH-] is discussed. Precisely controlled release behavior enables corrosion protection in the case of depassivation. The release process is characterized over a designated range of pH values, and its release characteristics of the microcapsules, triggered by decreasing pH value, are captured by observing that the core crystals are released when exposed to a signal (stimulus). The aim of corrosion protection of steel bar is achieved through the constantly-stabilized passive film, and its stability is promoted using continuous calcium hydroxide released from the microcapsule, restoring alkaline conditions. The test results exhibited that the release process of the microcapsules is a function of time. Moreover, the release rate of core materials could interact with environmental pH value, in which the release rate is found to increase remarkably with decreasing pH value, but is inhibited by high pH levels.

Self-immunity microcapsules for corrosion protection of steel bar in reinforced concrete.

PubMed

Wang, Yanshuai; Fang, Guohao; Ding, Weijian; Han, Ningxu; Xing, Feng; Dong, Biqin

2015-12-17

A novel microcapsule-based self-immunity system for reinforced concrete is proposed. Its feasibility for hindering the corrosion of steel rebar by means of lifting the threshold value of [Cl(-)]/[OH(-)] is discussed. Precisely controlled release behavior enables corrosion protection in the case of depassivation. The release process is characterized over a designated range of pH values, and its release characteristics of the microcapsules, triggered by decreasing pH value, are captured by observing that the core crystals are released when exposed to a signal (stimulus). The aim of corrosion protection of steel bar is achieved through the constantly-stabilized passive film, and its stability is promoted using continuous calcium hydroxide released from the microcapsule, restoring alkaline conditions. The test results exhibited that the release process of the microcapsules is a function of time. Moreover, the release rate of core materials could interact with environmental pH value, in which the release rate is found to increase remarkably with decreasing pH value, but is inhibited by high pH levels.

A research for Class II defect Bored Pile’s Accept Criteria: A case of Penang Second Marine bridge

NASA Astrophysics Data System (ADS)

Huang, Kang

2018-03-01

The aim of this preliminary research is to study the accept criteria of class II bored pile with subtle defect. According to a detailed comparison of the existed different standards, Chinese ones are more applicable especially for the large diameter bored piles. Through the concrete coring at pile No P25-03 of this case and the comparison to the actual calculation, the Class II pile’s defects were very minor. Comparison was also made for the effects on pile structural capacities before and after repair of the defects. the feasible repair proposal may bring forward to more defects to the piles. The Class II piles don’t need any further repairation when piles have typical of similar character and sonic logging test result with P25-03‘s one. For other Class II piles with some differences in characters, verification is needed through further concrete coring on the pile. The recommendation of this research could be adopted for the similar huge marine structures which installed large diameter bored piles.

Development of Vegetation-Pervious Concrete in Grid Beam System for Soil Slope Protection

PubMed Central

Bao, Xiaohua; Liao, Wenyu; Dong, Zhijun; Wang, Shanyong; Tang, Waiching

2017-01-01

One of the most efficient and environmentally friendly methods for preventing a landslide on a slope is to vegetate it. Vegetation-pervious concretes have a promising potential for soil protection. In this study, the vegetation-pervious concrete with low alkalinity was developed and studied. Combined with a grid beam structure system, the stability and strength between the vegetation-pervious concrete and base soil are believed to be enhanced effectively. For improving plant adaptability, the alkalinity of concrete can be decreased innovatively by adding a self-designed admixture into the cement paste. The effects of the admixture content on alkalinity and compressive strength of the hardened pervious concrete were investigated using X-ray diffraction (XRD) and compression test, respectively. Meanwhile, the permeability of the vegetation-pervious concrete was studied as well. Through comparing with ordinary pervious concrete, the effect of low alkaline pervious concrete on vegetation growth was investigated in a small-scale field for ten weeks. The test results indicated that the alkalinity of the cement samples decreased with the increase of admixture content, and the vegetation grew successfully on previous concrete. By increasing the admixture content to approximately 3.6%, the compressive strength of pervious concrete was more than 25 MPa. PMID:28772454

Characterization of concrete from Roman theatre and amphitheater in Emerita Augusta (Mérida, Spain)

NASA Astrophysics Data System (ADS)

Mota-Lopez, Maria Isabel; Fort, Rafael; Alvarez de Buergo, Monica; Pizzo, Antonio; Maderuelo-Sanz, Ruben; Meneses-Rodríguez, Juan Miguel

2016-04-01

The restoration of historical buildings is very important for the history and culture of the cities and their population. It requires an advanced knowledge of the building materials used for the construction of these structures. Previously to any intervention in historical buildings, it is necessary a historic-scientific study of the original material. Historic mortars or concretes can reveal us different composition and the dependence on the geographical location and the time period of its construction. Historical concretes are complex systems that contain aerial or hydraulic binders or a blend of them, with aggregates, not always crystalline, and others elements that interact with the binder. The use of different techniques for microstructural characterization of materials, like optical microscopy, X-ray diffractometry or petrophysical analysis, allows the determination of the composition and some properties of these concretes. However, each technique has its own limits and, in many cases, several characterization techniques must be used to obtain coherent and reliable results. The present study focuses on the compositional characterization of Roman concrete from Roman buildings for public spectacles of Emerita Augusta, Mérida, Spain. An advanced knowledge of the Roman concrete composition is required to get a reliable restoration and preservation of these ancient monuments. Various samples of concrete were extracted from different zones from this archaeological site. The concrete was studied through mineralogical analysis (petrographic microscope and XRD) and petrophysical properties determination (bulk and real density, open porosity, mercury porosimetry intrusion, compressive strength and Ultrasound propagation velocity). The results obtained allow us to know the original composition of the concrete and the provenance of the aggregates used in it. Acknowledgements: Community of Madrid for financing Geomateriales2 program (P2013/MIT2914), to the funding provided by BIA 2014-53911-R project and to the Consortium for the Monumental City of Merida for the permission granted to collect concrete samples.

Retrofitting the AutoBayes Program Synthesis System with Concrete Syntax

NASA Technical Reports Server (NTRS)

Fischer, Bernd; Visser, Eelco

2004-01-01

AutoBayes is a fully automatic, schema-based program synthesis system for statistical data analysis applications. Its core component is a schema library. i.e., a collection of generic code templates with associated applicability constraints which are instantiated in a problem-specific way during synthesis. Currently, AutoBayes is implemented in Prolog; the schemas thus use abstract syntax (i.e., Prolog terms) to formulate the templates. However, the conceptual distance between this abstract representation and the concrete syntax of the generated programs makes the schemas hard to create and maintain. In this paper we describe how AutoBayes is retrofitted with concrete syntax. We show how it is integrated into Prolog and describe how the seamless interaction of concrete syntax fragments with AutoBayes's remaining legacy meta-programming kernel based on abstract syntax is achieved. We apply the approach to gradually mitigate individual schemas without forcing a disruptive migration of the entire system to a different First experiences show that a smooth migration can be achieved. Moreover, it can result in a considerable reduction of the code size and improved readability of the code. In particular, abstracting out fresh-variable generation and second-order term construction allows the formulation of larger continuous fragments.

An Embedded Stress Sensor for Concrete SHM Based on Amorphous Ferromagnetic Microwires

PubMed Central

Olivera, Jesús; González, Margarita; Fuente, José Vicente; Varga, Rastislav; Zhukov, Arkady; Anaya, José Javier

2014-01-01

A new smart concrete aggregate design as a candidate for applications in structural health monitoring (SHM) of critical elements in civil infrastructure is proposed. The cement-based stress/strain sensor was developed by utilizing the stress/strain sensing properties of a magnetic microwire embedded in cement-based composite (MMCC). This is a contact-less type sensor that measures variations of magnetic properties resulting from stress variations. Sensors made of these materials can be designed to satisfy the specific demand for an economic way to monitor concrete infrastructure health. For this purpose, we embedded a thin magnetic microwire in the core of a cement-based cylinder, which was inserted into the concrete specimen under study as an extra aggregate. The experimental results show that the embedded MMCC sensor is capable of measuring internal compressive stress around the range of 1–30 MPa. Two stress sensing properties of the embedded sensor under uniaxial compression were studied: the peak amplitude and peak position of magnetic switching field. The sensitivity values for the amplitude and position within the measured range were 5 mV/MPa and 2.5 μs/MPa, respectively. PMID:25347582

Quality control of concrete at the stage of designing its composition and technology

NASA Astrophysics Data System (ADS)

Kudyakov, A.; Prischepa, I.; Kiselev, D.; Prischepa, B.

2016-01-01

The results of tests on samples of foam concrete with a hardening accelerator are presented. As the setting and hardening accelerators the following chemical additives were used: Universal-P-2 and Asilin 12. All additives were added into the insulating foam concrete mix of brand D 400 in the amount of 0.5% to 1% of cement weight. By using of additives in foam concrete technology - hardening accelerators Asilin 12 and Universal P2 in the amount of 0.5 % - and 1.0% by weight of cement foam concrete structure formation is accelerated and increases strength by 60%. For the industrial preparation of foam concrete mix technological regulations are worked out, in which it is recommended to use additives - hardening accelerators Asilin 12 in the amount of 0.5% and Universal P2 - 1% of cement weight.

An assessment of the CORCON-MOD3 code. Part 1: Thermal-hydraulic calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strizhov, V.; Kanukova, V.; Vinogradova, T.

1996-09-01

This report deals with the subject of CORCON-Mod3 code validation (thermal-hydraulic modeling capability only) based on MCCI (molten core concrete interaction) experiments conducted under different programs in the past decade. Thermal-hydraulic calculations (i.e., concrete ablation, melt temperature, melt energy, concrete temperature, and condensible and non-condensible gas generation) were performed with the code, and compared with the data from 15 experiments, conducted at different scales using both simulant (metallic and oxidic) and prototypic melt materials, using different concrete types, and with and without an overlying water pool. Sensitivity studies were performed in a few cases involving, for example, heat transfer frommore » melt to concrete, condensed phase chemistry, etc. Further, special analysis was performed using the ACE L8 experimental data to illustrate the differences between the experimental and the reactor conditions, and to demonstrate that with proper corrections made to the code, the calculated results were in better agreement with the experimental data. Generally, in the case of dry cavity and metallic melts, CORCON-Mod3 thermal-hydraulic calculations were in good agreement with the test data. For oxidic melts in a dry cavity, uncertainties in heat transfer models played an important role for two melt configurations--a stratified geometry with segregated metal and oxide layers, and a heterogeneous mixture. Some discrepancies in the gas release data were noted in a few cases.« less

Crystallized alkali-silica gel in concrete from the late 1890s

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterson, Karl; Gress, David; Van Dam, Tom

The Elon Farnsworth Battery, a concrete structure completed in 1898, is in an advanced state of disrepair. To investigate the potential for rehabilitation, cores were extracted from the battery. Petrographic examination revealed abundant deposits of alkali silica reaction products in cracks associated with the quartz rich metasedimentary coarse aggregate. The products of the alkali silica reaction are variable in composition and morphology, including both amorphous and crystalline phases. The crystalline alkali silica reaction products are characterized by quantitative X-ray energy dispersive spectrometry (EDX) and X-ray diffraction (XRD). The broad extent of the reactivity is likely due to elevated alkali levelsmore » in the cements used.« less

Thyra Abstract Interface Package

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartlett, Roscoe A.

2005-09-01

Thrya primarily defines a set of abstract C++ class interfaces needed for the development of abstract numerical atgorithms (ANAs) such as iterative linear solvers, transient solvers all the way up to optimization. At the foundation of these interfaces are abstract C++ classes for vectors, vector spaces, linear operators and multi-vectors. Also included in the Thyra package is C++ code for creating concrete vector, vector space, linear operator, and multi-vector subclasses as well as other utilities to aid in the development of ANAs. Currently, very general and efficient concrete subclass implementations exist for serial and SPMD in-core vectors and multi-vectors. Codemore » also currently exists for testing objects and providing composite objects such as product vectors.« less

Computational Psychosomatics and Computational Psychiatry: Toward a Joint Framework for Differential Diagnosis.

PubMed

Petzschner, Frederike H; Weber, Lilian A E; Gard, Tim; Stephan, Klaas E

2017-09-15

This article outlines how a core concept from theories of homeostasis and cybernetics, the inference-control loop, may be used to guide differential diagnosis in computational psychiatry and computational psychosomatics. In particular, we discuss 1) how conceptualizing perception and action as inference-control loops yields a joint computational perspective on brain-world and brain-body interactions and 2) how the concrete formulation of this loop as a hierarchical Bayesian model points to key computational quantities that inform a taxonomy of potential disease mechanisms. We consider the utility of this perspective for differential diagnosis in concrete clinical applications. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

C3H7NO2S effect on concrete steel-rebar corrosion in 0.5 M H2SO4 simulating industrial/microbial environment

NASA Astrophysics Data System (ADS)

Okeniyi, Joshua Olusegun; Nwadialo, Christopher Chukwuweike; Olu-Steven, Folusho Emmanuel; Ebinne, Samaru Smart; Coker, Taiwo Ebenezer; Okeniyi, Elizabeth Toyin; Ogbiye, Adebanji Samuel; Durotoye, Taiwo Omowunmi; Badmus, Emmanuel Omotunde Oluwasogo

2017-02-01

This paper investigates C3H7NO2S (Cysteine) effect on the inhibition of reinforcing steel corrosion in concrete immersed in 0.5 M H2SO4, for simulating industrial/microbial environment. Different C3H7NO2S concentrations were admixed, in duplicates, in steel-reinforced concrete samples that were partially immersed in the acidic sulphate environment. Electrochemical monitoring techniques of open circuit potential, as per ASTM C876-91 R99, and corrosion rate, by linear polarization resistance, were then employed for studying anticorrosion effect in steel-reinforced concrete samples by the organic hydrocarbon admixture. Analyses of electrochemical test-data followed ASTM G16-95 R04 prescriptions including probability distribution modeling with significant testing by Kolmogorov-Smirnov and student's t-tests statistics. Results established that all datasets of corrosion potential distributed like the Normal, the Gumbel and the Weibull distributions but that only the Weibull model described all the corrosion rate datasets in the study, as per the Kolmogorov-Smirnov test-statistics. Results of the student's t-test showed that differences of corrosion test-data between duplicated samples with the same C3H7NO2S concentrations were not statistically significant. These results indicated that 0.06878 M C3H7NO2S exhibited optimal inhibition efficiency η = 90.52±1.29% on reinforcing steel corrosion in the concrete samples immersed in 0.5 M H2SO4, simulating industrial/microbial service-environment.

Silica dust exposures during selected construction activities.

PubMed

Flanagan, Mary Ellen; Seixas, Noah; Majar, Maria; Camp, Janice; Morgan, Michael

2003-01-01

This study characterized exposure for dust-producing construction tasks. Eight common construction tasks were evaluated for quartz and respirable dust exposure by collecting 113 personal task period samples for cleanup; demolition with handheld tools; concrete cutting; concrete mixing; tuck-point grinding; surface grinding; sacking and patching concrete; and concrete floor sanding using both time-integrating filter samples and direct-reading respirable dust monitors. The geometric mean quartz concentration was 0.10 mg/m(3) (geometric standard deviation [GSD]=4.88) for all run time samples, with 71% exceeding the threshold limit value. Activities with the highest exposures were surface grinding, tuck-point grinding, and concrete demolition (GM[GSD] of 0.63[4.12], 0.22[1.94], and 0.10[2.60], respectively). Factors recorded each minute were task, tool, work area, respiratory protection and controls used, estimated cross draft, and whether anyone nearby was making dust. Factors important to exposure included tool used, work area configuration, controls employed, cross draft, and in some cases nearby dust. More protective respirators were employed as quartz concentration increased, although respiratory protection was found to be inadequate for 42% of exposures. Controls were employed for only 12% of samples. Exposures were reduced with three controls: box fan for surface grinding and floor sanding, and vacuum/shroud for surface grinding, with reductions of 57, 50, and 71%, respectively. Exposures were higher for sweeping compound, box fan for cleanup, ducted fan dilution, and wetted substrate. Construction masons and laborers are frequently overexposed to silica. The usual protection method, respirators, was not always adequate, and engineering control use was infrequent and often ineffective.

Long-term Metal Performance of Three Permeable Pavements

EPA Science Inventory

EPA constructed a 4,000-m2 parking lot surfaced with three permeable pavements (permeable interlocking concrete pavers, pervious concrete, and porous asphalt) on the Edison Environmental Center in Edison, NJ in 2009. Samples from each permeable pavement infiltrate were collected...

Effects of micro-sized and nano-sized WO3 on mass attenauation coefficients of concrete by using MCNPX code.

PubMed

Tekin, H O; Singh, V P; Manici, T

2017-03-01

In the present work the effect of tungsten oxide (WO 3 ) nanoparticles on mass attenauation coefficients of concrete has been investigated by using MCNPX (version 2.4.0). The validation of generated MCNPX simulation geometry has been provided by comparing the results with standard XCOM data for mass attenuation coefficients of concrete. A very good agreement between XCOM and MCNPX have been obtained. The validated geometry has been used for definition of nano-WO 3 and micro-WO 3 into concrete sample. The mass attenuation coefficients of pure concrete and WO 3 added concrete with micro-sized and nano-sized have been compared. It was observed that shielding properties of concrete doped with WO 3 increased. The results of mass attenauation coefficients also showed that the concrete doped with nano-WO 3 significanlty improve shielding properties than micro-WO 3 . It can be concluded that addition of nano-sized particles can be considered as another mechanism to reduce radiation dose. Copyright © 2016 Elsevier Ltd. All rights reserved.

Vertical electrical impedance evaluation of asphalt overlays on concrete bridge decks

NASA Astrophysics Data System (ADS)

Baxter, Jared S.; Guthrie, W. Spencer; Waters, Tenli; Barton, Jeffrey D.; Mazzeo, Brian A.

2018-04-01

Vertical electrical impedance scanning of concrete bridge decks is a non-destructive method for quantifying the degree of protection provided to steel reinforcement against the ingress of corrosive agents. Four concrete bridge decks with asphalt overlays in northern Utah were evaluated using scanning vertical electrical impedance measurements in this study. At the time of testing, the bridges ranged in age from 21 to 34 years, and asphalt overlays had been in place for 7 to 22 years, depending on the bridge. Electrical impedance measurements were collected using a previously constructed apparatus that consisted of six probes spanning a transverse distance of 12 ft. The impedance measurements were compared to surface cracking observations and cores obtained from the same four bridge decks. The results presented in this paper demonstrate the utility of scanning vertical electrical impedance measurements for detecting cracks in asphalt overlays and quantifying their severity. In addition, the results demonstrate the sensitivity of impedance measurements to the presence of an intact membrane beneath the asphalt overlay.

Abstract Word Definition in Patients with Amnestic Mild Cognitive Impairment

PubMed Central

Kim, Soo Ryon; Baek, Min Jae; Kim, HyangHee

2015-01-01

The aims of this study were to investigate concrete and abstract word definition ability (1) between patients with amnestic mild cognitive impairment (aMCI) and normal adults and (2) between the aMCI subtypes (i.e., amnestic single-domain MCI and amnestic multidomain MCI; asMCI and amMCI) and normal controls. The 68 patients with aMCI (29 asMCI and 39 amMCI) and 93 age- and education-matched normal adults performed word definition tasks composed of five concrete (e.g., train) and five abstract nouns (e.g., jealousy). Task performances were analyzed on total score, number of core meanings, and number of supplementary meanings. The results were as follows. First, the aMCI patients scored significantly poorer than the normal controls in only abstract word definition. Second, both subtypes of aMCI performed worse than the controls in only abstract word definition. In conclusion, a definition task of abstract rather than concrete concepts may provide richer information to show semantic impairment of aMCI. PMID:26347214

EEG beta-power changes reflect motor involvement in abstract action language processing.

PubMed

Schaller, Franziska; Weiss, Sabine; Müller, Horst M

2017-05-01

Brain oscillations in the α- and β-range become suppressed during motor processing and motor imagery. It has recently been discussed that such power changes also occur during action language processing. In our study, we compared β 2 -oscillations (16-25Hz) during the observation of prototypical arm movements (revealed via motion tracking) as well as during semantic processing of concrete and abstract sentences containing arm-related action verbs. Whereas we did find a strong desynchronization in the β 2 -range during action observation, the processing of action sentences evoked a rather weak desynchronization. However, this desynchronization occurred for action verbs in both concrete and abstract contexts. These results might indicate a tendency for abstract action language to be processed similar to concrete action language rather than abstract sentences. The oscillation patterns reflect the close relationship between language comprehension and motor functions - one of the core claims of current theories on embodied cognition. Copyright © 2017 Elsevier Inc. All rights reserved.

Reinforcing of Cement Composites by Estabragh Fibres

NASA Astrophysics Data System (ADS)

Merati, A. A.

2014-04-01

The influence of Estabragh fibres has been studied to improve the performance characteristics of the reinforced cement composites. The concrete shrinkage was evaluated by counting the number of cracks and measuring the width of cracks on the surface of concrete specimens. Although, the Estabragh fibres lose their strength in an alkali environment of cement composites, but, the ability of Estabragh fibres to bridge on the micro cracks in the concrete matrix causes to decrease the width of the cracks on the surface of the concrete samples in comparison with the plain concrete. However, considering the mechanical properties of specimens such as bending strength and impact resistance, the specimens with 0.25 % of Estabragh fibre performed better in all respects compared to the physical and mechanical properties of reinforced cement composite of concrete. Consequently, by adding 0.25 % of Estabragh fibres to the cement composite of concrete, a remarkable improvement in physical and mechanical properties of fibre-containing cement composite is achieved.

Technological parameters influence on the non-autoclaved foam concrete characteristics

NASA Astrophysics Data System (ADS)

Bartenjeva, Ekaterina; Mashkin, Nikolay

2017-01-01

Foam concretes are used as effective heat-insulating materials. The porous structure of foam concrete provides good insulating and strength properties that make them possible to be used as heat-insulating structural materials. Optimal structure of non-autoclaved foam concrete depends on both technological factors and properties of technical foam. In this connection, the possibility to manufacture heat-insulation structural foam concrete on a high-speed cavity plant with the usage of protein and synthetic foamers was estimated. This experiment was carried out using mathematical planning method, and in this case mathematical models were developed that demonstrated the dependence of operating performance of foam concrete on foaming and rotation speed of laboratory plant. The following material properties were selected for the investigation: average density, compressive strength, bending strength and thermal conductivity. The influence of laboratory equipment technological parameters on technical foam strength and foam stability coefficient in the cement paste was investigated, physical and mechanical properties of non-autoclaved foam concrete were defined based on investigated foam. As a result of investigation, foam concrete samples were developed with performance parameters ensuring their use in production. The mathematical data gathered demonstrated the dependence of foam concrete performance on the technological regime.

Effect of Gum Arabic karroo as a Water-Reducing Admixture in Concrete

PubMed Central

Mbugua, Rose; Salim, Ramadhan; Ndambuki, Julius

2016-01-01

Concrete is one of the most popular construction materials in the world. Chemical admixtures are ingredients added to concrete to enhance its properties. However, most chemical admixtures on the market today are expensive, thereby making them out of reach for small consumers of concrete. In Africa, use of chemical admixtures is rare despite the harsh weather conditions. In the current study, Gum from Acacia karroo (GAK) was used as a water-reducing admixture in concrete. A slump test, density and compressive strength were studied using different dosages of GAK while neat concrete was the control. Results showed that slump increased by 200% at a 2% dosage of GAK. This enabled reduction of water-to-binder (w/b) ratio from 0.61 to 0.48 for samples with a 3% dosage. Reduction in w/b resulted in increased compressive strength of 37.03% above the control after 180 days of curing for a 3% dosage. XRD studies also showed a decreased rate of hydration in the presence of GAK in concrete. It was concluded that GAK can be used in concrete as a water-reducing admixture, which is environmentally-friendly, thus producing sustainable and greener concrete. PMID:28787879

Effect of Gum Arabic karroo as a Water-Reducing Admixture in Concrete.

PubMed

Mbugua, Rose; Salim, Ramadhan; Ndambuki, Julius

2016-01-28

Concrete is one of the most popular construction materials in the world. Chemical admixtures are ingredients added to concrete to enhance its properties. However, most chemical admixtures on the market today are expensive, thereby making them out of reach for small consumers of concrete. In Africa, use of chemical admixtures is rare despite the harsh weather conditions. In the current study, Gum from Acacia karroo (GAK) was used as a water-reducing admixture in concrete. A slump test, density and compressive strength were studied using different dosages of GAK while neat concrete was the control. Results showed that slump increased by 200% at a 2% dosage of GAK. This enabled reduction of water-to-binder (w/b) ratio from 0.61 to 0.48 for samples with a 3% dosage. Reduction in w/b resulted in increased compressive strength of 37.03% above the control after 180 days of curing for a 3% dosage. XRD studies also showed a decreased rate of hydration in the presence of GAK in concrete. It was concluded that GAK can be used in concrete as a water-reducing admixture, which is environmentally-friendly, thus producing sustainable and greener concrete.

Influence of increasing amount of recycled concrete powder on mechanical properties of cement paste

NASA Astrophysics Data System (ADS)

Topič, Jaroslav; Prošek, Zdeněk; Plachý, Tomáš

2017-09-01

This paper deals with using fine recycled concrete powder in cement composites as micro-filler and partial cement replacement. Binder properties of recycled concrete powder are given by exposed non-hydrated cement grains, which can hydrate again and in small amount replace cement or improve some mechanical properties. Concrete powder used in the experiments was obtained from old railway sleepers. Infrastructure offer more sources of old concrete and they can be recycled directly on building site and used again. Experimental part of this paper focuses on influence of increasing amount of concrete powder on mechanical properties of cement paste. Bulk density, shrinkage, dynamic Young’s modulus, compression and flexural strength are observed during research. This will help to determine limiting amount of concrete powder when decrease of mechanical properties outweighs the benefits of cement replacement. The shrinkage, dynamic Young’s modulus and flexural strength of samples with 20 to 30 wt. % of concrete powder are comparable with reference cement paste or even better. Negative effect of concrete powder mainly influenced the compression strength. Only a 10 % cement replacement reduced compression strength by about 25 % and further decrease was almost linear.

Effect of silica-palm shell carbon composite additive in enhancing the strength of the concrete in the oil-well cementing job

NASA Astrophysics Data System (ADS)

Novriansyah, A.; Mursyidah, U.; Novrianti; Putri, S. S.; Riswati, S. S.

2018-04-01

This study provides an analysis of composite additive effect to concrete’s strength in the oil-well cementing job. The composite additive is originated from the nano-sized form of silica and charcoal from palm shell waste. The quality of the concrete will be determined from its porosity, compressive strength, and shear bond strength parameters. Those parameters must be reliable base on the most respectable standards in oil and gas industry, in this study we use the standard from American Petroleum Institute (API). Six concrete samples with different concentration will be tested to obtain these parameters. The result from the test shown a decrement trend of the porosity while the concentration is increased. In contrast, the highest values of compressive strength and shear bond strength are obtained from the sample with higher additive concentration. The optimum strength was obtained in sample with 0.02% The results become clearly proven through verification by scanning electron image where the additive has successfully fill the voids in the concrete’s sample, resulting in strength enhancement of the sample.

Reactivity change in a fast-spectrum space power reactor due to a 328-meter-per-second (1075-ft/sec) impact

NASA Technical Reports Server (NTRS)

Peoples, J. A., Jr.; Puthoff, R. L.

1973-01-01

Application of nuclear reactors in space will present operational problems. One such problem is the possibility of an earth impact at velocities in excess of 305 m/sec (1000 ft/sec). This report shows the results of an impact against concrete at 328 m/sec (1075 ft/sec) and examines the deformed core to estimate the range of activity inserted as a result of the impact. The results of this examination are that the deformation of the reactor core within the containment vessel left only an estimated 2.7 percent void in the core and that the reactivity inserted due to this impact deformation could be from 4.0 to 10.25 dollars.

Material Concerns: Evaluating Sulfur Concrete for use in the Lunar Environment

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Toutanji, Houssam

2006-01-01

On Earth sulfur "concrete" is an established construction material that has good mechanical properties, generally better than Portland cement, and can be used in corrosive environments. Troilite (FeS) has been found on the moon and raises the question of using extracted sulfur as a lunar construction material, an attractive alternative to conventional concrete as it does not require water. Troilite reduction to elemental sulfur and using it to make concrete in a lunar setting has been previously discussed. However, little has been experimentally done to evaluate its performance in the extreme lunar environment. This study subjected sets of sulfur concrete samples, prepared using JSC-1 lunar simulant, to I ) extended periods of high vacuum and 2) extreme temperature cycles. Here an overview of sulfur concrete and experimentally assessed properties, put in context of the lunar environment, is presented and discussed.

Quality control of concrete at the stage of designing its composition and technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kudyakov, A., E-mail: kudyakow@mail.tomsknet.ru; Prischepa, I., E-mail: ingaprishepa@mail.ru; Kiselev, D.

The results of tests on samples of foam concrete with a hardening accelerator are presented. As the setting and hardening accelerators the following chemical additives were used: Universal-P-2 and Asilin 12. All additives were added into the insulating foam concrete mix of brand D 400 in the amount of 0.5% to 1% of cement weight. By using of additives in foam concrete technology – hardening accelerators Asilin 12 and Universal P2 in the amount of 0.5 % - and 1.0% by weight of cement foam concrete structure formation is accelerated and increases strength by 60%. For the industrial preparation ofmore » foam concrete mix technological regulations are worked out, in which it is recommended to use additives – hardening accelerators Asilin 12 in the amount of 0.5% and Universal P2 - 1% of cement weight.« less

A Mars Sample Return Sample Handling System

NASA Technical Reports Server (NTRS)

Wilson, David; Stroker, Carol

2013-01-01

We present a sample handling system, a subsystem of the proposed Dragon landed Mars Sample Return (MSR) mission [1], that can return to Earth orbit a significant mass of frozen Mars samples potentially consisting of: rock cores, subsurface drilled rock and ice cuttings, pebble sized rocks, and soil scoops. The sample collection, storage, retrieval and packaging assumptions and concepts in this study are applicable for the NASA's MPPG MSR mission architecture options [2]. Our study assumes a predecessor rover mission collects samples for return to Earth to address questions on: past life, climate change, water history, age dating, understanding Mars interior evolution [3], and, human safety and in-situ resource utilization. Hence the rover will have "integrated priorities for rock sampling" [3] that cover collection of subaqueous or hydrothermal sediments, low-temperature fluidaltered rocks, unaltered igneous rocks, regolith and atmosphere samples. Samples could include: drilled rock cores, alluvial and fluvial deposits, subsurface ice and soils, clays, sulfates, salts including perchlorates, aeolian deposits, and concretions. Thus samples will have a broad range of bulk densities, and require for Earth based analysis where practical: in-situ characterization, management of degradation such as perchlorate deliquescence and volatile release, and contamination management. We propose to adopt a sample container with a set of cups each with a sample from a specific location. We considered two sample cups sizes: (1) a small cup sized for samples matching those submitted to in-situ characterization instruments, and, (2) a larger cup for 100 mm rock cores [4] and pebble sized rocks, thus providing diverse samples and optimizing the MSR sample mass payload fraction for a given payload volume. We minimize sample degradation by keeping them frozen in the MSR payload sample canister using Peltier chip cooling. The cups are sealed by interference fitted heat activated memory alloy caps [5] if the heating does not affect the sample, or by crimping caps similar to bottle capping. We prefer cap sealing surfaces be external to the cup rim to prevent sample dust inside the cups interfering with sealing, or, contamination of the sample by Teflon seal elements (if adopted). Finally the sample collection rover, or a Fetch rover, selects cups with best choice samples and loads them into a sample tray, before delivering it to the Earth Return Vehicle (ERV) in the MSR Dragon capsule as described in [1] (Fig 1). This ensures best use of the MSR payload mass allowance. A 3 meter long jointed robot arm is extended from the Dragon capsule's crew hatch, retrieves the sample tray and inserts it into the sample canister payload located on the ERV stage. The robot arm has capacity to obtain grab samples in the event of a rover failure. The sample canister has a robot arm capture casting to enable capture by crewed or robot spacecraft when it returns to Earth orbit

Monitoring biocalcification potential of Lysinibacillus sp. isolated from alluvial soils for improved compressive strength of concrete.

PubMed

Vashisht, Rajneesh; Attri, Sampan; Sharma, Deepak; Shukla, Abhilash; Goel, Gunjan

2018-03-01

The present study reports the potential of newly isolated calcite precipitating bacteria isolated from alluvial soil to improve the strength and durability of concrete. A total of sixteen samples of alluvial soil and sewage were collected from the different locations of province Solan (India). For isolation, enrichment culture technique was used to enrich calcite precipitating strains in Urea broth. After enrichment, fourteen distinct bacterial strains were obtained on Urea agar. Based on qualitative and quantitative screening for urease activity, five isolates were obtained possessing higher calcite formation and urease activities (38-77 μmhos/cm) as compared with standard strain of Bacillus megaterium MTCC 1684 (77 μmhos/cm). An isolate I13 identified as Lysinibacillus sp. was selected for self healing property in the concrete mix of M20. An improved compressive strength of 1.5 fold was observed in concrete samples amended with Lysinibacillus sp. over the concrete amended with B. megaterium MTCC 1684 after 28 days of curing. The higher calcite precipitation activity was indicated in Lysinibacillus sp. by FE-SEM micrographs and EDX analysis. Copyright © 2017 Elsevier GmbH. All rights reserved.

Strength and Microstructure of Concrete with Iron Ore Tailings as Replacement for River Sand

NASA Astrophysics Data System (ADS)

Umara Shettima, Ali; Ahmad, Yusof; Warid Hussin, Mohd; Zakari Muhammad, Nasiru; Eziekel Babatude, Ogunbode

2018-03-01

River Sand is one of the basic ingredients used in the production of concrete. Consequently, continuous consumption of sand in construction industry contributes significantly to depletion of natural resources. To achieve more sustainable construction materials, this paper reports the use of iron ore tailings (IOT) as replacement for river sand in concrete production. IOT is a waste product generated from the production of iron ore and disposed to land fill without any economic value. Concrete mixtures containing different amount of IOT were designed for grade C30 with water to cement ratio of 0.60. The percentage ratios of the river sand replacements by IOT were 25%, 50%, 75% and 100%. Concrete microstructure test namely, XRD and Field Emission Scanned Electron Microscopic/Energy dispersive X-ray Spectroscopy (FESEM/EDX) were conducted for control and IOT concretes in order to determine the interaction and performance of the concrete containing IOT. Test results indicated that the slump values of 130 mm and 80 to 110 mm were recorded for the control and IOT concretes respectively. The concrete sample of 50% IOT recorded the highest compressive strength of 37.7 MPa at 28 days, and the highest flexural strength of 5.5 MPa compared to 4.7 MPa for reference concrete. The texture of the IOT is rough and angular which was able to improve the strength of the concrete.

Turn Basin Construction

NASA Image and Video Library

2017-06-14

Modifications are underway at the Launch Complex 39 turn basin wharf at NASA's Kennedy Space Center in Florida to prepare for the arrival of the agency's massive Space Launch System (SLS) core stage aboard the barge Pegasus. A crane will be used to lift up precast concrete poles and position them to be driven to a depth of about 70 feet into the bedrock below the water around the turn basin. The upgrades are necessary to accommodate the 300,000-pound core booster aboard the modified Pegasus barge. The Ground Systems Development and Operations Program is overseeing the upgrades to the turn basin wharf.

Turn Basin Construction

NASA Image and Video Library

2017-06-14

Modifications are underway at the Launch Complex 39 turn basin wharf at NASA's Kennedy Space Center in Florida to prepare for the arrival of the agency's massive Space Launch System (SLS) core stage aboard the barge Pegasus. Precast concrete poles are being driven to a depth of about 70 feet into the bedrock below the water around the turn basin. The upgrades are necessary to accommodate the increased weight of the core stage along with ground support and transportation equipment aboard the modified barge Pegasus. The Ground Systems Development and Operations Program is overseeing the upgrades to the turn basin wharf.

The Common Core Initiative, Education Outcomes, and American Indian/Alaska Native Students: Observations and Recommendations

ERIC Educational Resources Information Center

Nelson-Barber, Sharon; Trumbull, Elise

2015-01-01

This monograph explores the ways in which large-scale school reform efforts play out in American Indian/Alaska Native communities and schools, starting from a historical and cultural perspective, and focusing on the translation of research into concrete steps leading to American Indian/Alaska Native student academic success and personal well-being.

Teaching Multiplication with Regrouping Using the Concrete-Representational-Abstract Sequence and the Strategic Instruction Model

ERIC Educational Resources Information Center

Flores, Margaret M.; Franklin, Toni M.

2014-01-01

The Common Core State Standards (2010) involve the demonstration of conceptual knowledge of numbers and operations. For students who struggle with mathematics and have not responded to instruction, it is important that interventions emphasize this understanding. In order to address conceptual understanding of numbers and operations in meeting the…

Study of some health physics parameters of bismuth-ground granulated blast furnace slag shielding concretes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Sandeep, E-mail: sandeep0078monu@gmail.com; Singh, Sukhpal, E-mail: sukhpal-78@rediffmail.com

2016-05-06

The Bismuth-ground granulated blastfurnace slang (Bi-GGBFS) concrete samples were prepared. The weight percentage of different elements present in Bi-GGBFS Shielding concretewas evaluated by Energy Dispersive X-ray Microanalysis (EDX). The exposure rate and absorbed dose rate characteristics were calculated theoretically for radioactive sources namely {sup 241}Am and {sup 137}Cs. Our calculations reveal that the Bi-GGBFS concretes are effective in shielding material for gamma radiations.

In situ alkali-silica reaction observed by x-ray microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurtis, K.E.; Monteiro, P.J.M.; Brown, J.T.

1997-04-01

In concrete, alkali metal ions and hydroxyl ions contributed by the cement and reactive silicates present in aggregate can participate in a destructive alkali-silica reaction (ASR). This reaction of the alkalis with the silicates produces a gel that tends to imbibe water found in the concrete pores, leading to swelling of the gel and eventual cracking of the affected concrete member. Over 104 cases of alkali-aggregate reaction in dams and spillways have been reported around the world. At present, no method exists to arrest the expansive chemical reaction which generates significant distress in the affected structures. Most existing techniques availablemore » for the examination of concrete microstructure, including ASR products, demand that samples be dried and exposed to high pressure during the observation period. These sample preparation requirements present a major disadvantage for the study of alkali-silica reaction. Given the nature of the reaction and the affect of water on its products, it is likely that the removal of water will affect the morphology, creating artifacts in the sample. The purpose of this research is to observe and characterize the alkali-silica reaction, including each of the specific reactions identified previously, in situ without introducing sample artifacts. For observation of unconditioned samples, x-ray microscopy offers an opportunity for such an examination of the alkali-silica reaction. Currently, this investigation is focusing on the effect of calcium ions on the alkali-silica reaction.« less

Guidelines for Sampling, Assessing, and Restoring Defective Grout in Prestressed Concrete Bridge Post-Tensioning Ducts

DOT National Transportation Integrated Search

2013-10-01

A significant proportion of the United States bridge inventory is based on bonded post-tensioned (PT) concrete construction. An important aspect of maintaining corrosion protection of these PT systems is assuring that tendon ducts are properly groute...

Guidelines for sampling, assessing, and restoring defective grout in prestressed concrete bridge post-tensioning ducts.

DOT National Transportation Integrated Search

2013-10-01

"A significant proportion of the U.S. bridge inventory is based on bonded post-tensioned (PT) concrete construction. An : important aspect of maintaining corrosion protection of these PT systems is assuring that tendon ducts are properly grouted : wi...

Performances of Metal Concentrations from Three Permeable Pavement Infiltrates

EPA Science Inventory

The U.S. Environmental Protection Agency designed and constructed a 4000-m2 parking lot in Edison, New Jersey in 2009. The parking lot is surfaced with three permeable pavements: permeable interlocking concrete pavers, pervious concrete, and porous asphalt. Water sampling was con...

Performances of Metal Concentrations from Three Permeable Pavement Infiltrates

EPA Science Inventory

The U.S. Environmental Protection Agency constructed a 4000-m2 parking lot in Edison, New Jersey in 2009. The parking lot is surfaced with three permeable pavements [permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA)]. Samples of each p...

Investigation of air-entraining admixture dosage in fly ash concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ley, M.T.; Harris, N.J.; Folliard, K.J.

The amount of air-entraining admixture (AEA) needed to achieve a target air content in fresh concrete can vary significantly with differences in the fly ash used in the concrete. The work presented in this paper evaluates the ability to predict the AEA dosage on the basis of tests on the fly ash alone. All results were compared with the dosage of AEA required to produce an air content of 6% in fresh concrete. Fly ash was sampled from six separate sources. For four of these sources, samples were obtained both before and after the introduction of 'low-NOx burners'. Lack ofmore » definitive data about the coal itself or the specifics of the burning processes prevents the ability to draw specific conclusions about the impact of low-NOx burners on AEA demand. Nevertheless, the data suggest that modification of the burning process to meet environmental quality standards may affect the fly ash-AEA interaction.« less

Interrelating the breakage and composition of mined and drill core coal

NASA Astrophysics Data System (ADS)

Wilson, Terril Edward

Particle size distribution of coal is important if the coal is to be beneficiated, or if a coal sales contract includes particle size specifications. An exploration bore core sample of coal ought to be reduced from its original cylindrical form to a particle size distribution and particle composition that reflects, insofar as possible, a process stream of raw coal it represents. Often, coal cores are reduced with a laboratory crushing machine, the product of which does not match the raw coal size distribution. This study proceeds from work in coal bore core reduction by Australian investigators. In this study, as differentiated from the Australian work, drop-shatter impact breakage followed by dry batch tumbling in steel cylinder rotated about its transverse axis are employed to characterize the core material in terms of first-order and zeroth-order breakage rate constants, which are indices of the propensity of the coal to degrade during excavation and handling. Initial drop-shatter and dry tumbling calibrations were done with synthetic cores composed of controlled low-strength concrete incorporating fly ash (as a partial substitute for Portland cement) in order to reduce material variables and conserve difficult-to-obtain coal cores. Cores of three different coalbeds--Illinois No. 6, Upper Freeport, and Pocahontas No. 5 were subjected to drop-shatter and dry batch tumbling tests to determine breakage response. First-order breakage, characterized by a first-order breakage index for each coal, occurred in the drop-shatter tests. First- and zeroth-order breakage occurred in dry batch tumbling; disappearance of coarse particles and creation of fine particles occurred in a systematic way that could be represented mathematically. Certain of the coal cores available for testing were dry and friable. Comparison of coal preparation plant feed with a crushed bore core and a bore core prepared by drop-shatter and tumbling (all from the same Illinois No.6 coal mining property) indicated that the size distribution and size fraction composition of the drop-shattered/tumbled core more closely resembled the plant feed than the crushed core. An attempt to determine breakage parameters (to allow use of selection and breakage functions and population balance models in the description of bore core size reduction) was initiated. Rank determination of the three coal types was done, indicating that higher rank associates with higher breakage propensity. The two step procedure of drop-shatter and dry batch tumbling simulates the first-order (volume breakage) and zeroth-order (abrasion of particle surfaces) that occur in excavation and handling operations, and is appropriate for drill core reduction prior to laboratory analysis.

Photoactive roadways: Determination of CO, NO and VOC uptake coefficients and photolabile side product yields on TiO2 treated asphalt and concrete

NASA Astrophysics Data System (ADS)

Toro, C.; Jobson, B. T.; Haselbach, L.; Shen, S.; Chung, S. H.

2016-08-01

This work reports uptake coefficients and by-product yields of ozone precursors onto two photocatalytic paving materials (asphalt and concrete) treated with a commercial TiO2 surface application product. The experimental approach used a continuously stirred tank reactor (CSTR) and allowed for testing large samples with the same surface morphology encountered with real urban surfaces. The measured uptake coefficient (γgeo) and surface resistances are useful for parametrizing dry deposition velocities in air quality model evaluation of the impact of photoactive surfaces on urban air chemistry. At 46% relative humidity, the surface resistance to NO uptake was ∼1 s cm-1 for concrete and ∼2 s cm-1 for a freshly coated older roadway asphalt sample. HONO and NO2 were detected as side products from NO uptake to asphalt, with NO2 molar yields on the order of 20% and HONO molar yields ranging between 14 and 33%. For concrete samples, the NO2 molar yields increased with the increase of water vapor, ranging from 1% to 35% and HONO was not detected as a by-product. Uptake of monoaromatic VOCs to the asphalt sample set displayed a dependence on the compound vapor pressure, and was influenced by competitive adsorption from less volatile VOCs. Formaldehyde and acetaldehyde were detected as byproducts, with molar yields ranging from 5 to 32%.

Recycling of water-susceptible pavements

NASA Astrophysics Data System (ADS)

Maupin, G. W.

1980-05-01

Several bituminous concrete interstate pavements that experienced failures suspected to have been caused by stripping were investigated. On two projects, the degree of deterioration, potential serviceability, and possible remedial measures were studied. Cores were taken to determine the degreee of stripping and tensile strength, and dynaflect tests were performed. An emulsion mix design was developed for stripped bituminous concrete removed from another project with the expectation that it could be used as a surface mix on a highway with a low traffic volume. While this expectation was not realized, it was concluded that the material is suitable for use in a base mix. A maintenance resurfacing on a fourth project that experienced stripping failure is being monitored and the performance is being evaluated.

Cognitive Metaphor Theory and the Metaphysics of Immediacy.

PubMed

Madsen, Mathias W

2016-05-01

One of the core tenets of cognitive metaphor theory is the claim that metaphors ground abstract knowledge in concrete, first-hand experience. In this paper, I argue that this grounding hypothesis contains some problematic conceptual ambiguities and, under many reasonable interpretations, empirical difficulties. I present evidence that there are foundational obstacles to defining a coherent and cognitively valid concept of "metaphor" and "concrete meaning," and some general problems with singling out certain domains of experience as more immediate than others. I conclude from these considerations that whatever the facts are about the comprehension of individual metaphors, the available evidence is incompatible with the notion of an underlying conceptual structure organized according to the immediacy of experience. Copyright © 2015 Cognitive Science Society, Inc.

Correlation of Water Quality Parameters with Metal Concentrations in Permeable Pavement Infiltrate

EPA Science Inventory

EPA constructed a 4,000-m2 parking lot for research and demonstration of three permeable pavements [permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA)] at the Edison Environmental Center in Edison, NJ in 2009. Infiltrate samples from e...

Progress Implementing a Model-Based Iterative Reconstruction Algorithm for Ultrasound Imaging of Thick Concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Almansouri, Hani; Johnson, Christi R; Clayton, Dwight A

All commercial nuclear power plants (NPPs) in the United States contain concrete structures. These structures provide important foundation, support, shielding, and containment functions. Identification and management of aging and the degradation of concrete structures is fundamental to the proposed long-term operation of NPPs. Concrete structures in NPPs are often inaccessible and contain large volumes of massively thick concrete. While acoustic imaging using the synthetic aperture focusing technique (SAFT) works adequately well for thin specimens of concrete such as concrete transportation structures, enhancements are needed for heavily reinforced, thick concrete. We argue that image reconstruction quality for acoustic imaging in thickmore » concrete could be improved with Model-Based Iterative Reconstruction (MBIR) techniques. MBIR works by designing a probabilistic model for the measurements (forward model) and a probabilistic model for the object (prior model). Both models are used to formulate an objective function (cost function). The final step in MBIR is to optimize the cost function. Previously, we have demonstrated a first implementation of MBIR for an ultrasonic transducer array system. The original forward model has been upgraded to account for direct arrival signal. Updates to the forward model will be documented and the new algorithm will be assessed with synthetic and empirical samples.« less

Progress implementing a model-based iterative reconstruction algorithm for ultrasound imaging of thick concrete

NASA Astrophysics Data System (ADS)

Almansouri, Hani; Johnson, Christi; Clayton, Dwight; Polsky, Yarom; Bouman, Charles; Santos-Villalobos, Hector

2017-02-01

All commercial nuclear power plants (NPPs) in the United States contain concrete structures. These structures provide important foundation, support, shielding, and containment functions. Identification and management of aging and the degradation of concrete structures is fundamental to the proposed long-term operation of NPPs. Concrete structures in NPPs are often inaccessible and contain large volumes of massively thick concrete. While acoustic imaging using the synthetic aperture focusing technique (SAFT) works adequately well for thin specimens of concrete such as concrete transportation structures, enhancements are needed for heavily reinforced, thick concrete. We argue that image reconstruction quality for acoustic imaging in thick concrete could be improved with Model-Based Iterative Reconstruction (MBIR) techniques. MBIR works by designing a probabilistic model for the measurements (forward model) and a probabilistic model for the object (prior model). Both models are used to formulate an objective function (cost function). The final step in MBIR is to optimize the cost function. Previously, we have demonstrated a first implementation of MBIR for an ultrasonic transducer array system. The original forward model has been upgraded to account for direct arrival signal. Updates to the forward model will be documented and the new algorithm will be assessed with synthetic and empirical samples.

Mechanical properties of bio self-healing concrete containing immobilized bacteria with iron oxide nanoparticles.

PubMed

Seifan, Mostafa; Sarmah, Ajit K; Samani, Ali Khajeh; Ebrahiminezhad, Alireza; Ghasemi, Younes; Berenjian, Aydin

2018-05-01

Concrete is arguably one of the most important and widely used materials in the world, responsible for the majority of the industrial revolution due to its unique properties. However, it is susceptible to cracking under internal and external stresses. The generated cracks result in a significant reduction in the concrete lifespan and an increase in maintenance and repair costs. In recent years, the implementation of bacterial-based healing agent in the concrete matrix has emerged as one of the most promising approaches to address the concrete cracking issue. However, the bacterial cells need to be protected from the high pH content of concrete as well as the exerted shear forces during preparation and hardening stages. To address these issues, we propose the magnetic immobilization of bacteria with iron oxide nanoparticles (IONs). In the present study, the effect of the designed bio-agent on mechanical properties of concrete (compressive strength and drying shrinkage) is investigated. The results indicate that the addition of immobilized Bacillus species with IONs in concrete matrix contributes to increasing the compressive strength. Moreover, the precipitates in the bio-concrete specimen were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The characterization studies confirm that the precipitated crystals in bio-concrete specimen were CaCO 3 , while no precipitation was observed in the control sample.

Axial Compression Behavior of a New Type of Prefabricated Concrete Sandwich Wall Panel

NASA Astrophysics Data System (ADS)

Qun, Xie; Shuai, Wang; Chun, Liu

2018-03-01

A novel type of prefabricated concrete sandwich wall panel which could be used as a load-bearing structural element in buildings has been presented in this paper. Compared with the traditional sandwich panels, there are several typical characteristics for this wall system, including core columns confined by spiral stirrup along the cross-section of panel with 600mm spacing, precast foamed concrete block between two structural layers as internal insulation part, and a three-dimensional (3D) steel wire skeleton in each layer which is composed of two vertical steel wire meshes connected by horizontally short steel bar. All steel segments in the panel are automatically prefabricated in factory and then are assembled to form steel system in site. In order to investigate the structural behavior of this wall panel, two full-scale panels have been experimentally studied under axial compressive load. The test results show that the wall panel presents good load-bearing capacity and integral stiffness without out-of-plane flexural failure. Compared to the panel with planar steel wire mesh in concrete layer, the panel with 3D steel wire skeleton presents higher strength and better rigidity even in the condition of same steel ratio in panels which verifies that the 3D steel skeleton could greatly enhance the structural behavior of sandwich panel.

Direct Experimental Evidence for Differing Reactivity Alterations of Minerals following Irradiation: The Case of Calcite and Quartz

NASA Astrophysics Data System (ADS)

Pignatelli, Isabella; Kumar, Aditya; Field, Kevin G.; Wang, Bu; Yu, Yingtian; Le Pape, Yann; Bauchy, Mathieu; Sant, Gaurav

2016-01-01

Concrete, used in the construction of nuclear power plants (NPPs), may be exposed to radiation emanating from the reactor core. Until recently, concrete has been assumed immune to radiation exposure. Direct evidence acquired on Ar+-ion irradiated calcite and quartz indicates, on the contrary, that, such minerals, which constitute aggregates in concrete, may be significantly altered by irradiation. More specifically, while quartz undergoes disordering of its atomic structure resulting in a near complete lack of periodicity, calcite only experiences random rotations, and distortions of its carbonate groups. As a result, irradiated quartz shows a reduction in density of around 15%, and an increase in chemical reactivity, described by its dissolution rate, similar to a glassy silica. Calcite however, shows little change in dissolution rate - although its density noted to reduce by ≈9%. These differences are correlated with the nature of bonds in these minerals, i.e., being dominantly ionic or covalent, and the rigidity of the mineral’s atomic network that is characterized by the number of topological constraints (nc) that are imposed on the atoms in the network. The outcomes have major implications on the durability of concrete structural elements formed with calcite or quartz bearing aggregates in nuclear power plants.

Direct Experimental Evidence for Differing Reactivity Alterations of Minerals following Irradiation: The Case of Calcite and Quartz

PubMed Central

Pignatelli, Isabella; Kumar, Aditya; Field, Kevin G.; Wang, Bu; Yu, Yingtian; Le Pape, Yann; Bauchy, Mathieu; Sant, Gaurav

2016-01-01

Concrete, used in the construction of nuclear power plants (NPPs), may be exposed to radiation emanating from the reactor core. Until recently, concrete has been assumed immune to radiation exposure. Direct evidence acquired on Ar+-ion irradiated calcite and quartz indicates, on the contrary, that, such minerals, which constitute aggregates in concrete, may be significantly altered by irradiation. More specifically, while quartz undergoes disordering of its atomic structure resulting in a near complete lack of periodicity, calcite only experiences random rotations, and distortions of its carbonate groups. As a result, irradiated quartz shows a reduction in density of around 15%, and an increase in chemical reactivity, described by its dissolution rate, similar to a glassy silica. Calcite however, shows little change in dissolution rate - although its density noted to reduce by ≈9%. These differences are correlated with the nature of bonds in these minerals, i.e., being dominantly ionic or covalent, and the rigidity of the mineral’s atomic network that is characterized by the number of topological constraints (nc) that are imposed on the atoms in the network. The outcomes have major implications on the durability of concrete structural elements formed with calcite or quartz bearing aggregates in nuclear power plants. PMID:26822012

Direct experimental evidence for differing reactivity alterations of minerals following irradiation. The case of calcite and quartz

DOE PAGES

Pignatelli, Isabella; Kumar, Aditya; Field, Kevin G.; ...

2016-01-29

Concrete, used in the construction of nuclear power plants (NPPs), may be exposed to radiation emanating from the reactor core. Until recently, concrete has been assumed immune to radiation exposure. Direct evidence acquired on Ar+ -ion irradiated calcite and quartz indicates, on the contrary, that, such minerals, which constitute aggregates in concrete, may be significantly altered by irradiation. More specifically, while quartz undergoes disordering of its atomic structure resulting in a near complete lack of periodicity, calcite only experiences random rotations, and distortions of its carbonate groups. As a result, irradiated quartz shows a reduction in density of around 15%,more » and an increase in chemical reactivity, described by its dissolution rate, similar to a glassy silica. However, calcite shows little change in dissolution rate - although its density noted to reduce by 9%. These differences are correlated with the nature of bonds in these minerals, i.e., being dominantly ionic or covalent, and the rigidity of the mineral's atomic network that is characterized by the number of topological constraints (nc) that are imposed on the atoms in the network. Our outcomes have major implications on the durability of concrete structural elements formed with calcitic or quartzitic aggregates in nuclear power plants.« less

Relating the Electrical Resistance of Fresh Concrete to Mixture Proportions.

PubMed

Obla, K; Hong, R; Sherman, S; Bentz, D P; Jones, S Z

2018-01-01

Characterization of fresh concrete is critical for assuring the quality of our nation's constructed infrastructure. While fresh concrete arriving at a job site in a ready-mixed concrete truck is typically characterized by measuring temperature, slump, unit weight, and air content, here the measurement of the electrical resistance of a freshly cast cylinder of concrete is investigated as a means of assessing mixture proportions, specifically cement and water contents. Both cement and water contents influence the measured electrical resistance of a sample of fresh concrete: the cement by producing ions (chiefly K + , Na + , and OH - ) that are the main source of electrical conduction; and the water by providing the main conductive pathways through which the current travels. Relating the measured electrical resistance to attributes of the mixture proportions, such as water-cement ratio by mass ( w/c ), is explored for a set of eleven different concrete mixtures prepared in the laboratory. In these mixtures, w/c , paste content, air content, fly ash content, high range water reducer dosage, and cement alkali content are all varied. Additionally, concrete electrical resistance data is supplemented by measuring the resistivity of its component pore solution obtained from 5 laboratory-prepared cement pastes with the same proportions as their corresponding concrete mixtures. Only measuring the concrete electrical resistance can provide a prediction of the mixture's paste content or the product w*c ; conversely, when pore solution resistivity is also available, w/c and water content of the concrete mixture can be reasonably assessed.

Relating the Electrical Resistance of Fresh Concrete to Mixture Proportions

PubMed Central

Obla, K.; Hong, R.; Sherman, S.; Bentz, D.P.; Jones, S.Z.

2018-01-01

Characterization of fresh concrete is critical for assuring the quality of our nation’s constructed infrastructure. While fresh concrete arriving at a job site in a ready-mixed concrete truck is typically characterized by measuring temperature, slump, unit weight, and air content, here the measurement of the electrical resistance of a freshly cast cylinder of concrete is investigated as a means of assessing mixture proportions, specifically cement and water contents. Both cement and water contents influence the measured electrical resistance of a sample of fresh concrete: the cement by producing ions (chiefly K+, Na+, and OH-) that are the main source of electrical conduction; and the water by providing the main conductive pathways through which the current travels. Relating the measured electrical resistance to attributes of the mixture proportions, such as water-cement ratio by mass (w/c), is explored for a set of eleven different concrete mixtures prepared in the laboratory. In these mixtures, w/c, paste content, air content, fly ash content, high range water reducer dosage, and cement alkali content are all varied. Additionally, concrete electrical resistance data is supplemented by measuring the resistivity of its component pore solution obtained from 5 laboratory-prepared cement pastes with the same proportions as their corresponding concrete mixtures. Only measuring the concrete electrical resistance can provide a prediction of the mixture’s paste content or the product w*c; conversely, when pore solution resistivity is also available, w/c and water content of the concrete mixture can be reasonably assessed. PMID:29882546

Correlation of Traditional Water Quality Parameters with Metal Concentrations in Permeable Pavement Infiltrate

EPA Science Inventory

EPA constructed a 4,000-m2 parking lot for research and demonstration of three permeable pavements [permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA)] at the Edison Environmental Center in Edison, NJ in 2009. Infiltrate samples from e...

Petrographic manual : petrographic methods of examining hardened concrete, including introduction, sample preparation, questions and suggestions, and reading list.

DOT National Transportation Integrated Search

1991-01-01

This manual was undertaken to record for all persons wishing to do concrete petrography the petrographic procedures that have been found useful here at the Virginia Transportation Research Council. This interim report is made up of the introduction, ...

The Concrete-Representational-Abstract Sequence of Instruction in Mathematics Classrooms

ERIC Educational Resources Information Center

Mudaly, Vimolan; Naidoo, Jayaluxmi

2015-01-01

The purpose of this paper is to explore how master mathematics teachers use the concrete-representational-abstract (CRA) sequence of instruction in mathematics classrooms. Data was collected from a convenience sample of six master teachers by observations, video recordings of their teaching, and semi-structured interviews. Data collection also…

Feasibility of atomic and molecular laser induced breakdown spectroscopy (LIBS) to in-situ determination of chlorine in concrete : final report.

DOT National Transportation Integrated Search

2016-10-01

Laser-induced breakdown spectroscopy (LIBS) has been studied as a fast method of detecting chlorine in concrete samples. Both single pulse (SP) and double pulse (DP) experiments have been tested. Several combinations of lasers (Neodymium-Yttrium Alum...

Hypothesis Sampling Systems among Preoperational and Concrete Operational Kindergarten Children

ERIC Educational Resources Information Center

Gholson, Barry; And Others

1976-01-01

Preoperational and concrete operational kindergarten children received stimulus differentiation training, either with or without feedback, and then a series of discrimination learning problems in which a blank trial probe was used to detect a child's hypothesis after each feedback trial. Piagetian stage theory requires elaboration to account…

The durability of concrete containing recycled tyres as a partial replacement of fine aggregate

NASA Astrophysics Data System (ADS)

Syamir Senin, Mohamad; Shahidan, Shahiron; Syazani Leman, Alif; Othman, Nurulain; Shamsuddin, Shamrul-mar; Ibrahim, M. H. W.; Zuki, S. S. Mohd

2017-11-01

Nowadays, uncontrolled disposal of waste materials such as tyres can affect the environment. Therefore, careful management of waste disposal must be done in order to conserve the environment. Waste tyres can be use as a replacement for both fine aggregate and coarse aggregate in the production of concrete. This research was conducted to assess the durability of concrete containing recycled tyres which have been crushed into fine fragments to replace fine aggregate in the concrete mix. This study presents an overview of the use of waste rubber as a partial replacement of natural fine aggregate in a concrete mix. 36 concrete cubes measuring 100mm × 100mm × 100mm and 12 concrete cubes measuring 150mm × 150mm × 150mm were prepared and added with different percentages of rubber from recycled tyres (0%, 3%, 5% and 7%) as fine aggregate replacement. The results obtained show that the replacement of fine aggregate with 7% of rubber recorded a compressive strength of 43.7MPa while the addition of 3% of rubber in the concrete sample recorded a high compressive strength of 50.8MPa. This shows that there is a decrease in the strength and workability of concrete as the amount of rubber used a replacement for fine aggregate in concrete increases. On the other hand, the water absorption test indicated that concrete which contains rubber has better water absorption ability. In this study, 3% of rubber was found to be the optimal percentage as a partial replacement for fine aggregate in the production of concrete.

Testing an Impedance Non-destructive Method to Evaluate Steel-Fiber Concrete Samples

NASA Astrophysics Data System (ADS)

Komarkova, Tereza; Fiala, Pavel; Steinbauer, Miloslav; Roubal, Zdenek

2018-02-01

Steel-fiber reinforced concrete is a composite material characterized by outstanding tensile properties and resistance to the development of cracks. The concrete, however, exhibits such characteristics only on the condition that the steel fibers in the final, hardened composite have been distributed evenly. The current methods to evaluate the distribution and concentration of a fiber composite are either destructive or exhibit a limited capability of evaluating the concentration and orientation of the fibers. In this context, the paper discusses tests related to the evaluation of the density and orientation of fibers in a composite material. Compared to the approaches used to date, the proposed technique is based on the evaluation of the electrical impedance Z in the band close to the resonance of the sensor-sample configuration. Using analytically expressed equations, we can evaluate the monitored part of the composite and its density at various depths of the tested sample. The method employs test blocks of composites, utilizing the resonance of the measuring device and the measured sample set; the desired state occurs within the interval of between f=3 kHz and 400 kHz.

Evaluation of concrete cover by surface wave technique: Identification procedure

NASA Astrophysics Data System (ADS)

Piwakowski, Bogdan; Kaczmarek, Mariusz; Safinowski, Paweł

2012-05-01

Concrete cover degradation is induced by aggressive agents in ambiance, such as moisture, chemicals or temperature variations. Due to degradation usually a thin (a few millimeters thick) surface layer has porosity slightly higher than the deeper sound material. The non destructive evaluation of concrete cover is vital to monitor the integrity of concrete structures and prevent their irreversible damage. In this paper the methodology applied by the classical technique used for ground structure recovery called Multichanel Analysis of Surface Waves is discussed as the NDT tool in civil engineering domain to characterize the concrete cover. In order to obtain the velocity as a function of sample depth the dispersion of surface waves is used as an input for solving inverse problem. The paper describes the inversion procedure and provides the practical example of use of developed system.

Teaching Algebra-Based Concepts to Students with Learning Disabilities: The Effects of Preteaching Using a Gradual Instructional Sequence

ERIC Educational Resources Information Center

Watt, Sarah Jean

2013-01-01

Research to identify validated instructional approaches to teach math to students with LD and those at-risk for failure in both core and supplemental instructional settings is necessary to assist teachers in closing the achievement gaps that exist across the country. The concrete-to-representational-to-abstract instructional sequence (CRA) has…

75 FR 18826 - FPL Energy Maine Hydro LLC, Madison Paper Industries, and Merimil Limited Partnership; Notice of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-13

... fishway (inactive); and (e) a 734-foot earth dike with a concrete core wall; (2) a 9,700-acre reservoir... downstream demands for hydroelectric generation in the Kennebec River and for flood control. Reservoir fluctuations follow an annual cycle under which reservoir levels are reduced during the fall and winter to...

State of the Art Reinforcement for Concrete Bridge Decks

DTIC Science & Technology

2009-02-01

Microcomposite Martensitic Ferretic Steel (MMFX 2) • Initial proprietary technology developed at the University of California Berkeley by...Center US Army Corps of Engineers Microcomposite Steel Microcomposite Steels , Packet Lath Martensite Dislocated laths of martensite enveloped by... steel cladding with carbon steel core • Patented “green” process bonds stainless steel to carbon steel • Optimizes stainless steel’s very high

Innovative Retrofit Insulation Strategies for Concrete Masonry Foundations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huelman, P.; Goldberg, L.; Jacobson, R.

This study was designed to test a new approach for foundation insulation retrofits, with the goal of demonstrating improved moisture control, improved occupant comfort, and reduced heat loss. Because conducting experimental research on existing below-grade assemblies is very difficult, most of the results are based on simulations. The retrofit approach consists of filling open concrete block cores with an insulating material and adding R-10 exterior insulation that extends 1 ft below grade. The core fill is designed to improve the R-value of the foundation wall and increase the interior wall surface temperature, but more importantly to block convection currents thatmore » could otherwise increase moisture loads on the foundation wall and interior space. The exterior insulation significantly reduces heat loss through the most exposed part of the foundation and further increases the interior wall surface temperature. This improves occupant comfort and decreases the risk of condensation. Such an insulation package avoids the full-depth excavation necessary for exterior insulation retrofits, reduces costs, and eliminates the moisture and indoor air quality risks associated with interior insulation retrofits. Retrofit costs for the proposed approach were estimated at roughly half those of a full-depth exterior insulation retrofit.« less

The Influence of Phase Change Materials on the Properties of Self-Compacting Concrete.

PubMed

Fenollera, María; Míguez, José Luis; Goicoechea, Itziar; Lorenzo, Jaime; Ángel Álvarez, Miguel

2013-08-15

The aim of this paper is to research new thermally-efficient concrete walls, analyzing the mechanical behavior of a self-compacting concrete to manufacture an uncoated solid structural panel, with the incorporation of a micro-encapsulated phase change material as additive. Different dosages are tested and mechanical properties of the product obtained from the molding of concrete specimens are evaluated, testing mechanical compressive strength, slump flow, and density. The results reveal the optimum percentage of additive in the mixture that enables compliance with the technical specifications required by the product to be manufactured. A test is also performed for measuring the thermal conductivity for the optimal sample obtained and it evidences the reduction thereof.

Detection of chlorine with concentration of 0.18 kg/m{sup 3} in concrete by laser-induced breakdown spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugiyama, K.; Fujii, T.; Matsumura, T.

2010-05-01

The chlorine concentration in concrete samples was measured by laser-induced breakdown spectroscopy (LIBS). One or two pulsed second harmonic Nd:YAG lasers ({lambda}=532 nm) were used for the generation of laser-induced breakdown, and an intensified CCD camera, spectrometer, and optical bundle fiber were used for spectral measurement. To maximize the spectral intensity of the chlorine fluorescence line at a wavelength of 837.59 nm, the time delay between laser irradiation and spectral measurement, the time delay between the two laser pulses in double-pulse measurement, and the gate width of the spectral measurement were optimized. The linear relationship between the spectral intensity ofmore » the chlorine fluorescence line and the chlorine concentration was verified for pressed samples with chlorine concentrations from 0.18 to 5.4 kg/m{sup 3}. The signal-to-noise ratio was higher than 2 for the sample with a chlorine concentration of 0.18 kg/m{sup 3} (0.008 wt. %). Thus, a chlorine concentration of 0.6 kg/m{sup 3}, at which the reinforcing bars in concrete structures start to corrode, can be detected. These results show that LIBS is effective for the quantitative measurement of chlorine concentration in concrete with high sensitivity.« less

Alkali-activated concrete with Serbian fly ash and its radiological impact.

PubMed

Nuccetelli, Cristina; Trevisi, Rosabianca; Ignjatović, Ivan; Dragaš, Jelena

2017-03-01

The present paper reports the results of a study on different types of fly ash from Serbian coal burning power plants and their potential use as a binder in alkali-activated concrete (AAC) depending on their radiological and mechanical properties. Five AAC mixtures with different types of coal burning fly ash and one type of blast furnace slag were designed. Measurements of the activity concentrations of 40 K, 226 Ra and 232 Th were done both on concrete constituents (fly ash, blast furnace slag and aggregate) and on the five solid AAC samples. Experimental results were compared by using the activity concentration assessment tool for building materials - the activity concentration index I, as introduced by the EU Basic Safety Standards (CE, 2014). All five designed alkali-activated concretes comply with EU BSS screening requirements for indoor building materials. Finally, index I values were compared with the results of the application of a more accurate index - I(ρd), which accounts for thickness and density of building materials (Nuccetelli et al., 2015a). Considering the actual density and thickness of each concrete sample index - I(ρd) values are lower than index I values. As an appendix, a synthesis of main results concerning mechanical and chemical properties is provided. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermomagnetic Analyses to Test Concrete Stability

NASA Astrophysics Data System (ADS)

Geiss, C. E.; Gourley, J. R.

2017-12-01

Over the past decades pyrrhotite-containing aggregate has been used in concrete to build basements and foundations in central Connecticut. The sulphur in the pyrrhotite reacts to several secondary minerals, and associated changes in volume lead to a loss of structural integrity. As a result hundreds of homes have been rendered worthless as remediation costs often exceed the value of the homes and the value of many other homes constructed during the same time period is in question as concrete provenance and potential future structural issues are unknown. While minor abundances of pyrrhotite are difficult to detect or quantify by traditional means, the mineral is easily identified through its magnetic properties. All concrete samples from affected homes show a clear increase in magnetic susceptibility above 220°C due to the γ - transition of Fe9S10 [1] and a clearly defined Curie-temperature near 320°C for Fe7S8. X-ray analyses confirm the presence of pyrrhotite and ettringite in these samples. Synthetic mixtures of commercially available concrete and pyrrhotite show that the method is semiquantitative but needs to be calibrated for specific pyrrhotite mineralogies. 1. Schwarz, E.J., Magnetic properties of pyrrhotite and their use in applied geology and geophysics. 1975, Geological Survey of Canada : Ottawa, ON, Canada: Canada.

Monitoring the self-healing process of biomimetic mortar using coda wave interferometry method

NASA Astrophysics Data System (ADS)

Liu, Shukui; Basaran, Zeynep; Zhu, Jinying; Ferron, Raissa

2014-02-01

Internal stresses might induce microscopic cracks in concrete, which can provide pathways for ingress of harmful chemicals and can lead to loss of strength. Recent research in concrete materials suggests that it might be possible to develop a smart cement-based material that is capable of self-healing by leveraging the metabolic activity of microorganisms to provide biomineralization. Limited research on biomineralization in cement-based systems has shown promising results that healing of cracks can occur on the surface of concrete and reduce permeability. This paper presents the results from an investigation regarding the potential for a cement-based material to repair itself internally through biomineralization. Compressive strength test and coda wave interferometry (CWI) analyses were conducted on mortar samples that were loaded to 70% of their compressive strength and cured in different conditions. Experimental results indicate that the damaged mortar samples with microorganisms showed significantly higher strength development and higher increase of ultrasonic wave velocity compared to samples without microorganisms at 7 and 28 days.

The importance of actions and the worth of an object: dissociable neural systems representing core value and economic value.

PubMed

Brosch, Tobias; Coppin, Géraldine; Schwartz, Sophie; Sander, David

2012-06-01

Neuroeconomic research has delineated neural regions involved in the computation of value, referring to a currency for concrete choices and decisions ('economic value'). Research in psychology and sociology, on the other hand, uses the term 'value' to describe motivational constructs that guide choices and behaviors across situations ('core value'). As a first step towards an integration of these literatures, we compared the neural regions computing economic value and core value. Replicating previous work, economic value computations activated a network centered on medial orbitofrontal cortex. Core value computations activated medial prefrontal cortex, a region involved in the processing of self-relevant information and dorsal striatum, involved in action selection. Core value ratings correlated with activity in precuneus and anterior prefrontal cortex, potentially reflecting the degree to which a core value is perceived as internalized part of one's self-concept. Distributed activation pattern in insula and ACC allowed differentiating individual core value types. These patterns may represent evaluation profiles reflecting prototypical fundamental concerns expressed in the core value types. Our findings suggest mechanisms by which core values, as motivationally important long-term goals anchored in the self-schema, may have the behavioral power to drive decisions and behaviors in the absence of immediately rewarding behavioral options.

Effects of surface topography and vibrations on wetting: Superhydrophobicity, icephobicity and corrosion resistance

NASA Astrophysics Data System (ADS)

Ramachandran, Rahul

Concrete and metallic materials are widely used in construction and water industry. The interaction of both these materials with water and ice (or snow) produces undesirable results and is therefore of interest. Water that gets absorbed into the pores of dry concrete expands on freezing and can lead to crack formation. Also, the ice accretion on concrete surfaces such as roadways can have disastrous consequence. Metallic components used in the water industry undergo corrosion due to contact with aqueous corrosive solutions. Therefore, it is desirable to make concrete water/ice-repellent, and to make metallic surfaces corrosion-resistant. Recent advances in micro/nanotechnology have made it possible to design functional micro/nanostructured surfaces with micro/nanotopography providing low adhesion. Some examples of such surfaces are superhydrophobic surfaces, which are extremely water repellent, and icephobic surfaces, which have low ice adhesion, repel incoming water droplets before freezing, or delay ice nucleation. This dissertation investigates the effects of surface micro/nanotopography and small amplitude fast vibrations on the wetting and adhesion of concrete with the goal of producing hydrophobic and icephobic concrete, and on the wetting of metallic surfaces to prevent corrosion. The relationship between surface micro/nanotopography and small fast vibrations is established using the method of separation of motions. Both these small scale effects can be substituted by an effective force or energy. The structure-property relationships in materials and surfaces are established. Both vibrations as well as surface micro/nanopatterns can affect wetting properties such as contact angle and surface free energy. Hydrophobic engineered cementitious composite samples are produced by controlling their surface topography and surface free energy. The surface topography is controlled by varying the concrete mixture composition. The surface free energy of concrete is lowered using a hydrophobic emulsion. The hydrophobic concrete samples were able to repel incoming water droplets as well as resist droplet pinning. Corrosion resistance is achieved in cast iron samples by rendering them superhydrophobic. The corrosion resistance of superhydrophobic surfaces with micro/nanotopography may be explained by the low effective contact area with the electrolyte. The experimental results matched the theoretical predictions based on surface roughness and wettability. The icephobicity of engineered cementitious composite samples is achieved by hydrophobization, by using coatings containing dielectric material (such as polyvinyl alcohol fibers), and by controlling the surface topography. Two aspects of the icephobicity of concrete, namely, the repulsion of incoming water droplets before freezing and the ice adhesion strength, are investigated experimentally. It is found that icephobic performance of concrete depends on these parameters --- the hydrophobic emulsion concentration, the polyvinyl alcohol fiber content, the water to cement ratio, and the sand to cement ratio. The potential for biomimetic icephobicity of thermogenic skunk cabbage plant is investigated, and it is found that the surface topography of its leaves can affect the heat transfer from the plant to the surrounding snow. The hierarchical microstructure of the leaf surface coupled with its high adhesion to water suggests the presence of an impregnated wetting state, which can minimize the heat loss. Thus functional materials and surfaces, such as hydrophobic and icephobic engineered cementitious composites and corrosion resistant metallic surfaces, can be produced by controlling the surface micro/nanotopography.

Turn Basin Construction

NASA Image and Video Library

2017-06-14

Modifications are underway at the Launch Complex 39 turn basin wharf at NASA's Kennedy Space Center in Florida to prepare for the arrival of the agency's massive Space Launch System (SLS) core stage aboard the barge Pegasus. Equipment is staged and a crane will be used to lift up precast concrete poles and position them to be driven to a depth of about 70 feet into the bedrock below the water around the turn basin. The upgrades are necessary to accommodate the increased weight of the core stage along with ground support and transportation equipment aboard the modified barge Pegasus. The Ground Systems Development and Operations Program is overseeing the upgrades to the turn basin wharf.

Turn Basin Construction

NASA Image and Video Library

2017-06-14

Modifications are underway at the Launch Complex 39 turn basin wharf at NASA's Kennedy Space Center in Florida to prepare for the arrival of the agency's massive Space Launch System (SLS) core stage aboard the barge Pegasus. A crane will be used to lift up precast concrete poles and position them to be driven to a depth of about 70 feet into the bedrock below the water around the turn basin. The upgrades are necessary to accommodate the increased weight of the core stage along with ground support and transportation equipment aboard the modified barge Pegasus. The Ground Systems Development and Operations Program is overseeing the upgrades to the turn basin wharf.

The influence of the compression interface on the failure behavior and size effect of concrete

NASA Astrophysics Data System (ADS)

Kampmann, Raphael

The failure behavior of concrete materials is not completely understood because conventional test methods fail to assess the material response independent of the sample size and shape. To study the influence of strength and strain affecting test conditions, four typical concrete sample types were experimentally evaluated in uniaxial compression and analyzed for strength, deformational behavior, crack initiation/propagation, and fracture patterns under varying boundary conditions. Both low friction and conventional compression interfaces were assessed. High-speed video technology was used to monitor macrocracking. Inferential data analysis proved reliably lower strength results for reduced surface friction at the compression interfaces, regardless of sample shape. Reciprocal comparisons revealed statistically significant strength differences between most sample shapes. Crack initiation and propagation was found to differ for dissimilar compression interfaces. The principal stress and strain distributions were analyzed, and the strain domain was found to resemble the experimental results, whereas the stress analysis failed to explain failure for reduced end confinement. Neither stresses nor strains indicated strength reductions due to reduced friction, and therefore, buckling effects were considered. The high-speed video analysis revealed localize buckling phenomena, regardless of end confinement. Slender elements were the result of low friction, and stocky fragments developed under conventional confinement. The critical buckling load increased accordingly. The research showed that current test methods do not reflect the "true'' compressive strength and that concrete failure is strain driven. Ultimate collapse results from buckling preceded by unstable cracking.

Effect of Silica Fume on two-stage Concrete Strength

NASA Astrophysics Data System (ADS)

Abdelgader, H. S.; El-Baden, A. S.

2015-11-01

Two-stage concrete (TSC) is an innovative concrete that does not require vibration for placing and compaction. TSC is a simple concept; it is made using the same basic constituents as traditional concrete: cement, coarse aggregate, sand and water as well as mineral and chemical admixtures. As its name suggests, it is produced through a two-stage process. Firstly washed coarse aggregate is placed into the formwork in-situ. Later a specifically designed self compacting grout is introduced into the form from the lowest point under gravity pressure to fill the voids, cementing the aggregate into a monolith. The hardened concrete is dense, homogeneous and has in general improved engineering properties and durability. This paper presents the results from a research work attempt to study the effect of silica fume (SF) and superplasticizers admixtures (SP) on compressive and tensile strength of TSC using various combinations of water to cement ratio (w/c) and cement to sand ratio (c/s). Thirty six concrete mixes with different grout constituents were tested. From each mix twenty four standard cylinder samples of size (150mm×300mm) of concrete containing crushed aggregate were produced. The tested samples were made from combinations of w/c equal to: 0.45, 0.55 and 0.85, and three c/s of values: 0.5, 1 and 1.5. Silica fume was added at a dosage of 6% of weight of cement, while superplasticizer was added at a dosage of 2% of cement weight. Results indicated that both tensile and compressive strength of TSC can be statistically derived as a function of w/c and c/s with good correlation coefficients. The basic principle of traditional concrete, which says that an increase in water/cement ratio will lead to a reduction in compressive strength, was shown to hold true for TSC specimens tested. Using a combination of both silica fume and superplasticisers caused a significant increase in strength relative to control mixes.

Preparation and Mechanical Properties of Pressed Straw Concrete Brick

NASA Astrophysics Data System (ADS)

Sumarni, S.; Wijanarko, W.

2018-03-01

Rice straws have been widely used as wall filler material in China, Australia, and United States, by spinning them into hays with an approximate dimension of 40 cm of height, 40cm of thickness and 60 cm of width, using a machine. Then, the hays are placed into a wall frame until they fill it completely. After that, the wall frame is covered with wire mesh and plastered. In this research, rice straws are to be used as concrete brick fillers, by pressing the straws into hays and then putting them into the concrete brick mold along with mortar. The objective of this research is to investigate the mechanical properties of concrete brick, namely: compressive strength, specific gravity, and water absorption power. This research used experimental research method. It was conducted by using concrete bricks which had 400 cm of width, 200 cm of height, and 100 cm of thickness, made from rice straws, cement, sand, and water as the test sample. The straws were each made different by their volume. The mortars used in this research were made from cement, sand, and water, with the ratio of 1:7:0.5. The concrete bricks were made by pressing straws mixed with glue into hays, and then cut by determined variations of volume. The variations of hays volume were 0 m3, 0.000625 m3, 0.00075 m3, 0.000875 m3, 0.00125 m3, 0.0015 m3, 0.00175 m3, 0.001875 m3, 0.00225 m3, and 0.002625 m3. There were 3 samples for each volumes of hays. The result shows that the straw concrete bricks reached the maximum compressive strength of 1.92 MPa, specific gravity of 1,702 kg/m3, and water absorption level of 3.9 %. Based on the provided measurements of products in the Standar Nasional Indonesia (Indonesian product standardization), the concrete bricks produced attained the prescribed standard quality.

Three Permeable Pavements Performances for Priority Metal Pollutants and Metals Associated with Deicing Chemicals from Edison Parking Lot, NJ

EPA Science Inventory

The U.S. Environmental Protection Agency constructed a 4000-m2 parking lot in Edison, New Jersey in 2009. The parking lot is surfaced with three permeable pavements [permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA)]. Samples of each p...

Defining clogging potential for permeable concrete.

PubMed

Kia, Alalea; Wong, Hong S; Cheeseman, Christopher R

2018-08-15

Permeable concrete is used to reduce urban flooding as it allows water to flow through normally impermeable infrastructure. It is prone to clogging by particulate matter and predicting the long-term performance of permeable concrete is challenging as there is currently no reliable means of characterising clogging potential. This paper reports on the performance of a range of laboratory-prepared and commercial permeable concretes, close packed glass spheres and aggregate particles of varying size, exposed to different clogging methods to understand this phenomena. New methods were developed to study clogging and define clogging potential. The tests involved applying flowing water containing sand and/or clay in cycles, and measuring the change in permeability. Substantial permeability reductions were observed in all samples, particularly when exposed to sand and clay simultaneously. Three methods were used to define clogging potential based on measuring the initial permeability decay, half-life cycle and number of cycles to full clogging. We show for the first time strong linear correlations between these parameters for a wide range of samples, indicating their use for service-life prediction. Copyright © 2018 Elsevier Ltd. All rights reserved.

Measurement of concrete strength using the emission intensity ratio between Ca(II) 396.8 nm and Ca(I) 422.6 nm in a Nd:YAG laser-induced plasma.

PubMed

Tsuyuki, Kenichiro; Miura, Satoru; Idris, Nasrullah; Kurniawan, Koo Hendrik; Lie, Tjung Jie; Kagawa, Kiichiro

2006-01-01

An experiment to investigate the potential of a laser-induced plasma method for determining concrete compressive strength was conducted by focusing a Nd:YAG laser on concrete samples with different degrees of compressive strength. This technique was developed in light of the role of the shock wave in the generation of a laser-induced plasma. It was found that the speed of the shock front depends on the hardness of the sample. It was also found that a positive relationship exists between the speed of the shock front and the ionization rate of the ablated atoms. Hence, the ratio of the intensity between the Ca(II) 396.8 nm and Ca(I) 422.6 nm emission lines detected from the laser-induced plasma can be used to examine the hardness of the material. In fact, it was observed that the ratio changes with respect to the change in the concrete compressive strength. The findings also show that the ratio increases with time after the cement is mixed with water.

Thermal stability analysis under embankment with asphalt pavement and cement pavement in permafrost regions.

PubMed

Junwei, Zhang; Jinping, Li; Xiaojuan, Quan

2013-01-01

The permafrost degradation is the fundamental cause generating embankment diseases and pavement diseases in permafrost region while the permafrost degradation is related with temperature. Based on the field monitoring results of ground temperature along G214 Highway in high temperature permafrost regions, both the ground temperatures in superficial layer and the annual average temperatures under the embankment were discussed, respectively, for concrete pavements and asphalt pavements. The maximum depth of temperature field under the embankment for concrete pavements and asphalt pavements was also studied by using the finite element method. The results of numerical analysis indicate that there were remarkable seasonal differences of the ground temperatures in superficial layer between asphalt pavement and concrete pavement. The maximum influencing depth of temperature field under the permafrost embankment for every pavement was under the depth of 8 m. The thawed cores under both embankments have close relation with the maximum thawed depth, the embankment height, and the service time. The effective measurements will be proposed to keep the thermal stabilities of highway embankment by the results.

Thermal Stability Analysis under Embankment with Asphalt Pavement and Cement Pavement in Permafrost Regions

PubMed Central

Jinping, Li; Xiaojuan, Quan

2013-01-01

The permafrost degradation is the fundamental cause generating embankment diseases and pavement diseases in permafrost region while the permafrost degradation is related with temperature. Based on the field monitoring results of ground temperature along G214 Highway in high temperature permafrost regions, both the ground temperatures in superficial layer and the annual average temperatures under the embankment were discussed, respectively, for concrete pavements and asphalt pavements. The maximum depth of temperature field under the embankment for concrete pavements and asphalt pavements was also studied by using the finite element method. The results of numerical analysis indicate that there were remarkable seasonal differences of the ground temperatures in superficial layer between asphalt pavement and concrete pavement. The maximum influencing depth of temperature field under the permafrost embankment for every pavement was under the depth of 8 m. The thawed cores under both embankments have close relation with the maximum thawed depth, the embankment height, and the service time. The effective measurements will be proposed to keep the thermal stabilities of highway embankment by the results. PMID:24027444

Study on Predicting Axial Load Capacity of CFST Columns

NASA Astrophysics Data System (ADS)

Ravi Kumar, H.; Muthu, K. U.; Kumar, N. S.

2017-11-01

This work presents an analytical study and experimental study on the behaviour and ultimate load carrying capacity of axially compressed self-compacting concrete-filled steel tubular columns. Results of tests conducted by various researchers on 213 samples concrete-filled steel tubular columns are reported and present authors experimental data are reported. Two theoretical equations were derived for the prediction of the ultimate axial load strength of concrete-filled steel tubular columns. The results from prediction were compared with the experimental data. Validation to the experimental results was made.

Fly ash/Kaolin based geopolymer green concretes and their mechanical properties

PubMed Central

Okoye, F.N.; Durgaprasad, J.; Singh, N.B.

2015-01-01

Geopolymer concrete mixes were cast using fly ash, kaolin, sodium hydroxide, potassium hydroxide, sodium silicate and aggregates. Portland cement concrete (M30) was used as a reference sample. The effect of silica fume, temperature (40 °C, 60 °C, 80 °C, 100 °C and 120 °C), sodium and potassium hydroxides and different superplasticizers on the compressive strength are reported [1]. Maximum strength was found at 100 °C and 14 M alkali solution [1]. PMID:26693505

Fly ash/Kaolin based geopolymer green concretes and their mechanical properties.

PubMed

Okoye, F N; Durgaprasad, J; Singh, N B

2015-12-01

Geopolymer concrete mixes were cast using fly ash, kaolin, sodium hydroxide, potassium hydroxide, sodium silicate and aggregates. Portland cement concrete (M30) was used as a reference sample. The effect of silica fume, temperature (40 °C, 60 °C, 80 °C, 100 °C and 120 °C), sodium and potassium hydroxides and different superplasticizers on the compressive strength are reported [1]. Maximum strength was found at 100 °C and 14 M alkali solution [1].

Rapid Method for Sodium Hydroxide Fusion of Concrete and ...

EPA Pesticide Factsheets

Technical Fact Sheet Analysis Purpose: Qualitative analysis Technique: Alpha spectrometry Method Developed for: Americium-241, plutonium-238, plutonium-239, radium-226, strontium-90, uranium-234, uranium-235 and uranium-238 in concrete and brick samples Method Selected for: SAM lists this method for qualitative analysis of americium-241, plutonium-238, plutonium-239, radium-226, strontium-90, uranium-234, uranium-235 and uranium-238 in concrete or brick building materials. Summary of subject analytical method which will be posted to the SAM website to allow access to the method.

Assessment of the long-term durability of concrete in radioactive waste repositories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atkinson, A.; Goult, D.J.; Hearne, J.A.

1986-01-01

A preliminary assessment of the long-term durability of concrete in a repository sited in clay is presented. The assessment is based on recorded experience of concrete structures and both field and laboratory studies. It is also supported by results of the examination of a concrete sample which had been buried in clay for 43 years. The engineering lifetime of a 1 m thick reinforced concrete slab, with one face in contact with clay, and the way in which pH in the repository as a whole is likely to vary with time have both been estimated from available data. The estimatesmore » indicate that engineering lifetimes of about 10/sup 3/ years are expected (providing that sulfate resisting cement is used) and that pH is likely to remain above 10.5 for about 10/sup 6/ years.« less

Time dependent variation of carrying capacity of prestressed precast beam

NASA Astrophysics Data System (ADS)

Le, Tuan D.; Konečný, Petr; Matečková, Pavlína

2018-04-01

The article deals with the evaluation of the precast concrete element time dependent carrying capacity. The variation of the resistance is inherited property of laboratory as well as in-situ members. Thus the specification of highest, yet possible, laboratory sample resistance is important with respect to evaluation of laboratory experiments based on the test machine loading capabilities. The ultimate capacity is evaluated through the bending moment resistance of a simply supported prestressed concrete beam. The probabilistic assessment is applied. Scatter of random variables of compressive strength of concrete and effective height of the cross section is considered. Monte Carlo simulation technique is used to investigate the performance of the cross section of the beam with changes of tendons’ positions and compressive strength of concrete.

The Influence of Phase Change Materials on the Properties of Self-Compacting Concrete

PubMed Central

Fenollera, María; Míguez, José Luis; Goicoechea, Itziar; Lorenzo, Jaime; Ángel Álvarez, Miguel

2013-01-01

The aim of this paper is to research new thermally-efficient concrete walls, analyzing the mechanical behavior of a self-compacting concrete to manufacture an uncoated solid structural panel, with the incorporation of a micro-encapsulated phase change material as additive. Different dosages are tested and mechanical properties of the product obtained from the molding of concrete specimens are evaluated, testing mechanical compressive strength, slump flow, and density. The results reveal the optimum percentage of additive in the mixture that enables compliance with the technical specifications required by the product to be manufactured. A test is also performed for measuring the thermal conductivity for the optimal sample obtained and it evidences the reduction thereof. PMID:28811450

76 FR 23799 - Erie Boulevard Hydropower, L.P.; Notice of Application Accepted for Filing, Soliciting Motions To...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-28

... seasonal flash boards; (2) a 168-acre reservoir with a gross storage capacity of 3,234 acre-feet and a...; (2) a 159-acre reservoir with a gross storage capacity of 2,646 acre-feet and a normal maximum pool... reservoir, with concrete core walls and partially equipped with 10-inch-high flashboards; (3) a 79.2- acre...

Chew Bahir: A Key Site within the Hominin Sites and Paleolakes Drilling Project, towards a Half Million-Year Climate Record from Southern Ethiopia

NASA Astrophysics Data System (ADS)

Schaebitz, F.; Asrat, A.; Lamb, H. F.; Trauth, M. H.; Foerster, V. E.; Junginger, A.; Raub, T. D.; Gromig, R.; Viehberg, F. A.; Roberts, H. M.; Cohen, A.

2015-12-01

Chew Bahir, a saline mudflat today, is one of the five sites in East Africa, drilled within the framework of HSPDP (Hominin Site and Paleolakes Drilling Project). It is also one of the key sites of the Collaborative Research Centre (CRC-806) "Our way to Europe" aiming at the reconstruction of environmental conditions in the source region of modern man (H. sapiens). It is suggested that a changing environment could have triggered the mobility and dispersal of modern man. The oldest known fossils of anatomical modern humans (~195 ka BP) were found in the Omo basin, not more than 90km westwards of our drill site. The deposits in the tectonic basin of Chew Bahir in southern Ethiopia were cored in Nov. 2014 in two boreholes down to 280 m and 260 m below surface respectively. The overlapping long cores (drilled ~20 m apart from each other), were opened, scanned, described and sampled in low resolution in April 2015. The recovered sediments mostly contain green-greyish to light coloured and brown to reddish clays and silty clays, interbedded with some laminated mica-rich sand layers and occurrences of carbonate concretions and nodules, which decrease upcore. Here we will present a first set of results on the composite core, comprising mainly lithology and magnetic susceptibility (MS). Based on known sedimentation rates from pre-studies performed on short cores across the basin, we anticipate the deep drilled cores to cover at least 500 ka BP. Moreover, new insights into the role of post-depositional alteration, especially of clay minerals and zeolites, will be presented as a contribution to an improved understanding of formation processes. The results support the identification of wet and dry climate periods in the past. Those pronounced variations of moisture availability, are thought to have influenced the evolution and mobility of Homo sapiens sapiens.

Zinc thermal spray coatings for reinforced concrete: An AWS process standard

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sulit, R.A.

Zinc and aluminum thermal spray coatings (TSC) have been used for lining concrete weir in Great Britain since the 1950`s to maintain the dimensions of the weir for flow control concomitant with reduced wear and erosion of the concrete surfaces. This paper reports the development and the content of the ANSI/AWS C2.20-XX standard for the application of An TSC on concrete using flame and arc spray processes. This standard is formatted as an industrial process instruction: job description; safety; feedstock materials; equipment; a step-by-step method for surface preparation, thermal spraying; quality control; repair and maintenance of surface preparation, thermal spraying;more » quality control; repair and maintenance of Zn TSC on concrete; and a Job Control Record. Job planning and training and certification requirements are presented for An TSC inspectors and thermal spray operators. Four annexes are included in the standard: (a) historical summary of Zn TSC on concrete (b) sample job control record; (c) thermal spray operator qualification; and (d) portable adhesion testing for An TSC on concrete. This standard is based on the current literature and industrial equipment, process, and practices.« less

Persistence of termiticides in soil inside and outside miniature concrete foundations (Isoptera)

Treesearch

J.E. Mulrooney; T.L. Wagner; B.M. Kard; P.D. Gerard

2006-01-01

A cooperative study of termiticide longevity was initiated in 1990 between the Association of Structural Pest Control Regulatory Officials (ASPCRO), termiticide manufacturers, and the USDA Forest Service. By-the-label applications of seven termiticides were made to soil in trenches inside and outside miniature concrete foundations, and soil samples were collected at 1,...

Three Permeable Pavements Performances for Priority Metal Pollutants and Metals associated with Deicing Chemicals from Edison Parking Lot, NJ - abstract

EPA Science Inventory

The U.S. Environmental Protection Agency constructed a 4000-m2 parking lot in Edison, New Jersey in 2009. The parking lot is surfaced with three permeable pavements [permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA)]. Samples of each p...

A Comparison of Concrete and Virtual Manipulative Use in Third- and Fourth-Grade Mathematics

ERIC Educational Resources Information Center

Burns, Barbara A.; Hamm, Ellen M.

2011-01-01

The primary purpose of this classroom experiment was to examine the effectiveness of concrete (hands-on) manipulatives as compared with virtual (computer-based) manipulatives on student review of fraction concepts in third grade and introduction of symmetry concepts in fourth grade. A pretest-posttest design was employed with a sample of 91…

Sulfur determination in concrete samples using laser-induced breakdown spectroscopy and limestone standards

NASA Astrophysics Data System (ADS)

Hrdlička, Aleš; Hegrová, Jitka; Novotný, Karel; Kanický, Viktor; Prochazka, David; Novotný, Jan; Modlitbová, Pavlína; Sládková, Lucia; Pořízka, Pavel; Kaiser, Jozef

2018-04-01

A LIBS equipment operating at 532 nm was optimized and used for sulfur determination in concrete samples. The influence of He atmosphere in a gas-tight chamber (1000-200 mbar) on S I 921.29 nm line sensitivity, signal-to-background and signal-to-noise ratio was studied at gate delays 100-2000 ns. Wide range of gate delays from 500 to about 1000 ns and pressures from several hundreds of mbar to the atmospheric pressure can be used for the desired detection of sulfur. The LIBS quantification was done using a simple calibration method. A synthetic limestone enriched by defined amounts of sodium sulfate was newly employed for direct quantification of S in concrete. This powder material was pressed into pellets and ablated with the LIBS system. The average content of sulfur as SO3 in the samples was 0.41-0.70 wt% by LIBS and 0.43-0.61 wt% by a reference standard procedure employing gravimetry and Inductively Coupled Plasma Triple Quad Mass Spectrometry (ICP-QQQMS). The uncertainty of the yielded LIBS results covers also the dispersion of the points in the calibration line and ranges from 16 to 28% at the probability level of 95%. The uncertainty of the ICP-QQQMS results was almost 10%. No correction on different signal response on the limestone and on the concrete was necessary.

Fracture Properties of Polystyrene Aggregate Concrete after Exposure to High Temperatures

PubMed Central

Tang, Waiching; Cui, Hongzhi; Tahmasbi, Soheil

2016-01-01

This paper mainly reports an experimental investigation on the residual mechanical and fracture properties of polystyrene aggregate concrete (PAC) after exposure to high temperatures up to 800 degrees Celsius. The fracture properties namely, the critical stress intensity factor (KICS), the critical crack tip opening displacement (CTODC) for the Two-Parameter Model, and the fracture energy (GF) for the Fictitious Crack Model were examined using the three-point bending notched beam test, according to the RILEM recommendations. The effects of polystyrene aggregate (PA) content and temperature levels on the fracture and mechanical properties of concrete were investigated. The results showed that the mechanical properties of PAC significantly decreased with increase in temperature level and the extent of which depended on the PA content in the mixture. However, at a very high temperature of 800 °C, all samples showed 80 percent reduction in modulus of elasticity compared to room temperature, regardless of the level of PA content. Fracture properties of control concrete (C) and PAC were influenced by temperature in a similar manner. Increasing temperature from 25 °C to 500 °C caused almost 50% reduction of the fracture energy for all samples while 30% increase in fracture energy was occurred when the temperature increased from 500 °C to 800 °C. It was found that adding more PA content in the mixture lead to a more ductile behaviour of concrete. PMID:28773752

The effect of geothermal fluid composition in lime-pozzolan reactions on elastic and transport properties.

NASA Astrophysics Data System (ADS)

MacFarlane, J.; Vanorio, T.

2016-12-01

Calcium-Silicate-Hydrates (C-S-H) are a complex family of hydrates known to form within hyper-alkaline geothermal systems as well as concrete. Within both environments the formation of C-S-H can be linked to the lime-pozzolan reaction. Pozzolan's defined as a siliceous or alumino-siliceous material, which in itself possesses little or no cementing property, but in the presence of moisture chemically reacts with calcium hydroxide at ordinary temperatures to form cementitious compounds. C-S-H fibers have been discovered in a low permeability, caprock layer beneath the Campi Flegrei caldera, as well as within ancient Roman concrete made using volcanic ash and fluids from the Campi Flegrei region over 2000 years ago. By replicating the recipe for Roman concrete, fibrous minerals have been formed in laboratory experiments and imaged using a scanning electron microscope. The formation of C-S-H within concrete has been shown to depend on the mineral ions present, among other factors. Here, we report on how the geothermal fluid composition effects the elastic and transport properties of laboratory samples. Samples were made using the same volcanic ash as the Romans, called Pozzolana, slaked lime and geothermal fluid. Two geothermal fluids from the Campi Flegrei region were compared, as well as deionized water as a control. Preliminary results have shown changes in both the elastic and transport properties between sample sets made with geothermal fluid and the control. These changes are attributed to the structure of the C-S-H that forms in the lime-pozzolan reaction. Understanding how the geothermal fluid composition controls the properties of this reaction has implications for the understanding of both geothermal systems and concrete engineering.

Boiling water neutronic reactor incorporating a process inherent safety design

DOEpatents

Forsberg, C.W.

1985-02-19

A boiling-water reactor core is positioned within a prestressed concrete reactor vessel of a size which will hold a supply of coolant water sufficient to submerge and cool the reactor core by boiling for a period of at least one week after shutdown. Separate volumes of hot, clean (nonborated) water for cooling during normal operation and cool highly borated water for emergency cooling and reactor shutdown are separated by an insulated wall during normal reactor operation with contact between the two water volumes being maintained at interfaces near the top and bottom ends of the reactor vessel. Means are provided for balancing the pressure of the two water volumes at the lower interface zone during normal operation to prevent entry of the cool borated water into the reactor core region, for detecting the onset of excessive power to coolant flow conditions in the reactor core and for detecting low water levels of reactor coolant. Cool borated water is permitted to flow into the reactor core when low reactor coolant levels or excessive power to coolant flow conditions are encountered.

Boiling water neutronic reactor incorporating a process inherent safety design

DOEpatents

Forsberg, Charles W.

1987-01-01

A boiling-water reactor core is positioned within a prestressed concrete reactor vessel of a size which will hold a supply of coolant water sufficient to submerge and cool the reactor core by boiling for a period of at least one week after shutdown. Separate volumes of hot, clean (non-borated) water for cooling during normal operation and cool highly borated water for emergency cooling and reactor shutdown are separated by an insulated wall during normal reactor operation with contact between the two water volumes being maintained at interfaces near the top and bottom ends of the reactor vessel. Means are provided for balancing the pressure of the two volumes at the lower interface zone during normal operation to prevent entry of the cool borated water into the reactor core region, for detecting the onset of excessive power to coolant flow conditions in the reactor core and for detecting low water levels of reactor coolant. Cool borated water is permitted to flow into the reactor core when low reactor coolant levels or excessive power to coolant flow conditions are encountered.

Improving Non-Destructive Concrete Strength Tests Using Support Vector Machines

PubMed Central

Shih, Yi-Fan; Wang, Yu-Ren; Lin, Kuo-Liang; Chen, Chin-Wen

2015-01-01

Non-destructive testing (NDT) methods are important alternatives when destructive tests are not feasible to examine the in situ concrete properties without damaging the structure. The rebound hammer test and the ultrasonic pulse velocity test are two popular NDT methods to examine the properties of concrete. The rebound of the hammer depends on the hardness of the test specimen and ultrasonic pulse travelling speed is related to density, uniformity, and homogeneity of the specimen. Both of these two methods have been adopted to estimate the concrete compressive strength. Statistical analysis has been implemented to establish the relationship between hammer rebound values/ultrasonic pulse velocities and concrete compressive strength. However, the estimated results can be unreliable. As a result, this research proposes an Artificial Intelligence model using support vector machines (SVMs) for the estimation. Data from 95 cylinder concrete samples are collected to develop and validate the model. The results show that combined NDT methods (also known as SonReb method) yield better estimations than single NDT methods. The results also show that the SVMs model is more accurate than the statistical regression model. PMID:28793627

Evaluation of nonlinear impact resonance spectroscopy method for detecting delayed ettringite formation

NASA Astrophysics Data System (ADS)

Rashidi, M. M. N.; Paul, A.; Kim, J.-Y.; Jacobs, L. J.; Kurtis, K. E.

2015-03-01

The use of the Nonlinear Impact Resonance Acoustic Spectroscopy (NIRAS) method to monitor the evolution of damage due to delayed ettringite formation (DEF) is examined. In practice, the temperature of concrete during casting of precast concrete members or massive concrete structures may reach higher than 70°C which can provide suitable conditions for damage to occur due to DEF, particularly in concrete which is subsequently exposed to wet environments. While expansion - often in excess of 1% - is characteristic of DEF, the evolution of damage begins with microcracking. Unfortunately, there is no standard to test the susceptibility of materials or material combinations to DEF. On the other hand, NIRAS shows great sensitivity to the detection of microcracks and has been successfully applied to concrete to detect thermal and alkali silica reaction in concrete. In this preliminary research, the NIRAS method is used to discriminate among mortar samples which are relatively undamaged and those in the early stages of DEF. The results show that NIRAS could be a reliable and robust method in the detection of microcracks due to DEF.

Modeling the long-term durability of concrete barriers in the context of low-activity waste storage

NASA Astrophysics Data System (ADS)

Protière, Y.; Samson, E.; Henocq, P.

2013-07-01

The paper investigates the long-term durability of concrete barriers in contact with a cementitious wasteform designed to immobilize low-activity nuclear waste. The high-pH pore solution of the wasteform contains high concentration level of sulfate, nitrate, nitrite and alkalis. The multilayer concrete/wasteform system was modeled using a multiionic reactive transport model accounting for coupling between species, dissolution/ precipitation reactions, and feedback effect. One of the primary objectives was to investigate the risk associated with the presence of sulfate in the wasteform on the durability of concrete. Simulation results showed that formation of expansive phases, such as gypsum and ettringite, into the concrete barrier was not extensive. Based on those results, it was not possible to conclude that concrete would be severely damaged, even after 5,000 years. Lab work was performed to provide data to validate the modeling results. Paste samples were immersed in sulfate contact solutions and analyzed to measure the impact of the aggressive environment on the material. The results obtained so far tend to confirm the numerical simulations.

Analysis of Stress in Steel and Concrete in Cfst Push-Out Test Samples

NASA Astrophysics Data System (ADS)

Grzeszykowski, Bartosz; Szadkowska, Magdalena; Szmigiera, Elżbieta

2017-09-01

The paper presents the analysis of stress in steel and concrete in CFST composite elements subjected to push-out tests. Two analytical models of stress distribution are presented. The bond at the interface between steel and concrete in the initial phase of the push-out test is provided by the adhesion. Until the force reach a certain value, the slip between both materials does not occur or it is negligibly small, what ensures full composite action of the specimen. In the first analytical model the full bond between both materials was assumed. This model allows to estimate value of the force for which the local loss of adhesion in given cross section begins. In the second model it was assumed that the bond stress distribution is constant along the shear transfer length of the specimen. Based on that the formulas for triangle distribution of stress in steel and concrete for the maximum push-out force were derived and compared with the experimental results. Both models can be used to better understand the mechanisms of interaction between steel and concrete in composite steel-concrete columns.

Assessment of waterfront location in hardened concrete by GPR within COST Action TU1208

NASA Astrophysics Data System (ADS)

Rodríguez-Abad, Isabel; Klysz, Gilles; Balayssac, Jean Paul; Pajewski, Lara

2016-04-01

This work focuses on the analysis of the capability of Ground-Penetrating radar (GPR) technique for evaluating how the water penetrates into concrete samples by means of the assessment of the waterfront advance. Research activities have been carried out during a Short-Term Scientific Missions (STSMs) funded by the COST (European Cooperation in Science and Technology) Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar" in November 2015. The evaluation of water penetrability is crucial in most building materials, such us concrete, since, water and aggressive chemical agents dissolved therein contribute to the deterioration of the material. A number of techniques have been developed to measure their advance in concrete. Although the most common method for measuring water content is the gravimetric method by observing the change in mass, this method has a large number of disadvantages. In this context, non-destructive techniques as GPR play an interesting role. In particular, the application of GPR in the building materials area is providing very promising and interesting results regarding the building materials characterization and especially concrete deterioration evaluation [1-3]. In addition, recent experimental studies highlight the strong relation between wave propagation parameters (velocity and energy level) and water content advance [4-5]. Water content has a decisive influence on dielectric properties and those might be assessed by the study of the wave properties that are derived by using GPR. Therefore, the waterfront advance will result in a change on wave parameters. In line with this, this research is focused on the development of specific processing algorithms necessary to understand how the water penetrates and how the wave parameters will be affected regarding the location of the antenna in reference to the water absorption direction. For this purpose, concrete samples were manufactured, which after curing (90 days) and oven drying were immersed into water for a certain time. Then, GPR measurements, with a 2 GHz central frequency antenna, were performed at specific time intervals, placing the antenna on the same side of the concrete samples that was immersed into water. After conducting GPR measurements, concrete samples were broken in two pieces to perform the visual analysis of the waterfront advance. After processing the GPR records velocity increments ware calculated and analyzed. Very accurate adjustments were found between the velocity increments and the waterfront depth, regardless the wave peaks of the direct and reflected wave used to calculate velocity increments. These results are of quite importance, because even if we are not able to locate the waterfront reflection or if it is overlapped with the direct wave signal, we might predict the waterfront position with high reliability. Acknowledgement The Authors are grateful to COST - European Cooperation in Science and Technology (www.cost.eu) for funding the Action TU1208 "Civil engineering applications of Ground Penetrating Radar" (www.GPRadar.eu). References 1. W. Lai, S. Kou, W. Tsang, C. Poon, "Characterization of concrete properties from dielectric properties using ground penetrating radar," Cement and Concrete Research, Vol. 39, pp. 687-695, 2009. 2. W. Chen, P. Shen, Z. Shui, "Determination of water content in fresh concrete mix based on relative dielectric constant measurement," Construction and Building Materials, Vol. 34, pp. 306-312, 2012. 3. S. Senin, R. Hamid, "Ground penetrating radar wave attenuation models for estimation of moisture and chloride content in concrete slab," Construction and Building Materials, Vol. 106, pp. 659-669, 2016. 4.I. Rodríguez-Abad , R. Martínez-Sala, J. Mené Aparicio, G. Klysz, "Water penetrability in hardened concrete by GPR," Proceedings of the 15th International Conference on Ground Penetrating Radar, Brussels, Belgium, 2014. 5.I. Rodríguez-Abad, G. Klysz, R. Martínez-Sala, J.P. Balayssac, J. Mené Aparicio, "Waterfront depth analysis in hardened concrete by means of the nondestructive Ground-penetrating radar technique," IEEE Journal of Selected Topics In Applied Earth Observations and Remote Sensing. Digital Object Identifier 10.1109/JSTARS.2015.2449737, 2015.

Field testing of stiffened deep cement mixing piles under lateral cyclic loading

NASA Astrophysics Data System (ADS)

Raongjant, Werasak; Jing, Meng

2013-06-01

Construction of seaside and underground wall bracing often uses stiffened deep cement mixed columns (SDCM). This research investigates methods used to improve the level of bearing capacity of these SDCM when subjected to cyclic lateral loading via various types of stiffer cores. Eight piles, two deep cement mixed piles and six stiffened deep cement mixing piles with three different types of cores, H shape cross section prestressed concrete, steel pipe, and H-beam steel, were embedded though soft clay into medium-hard clay on site in Thailand. Cyclic horizontal loading was gradually applied until pile failure and the hysteresis loops of lateral load vs. lateral deformation were recorded. The lateral carrying capacities of the SDCM piles with an H-beam steel core increased by 3-4 times that of the DCM piles. This field research clearly shows that using H-beam steel as a stiffer core for SDCM piles is the best method to improve its lateral carrying capacity, ductility and energy dissipation capacity.

Study of the structure of concrete with C-14-PMMA method

NASA Astrophysics Data System (ADS)

Muuri, E.; Tikkanen, O.; Ikonen, J.; Siitari-Kauppi, M.; Autio, M.

2017-12-01

Cement is used widely in the construction industry and, additionally, in the waste management industry for the stabilization of hazardous materials because of its capacity for both physical and chemical immobilization of contaminants. Cementitious materials have also been suggested as the backfilling materials, for example, in deep geological repositories for the final disposal of spent nuclear fuel. As a result, it is necessary to study the structure of the materials in different conditions. In this study, the structure of concrete was studied with the polymethylmetacrylate (PMMA) method in samples from the construction industry. The spatial distribution of porosity was characterized using this autoradiography method that involves the impregnation of a dried rock sample of hand specimen size with 14C-labelled methyl methacrylate (MMA) in vacuum, thermally initiated polymerization, film and digital autoradiography, and porosity calculation routines relying on digital image processing techniques [1]. Three main components are clearly visible on the PMMA autoradiographs of the studied concrete samples, because of their contrasted porosity (Fig 1.). Ground matrix cement shows even porosity; 27.0±4.7 %. The other two phases are mineral grains and bubbles, which are classified into four categories against their size and quantity. Fig 1. The scanned surface of the concrete sample (left) and the corresponding autoradiograph (right), where the darkest areas are caused by larger activity, and thus, larger porosity. The exposure time used for the autoradiogram was three days. J. Sammaljärvi, L. Jokelainen, J. Ikonen, M. Siitari-Kauppi, Eng. Geol. 135-136, 52-59 (2012).

Comparative performance of conventional OPC concrete and HPC designed by densified mixture design algorithm

NASA Astrophysics Data System (ADS)

Huynh, Trong-Phuoc; Hwang, Chao-Lung; Yang, Shu-Ti

2017-12-01

This experimental study evaluated the performance of normal ordinary Portland cement (OPC) concrete and high-performance concrete (HPC) that were designed by the conventional method (ACI) and densified mixture design algorithm (DMDA) method, respectively. Engineering properties and durability performance of both the OPC and HPC samples were studied using the tests of workability, compressive strength, water absorption, ultrasonic pulse velocity, and electrical surface resistivity. Test results show that the HPC performed good fresh property and further showed better performance in terms of strength and durability as compared to the OPC.

Gas-cooled reactor programs. High-temperature gas-cooled reactor technology development program. Annual progress report, December 31, 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasten, P.R.; Rittenhouse, P.L.; Bartine, D.E.

1984-06-01

ORNL continues to make significant contributions to the national program. In the HTR fuels area, we are providing detailed statistical information on the fission product retention performance of irradiated fuel. Our studies are also providing basic data on the mechanical, physical, and chemical behavior of HTR materials, including metals, ceramics, graphite, and concrete. The ORNL has an important role in the development of improved HTR graphites and in the specification of criteria that need to be met by commercial products. We are also developing improved reactor physics design methods. Our work in component development and testing centers in the Componentmore » Flow Test Loop (CFTL), which is being used to evaluate the performance of the HTR core support structure. Other work includes experimental evaluation of the shielding effectiveness of the lower portions of an HTR core. This evaluation is being performed at the ORNL Tower Shielding Facility. Researchers at ORNL are developing welding techniques for attaching steam generator tubing to the tubesheets and are testing ceramic pads on which the core posts rest. They are also performing extensive testing of aggregate materials obtained from potential HTR site areas for possible use in prestressed concrete reactor vessels. During the past year we continued to serve as a peer reviewer of small modular reactor designs being developed by GA and GE with balance-of-plant layouts being developed by Bechtel Group, Inc. We have also evaluated the national need for developing HTRs with emphasis on the longer term applications of the HTRs to fossil conversion processes.« less

What are the Dominant Factors of Students’ Productive Skills in Construction Services?

NASA Astrophysics Data System (ADS)

Oroh, R. R.; S, Haris A.; Sugandi, R. M.; Isnandar

2018-02-01

The purpose of this study to determine the dominant factors of students’ productive skills in doing the work of concrete structures that fit the needs of construction services. Sample of the respondents is vocational high school students from several districts and cities in North Sulawesi, Indonesia. Data are obtained through the performance test instruments of student. Whereas, data analysis is performed using factor analysis. The result of this research show the dominant factors of the students’ productive skills in doing the work of concrete structures that is according to the need of construction services, namely: (a) factor the working of concrete casting consists of making scaffolding from good materials and conducting concrete casting according to working method; and (b) factor the working of concrete reinforcing consists of read the working drawings for concrete reinforcement and make the concrete formwork from good material. Some of the respondent’s students in doing some concrete structure work have done well, but not yet according to working drawings, working methods and technical specifications of the work. The learning is done in accordance with the competency-oriented school curriculum but the teaching materials given have not been maximized in accordance with the needs of productive skills required construction services industry. The results have an impact on the low absorption of graduates in the implementation of the construction services industry.

Description of core samples returned by Apollo 12

NASA Technical Reports Server (NTRS)

Lindsay, J. F.; Fryxell, R.

1971-01-01

Three core samples were collected by the Apollo 12 astronauts. Two are single cores, one of which (sample 12026) was collected close to the lunar module during the first extravehicular activity period and is 19.3 centimeters long. The second core (sample 12027) was collected at Sharp Crater during the second extravehicular activity period and is 17.4 centimeters long. The third sample is a double core (samples 12025 and 12028), which was collected near Halo Crater during the second extravehicular activity period. Unlike the other cores, the double-drive-tube core sample has complex layering with at least 10 clearly defined stratigraphic units. This core sample is approximately 41 centimeters long.

Turn Basin Construction

NASA Image and Video Library

2017-06-14

Modifications are underway at the Launch Complex 39 turn basin wharf at NASA's Kennedy Space Center in Florida to prepare for the arrival of the agency's massive Space Launch System (SLS) core booster aboard the barge Pegasus. Construction workers with Southeast Cherokee Construction Inc. work to shore up the turn basin area. A crane will be used to lift up precast concrete poles and position them to be driven to a depth of about 70 feet into the bedrock below the water around the turn basin. The upgrades are necessary to accommodate the 300,000-pound core booster aboard the modified Pegasus barge. The Ground Systems Development and Operations Program is overseeing the upgrades to the turn basin wharf.

JPRS Report, Science & Technology China: Energy

DTIC Science & Technology

1992-09-23

combined actual models and math - ematical models to conduct the research and established a total of nine actual models with boundary conditions supplied...10,000 ton-grade flotillas after the Three Gorges project is completed. Simulation experiments of actual passage of 10,000 ton-grade flotillas at...excavate the deep trench for the core wall of the weir for the second phase. Concrete tank cars, spreaders, and other equipment were also devel- oped

Music Students' Perception of the Use of Multi-Media Technology at the Graduate Level in Hong Kong Higher Education

ERIC Educational Resources Information Center

Ho, Wai-Chung

2007-01-01

The core purpose of this paper is to draw together research issues and concrete problems with the use of multimedia technology at the graduate level in higher music education by examining one university's responses to the challenges posed by the use of multimedia technology as a teaching and learning aid for music education. Between June and July…

Wall characterization for through-the-wall radar applications

NASA Astrophysics Data System (ADS)

Greneker, Gene; Rausch, E. O.

2008-04-01

There has been continuing interest in the penetration of multilayer building materials, such as wood walls with air gaps and concrete hollow core block, using through-the-wall (TTW) radar systems. TTW operational techniques and signal propagation paths vary depending on how the TTW system is intended to be operated. For example, the operator of a TTW radar may be required to place the radar against the intervening wall of interest while collecting data. Other operational doctrines allow the radar to be operated in a stand-off mode from the wall. The stand-off distances can vary from feet to hundreds of feet, depending on the type of radar being used. When a signal is propagated through a multilayer wall with air gaps between the material and the wall construction uses materials of radically different dielectric constants, attenuation may not be the only effect that the probing signal experiences passing through the wall. This paper presents measurements of a hollow core concrete block wall and the measurement of a standard wall constructed of siding and wallboard. Both types of walls are typically found in most U.S. homes. These limited measurements demonstrate that the type of wall being penetrated by a wideband signal can modify the probing signal.

Dikes under Pressure - Monitoring the Vulnerability of Dikes by Means of SAR Interferometry

NASA Astrophysics Data System (ADS)

Marzahn, Philip; Seidel, Moritz; Ludwig, Ralf

2016-04-01

Dikes are the main man made structures in flood protection systems for the protection of humans and economic values. Usually dikes are built with a sandy core and clay or concrete layer covering the core. Thus, dikes are prone to a vertical shrinkage due to soil physical processes such as reduction of pore space and gravity increasing the risk of a crevasse during floods. In addition, this vulnerability is amplified by a sea level rise due to climate change. To guarantee the stability of dikes, a labourer intensive program is carried out by national authorities monitoring the dikes by visual inspection. In the presented study, a quantitative approach is presented using SAR Interferometry for the monitoring of the stability of dikes from space. In particular, the vertical movement of dikes due to shrinkage is monitored using persistent scatterer interferometry. Therefore three different types of dikes have been investigated: a sea coast dike with a concrete cover, a sea coast dike with short grass cover and a smaller river dike with grass cover. All dikes are located in Germany. Results show the potential of the monitoring technique as well as spatial differences in the stability of dikes with subsidence rates in parts of a dike up to 7 mm/a.

A 12 year EDF study of concrete creep under uniaxial and biaxial loading

DOE PAGES

Charpin, Laurent; Le Pape, Yann; Coustabeau, Eric; ...

2017-11-04

This paper presents a 12-year-long creep and shrinkage experimental campaign on cylindrical and prismatic concrete samples under uniaxial and biaxial stress, respectively. The motivation for the study is the need for predicting the delayed strains and the pre-stress loss of concrete containment buildings of nuclear power plants. Two subjects are central in this regard: the creep strain's long-term evolution and the creep Poisson's ratio. A greater understanding of these areas is necessary to ensure reliable predictions of the long-term behavior of the concrete containment buildings.Long-term basic creep appears to evolve as a logarithm function of time in the range ofmore » 3 to 10 years of testing. Similar trends are observed for drying creep, autogenous shrinkage, and drying shrinkage testing, which suggests that all delayed strains obtained using different loading and drying conditions originate from a common mechanism.The creep Poisson's ratio derived from the biaxial tests is approximately constant over time for both the basic and drying creep tests (creep strains corrected by the shrinkage strain).It is also shown that the biaxial non-drying samples undergo a significant increase in Young's modulus after 10 years.« less

A 12 year EDF study of concrete creep under uniaxial and biaxial loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charpin, Laurent; Le Pape, Yann; Coustabeau, Eric

This paper presents a 12-year-long creep and shrinkage experimental campaign on cylindrical and prismatic concrete samples under uniaxial and biaxial stress, respectively. The motivation for the study is the need for predicting the delayed strains and the pre-stress loss of concrete containment buildings of nuclear power plants. Two subjects are central in this regard: the creep strain's long-term evolution and the creep Poisson's ratio. A greater understanding of these areas is necessary to ensure reliable predictions of the long-term behavior of the concrete containment buildings.Long-term basic creep appears to evolve as a logarithm function of time in the range ofmore » 3 to 10 years of testing. Similar trends are observed for drying creep, autogenous shrinkage, and drying shrinkage testing, which suggests that all delayed strains obtained using different loading and drying conditions originate from a common mechanism.The creep Poisson's ratio derived from the biaxial tests is approximately constant over time for both the basic and drying creep tests (creep strains corrected by the shrinkage strain).It is also shown that the biaxial non-drying samples undergo a significant increase in Young's modulus after 10 years.« less

Need to Identify Parameters of Concrete in the Weakest Zone of the Industrial Floor

NASA Astrophysics Data System (ADS)

Stawiski, Bohdan; Radzik, Łukasz

2017-10-01

The ways in which industrial floors are exploited leads to the requirement for the highest strength of their upper zone. Physical phenomena occurring during the compaction and hardening of the concrete cause different strength distributions. In the top zone of industrial floors, the strength is significantly lower (over a dozen MPa) than the strength in the bottom zone (several dozen MPa). Standard tests of control samples do not detect this fact. Processes for the application and finishing of embedded mineral-aggregate hardeners (dry shakes) can be regarded as uncontrolled. The effects of the use of dry shakes are not evaluated. In combination with the phenomenon of bleeding, they often fail by delamination. This paper presents the results of industrial floor testing. The ultrasonic pulse velocity method with dry point contact transducers was used. The results show how upper layer strength was reduced, and how dry shakes application affected the strength of the floor. The strength distribution in hardened concrete, which delaminated from the rest of the floor was presented as well. The extension of compulsory control tests of concrete samples was proposed. In the authors’ opinion, particular attention should be paid to 3 centimetres of the upper layer.

Remediation of 137Cs contaminated concrete using electrokinetic phenomena and ionic salt washes in nuclear energy contexts.

PubMed

Parker, Andrew J; Joyce, Malcolm J; Boxall, Colin

2017-10-15

This work describes the first known the use of electrokinetic treatments and ionic salt washes to remediate concrete contaminated with 137 Cs. A series of experiments were performed on concrete samples, contaminated with K + and 137 Cs, using a bespoke migration cell and an applied electric field (60V potential gradient and current limit of 35mA). Additionally, two samples were treated with an ionic salt wash (≤400molm -3 of KCl) alongside the electrokinetic treatment. The results show that the combined treatment produces removal efficiencies three times higher (>60%) than the electrokinetic treatment alone and that the decontamination efficiency appears to be proportional to the initial degree of contamination. Furthermore, the decontamination efficiencies are equivalent to previous electrokinetic studies that utilised hazardous chemical enhancement agents demonstrating the potential of the technique for use on nuclear licensed site. The results highlight the relationship between the initial contamination concentration within the concrete and achievable removal efficiency of electrokinetic treatment and other treatments. This information would be useful when selecting the most appropriate decontamination techniques for particular contamination scenarios. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of Crack Initiation, Propagation and Coalescence Behavior of Concrete and Rock Materials

NASA Astrophysics Data System (ADS)

Zengin, Enes; Abiddin Erguler, Zeynal

2017-04-01

There are many previously studies carried out to identify crack initiation, propagation and coalescence behavior of different type of rocks. Most of these studies aimed to understand and predict the probable instabilities on different engineering structures such as mining galleries or tunnels. For this purpose, in these studies relatively smaller natural rock and synthetic rock-like models were prepared and then the required laboratory tests were performed to obtain their strength parameters. By using results provided from these models, researchers predicted the rock mass behavior under different conditions. However, in the most of these studies, rock materials and models were considered as contains none or very few discontinuities and structural flaws. It is well known that rock masses naturally are extremely complex with respect to their discontinuities conditions and thus it is sometimes very difficult to understand and model their physical and mechanical behavior. In addition, some vuggy rock materials such as basalts and limestones also contain voids and gaps having various geometric properties. Providing that the failure behavior of these type of rocks controlled by the crack initiation, propagation and coalescence formed from their natural voids and gaps, the effect of these voids and gaps over failure behavior of rocks should be investigated. Intact rocks are generally preferred due to relatively easy side of their homogeneous characteristics in numerical modelling phases. However, it is very hard to extract intact samples from vuggy rocks because of their complex pore sizes and distributions. In this study, the feasibility of concrete samples to model and mimic the failure behavior vuggy rocks was investigated. For this purpose, concrete samples were prepared at a mixture of %65 cement dust and %35 water and their physical and mechanical properties were determined by laboratory experiments. The obtained physical and mechanical properties were used to constitute numerical models, and then uniaxial compressive strength (UCS) tests were performed on these models by using a commercial software called as Particle Flow Code (PFC2D). When the crack behavior of concrete samples obtained from both laboratory tests and numerical models are compared with the results of previous studies, a significant similarity was found. As a result, due to the observed similarity crack behavior between concretes and rocks, it can be concluded that intact concrete samples can be used for modelling purposes to understand the effect of voids and gaps on failure characteristics of vuggy rocks.

Irradiated recycled plastic as a concrete additive for improved chemo-mechanical properties and lower carbon footprint.

PubMed

Schaefer, Carolyn E; Kupwade-Patil, Kunal; Ortega, Michael; Soriano, Carmen; Büyüköztürk, Oral; White, Anne E; Short, Michael P

2018-01-01

Concrete production contributes heavily to greenhouse gas emissions, thus a need exists for the development of durable and sustainable concrete with a lower carbon footprint. This can be achieved when cement is partially replaced with another material, such as waste plastic, though normally with a tradeoff in compressive strength. This study discusses progress toward a high/medium strength concrete with a dense, cementitious matrix that contains an irradiated plastic additive, recovering the compressive strength while displacing concrete with waste materials to reduce greenhouse gas generation. Compressive strength tests showed that the addition of high dose (100kGy) irradiated plastic in multiple concretes resulted in increased compressive strength as compared to samples containing regular, non-irradiated plastic. This suggests that irradiating plastic at a high dose is a viable potential solution for regaining some of the strength that is lost when plastic is added to cement paste. X-ray Diffraction (XRD), Backscattered Electron Microscopy (BSE), and X-ray microtomography explain the mechanisms for strength retention when using irradiated plastic as a filler for cement paste. By partially replacing Portland cement with a recycled waste plastic, this design may have a potential to contribute to reduced carbon emissions when scaled to the level of mass concrete production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Defining a Conceptual Topography of Word Concreteness: Clustering Properties of Emotion, Sensation, and Magnitude among 750 English Words

PubMed Central

Troche, Joshua; Crutch, Sebastian J.; Reilly, Jamie

2017-01-01

Cognitive science has a longstanding interest in the ways that people acquire and use abstract vs. concrete words (e.g., truth vs. piano). One dominant theory holds that abstract and concrete words are subserved by two parallel semantic systems. We recently proposed an alternative account of abstract-concrete word representation premised upon a unitary, high dimensional semantic space wherein word meaning is nested. We hypothesize that a range of cognitive and perceptual dimensions (e.g., emotion, time, space, color, size, visual form) bound this space, forming a conceptual topography. Here we report a normative study where we examined the clustering properties of a sample of English words (N = 750) spanning a spectrum of concreteness in a continuous manner from highly abstract to highly concrete. Participants (N = 328) rated each target word on a range of 14 cognitive dimensions (e.g., color, emotion, valence, polarity, motion, space). The dimensions reduced to three factors: Endogenous factor, Exogenous factor, and Magnitude factor. Concepts were plotted in a unified, multimodal space with concrete and abstract concepts along a continuous continuum. We discuss theoretical implications and practical applications of this dataset. These word norms are freely available for download and use at http://www.reilly-coglab.com/data/. PMID:29075224

Defining a Conceptual Topography of Word Concreteness: Clustering Properties of Emotion, Sensation, and Magnitude among 750 English Words.

PubMed

Troche, Joshua; Crutch, Sebastian J; Reilly, Jamie

2017-01-01

Cognitive science has a longstanding interest in the ways that people acquire and use abstract vs. concrete words (e.g., truth vs. piano). One dominant theory holds that abstract and concrete words are subserved by two parallel semantic systems. We recently proposed an alternative account of abstract-concrete word representation premised upon a unitary, high dimensional semantic space wherein word meaning is nested. We hypothesize that a range of cognitive and perceptual dimensions (e.g., emotion, time, space, color, size, visual form) bound this space, forming a conceptual topography. Here we report a normative study where we examined the clustering properties of a sample of English words ( N = 750) spanning a spectrum of concreteness in a continuous manner from highly abstract to highly concrete. Participants ( N = 328) rated each target word on a range of 14 cognitive dimensions (e.g., color, emotion, valence, polarity, motion, space). The dimensions reduced to three factors: Endogenous factor, Exogenous factor, and Magnitude factor. Concepts were plotted in a unified, multimodal space with concrete and abstract concepts along a continuous continuum. We discuss theoretical implications and practical applications of this dataset. These word norms are freely available for download and use at http://www.reilly-coglab.com/data/.

Diagenetic Carbonates Related to Hydrocarbon-rich Fluid Seepage in the Nile Deep Sea Fan (East Mediterranean Sea)

NASA Astrophysics Data System (ADS)

Pierre, C.; Gontharet, S.; Blanc-Valleron, M. M.; Bayon, G.; Dupré, S.; Mascle, J.

2017-12-01

During the NAUTINIL (September-October 2003), MIMES (July 2004), BIONIL (October 2006) and MEDECO2 (November 2007) cruises, coring and submersible dives were realized in the Nile Deep Sea Fan (NDSF) area. Active fluid venting sites were identified by the presence of living benthic organisms and by methane plumes in the bottom waters above the seeping structures. At all sites, hard carbonate crusts cover irregularly the sea floor. The sediments from the venting areas are organic-rich, contain sometimes carbonate concretions and have a strong H2S smell indicative of active sulfate reduction. The mineralogy of carbonate crusts is dominated by aragonite and Mg-calcite; the mineralogy of concretions is more complex, with mixtures of Mg-calcite, dolomite and ankerite. The oxygen and carbon isotopic compositions of the carbonate from crusts and concretions exhibit large variations (-2.8< δ18O ‰ VPDB <+9.5; -42.6< δ13C ‰ VPDB <+22.4). The wide range of δ18O values reflects variable sources of fluids. Most of the authigenic carbonates from the NDSF were precipitated in isotopic equilibrium with the Mediterranean bottom water. The carbonate crusts and concretions from the brine seeps of the north-western NDSF are enriched in 18O indicating that a source of 18O-rich fluids originated from depth. Differently, a few crusts and concretions from the eastern NDSF exhibit relatively low δ18O values, which are due to precipitation at warm temperatures. The very low δ13C values of the diagenetic carbonates indicate that methane and possibly other heavier hydrocarbons were the major source of carbon that was oxidized as bicarbonate mostly through bacterial sulfate reduction coupled with anaerobic methane oxidation within the anoxic sediment. The very positive δ13C values of the diagenetic carbonates from many carbonate concretions are related to the production of 13C-rich CO2 during methanogenesis within the sub-seafloor sediments.

Mathematical modeling of microbially induced crown corrosion in wastewater collection systems and laboratory investigation and modeling of sulfuric acid corrosion of concrete

NASA Astrophysics Data System (ADS)

Jahani, Fereidoun

In the model for microbially induced crown corrosion, the diffusion of sulfide inside the concrete pores, its biological conversion to sulfuric acid, and the corrosion of calcium carbonate aggregates are represented. The corrosion front is modeled as a moving boundary. The location of the interface between the corrosion layer and the concrete is determined as part of the solution to the model equations. This model consisted of a system of one dimensional reaction-diffusion equations coupled to an equation describing the movement of the corrosion front. The equations were solved numerically using finite element Galerkin approximation. The concentration profiles of sulfide in the air and the liquid phases, the pH as a function of concrete depth, and the position of the corrosion front. A new equation for the corrosion rate was also derived. A more specific model for the degradation of a concrete specimen exposed to a sulfuric acid solution was also studied. In this model, diffusion of hydrogen ions and their reaction with alkaline components of concrete were expressed using Fick's Law of diffusion. The model equations described the moving boundary, the dissolution rate of alkaline components in the concrete, volume increase of sulfuric acid solution over the concrete specimen, and the boundary conditions on the surface of the concrete. An apparatus was designed and experiments were performed to measure pH changes on the surface of concrete. The data were used to calculate the dissolution rate of the concrete and, with the model, to determine the diffusion rate of sulfuric acid in the corrosion layer and corrosion layer thickness. Electrochemical Impedance Spectroscopy (EIS) was used to study the corrosion rate of iron pins embedded in the concrete sample. The open circuit potential (OCP) determined the onset of corrosion on the surface of the pins. Visual observation of the corrosion layer thickness was in good agreement with the simulation results.

Determination of Coefficient of Thermal Expansion (CTE) of 20MPa Mass Concrete Using Granite Aggregate

NASA Astrophysics Data System (ADS)

Chee Siang, GO

2017-07-01

Experimental test was carried out to determine the coefficient of thermal expansion (CTE) value of 20MPa mass concrete using granite aggregate. The CTE value was established using procedure proposed by Kada et al. 2002 in determining the magnitude of early-ages CTE through laboratory test which is a rather accurate way by eliminating any possible superimposed effect of others early-age thermal deformation shrinkages such as autogenous, carbonation, plastic and drying shrinkage. This was done by submitting granite concrete block samples instrumented with ST4 vibrating wire extensometers to thermal shocks. The response of the concrete samples to this shock results in a nearly instantaneous deformation, which are measured by the sensor. These deformations, as well as the temperature signal, are used to calculate the CTE. By repeating heat cycles, the variation in the early-ages of concrete CTE over time was monitored and assessed for a period of upto 7 days. The developed CTE value facilitating the verification and validation of actual maximum permissible critical temperature differential limit (rather than arbitrarily follow published value) of cracking potential. For thick sections, internal restraint is dominant and this is governed by differentials mainly. Of the required physical properties for thermal modelling, CTE is of paramount importance that with given appropriate internal restraint factor the condition of cracking due to internal restraint is governs by equation, ΔTmax= 3.663ɛctu / αc. Thus, it can be appreciated that an increase in CTE will lower the maximum allowable differential for cracking avoidance in mass concrete while an increase of tensile strain capacity will increase the maximum allowable temperature differential.

43 CFR 3593.1 - Core or test hole cores, samples, cuttings.

Code of Federal Regulations, 2014 CFR

2014-10-01

.... (d) When drilling on lands with potential for encountering high pressure oil, gas or geothermal... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Core or test hole cores, samples, cuttings...) EXPLORATION AND MINING OPERATIONS Bore Holes and Samples § 3593.1 Core or test hole cores, samples, cuttings...

43 CFR 3593.1 - Core or test hole cores, samples, cuttings.

Code of Federal Regulations, 2012 CFR

2012-10-01

.... (d) When drilling on lands with potential for encountering high pressure oil, gas or geothermal... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Core or test hole cores, samples, cuttings...) EXPLORATION AND MINING OPERATIONS Bore Holes and Samples § 3593.1 Core or test hole cores, samples, cuttings...

43 CFR 3593.1 - Core or test hole cores, samples, cuttings.

Code of Federal Regulations, 2013 CFR

2013-10-01

.... (d) When drilling on lands with potential for encountering high pressure oil, gas or geothermal... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Core or test hole cores, samples, cuttings...) EXPLORATION AND MINING OPERATIONS Bore Holes and Samples § 3593.1 Core or test hole cores, samples, cuttings...

43 CFR 3593.1 - Core or test hole cores, samples, cuttings.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... (d) When drilling on lands with potential for encountering high pressure oil, gas or geothermal... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Core or test hole cores, samples, cuttings...) EXPLORATION AND MINING OPERATIONS Bore Holes and Samples § 3593.1 Core or test hole cores, samples, cuttings...

Damage development, phase changes, transport properties, and freeze-thaw performance of cementitious materials exposed to chloride based salts

NASA Astrophysics Data System (ADS)

Farnam, Yaghoob

Recently, there has been a dramatic increase in premature deterioration in concrete pavements and flat works that are exposed to chloride based salts. Chloride based salts can cause damage and deterioration in concrete due to the combination of factors which include: increased saturation, ice formation, salt crystallization, osmotic pressure, corrosion in steel reinforcement, and/or deleterious chemical reactions. This thesis discusses how chloride based salts interact with cementitious materials to (1) develop damage in concrete, (2) create new chemical phases in concrete, (3) alter transport properties of concrete, and (4) change the concrete freeze-thaw performance. A longitudinal guarded comparative calorimeter (LGCC) was developed to simultaneously measure heat flow, damage development, and phase changes in mortar samples exposed to sodium chloride (NaCl), calcium chloride (CaCl 2), and magnesium chloride (MgCl2) under thermal cycling. Acoustic emission and electrical resistivity measurements were used in conjunction with the LGCC to assess damage development and electrical response of mortar samples during cooling and heating. A low-temperature differential scanning calorimetry (LT-DSC) was used to evaluate the chemical interaction that occurs between the constituents of cementitious materials (i.e., pore solution, calcium hydroxide, and hydrated cement paste) and salts. Salts were observed to alter the classical phase diagram for a salt-water system which has been conventionally used to interpret the freeze-thaw behavior in concrete. An additional chemical phase change was observed for a concrete-salt-water system resulting in severe damage in cementitious materials. In a cementitious system exposed to NaCl, the chemical phase change occurs at a temperature range between -6 °C and 8 °C due to the presence of calcium sulfoaluminate phases in concrete. As a result, concrete exposed to NaCl can experience additional freeze-thaw cycles due to the chemical phase change creating cracks and damage to concrete under freezing and thawing. In a cementitious system exposed to CaCl2, the chemical phase change is mainly due to the presence of calcium hydroxide (CH) in concrete. Calcium hydroxide can react with CaCl2 solution producing calcium oxychloride. Calcium oxychloride forms at room temperature (i.e., 23 °C) for CaCl 2 salt concentrations at or above ~ 12 % by mass in the solution creating expansion and degradation in concrete. In a cementitious system exposed to MgCl2, it was observed that MgCl2 can be entirely consumed in concrete by reacting with CH and produce CaCl2. As such, it followed a response that is more similar to the concrete-CaCl2-water system than that of the MgCl2-water phase diagram. Formation of calcium/magnesium oxychloride is most likely the main source of the chemical phase change (which can cause damage) in concrete exposed to MgCl2. During the LGCC testing for CaCl2 and MgCl2 salts, it was found that the chemical reactions occur rapidly (~ 10 min) and can cause a significant decrease in subsequent fluid ingress into exposed concrete in comparison to NaCl. Isothermal calorimetry, fluid absorption, oxygen permeability, oxygen diffusivity, and X-ray fluorescence testing showed that the formation of calcium oxychloride in concrete exposed to CaCl2 and MgCl 2 can block or fill in the concrete pores on the surface of the specimen; thereby decreasing the CaCl2 and MgCl2 fluid ingress into the concrete. To mitigate the damage and degradation due to the chemical phase transition, two approaches were evaluated: (1) use of a cementitious binder that does not react with salts, and (2) use of a new practical technology to melt ice and snow, thereby decreasing the demand for deicing salt usage. For the first approach, carbonated calcium silicate based cement (CCSC) was used and the CCSC mortar showed a promising performance and resistance to salt degradation than an ordinary portland mortar does. For the second approach, phase change materials (PCM), including paraffin oil and methyl laurate, were used to store heat in concrete elements and release the stored heat during cooling to reduce ice formation and snow accumulation on the surface of concrete. PCM approach also showed a promising performance in melting ice and snow, thereby decreasing the demand for salt usage.

An ERP study of recognition memory for concrete and abstract pictures in school-aged children

PubMed Central

Boucher, Olivier; Chouinard-Leclaire, Christine; Muckle, Gina; Westerlund, Alissa; Burden, Matthew J.; Jacobson, Sandra W.; Jacobson, Joseph L.

2016-01-01

Recognition memory for concrete, nameable pictures is typically faster and more accurate than for abstract pictures. A dual-coding account for these findings suggests that concrete pictures are processed into verbal and image codes, whereas abstract pictures are encoded in image codes only. Recognition memory relies on two successive and distinct processes, namely familiarity and recollection. Whether these two processes are similarly or differently affected by stimulus concreteness remains unknown. This study examined the effect of picture concreteness on visual recognition memory processes using event-related potentials (ERPs). In a sample of children involved in a longitudinal study, participants (N = 96; mean age = 11.3 years) were assessed on a continuous visual recognition memory task in which half the pictures were easily nameable, everyday concrete objects, and the other half were three-dimensional abstract, sculpture-like objects. Behavioral performance and ERP correlates of familiarity and recollection (respectively, the FN400 and P600 repetition effects) were measured. Behavioral results indicated faster and more accurate identification of concrete pictures as “new” or “old” (i.e., previously displayed) compared to abstract pictures. ERPs were characterised by a larger repetition effect, on the P600 amplitude, for concrete than for abstract images, suggesting a graded recollection process dependant on the type of material to be recollected. Topographic differences were observed within the FN400 latency interval, especially over anterior-inferior electrodes, with the repetition effect more pronounced and localized over the left hemisphere for concrete stimuli, potentially reflecting different neural processes underlying early processing of verbal/semantic and visual material in memory. PMID:27329352

Isolation and identification of bacteria to improve the strength of concrete.

PubMed

Krishnapriya, S; Venkatesh Babu, D L; G, Prince Arulraj

2015-05-01

The objective of this research work is to isolate and identify calcite precipitating bacteria and to check the suitability of these bacteria for use in concrete to improve its strength. Bacteria to be incorporated in concrete should be alkali resistant to endure the high pH of concrete and endospore forming to withstand the mechanical stresses induced in concrete during mixing. They must exhibit high urease activity to precipitate calcium carbonate in the form of calcite. Bacterial strains were isolated from alkaline soil samples of a cement factory and were tested for urease activity, potential to form endospores and precipitation of calcium carbonate. Based on these results, three isolates were selected and identified by 16S rRNA gene sequencing. They were identified as Bacillus megaterium BSKAU, Bacillus licheniformis BSKNAU and Bacillus flexus BSKNAU. The results were compared with B. megaterium MTCC 1684 obtained from Microbial Type Culture Collection and Gene Bank, Chandigarh, India. Experimental work was carried out to assess the influence of bacteria on the compressive strength and tests revealed that bacterial concrete specimens showed enhancement in compressive strength. The efficiency of bacteria toward crack healing was also tested. Substantial increase in strength and complete healing of cracks was observed in concrete specimens cast with B. megaterium BSKAU, B. licheniformis BSKNAU and B. megaterium MTCC 1684. This indicates the suitability of these bacterial strains for use in concrete. The enhancement of strength and healing of cracks can be attributed to the filling of cracks in concrete by calcite which was visualized by scanning electron microscope. Copyright © 2015 Elsevier GmbH. All rights reserved.

The MELTSPREAD Code for Modeling of Ex-Vessel Core Debris Spreading Behavior, Code Manual – Version3-beta

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmer, M. T.

MELTSPREAD3 is a transient one-dimensional computer code that has been developed to predict the gravity-driven flow and freezing behavior of molten reactor core materials (corium) in containment geometries. Predictions can be made for corium flowing across surfaces under either dry or wet cavity conditions. The spreading surfaces that can be selected are steel, concrete, a user-specified material (e.g., a ceramic), or an arbitrary combination thereof. The corium can have a wide range of compositions of reactor core materials that includes distinct oxide phases (predominantly Zr, and steel oxides) plus metallic phases (predominantly Zr and steel). The code requires input thatmore » describes the containment geometry, melt “pour” conditions, and cavity atmospheric conditions (i.e., pressure, temperature, and cavity flooding information). For cases in which the cavity contains a preexisting water layer at the time of RPV failure, melt jet breakup and particle bed formation can be calculated mechanistically given the time-dependent melt pour conditions (input data) as well as the heatup and boiloff of water in the melt impingement zone (calculated). For core debris impacting either the containment floor or previously spread material, the code calculates the transient hydrodynamics and heat transfer which determine the spreading and freezing behavior of the melt. The code predicts conditions at the end of the spreading stage, including melt relocation distance, depth and material composition profiles, substrate ablation profile, and wall heatup. Code output can be used as input to other models such as CORQUENCH that evaluate long term core-concrete interaction behavior following the transient spreading stage. MELTSPREAD3 was originally developed to investigate BWR Mark I liner vulnerability, but has been substantially upgraded and applied to other reactor designs (e.g., the EPR), and more recently to the plant accidents at Fukushima Daiichi. The most recent round of improvements that are documented in this report have been specifically implemented to support industry in developing Severe Accident Water Management (SAWM) strategies for Boiling Water Reactors.« less

Fracture Properties of Polystyrene Aggregate Concrete after Exposure to High Temperatures.

PubMed

Tang, Waiching; Cui, Hongzhi; Tahmasbi, Soheil

2016-07-28

This paper mainly reports an experimental investigation on the residual mechanical and fracture properties of polystyrene aggregate concrete (PAC) after exposure to high temperatures up to 800 degrees Celsius. The fracture properties namely, the critical stress intensity factor ( K I C S ), the critical crack tip opening displacement ( CTOD C ) for the Two-Parameter Model, and the fracture energy ( G F ) for the Fictitious Crack Model were examined using the three-point bending notched beam test, according to the RILEM recommendations. The effects of polystyrene aggregate (PA) content and temperature levels on the fracture and mechanical properties of concrete were investigated. The results showed that the mechanical properties of PAC significantly decreased with increase in temperature level and the extent of which depended on the PA content in the mixture. However, at a very high temperature of 800 °C, all samples showed 80 percent reduction in modulus of elasticity compared to room temperature, regardless of the level of PA content. Fracture properties of control concrete (C) and PAC were influenced by temperature in a similar manner. Increasing temperature from 25 °C to 500 °C caused almost 50% reduction of the fracture energy for all samples while 30% increase in fracture energy was occurred when the temperature increased from 500 °C to 800 °C. It was found that adding more PA content in the mixture lead to a more ductile behaviour of concrete.

Study of critical behavior in concrete during curing by application of dynamic linear and nonlinear means.

PubMed

Lacouture, Jean-Christoph; Johnson, Paul A; Cohen-Tenoudji, Frederic

2003-03-01

The monitoring of both linear and nonlinear elastic properties of a high performance concrete during curing is presented by application of compressional and shear waves. To follow the linear elastic behavior, both compressional and shear waves are used in wide band pulse echo mode. Through the value of the complex reflection coefficient between the cell material (Lucite) and the concrete within the cell, the elastic moduli are calculated. Simultaneously, the transmission of a continuous compressional sine wave at progressively increasing drive levels permits us to calculate the nonlinear properties by extracting the harmonics amplitudes of the signal. Information regarding the chemical evolution of the concrete based upon the reaction of hydration of cement is obtained by monitoring the temperature inside the sample. These different types of measurements are linked together to interpret the critical behavior.

Asphalt-Rubber SAMI (Stress-Absorbing Membrane Interlayers) Field Evaluation.

DTIC Science & Technology

1986-04-01

revealed that there was promise in using the material as an interlayer to prevent the reflection of cracks from an old pavement to a new asphalt -concrete...reflection cracking , and (2) that asphalt - rubber interlayers should be investigated in conjunction with conventional asphalt -concrete overlays. An... Asphalt -rubber samples were taken and tested and construction activities were documented. The performance has been monitored by conducting crack

Novel biochar-concrete composites: Manufacturing, characterization and evaluation of the mechanical properties.

PubMed

Akhtar, Ali; Sarmah, Ajit K

2018-03-01

In this study, biochar, a carbonaceous solid material produced from three different waste sources (poultry litter, rice husk and pulp and paper mill sludge) was utilized to replace cement content up to 1% of total volume and the effect of individual biochar mixed with cement on the mechanical properties of concrete was investigated through different characterization techniques. A total of 168 samples were prepared for mechanical testing of biochar added concrete composites. The results showed that pulp and paper mill sludge biochar at 0.1% replacement of total volume resulted in compressive strength close to the control specimen than the rest of the biochar added composites. However, rice husk biochar at 0.1% slightly improved the splitting tensile strength with pulp and papermill sludge biochar produced comparable values. Biochar significantly improved the flexural strength of concrete in which poultry litter and rice husk biochar at 0.1% produced optimum results with 20% increment than control specimens. Based on the findings, we conclude that biochar has the potential to improve the concrete properties while replacing the cement in minor fractions in conventional concrete applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Coring Sample Acquisition Tool

NASA Technical Reports Server (NTRS)

Haddad, Nicolas E.; Murray, Saben D.; Walkemeyer, Phillip E.; Badescu, Mircea; Sherrit, Stewart; Bao, Xiaoqi; Kriechbaum, Kristopher L.; Richardson, Megan; Klein, Kerry J.

2012-01-01

A sample acquisition tool (SAT) has been developed that can be used autonomously to sample drill and capture rock cores. The tool is designed to accommodate core transfer using a sample tube to the IMSAH (integrated Mars sample acquisition and handling) SHEC (sample handling, encapsulation, and containerization) without ever touching the pristine core sample in the transfer process.

Evaluating Core Quality for a Mars Sample Return Mission

NASA Technical Reports Server (NTRS)

Weiss, D. K.; Budney, C.; Shiraishi, L.; Klein, K.

2012-01-01

Sample return missions, including the proposed Mars Sample Return (MSR) mission, propose to collect core samples from scientifically valuable sites on Mars. These core samples would undergo extreme forces during the drilling process, and during the reentry process if the EEV (Earth Entry Vehicle) performed a hard landing on Earth. Because of the foreseen damage to the stratigraphy of the cores, it is important to evaluate each core for rock quality. However, because no core sample return mission has yet been conducted to another planetary body, it remains unclear as to how to assess the cores for rock quality. In this report, we describe the development of a metric designed to quantitatively assess the mechanical quality of any rock cores returned from Mars (or other planetary bodies). We report on the process by which we tested the metric on core samples of Mars analogue materials, and the effectiveness of the core assessment metric (CAM) in assessing rock core quality before and after the cores were subjected to shocking (g forces representative of an EEV landing).

ROCK PHYSICS. Rock physics of fibrous rocks akin to Roman concrete explains uplifts at Campi Flegrei Caldera.

PubMed

Vanorio, Tiziana; Kanitpanyacharoen, Waruntorn

2015-08-07

Uplifts in the Campi Flegrei caldera reach values unsurpassed anywhere in the world (~2 meters). Despite the marked deformation, the release of strain appears delayed. The rock physics analysis of well cores highlights the presence of two horizons, above and below the seismogenic area, underlying a coupled process. The basement is a calc-silicate rock housing hydrothermal decarbonation reactions, which provide lime-rich fluids. The caprock above the seismogenic area has a pozzolanic composition and a fibril-rich matrix that results from lime-pozzolanic reactions. These findings provide evidence for a natural process reflecting that characterizing the cementitious pastes in modern and Roman concrete. The formation of fibrous minerals by intertwining filaments confers shear and tensile strength to the caprock, contributing to its ductility and increased resistance to fracture. Copyright © 2015, American Association for the Advancement of Science.

Technology Solutions Case Study: Innovative Retrofit Foundation Insulation Strategies, Minneapolis, Minnesota

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Basements in climates 6 & 7 can account for a fraction of a home's total heat loss when fully conditioned. These foundations are a source of moisture, with convection in open block cavities redistributing water from the wall base, usually when heating. Even when block cavities are capped, the cold foundation concrete can act as a moisture source for wood rim joist components that are in contact with the wall. As below-grade basements are increasingly retrofitted for habitable space, cold foundation walls pose increased challenges for moisture durability, energy use, and occupant comfort. To address this challenge, the NorthernSTAR Buildingmore » America Partnership evaluated a retrofit insulation strategy for foundations that is designed for use with open-core concrete block foundation walls. The three main goals were to improve moisture control, improve occupant comfort, and reduce heat loss.« less

Utilization of CO2 in High Performance Building and Infrastructure Products

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeCristofaro, Nicholas

The overall objective of DE-FE0004222 was to demonstrate that calcium silicate phases, in the form of either naturally-occuring minerals or synthetic compounds, could replace Portland cement in concrete manufacturing. The calcium silicate phases would be reacted with gaseous CO2 to create a carbonated concrete end-product. If successful, the project would offer a pathway to a significant reduction in the carbon footprint associated with the manufacture of cement and its use in concrete (approximately 816 kg of CO2 is emitted in the production of one tonne of Portland cement). In the initial phases of the Technical Evaluation, Rutgers University teamed withmore » Solidia Technologies to demonstrate that natural wollastonite (CaSiO3), milled to a particle size distribution consistent with that of Portland cement, could indeed fit this bill. The use of mineral wollastonite as a cementitious material would potentially eliminate the CO2 emitted during cement production altogether, and store an additional 250 kg of CO2 during concrete curing. However, it was recognized that mineral wollastonite was not available in volumes that could meaningfully impact the carbon footprint associated with the cement and concrete industries. At this crucial juncture, DE-FE0004222 was redirected to use a synthetic version of wollastonite, hereafter referred to as Solidia Cement™, which could be manufactured in conventional cement making facilities. This approach enables the new cementitious material to be made using existing cement industry raw material supply chains, capital equipment, and distribution channels. It would also offer faster and more complete access to the concrete marketplace. The latter phases of the Technical Evaluation, conducted with Solidia Cement made in research rotary kilns, would demonstrate that industrially viable CO2-curing practices were possible. Prototypes of full-scale precast concrete products such as pavers, concrete masonry units, railroad ties, hollow-core slabs, and aerated concrete were produced to verify the utility of the CO2-curing process. These products exhibited a range of part dimensions and densities that were representative of the precast concrete industry. In the subsequent Demonstration of Commercial Development phase, the characteristics and performance of Solidia Cement made at a LafargeHolcim cement plant were established. This Solidia Cement was then used to demonstrate the CO2-curing process within operating concrete plants. Pavers, concrete masonry units and roofing tiles were produced according to ASTM and manufacturer specifications. A number of attractive manufacturing economies were recognized when Solidia Cement-based concrete parts were compared to their Portland cement based counterparts. These include reduced raw materials waste, reduced dependence on admixtures to control efflorescence, shorter curing time to full concrete strength, faster equipment clean-up, reduced equipment maintenance, and improved inventory management. These economies make the adoption of the Solidia Cement / CO2-curing process attractive even in the absence of environmental incentives. The culminating activity of the Demonstration of Commercial Development phase was the conversion of 10% of the manufacturing capacity at a concrete paver and block company from Portland cement-based products to Solidia Cement-based products. The successful completion of the Demonstration of Commercial Development phase clearly illustrated the environmental benefits associated with Solidia Cement and Solidia Concrete technologies. The industrial production of Solidia Cement, as a low-lime alternative to traditional Portland cement, reduces CO2 emissions at the cement kiln from 816 kg of CO2 per tonne of Portland cement clinker to 570 kg per tonne of Solidia Cement clinker. Industrial scale CO2-curing of Solidia Concrete sequestered a net of 183 kg of CO2 per tonne of Solidia Cement used in concrete pavers. Taken together, these two effects reduced the CO2 footprint associated with the production and use of cement in concrete products by over 50% (a reduction of 430 kg of CO2 per tonne of cement). Applied at the first commercial Solidia Concrete manufacturing site, the two effects will combine to reduce the CO2 footprint associated with the production and use of cement by over 10,000 tonnes per year. When applied across the precast concrete industry in the U.S., it is estimated that the CO2 footprint will be reduced by 8.6 million tonnes per year (20 million tonnes of cement used in precast concrete x 430 kg of CO2 per tonne of cement). Applied across the entire concrete industry in the U.S., it is expected that 43 million tonnes of CO2 will be avoided per year (100 million tonnes of cement used in all concrete x 430 kg of CO2 per tonne of cement).« less

Effects of Elevated Temperature on Concrete with Recycled Coarse Aggregates

NASA Astrophysics Data System (ADS)

Salau, M. A.; Oseafiana, O. J.; Oyegoke, T. O.

2015-11-01

This paper discusses the effects of heating temperatures of 200°C, 400°C and 600°C each for 2 hours at a heating rate of 2.5°C/min on concrete with the content of Natural Coarse Aggregates (NCA) partially replaced with Recycled Coarse Aggregates (RCA), obtained from demolished building in the ratio of 0%, 15% and 30%.There was an initial drop in strength from 100°C to 200°C which is suspected to be due to the relatively weak interfacial bond between the RCA and the hardened paste within the concrete matrix;a gradual increase in strength continued from 200°C to 450°C and steady drop occurred again as it approached 600°C.With replacement proportion of 0%, 15% and 30% of NCA and exposure to peak temperature of 600°C, a relative concrete strength of 23.6MPa, 25.3MPa and 22.2MPa respectively can be achieved for 28 days curing age. Furthermore, RAC with 15% NCA replacement when exposed to optimum temperature of 450°C yielded high compressive strength comparable to that of control specimen (normal concrete). In addition, for all concrete samples only slight surface hairline cracks were noticed as the temperature approached 400°C. Thus, the RAC demonstrated behavior just like normal concrete and may be considered fit for structural use.

Effect of jute yarn on the mechanical behavior of concrete composites.

PubMed

Zakaria, Mohammad; Ahmed, Mashud; Hoque, Md Mozammel; Hannan, Abdul

2015-01-01

The objective of the study is to investigate the effect of introducing jute yarn on the mechanical properties of concrete. Jute fibre is produced abundantly in Bangladesh and hence, very cheap. The investigation on the enhancement of mechanical properties of concrete with jute yarn as reinforcement, if enhanced, will not only explore a way to improve the properties of concrete, it will also explore the use of jute and restrict the utilization of polymer which is environmentally detrimental. To accomplish the objective, an experimental investigation of the compressive, flexural and tensile strengths of Jute Yarn Reinforced Concrete composites (JYRCC) has been conducted. Cylinders, prisms and cubes of standard dimensions have been made to introducing jute yarn varying the mix ratio of the ingredients in concrete, water cement ratio, length and volume of yarn to know the effect of parameters as mentioned. Compressive, flexural and tensile strength tests had been conducted on the prepared samples by appropriate testing apparatus following Standards of tests. Mechanical properties of JYRCC were observed to be enhanced for a particular range of lengths of cut (10, 15, 20 and 25 mm) and volume content of jute yarn (0.1, 0.25, 0.5 and 0.75 %). The maximum increment of compressive, flexural and tensile strengths observed in the investigation are 33, 23 and 38 %, respectively with respect to concrete without jute yarn.

Development work for a borax internal core-catcher for a gas-cooled fast reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donne, M.D.; Dorner, S.; Schumacher, G.

1978-07-01

Preliminary thermal calculations show that a corecatcher, which is able to cope with the complete meltdown of the core and blankets of a 1000-MW(electric) gas-cooled fast reactor, appears to be feasible. This core-catcher is based on borax (Na/sub 2/B/sub 4/O/sub 7/) dissolving the oxide fuel and the fission products occurring in oxide form. The borax is contained in steel boxes forming a 2.2-m-thick slab on the base of the reactor cavity inside the prestressed concrete reactor vessel (PCRV), just underneath the reactor core. After a complete meltdown accident, the fission products, in oxide form, are dispersed in the pool formedmore » by the liquid borax. The metallic fission products are contained in the steel lying below the borax pool and in contact with the water-cooled PCRV liner. The volumetric power density of the molten core is conveniently reduced as it is dissolved in the borax, and the resulting heat fluxes at the borders of the pool can be safely carried away through the PCRV liner and its water cooling system.« less

Asphalt additives in thick hot mixed asphalt-concrete pavements. Research report (Interim), Sep 86-Oct 90

DOE Office of Scientific and Technical Information (OSTI.GOV)

Button, J.W.; Prapnnachari, S.

Asphalt concrete field test pavements were placed in District 19 north of Texarkana on US-59/71 in 1987 and 1988 to evaluate the ability of certain asphalt additives to enhance resistance to cracking and rutting. Two 10-inch thick and 0.9 mile (approx.) long test pavements and a similar untreated control section were constructed in the northbound and southbound lanes for a total of 6 field trials. Asphalt additives were incorporated in both the 8-inch base and the overlying 2-inch surface layers. The additives evaluated included Goodyear LPF 5812, Chemkrete-CTI 102, Exxon Polybilt 102, and Styrelf 13. Samples of paving materials includingmore » aggregates, asphalts, compacted mixes, and pavement cores were collected, conveyed to the laboratory, and tested to provide detailed documentation of their properties. Tests included rheological properties of the binders before and after artificial aging, characterization of aggregate, Hveem and Marshall stability, stiffness as a function of temperature, tensile properties before and after moisture conditioning and artificial aging, air void content, creep, and permanent deformation. Field tests and visual evaluations have been conducted to objectively evaluate field performance. Results of these tests are reported herein. Within 6 months after construction of the base layers and prior to placement of the surface course, the Chemkrete modified base became severely cracked. As a result, the surface mix placed on this base section was treated with Goodyear latex rather than Chemkrete. All other modified pavements and the control section have performed well and exhibited essentially equivalent performance after 2 1/2 years in service.« less

Moisture sensor based on evanescent wave light scattering by porous sol-gel silica coating

DOEpatents

Tao, Shiquan; Singh, Jagdish P.; Winstead, Christopher B.

2006-05-02

An optical fiber moisture sensor that can be used to sense moisture present in gas phase in a wide range of concentrations is provided, as well techniques for making the same. The present invention includes a method that utilizes the light scattering phenomenon which occurs in a porous sol-gel silica by coating an optical fiber core with such silica. Thus, a porous sol-gel silica polymer coated on an optical fiber core forms the transducer of an optical fiber moisture sensor according to an embodiment. The resulting optical fiber sensor of the present invention can be used in various applications, including to sense moisture content in indoor/outdoor air, soil, concrete, and low/high temperature gas streams.

Turn Basin Construction

NASA Image and Video Library

2017-06-14

Modifications are underway at the Launch Complex 39 turn basin wharf at NASA's Kennedy Space Center in Florida to prepare for the arrival of the agency's massive Space Launch System (SLS) core stage aboard the barge Pegasus. Tammy Kelly, in the center, site manager, with Southeast Cherokee Construction Inc. talks with construction workers. A crane will be used to lift up precast concrete poles and position them to be driven to a depth of about 70 feet into the bedrock below the water around the turn basin. The upgrades are necessary to accommodate the increased weight of the core stage along with ground support and transportation equipment aboard the modified barge Pegasus. The Ground Systems Development and Operations Program is overseeing the upgrades to the turn basin wharf.

Turn Basin Construction

NASA Image and Video Library

2017-06-14

Modifications are underway at the Launch Complex 39 turn basin wharf at NASA's Kennedy Space Center in Florida to prepare for the arrival of the agency's massive Space Launch System (SLS) core stage aboard the barge Pegasus. In the foreground is Tammy Kelly, site manager, with Southeast Cherokee Construction Inc. A crane will be used to lift up precast concrete poles and position them to be driven to a depth of about 70 feet into the bedrock below the water around the turn basin. The upgrades are necessary to accommodate the increased weight of the core stage along with ground support and transportation equipment aboard the modified barge Pegasus. The Ground Systems Development and Operations Program is overseeing the upgrades to the turn basin wharf.

Evaluating Long-Term Impacts of Soil-Mixing Source-Zone Treatment using Cryogenic Core Collection

DTIC Science & Technology

2017-06-01

to (a) coring equipment freezing downhole, (b) freezing or binding of the core sample in barrel, and ( c ) running out of LN in the vicinity of sampling...encountered due to (a) coring equipment freezing downhole, (b) freezing or binding of the core sample in barrel, and ( c ) running out of LN in the...equipment freezing downhole, (b) freezing or binding of the core sample in barrel, and ( c ) running out of LN in the vicinity of sampling. Downhole

Matt waste from glass separated collection: an eco-sustainable addition for new building materials.

PubMed

Bignozzi, M C; Saccani, A; Sandrolini, F

2009-01-01

Matt waste (MW), a by-product of purification processes of cullet derived from separated glass waste collection, has been studied as filler for self-compacting concrete and as an addition for newly blended cement. Properties of self-compacting concrete compared to reference samples are reported. They include characteristics at the fresh and hardened states, and the compressive strength and porosity of mortar samples that were formulated with increasing amounts of MW to be used as cement replacement (up to 50wt.%). The effects of matt waste are discussed with respect to the mechanical and microstructural characteristics of the resulting new materials.

Measurement and simulation of millimeter wave scattering cross-sections from steel-reinforced concrete

NASA Astrophysics Data System (ADS)

Hassan, A. M.; Martys, N. S.; Garboczi, E. J.; McMichael, R. D.; Stiles, M. D.; Plusquellic, D. F.; Stutzman, P. E.; Wang, S.; Provenzano, V.; Surek, J. T.; Novotny, D. R.; Coder, J. B.; Janezic, M. D.; Kim, S.

2014-02-01

Some iron oxide corrosion products exhibit antiferromagnetic magnetic resonances (AFMR) at frequencies on the order of 100 GHz at ambient temperatures. AFMR can be detected in laboratory conditions, which serves as the basis for a new non-destructive spectroscopic method for detecting early corrosion. When attempting to measure the steel corrosion in reinforced concrete in the field, rebar geometry must be taken into account. Experiments and numerical simulations have been developed at frequencies near 100 GHz to sort out these effects. The experimental setup involves a vector network analyzer with converter heads to up-convert the output frequency, which is then connected to a horn antenna followed by a 7.5 cm diameter polymer lens to focus the waves on the sample. Two sets of samples were studied: uniform cylindrical rods and rebar corrosion samples broken out of concrete with different kinds of coatings. Electromagnetic scattering from uniform rods were calculated numerically using classical modal expansion. A finite-element electromagnetic solver was used to model more complex rebar geometry and non-uniform corrosion layers. Experimental and numerical data were compared to help quantify and understand the anticipated effect of local geometrical features on AFMR measurements.

New Medium for Isolation of Bacteria From Cement Kiln Dust with a Potential to Apply in Bio-Concrete

NASA Astrophysics Data System (ADS)

Alshalif, A. F.; Irwan, J. M.; Othman, N.; Al-Gheethi, A.

2018-04-01

The present study aimed to introduce a new isolation medium named kiln dust medium (KDM) for recovering of bacteria from cement kiln dust with high pH (>pH 11) without the need for nutrients additives. The cement kiln dust samples were collected from five different areas of Cement Industries of Malaysia Berhad (CIMA). The bacterial isolates were recovered on KDM by direct plating technique. The chemical components for all collected samples were identified using X-ray fluorescence (XRF). The primary identification for the bacterial isolates indicated that these bacteria belongs to Bacillus spp. Based on the morphological characteristics. The growth curve of the bacterial strains was monitored using the optical density (OD) with 650 nm wavelength, which in role confirmed that all isolated bacteria had the ability to grow successfully in the proposed medium. The ability of the bacterial strains to grow at high pH reflects their potential in the bio-concrete applications (aerated and non-aerated concrete). These findings indicated that the cement kiln dust samples from Cement Industries represent the most appropriate source for bacteria used in the bioconcrete.

Application-Oriented Chemical Optimization of a Metakaolin Based Geopolymer.

PubMed

Ferone, Claudio; Colangelo, Francesco; Roviello, Giuseppina; Asprone, Domenico; Menna, Costantino; Balsamo, Alberto; Prota, Andrea; Cioffi, Raffaele; Manfredi, Gaetano

2013-05-10

In this study the development of a metakaolin based geopolymeric mortar to be used as bonding matrix for external strengthening of reinforced concrete beams is reported. Four geopolymer formulations have been obtained by varying the composition of the activating solution in terms of SiO₂/Na₂O ratio. The obtained samples have been characterized from a structural, microstructural and mechanical point of view. The differences in structure and microstructure have been correlated to the mechanical properties. A major issue of drying shrinkage has been encountered in the high Si/Al ratio samples. In the light of the characterization results, the optimal geopolymer composition was then applied to fasten steel fibers to reinforced concrete beams. The mechanical behavior of the strengthened reinforced beams was evaluated by four-points bending tests, which were performed also on reinforced concrete beams as they are for comparison. The preliminary results of the bending tests point out an excellent behavior of the geopolymeric mixture tested, with the failure load of the reinforced beams roughly twice that of the control beam.

Rapid Radiochemical Method for Isotopic Uranium in Building ...

EPA Pesticide Factsheets

Technical Fact Sheet Analysis Purpose: Qualitative analysis Technique: Alpha spectrometry Method Developed for: Uranium-234, uranium-235, and uranium-238 in concrete and brick samples Method Selected for: SAM lists this method for qualitative analysis of uranium-234, uranium-235, and uranium-238 in concrete or brick building materials. Summary of subject analytical method which will be posted to the SAM website to allow access to the method.

Interactions of ClO2 and H2O2 Fumigants with Dirt and Grime ...

EPA Pesticide Factsheets

Report The primary objective of this research was to evaluate the impact that dirt and grime, as present on unpainted subway concrete, may have on fumigation efficacy. Other objectives include determining which sampling procedure provides better recovery from grimed and cleaned concrete, and characterizing subway material before and after cleaning using a prescribed method from the New York City Metropolitan Transportation Authority (MTA).

Reactive transport modelling of a high-pH infiltration test in concrete

NASA Astrophysics Data System (ADS)

Chaparro, M. Carme; Soler, Josep M.; Saaltink, Maarten W.; Mäder, Urs K.

2017-06-01

A laboratory-scale tracer test was carried out to characterize the transport properties of concrete from the Radioactive Waste Disposal Facility at El Cabril (Spain). A hyperalkaline solution (K-Ca-OH, pH = 13.2) was injected into a concrete sample under a high entry pressure in order to perform the experiment within a reasonable time span, obtaining a decrease of permeability by a factor of 1000. The concentrations of the tracers, major elements (Ca2+, SO4 2 - , K+ and Na+) and pH were measured at the outlet of the concrete sample. A reactive transport model was built based on a double porosity conceptual model, which considers diffusion between a mobile zone, where water can flow, and an immobile zone without any advective transport. The numerical model assumed that all reactions took place in the immobile zone. The cement paste consists of C-S-H gel, portlandite, ettringite, calcite and gypsum, together with residual alite and belite. Two different models were compared, one with portlandite in equilibrium (high initial surface area) and another one with portlandite reaction controlled by kinetics (low initial surface area). Overall the results show dissolution of alite, belite, gypsum, quartz, C-S-H gel and ettringite and precipitation of portlandite and calcite. Permeability could have decreased due to mineral precipitation.

Methane-derived carbonates form at the sediment-bedrock interface in a shallow marine gas seep.

NASA Astrophysics Data System (ADS)

Kimball, J.; Ding, H.; Valentine, D. L.

2006-12-01

Hydrocarbon seeps occur world-wide, and release large quantities of oil and natural gas to the ocean and atmosphere. One of the world's most prolific hydrocarbon seep fields is located just offshore from Goleta, CA, and serves as the study site for this investigation. In the course of investigating gas fluxes from a 10 m deep coastal seep, samples of seafloor bedrock were collected by scuba diving during a time of low sediment burden. These samples were found to be concretions composed primarily of carbonate-cemented sand. The delta13C values of the carbonate range from -25 to -32 per mille, and indicate a role for methane oxidation in the formation of the carbonates. Long chain fatty acids were extracted from the concretions and were quantified, identified, and analyzed for their 13C composition. Fatty acids typical of sulfate reducing bacteria were observed, and interpreted as a signature of anoxia. Further mineralogical and isotopic studies are planned. From these observations we interpret a shallow water origin for these concretions, whereby the seasonal migration of sand to the seep environment drives anoxia and anaerobic methane oxidation at the sediment-bedrock interface. The alkalinity generated from sulfate reduction causes the precipitation of methane-derived carbonate- which forms a concretion with sand.

Non-Arbitrariness in Mapping Word Form to Meaning: Cross-Linguistic Formal Markers of Word Concreteness.

PubMed

Reilly, Jamie; Hung, Jinyi; Westbury, Chris

2017-05-01

Arbitrary symbolism is a linguistic doctrine that predicts an orthogonal relationship between word forms and their corresponding meanings. Recent corpora analyses have demonstrated violations of arbitrary symbolism with respect to concreteness, a variable characterizing the sensorimotor salience of a word. In addition to qualitative semantic differences, abstract and concrete words are also marked by distinct morphophonological structures such as length and morphological complexity. Native English speakers show sensitivity to these markers in tasks such as auditory word recognition and naming. One unanswered question is whether this violation of arbitrariness reflects an idiosyncratic property of the English lexicon or whether word concreteness is a marked phenomenon across other natural languages. We isolated concrete and abstract English nouns (N = 400), and translated each into Russian, Arabic, Dutch, Mandarin, Hindi, Korean, Hebrew, and American Sign Language. We conducted offline acoustic analyses of abstract and concrete word length discrepancies across languages. In a separate experiment, native English speakers (N = 56) with no prior knowledge of these foreign languages judged concreteness of these nouns (e.g., Can you see, hear, feel, or touch this? Yes/No). Each naïve participant heard pre-recorded words presented in randomized blocks of three foreign languages following a brief listening exposure to a narrative sample from each respective language. Concrete and abstract words differed by length across five of eight languages, and prediction accuracy exceeded chance for four of eight languages. These results suggest that word concreteness is a marked phenomenon across several of the world's most widely spoken languages. We interpret these findings as supportive of an adaptive cognitive heuristic that allows listeners to exploit non-arbitrary mappings of word form to word meaning. Copyright © 2016 Cognitive Science Society, Inc.

An ERP study of recognition memory for concrete and abstract pictures in school-aged children.

PubMed

Boucher, Olivier; Chouinard-Leclaire, Christine; Muckle, Gina; Westerlund, Alissa; Burden, Matthew J; Jacobson, Sandra W; Jacobson, Joseph L

2016-08-01

Recognition memory for concrete, nameable pictures is typically faster and more accurate than for abstract pictures. A dual-coding account for these findings suggests that concrete pictures are processed into verbal and image codes, whereas abstract pictures are encoded in image codes only. Recognition memory relies on two successive and distinct processes, namely familiarity and recollection. Whether these two processes are similarly or differently affected by stimulus concreteness remains unknown. This study examined the effect of picture concreteness on visual recognition memory processes using event-related potentials (ERPs). In a sample of children involved in a longitudinal study, participants (N=96; mean age=11.3years) were assessed on a continuous visual recognition memory task in which half the pictures were easily nameable, everyday concrete objects, and the other half were three-dimensional abstract, sculpture-like objects. Behavioral performance and ERP correlates of familiarity and recollection (respectively, the FN400 and P600 repetition effects) were measured. Behavioral results indicated faster and more accurate identification of concrete pictures as "new" or "old" (i.e., previously displayed) compared to abstract pictures. ERPs were characterized by a larger repetition effect, on the P600 amplitude, for concrete than for abstract images, suggesting a graded recollection process dependent on the type of material to be recollected. Topographic differences were observed within the FN400 latency interval, especially over anterior-inferior electrodes, with the repetition effect more pronounced and localized over the left hemisphere for concrete stimuli, potentially reflecting different neural processes underlying early processing of verbal/semantic and visual material in memory. Copyright © 2016 Elsevier B.V. All rights reserved.

Changes in the Strength of the Polymer Concrete Used in the Electroplating Vats Under Operational Load

NASA Astrophysics Data System (ADS)

Radna, Lidia; Sakharov, Volodymyr

2017-12-01

Due to the strong and aggressive electrolyte media and thermal load, design of the electroplating vats in the copper industry often relies on the resin concrete. The article presents the results of the strength tests of the polymer concrete based on the "Derakane" resin, used in the construction of electroplating vats. Samples were taken from the real vats - both new and 17-year old. Strength tests included compression and bending tensile strength test. To assess the effect of operational conditions the tests were performed on the same-age vats, some of which were never used while others were subjected to the operational load. During the operation, the vats sustained load of the anode and cathode weights, cyclic electrolyte loading with a temperatures up to 60°C. As a result, it was noted that the operational conditions led to the increased strength of the polymer concrete material.

Thermal Response Of An Aerated Concrete Wall With Micro-Encapsulated Phase Change Material

NASA Astrophysics Data System (ADS)

Halúzová, Dušana

2015-06-01

For many years Phase Change Materials (PCM) have attracted attention due to their ability to store large amounts of thermal energy. This property makes them a candidate for the use of passive heat storage. In many applications, they are used to avoid the overheating of the temperature of an indoor environment. This paper describes the behavior of phase change materials that are inbuilt in aerated concrete blocks. Two building samples of an aerated concrete wall were measured in laboratory equipment called "twin-boxes". The first box consists of a traditional aerated concrete wall; the second one has additional PCM micro-encapsulated in the wall. The heat flux through the wall was measured and compared to simulation results modeled in the ESP-r program. This experimental measurement provides a foundation for a model that can be used to analyze further building constructions.

Testing Silica Fume-Based Concrete Composites under Chemical and Microbiological Sulfate Attacks

PubMed Central

Estokova, Adriana; Kovalcikova, Martina; Luptakova, Alena; Prascakova, Maria

2016-01-01

Current design practices based on descriptive approaches to concrete specification may not be appropriate for the management of aggressive environments. In this study, the durability of cement-based materials with and without the addition of silica fume, subjected to conditions that leach calcium and silicon, were investigated. Chemical corrosion was simulated by employing various H2SO4 and MgSO4 solutions, and biological corrosion was simulated using Acidithiobacillus sp. bacterial inoculation, leading to disrupted and damaged surfaces; the samples’ mass changes were studied following both chemical and biological attacks. Different leaching trends were observed via X-ray fluorescence when comparing chemical with biological leaching. Lower leaching rates were found for concrete samples fortified with silica fume than those without silica fume. X-ray diffraction and scanning electron microscopy confirmed a massive sulfate precipitate formation on the concrete surface due to bacterial exposure. PMID:28773452

Physical properties of concrete made with Apollo 16 lunar soil sample

NASA Technical Reports Server (NTRS)

Lin, T. D.; Love, H.; Stark, D.

1992-01-01

This paper describes the first phase of the long-term investigation for the construction of concrete lunar bases. In this phase, petrographic and scanning electron microscope examinations showed that the morphology and elemental composition of the lunar soil made it suitable for use as a fine aggregate for concrete. Based on this finding, calcium aluminate cement and distilled water were mixed with the lunar soil to fabricate test specimens. The test specimens consisted of a 1-in cube, a 1/2-in cube, and three 0.12 x 0.58 x 3.15-in beam specimens. Tests were performed on these specimens to determine compressive strength, modulus of rupture, modulus of elasticity, and thermal coefficient of expansion. Based on examination of the material and test results, it is concluded that lunar soil can be used as a fine aggregate for concrete.

Measuring dielectric properties of concrete by a wide coaxial probe with an open end

NASA Astrophysics Data System (ADS)

Filali, B.; Rhazi, J. E.; Ballivy, G.

2006-05-01

We present nondestructive measurements of dielectric properties of concrete and mortar. The measures are made using a coaxial probe with a 32.5 mm open end, engineered specially for this work. The frequency domain goes from 100 to 900 MHz and includes frequently found frequencies in radars used for the auscultation of concrete structures. The probe was calibrated, and the measures were validated successfully on two solutions of different salinity, as well as on limestone and granite samples. Measures were also carried out on two mortars and six concretes of different recipes. We studied the effect of porosity and water content on the measures. The statistical analysis of the results indicates thatthe dispersion of measurements on these heterogeneous materials (granulometry from 5 to 20 nm) is comparable to that observed in limestone and granite. Our results confirm those from other authors who used more complicated techniques.

Performance of asphaltic concrete incorporating styrene butadiene rubber subjected to varying aging condition

NASA Astrophysics Data System (ADS)

Salah, Faisal Mohammed; Jaya, Ramadhansyah Putra; Mohamed, Azman; Hassan, Norhidayah Abdul; Rosni, Nurul Najihah Mad; Mohamed, Abdullahi Ali; Agussabti

2017-12-01

The influence of styrene butadiene rubber (SBR) on asphaltic concrete properties at different aging conditions was presented in this study. These aging conditions were named as un-aged, short-term, and long-term aging. The conventional asphalt binder of penetration grade 60/70 was used in this work. Four different levels of SBR addition were employed (i.e., 0 %, 1 %, 3 %, and 5 % by binder weight). Asphalt concrete mixes were prepared at selected optimum asphalt content (5 %). The performance was evaluated based on Marshall Stability, resilient modulus, and dynamic creep tests. Results indicated the improving stability and permanent deformation characteristics that the mixes modified with SBR polymer have under aging conditions. The result also showed that the stability, resilient modulus, and dynamic creep tests have the highest rates compared to the short-term aging and un-aged samples. Thus, the use of 5 % SBR can produce more durable asphalt concrete mixtures with better serviceability.

Microbial fouling and corrosion of carbon steel in deep anoxic alkaline groundwater.

PubMed

Rajala, Pauliina; Bomberg, Malin; Vepsäläinen, Mikko; Carpén, Leena

2017-02-01

Understanding the corrosion of carbon steel materials of low and intermediate level radioactive waste under repository conditions is crucial to ensure the safe storage of radioactive contaminated materials. The waste will be in contact with the concrete of repository silos and storage containers, and eventually with groundwater. In this study, the corrosion of carbon steel under repository conditions as well as the microbial community forming biofilm on the carbon steel samples, consisting of bacteria, archaea, and fungi, was studied over a period of three years in a groundwater environment with and without inserted concrete. The number of biofilm forming bacteria and archaea was 1,000-fold lower, with corrosion rates 620-times lower in the presence of concrete compared to the natural groundwater environment. However, localized corrosion was detected in the concrete-groundwater environment indicating the presence of local microenvironments where the conditions for pitting corrosion were favorable.

Sulfur 'Concrete' for Lunar Applications - Environmental Considerations

NASA Technical Reports Server (NTRS)

Grugel, R. N.

2008-01-01

Commercial use of sulfur concrete on Earth is well established, particularly in corrosive, e.g., acid and salt, environments. Having found troilite (FeS) on the Moon raises the question of using extracted sulfur as a lunar construction material, an attractive alternative to conventional concrete as it does not require water. For the purpose of this Technical Memorandum, it is assumed that lunar ore is mined, refined, and the raw sulfur processed with appropriate lunar regolith to form, for example, bricks. With this stipulation, it is then noted that the viability of sulfur concrete in a lunar environment, which is characterized by lack of an atmosphere and extreme temperatures, is not well understood. The work presented here evaluates two sets of small sulfur concrete samples that have been prepared using JSC-1 lunar simulant as an aggregate addition. One set was subjected to extended periods in high vacuum to evaluate sublimation issues, and the other was cycled between room and liquid nitrogen temperatures to investigate their subsequent mechanical integrity. Results are presented from both investigations, discussed, and put into the context of the lunar environment.

Sulfur "Concrete" for Lunar Applications - Sublimation Concerns

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Toutanji, Houssam

2006-01-01

Melting sulfur and mixing it with an aggregate to form "concrete" is commercially well established and constitutes a material that is particularly well-suited for use in corrosive environments. Discovery of the mineral troilite (FeS) on the moon poses the question of extracting the sulfur for use as a lunar construction material. This would be an attractive alternative to conventional concrete as it does not require water. However, the viability of sulfur concrete in a lunar environment, which is characterized by lack of an atmosphere and extreme temperatures, is not well understood. Here it is assumed that the lunar ore can be mined, refined, and the raw sulfur melded with appropriate lunar regolith to form, for example, bricks. This study evaluates pure sulfur and two sets of small sulfur concrete samples that have been prepared using JSC-1 lunar stimulant and SiO2 powder as aggregate additions. Each set was subjected to extended periods in a vacuum environment to evaluate sublimation issues. Results from these experiments are presented and discussed within the context of the lunar environment.

Influence of synthetic calcium silicates on the strength properties of fine-grained concrete

NASA Astrophysics Data System (ADS)

Yarusova, S. B.; Gordienko, P. S.; Kozin, A. V.; Zhevtun, I. G.; Perfilev, A. V.

2018-04-01

The effect of additives based on acicular calcium hydrosilicates (xonotlite and tobermorite) and wollastonite, obtained from boric acid production waste in autoclave synthesis at a temperature of 220 °C, on the strength of fine-grained concrete, has been studied in this paper. It was shown that when the calcium hydrosilicates and wollastonite are introduced, an increase in the strength characteristics of concrete is observed. After heat and moisture treatment, the maximum increase in strength is observed with the addition of 4% of mass content of calcium hydrosilicates and 6% of mass content of wollastonite. After 28 days of hardening under normal conditions, the maximum increase in strength of concrete is observed with the addition of 4% of mass content of both types of additives. It was shown that the water absorption of concrete decreases with a maximum when 4% of mass content is added, as in the case of the introduction of calcium hydrosilicates, and wollastonite. With a further increase in the number of additives, the amount of water absorption increases, but these values remain below the values for the control sample without additives.

Novel Concrete Chemistry Achieved with Low Dose Gamma Radiation Curing and Resistance to Neutron Activation

NASA Astrophysics Data System (ADS)

Burnham, Steven Robert

As much as 50% of ageing-related problems with concrete structures can be attributed to con-struction deficiencies at the time of placement. The most influential time affecting longevity of concrete structures is the curing phase, or commonly the initial 28 days following its placement. A novel advanced atomistic analysis of novel concrete chemistry is presented in this dissertation with the objective to improve concrete structural properties and its longevity. Based on experiments and computational models, this novel concrete chemistry is discussed in two cases: (a) concrete chemistry changes when exposed to low-dose gamma radiation in its early curing stage, thus improving its strength in a shorter period of time then curing for the conventional 28 days; (b) concrete chemistry is controlled by its atomistic components to assure strength is not reduced but that its activation due to long-term exposure to neutron flux in nuclear power plants is negligible. High dose gamma radiation is well documented as a degradation mechanism that decreases concrete's compressive strength; however, the effects of low-dose gamma radiation on the initial curing phase of concrete, having never been studied before, proved its compressive strength increases. Using a 137 Cs source, concrete samples were subjected to gamma radiation during the initial curing phase for seven, 14, and 28 days. The compressive strength after seven days is improved for gamma cured concrete by 24% and after 14 days by 76%. Concrete shows no improvement in compressive strength after 28 days of exposure to gamma radiation, showing that there is a threshold effect. Scanning Electron Microscopy is used to examine the microstructure of low-dose gamma radiation where no damage to its microstructure is found, showing no difference between gamma cured and conventionally cured concrete. Molecular dynamics modeling based on the MOPAC package is used to study how gamma radiation during the curing stage improves compressive strength of concrete. The modeling shows that when radiolysis occurs in freshly mixed concrete, the reactivity between key molecules responsible for bonding between cement and aggregate is enhanced due to improved reactivity at the molecular level. A new method is developed that successfully controls a concrete chemistry at the atomistic level by assuring its long-term exposure to neutron flux in nuclear power plants will not activate the dome wall to the level of low-level radioactive waste. This methodology is established to detect and select the level of trace elemental composition in concrete based on a low-flux neutron activation analysis (NAA). By carefully selecting aggregates that do not contain certain elements that activate to high concentrations after decades of concrete exposure to neutron flux, the end of life for concrete is improved by declassifying it as low-level radioactive waste. Directly, it improves economy of commissioning nuclear power plants to be built in near future and reducing important quantities of waste to be disposed at high costs.

Evaluation of a Dust Control for a Small Slab-Riding Dowel Drill for Concrete Pavement

PubMed Central

Echt, Alan; Mead, Kenneth

2016-01-01

Purpose To assess the effectiveness of local exhaust ventilation to control respirable crystalline silica exposures to acceptable levels during concrete dowel drilling. Approach Personal breathing zone samples for respirable dust and crystalline silica were collected while laborers drilled holes 3.5 cm diameter by 36 cm deep in a concrete slab using a single-drill slab-riding dowel drill equipped with local exhaust ventilation. Data were collected on air flow, weather, and productivity. Results All respirable dust samples were below the 90 µg detection limit which, when combined with the largest sample volume, resulted in a minimum detectable concentration of 0.31 mg m−3. This occurred in a 32-min sample collected when 27 holes were drilled. Quartz was only detected in one air sample; 0.09 mg m−3 of quartz was found on an 8-min sample collected during a drill maintenance task. The minimum detectable concentration for quartz in personal air samples collected while drilling was performed was 0.02 mg m−3. The average number of holes drilled during each drilling sample was 23. Over the course of the 2-day study, air flow measured at the dust collector decreased from 2.2 to 1.7 m3 s−1. Conclusions The dust control performed well under the conditions of this test. The initial duct velocity with a clean filter was sufficient to prevent settling, but gradually fell below the recommended value to prevent dust from settling in the duct. The practice of raising the drill between each hole may have prevented the dust from settling in the duct. A slightly higher flow rate and an improved duct design would prevent settling without regard to the position of the drill. PMID:26826033

Evaluation of a Dust Control for a Small Slab-Riding Dowel Drill for Concrete Pavement.

PubMed

Echt, Alan; Mead, Kenneth

2016-05-01

To assess the effectiveness of local exhaust ventilation to control respirable crystalline silica exposures to acceptable levels during concrete dowel drilling. Personal breathing zone samples for respirable dust and crystalline silica were collected while laborers drilled holes 3.5 cm diameter by 36 cm deep in a concrete slab using a single-drill slab-riding dowel drill equipped with local exhaust ventilation. Data were collected on air flow, weather, and productivity. All respirable dust samples were below the 90 µg detection limit which, when combined with the largest sample volume, resulted in a minimum detectable concentration of 0.31 mg m(-3). This occurred in a 32-min sample collected when 27 holes were drilled. Quartz was only detected in one air sample; 0.09 mg m(-3) of quartz was found on an 8-min sample collected during a drill maintenance task. The minimum detectable concentration for quartz in personal air samples collected while drilling was performed was 0.02 mg m(-3). The average number of holes drilled during each drilling sample was 23. Over the course of the 2-day study, air flow measured at the dust collector decreased from 2.2 to 1.7 m(3) s(-1). The dust control performed well under the conditions of this test. The initial duct velocity with a clean filter was sufficient to prevent settling, but gradually fell below the recommended value to prevent dust from settling in the duct. The practice of raising the drill between each hole may have prevented the dust from settling in the duct. A slightly higher flow rate and an improved duct design would prevent settling without regard to the position of the drill. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2016.

Concurrent Ultrasonic Tomography and Acoustic Emission in Solid Materials

NASA Astrophysics Data System (ADS)

Chow, Thomas M.

A series of experiments were performed to detect stress induced changes in the elastic properties of various solid materials. A technique was developed where these changes were monitored concurrently by two methods, ultrasonic tomography and acoustic emission monitoring. This thesis discusses some experiments in which acoustic emission (AE) and ultrasonic tomography were performed on various samples of solid materials including rocks, concrete, metals, and fibre reinforced composites. Three separate techniques were used to induce stress in these samples. Disk shaped samples were subject to stress via diametral loading using an indirect tensile test geometry. Cylindrical samples of rocks and concrete were subject to hydraulic fracture tests, and rectangular samples of fibre reinforced composite were subject to direct tensile loading. The majority of the samples were elastically anisotropic. Full waveform acoustic emission and tomographic data were collected while these samples were under load to give information concerning changes in the structure of the material as it was undergoing stress change and/or failure. Analysis of this data indicates that AE and tomographic techniques mutually compliment each other to give a view of the stress induced elastic changes in the tested samples.

Flexural strength and behaviour of SFRSCC ribbed slab under four point bending

NASA Astrophysics Data System (ADS)

Ahmad, Hazrina; Hashim, Mohd Hisbany Mohd; Bakar, Afidah Abu; Hamzah, Siti Hawa; Rahman, Fadhillah Abdul

2017-11-01

An experimental investigation was carried out to study the ultimate strength and behaviour of SFRSCC ribbed slab under four point bending. Comparison was been made between ribbed slab that was fully reinforced with steel fibres (SFWS) with conventionally reinforced concrete ribbed slab (CS and CRC). The volume fraction of the 35 mm hooked end steel fibres used in the mix was 1% (80 kg/m3) with the aspect ratio of 65. Three full scale slab samples with the dimension of 2.8 x 1.2 m with 0.2 m thickness was constructed for the purpose of this study. The slab samples was loaded until failure in a four point bending test. As a whole, based on the results, it can be concluded that the performance of the steel fiber reinforced samples (SFWS) was found to be almost equivalent to the conventionally reinforced concrete ribbed slab sample (CRC).

Development of high shrinkage polyethylene terephthalate (PET) shape memory polymer tendons for concrete crack closure

NASA Astrophysics Data System (ADS)

Teall, Oliver; Pilegis, Martins; Sweeney, John; Gough, Tim; Thompson, Glen; Jefferson, Anthony; Lark, Robert; Gardner, Diane

2017-04-01

The shrinkage force exerted by restrained shape memory polymers (SMPs) can potentially be used to close cracks in structural concrete. This paper describes the physical processing and experimental work undertaken to develop high shrinkage die-drawn polyethylene terephthalate (PET) SMP tendons for use within a crack closure system. The extrusion and die-drawing procedure used to manufacture a series of PET tendon samples is described. The results from a set of restrained shrinkage tests, undertaken at differing activation temperatures, are also presented along with the mechanical properties of the most promising samples. The stress developed within the tendons is found to be related to the activation temperature, the cross-sectional area and to the draw rate used during manufacture. Comparisons with commercially-available PET strip samples used in previous research are made, demonstrating an increase in restrained shrinkage stress by a factor of two for manufactured PET filament samples.

On the Processing of Spalling Experiments. Part I: Identification of the Dynamic Tensile Strength of Concrete

NASA Astrophysics Data System (ADS)

Forquin, P.; Lukić, B.

2017-11-01

The spalling technique based on the use of a single Hopkinson bar put in contact with the tested sample has been widely adopted as a reliable method for obtaining the tensile response of concrete and rock-like materials at strain rates up-to 200 s- 1. However, the traditional processing method, based on the use of Novikov acoustic approach and the rear face velocity measurement, remains quite questionable due to strong approximations of this data processing method. Recently a new technique for deriving cross-sectional stress fields of a spalling sample filmed with an ultra-high speed camera and based on using the full field measurements and the virtual fields method (VFM) was proposed. In the present work, this topic is perused by performing several spalling tests on ordinary concrete at high acquisition speed of 1Mfps to accurately measure the tensile strength, Young's modulus, strain-rate at failure and stress-strain response of concrete at high strain-rate. The stress-strain curves contain more measurement points for a more reliable identification. The observed tensile stiffness is up-to 50% lower than the initial compressive stiffness and the obtained peak stress was about 20% lower than the one obtained by applying the Novikov method. In order to support this claim, numerical simulations were performed to show that the change of stiffness between compression and tension highly affects the rear-face velocity profile. This further suggests that the processing based only on the velocity "pullback" is quite sensitive and can produce an overestimate of the tensile strength in concrete and rock-like materials.

Analysis of "D" regions of RC structures based on example of frame corners

NASA Astrophysics Data System (ADS)

Michał, Szczecina; Andrzej, Winnicki

2018-01-01

Calculations of reinforcement of "D" regions of reinforced concrete structures is much difficult than for "B" regions and demands some specific approaches. Authors of the paper suggest to use both Strut-and-Tie (S&T) and Finite Element Method (FEM). The first of those methods allows to calculate required reinforcement and efficiency factor. In turn FEM can not only confirm S&T results but also gives information about crack width and pattern, strains and nodal displacement. Sample calculations were performed on example of frame corners under opening bending moment. Parameters of Concrete Damaged Plasticity model of concrete implemented in Abaqus were calibrated in tension and compressions test.

Turn Basin Construction

NASA Image and Video Library

2017-06-30

At NASA's Kennedy Space Center in Florida, cement is poured as part of a construction project to upgrade the turn basin wharf. The work includes driving multiple precast concrete piles to a depth of about 70 feet to accommodate arrival of the core stage for the agency's Space Launch System (SLS) rocket. When the stage for NASA's SLS departs the Michoud Assembly Facility in New Orleans, it will be shipped by the agency's modified barge to the Launch Complex 39 turn basin.

Analysis and seismic tests of composite shear walls with CFST columns and steel plate deep beams

NASA Astrophysics Data System (ADS)

Dong, Hongying; Cao, Wanlin; Wu, Haipeng; Zhang, Jianwei; Xu, Fangfang

2013-12-01

A composite shear wall concept based on concrete filled steel tube (CFST) columns and steel plate (SP) deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements: CFST columns; SP deep beams; and reinforced concrete (RC) strips. The RC strips are intended to allow the core structural elements — the CFST columns and SP deep beams — to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures.

Concreteness of idiographic worry and anticipatory processing.

PubMed

McGowan, Sarah Kate; Stevens, Elizabeth S; Behar, Evelyn; Judah, Matt R; Mills, Adam C; Grant, DeMond M

2017-03-01

Worry and anticipatory processing are forms of repetitive negative thinking (RNT) that are associated with maladaptive characteristics and negative consequences. One key maladaptive characteristic of worry is its abstract nature (Goldwin & Behar, 2012; Stöber & Borkovec, 2002). Several investigations have relied on inductions of worry that are social-evaluative in nature, which precludes distinctions between worry and RNT about social-evaluative situations. The present study examined similarities and distinctions between worry and anticipatory processing on potentially important maladaptive characteristics. Participants (N = 279) engaged in idiographic periods of uninstructed mentation, worry, and anticipatory processing and provided thought samples during each minute of each induction. Thought samples were assessed for concreteness, degree of verbal-linguistic activity, and degree of imagery-based activity. Both worry and anticipatory processing were characterized by reduced concreteness, increased abstraction of thought over time, and a predominance of verbal-linguistic activity. However, worry was more abstract, more verbal-linguistic, and less imagery-based relative to anticipatory processing. Finally, worry demonstrated reductions in verbal-linguistic activity over time, whereas anticipatory processing demonstrated reductions in imagery-based activity over time. Worry was limited to non-social topics to distinguish worry from anticipatory processing, and may not represent worry that is social in nature. Generalizability may also be limited by use of an undergraduate sample. Results from the present study provide support for Stöber's theory regarding the reduced concreteness of worry, and suggest that although worry and anticipatory processing share some features, they also contain characteristics unique to each process. Published by Elsevier Ltd.

Personality differences in mental imagery and the effects on verbal memory.

PubMed

McDougall, Siné; Pfeifer, Gaby

2012-11-01

This study examined the effects of extraversion and neuroticism on participants' reported vividness of visual imagery and on their memory performance for concrete and abstract nouns. Groups of extraverts (n = 15) and introverts (n = 15) were selected from a larger original sample and asked to remember a series of concrete and abstract nouns, including a set of lexically ambiguous concrete homonyms (e.g., earth = 1. planet, 2. soil). Extraverts reported more vivid imagery than introverts but this did not translate into better recall for extraverts, even for concrete stimuli. Recall was best for unambiguous concrete nouns, followed by concrete homonyms, then abstract nouns. While initial analyses suggested that there was an interaction between extraversion and the type of word presented, later analyses revealed that neuroticism was the main driver in differences in recall between different word types. While differences in recall were best explained by context availability theory (Schwanenflugel, 1991) rather than dual coding theory (Paivio, 1991), questions remain about the power of either theory to explain the role of individual differences in personality on recall, particularly given that imagery vividness effects were related to extraversion while differences in recall were related to neuroticism. The implications of these findings for future research and theoretical development are discussed. ©2012 The British Psychological Society.

Compressive strength and hydration processes of concrete with recycled aggregates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koenders, Eduardus A.B., E-mail: e.a.b.koenders@coc.ufrj.br; Microlab, Delft University of Technology; Pepe, Marco, E-mail: mapepe@unisa.it

2014-02-15

This paper deals with the correlation between the time evolution of the degree of hydration and the compressive strength of Recycled Aggregate Concrete (RAC) for different water to cement ratios and initial moisture conditions of the Recycled Concrete Aggregates (RCAs). Particularly, the influence of such moisture conditions is investigated by monitoring the hydration process and determining the compressive strength development of fully dry or fully saturated recycled aggregates in four RAC mixtures. Hydration processes are monitored via temperature measurements in hardening concrete samples and the time evolution of the degree of hydration is determined through a 1D hydration and heatmore » flow model. The effect of the initial moisture condition of RCAs employed in the considered concrete mixtures clearly emerges from this study. In fact, a novel conceptual method is proposed to predict the compressive strength of RAC-systems, from the initial mixture parameters and the hardening conditions. -- Highlights: •The concrete industry is more and more concerned with sustainability issues. •The use of recycled aggregates is a promising solution to enhance sustainability. •Recycled aggregates affect both hydration processes and compressive strength. •A fundamental approach is proposed to unveil the influence of recycled aggregates. •Some experimental comparisons are presented to validate the proposed approach.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haudebourg, Raphael; Fichet, Pascal; Goutelard, Florence

The detection (location and quantification) of nuclear facilities to be dismantled possible contamination with low-range particles emitters ({sup 3}H, other low-energy β emitters, a emitters) remains a tedious and expensive task. Indeed, usual remote counters show a too low sensitivity to these non-penetrating radiations, while conventional wipe tests are irrelevant for fixed radioactivity evaluation. The only method to accurately measure activity levels consists in sampling and running advanced laboratory analyses (spectroscopy, liquid scintillation counting, pyrolysis...). Such measurements generally induce sample preparation, waste production (destructive analyses, solvents), nuclear material transportation, long durations, and significant labor mobilization. Therefore, the search for themore » limitation of their number and cost easily conflicts with the necessity to perform a dense screening for sampling (to maximize the representativeness of the samples), in installations of thousands of square meters (floors, wells, ceilings), plus furniture, pipes, and other wastes. To overcome this contradiction, Digital Autoradiography (D. A.) was re-routed from bio molecular research to radiological mapping of nuclear installations under dismantling and to waste and sample analysis. After in-situ exposure to the possibly-contaminated areas to investigate, commercial reusable radiosensitive phosphor screens (of a few 100 cm{sup 2}) were scanned in the proper laboratory device and sharp quantitative images of the radioactivity could be obtained. The implementation of geostatistical tools in the data processing software enabled the exhaustive characterization of concrete floors at a rate of 2 weeks / 100 m{sup 2}, at lowest costs. Various samples such as drilled cores, or tank and wood pieces, were also successfully evaluated with this method, for decisive results. Thanks to the accurate location of potential contamination spots, this approach ensures relevant and representative sampling for further laboratory analyses and should be inserted in the range of common tools used in dismantling. (authors)« less

Constraining pathways of microbial mediation for carbonate concretions of the Miocene Monterey Formation using carbonate-associated sulfate

NASA Astrophysics Data System (ADS)

Loyd, Sean J.; Berelson, William M.; Lyons, Timothy W.; Hammond, Douglas E.; Corsetti, Frank A.

2012-02-01

Carbonate concretions can form as a result of organic matter degradation within sediments. However, the ability to determine specific processes and timing relationships to particular concretions has remained elusive. Previously employed proxies (e.g., carbon and oxygen isotopes) cannot uniquely distinguish among diagenetic alkalinity sources generated by microbial oxidation of organic matter using oxygen, nitrate, metal oxides, and sulfate as electron acceptors, in addition to degradation by thermal decarboxylation. Here, we employ concentrations of carbonate-associated sulfate (CAS) and δ 34S CAS (along with more traditional approaches) to determine the specific nature of concretion authigenesis within the Miocene Monterey Formation. Integrated geochemical analyses reveal that at least three specific organo-diagenetic reaction pathways can be tied to concretion formation and that these reactions are largely sample-site specific. One calcitic concretion from the Phosphatic Shale Member at Naples Beach yields δ 34S CAS values near Miocene seawater sulfate (˜+22‰ VCDT), abundant CAS (ca. 1000 ppm), depleted δ 13C carb (˜-11‰ VPDB), and very low concentrations of Fe (ca. 700 ppm) and Mn (ca. 15 ppm)—characteristics most consistent with shallow formation in association with organic matter degradation by nitrate, iron-oxides and/or minor sulfate reduction. Cemented concretionary layers of the Phosphatic Shale Member at Shell Beach display elevated δ 34S CAS (up to ˜+37‰), CAS concentrations of ˜600 ppm, mildly depleted δ 13C carb (˜-6‰), moderate amounts of Mn (ca. 250 ppm), and relatively low Fe (ca. 1700 ppm), indicative of formation in sediments dominated by sulfate reduction. Finally, concretions within a siliceous host at Montaña de Oro and Naples Beach show minimal CAS concentrations, positive δ 13C values, and the highest concentrations of Fe (ca. 11,300 ppm) and Mn (ca. 440 ppm), consistent with formation in sediments experiencing methanogenesis in a highly reducing environment. This study highlights the promise in combining CAS analysis with more traditional techniques to differentiate among diagenetic reactions as preserved in the geologic record and shows potential for unraveling subsurface biospheric processes in ancient samples with a high degree of specificity.

Water dynamics in hardened ordinary Portland cement paste or concrete: from quasielastic neutron scattering.

PubMed

Bordallo, Heloisa N; Aldridge, Laurence P; Desmedt, Arnaud

2006-09-14

Portland cement reacts with water to form an amorphous paste through a chemical reaction called hydration. In concrete the formation of pastes causes the mix to harden and gain strength to form a rock-like mass. Within this process lies the key to a remarkable peculiarity of concrete: it is plastic and soft when newly mixed, strong and durable when hardened. These qualities explain why one material, concrete, can build skyscrapers, bridges, sidewalks and superhighways, houses, and dams. The character of the concrete is determined by the quality of the paste. Creep and shrinkage of concrete specimens occur during the loss and gain of water from cement paste. To better understand the role of water in mature concrete, a series of quasielastic neutron scattering (QENS) experiments were carried out on cement pastes with water/cement ratio varying between 0.32 and 0.6. The samples were cured for about 28 days in sealed containers so that the initial water content would not change. These experiments were carried out with an actual sample of Portland cement rather than with the components of cement studied by other workers. The QENS spectra differentiated between three different water interactions: water that was chemically bound into the cement paste, the physically bound or "glassy water" that interacted with the surface of the gel pores in the paste, and unbound water molecules that are confined within the larger capillary pores of cement paste. The dynamics of the "glassy" and "unboud" water in an extended time scale, from a hundred picoseconds to a few nanoseconds, could be clearly differentiated from the data. While the observed motions on the picosecond time scale are mainly stochastic reorientations of the water molecules, the dynamics observed on the nanosecond range can be attributed to long-range diffusion. Diffusive motion was characterized by diffusion constants in the range of (0.6-2) 10(-9) m(2)/s, with significant reduction compared to the rate of diffusion for bulk water. This reduction of the water diffusion is discussed in terms of the interaction of the water with the calcium silicate gel and the ions present in the pore water.

Concrete waterproofing in nuclear industry.

PubMed

Scherbyna, Alexander N; Urusov, Sergei V

2005-01-01

One of the main points of aggregate safety during the transportation and storage of radioactive materials is to supply waterproofing for all constructions having direct contact with radiating substances and providing strength, seismic shielding etc. This is the problem with all waterside structures in nuclear industry and concrete installations in the treatment and storage of radioactive materials. In this connection, the problem of developing efficient techniques both for the repair of operating constructions and the waterproofing of new objects of the specified assignment is genuine. Various techniques of concrete waterproofing are widely applied in the world today. However, in conditions of radiation many of these techniques can bring not a profit but irreparable damage of durability and reliability of a concrete construction; for instance, when waterproofing materials contain organic constituents, polymers etc. Application of new technology or materials in basic construction elements requires in-depth analysis and thorough testing. The price of an error might be very large. A comparative analysis shows that one of the most promising types of waterproofing materials for radiation loaded concrete constructions is "integral capillary systems" (ICS). The tests on radiation, thermal and strength stability of ICS and ICS-treated concrete samples were initiated and fulfilled in RFNC-VNIITF. The main result is--ICS applying is increasing of waterproofing and strength properties of concrete in conditions of readiation The paper is devoted to describing the research strategy, the tests and their results and also to planning of new tests.

Maintenance and Durability of the Concrete External Layer of Curtain Walls in Prefabricated Technological Poznan Large Panel System

NASA Astrophysics Data System (ADS)

Jasiczak, Józef; Girus, Krzysztof

2017-10-01

The issue of usability and durability of large-panel building constructed several decades ago is a subject of an in-depth analysis of many domestic and foreign investments. When considering the durability of specific large-panel system, one should consider, among others, the process of making external walls. The long-term and direct impact of weather conditions on the external layer of curtain walls is significant for the durability of large-panel buildings. For the needs of the presented paper, in 2016, the survey of cracks and a series of other tests of large-panel façade, residential building constructed in 1986, in Poland, in the PLP process system - Rataje was executed. Several hundred large-size, triple-layer curtain-wall slab with a 6-cm, concrete exterior cladding layer anchored using pins and hangers with the load-bearing layer, a 9-cm insulation layer made of mineral wool, and a 21-cm structural layer were surveyed. Significant deviations in thicknesses of particular wall layers were proven. Other significant damages and defects of external layers were found. At the second stage, many tests, both nondestructive and destructive, were conducted. They involved determining mechanical properties of an external layer. The concrete thickness was measured using with a type N Schmidt sclerometer and core samples were taken from this layer in order to mark concrete’s compressive strength. The range of carbonation (by phenolphthalein method) and the actual location and condition of reinforcement were estimated using a ferromagnetic device to determine the condition of the external layer. The diagnosis conducted in such a manner was the verification of necessary repair of the walls and their thermal efficiency improvement while ensuring safe conditions of their operation and modern functional and utility requirements. It should be also emphasized that the method of diagnosing the external walls presented in this paper may be popularized when evaluating such facilities both in Poland and other countries of the Central Europe (Germany, Czechia, Slovakia, Lithuania, Bulgaria, and Ukraine).

Natural fault and fracture network versus anisotropy in the Lower Paleozoic rocks of Pomerania (Poland)

NASA Astrophysics Data System (ADS)

Haluch, Anna; Rybak-Ostrowska, Barbara; Konon, Andrzej

2017-04-01

Knowledge of the anisotropy of rock fabric, geometry and distribution of the natural fault and fracture network play a crucial role in the exploration for unconventional hydrocarbon recourses. Lower Paleozoic rocks from Pomerania within the Polish part of Peri-Baltic Basin, as prospective sequences, can be considered a laboratory for analysis of fault and fracture arrangement in relation to the mineral composition of the host rocks. A microstructural study of core samples from five boreholes in Pomerania indicate that the Silurian succession in the study area is predominantly composed of claystones and mudstones interbedded with thin layers of tuffites. Intervals with a high content of detrital quartz or diagenetic silica also occur. Most of the Silurian deposits are abundant in pyrite framboids forming layers or isolated small concretions. Early diagenetic carbonate concretions are also present. The direction and distribution of natural faults and fractures have resulted not only from paleostress. Preliminary study reveals that the fault and fracture arrangement is related to the mechanical properties of the host rocks that depend on their fabric and mineralogical composition: subvertical fractures in mudstones and limestones show steeper dips than those within the more clayey intervals; bedding-parallel fractures occur within organic-rich claystones and along the boundaries between different lithologies; tuffites and radiolaria-bearing siliceous mudstones are more brittle and show denser nets of fractures or wider mineral apertures; and, fracture refraction is observed at competence contrast or around spherical concretions. The fault and fracture mineralization itself is prone to the heterogenity of the rock profile. Thus, fractures infilled with calcite occur in all types of the studied rocks, but mineral growth is syntaxial within marly mudstones because of chemical uniformity, and antitaxial within sillicous mudstones. Fractures infilled with quartz are restricted to tuffites and claystones with biogenic silica. Matching the complex microstructural and mineralogical data with the geomechanical analysis of the host rocks will be the base for further studies on induced fault and fracture development. The study was supported by grant no.: 13-03-00-501-90-472946, funded by the National Centre for Research and Development (NCBiR)

Evaluating the integrity of the reinforced concrete structure repaired by epoxy injection using simulated transfer function of impact-echo response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Chia-Chi; Yu, Chih-peng; Wu, Jiunn-Hong

2014-02-18

Cracks and honeycombs are often found inside reinforced concrete (RC) structure caused by excessive external force, or improper casting of concrete. The repairing method usually involves epoxy injection. The impact-echo method, which is a sensitive for detecting of the interior voids, may not be applicable to assess the integrity of the repaired member as both air and epoxy are less in acoustic impedances. In this study, the repaired RC structure was evaluated by the simulated transfer function of the IE displacement waveform where the R-wave displacement waveform is used as a base of a simulated force-time function. The effect ofmore » different thickness of the epoxy layer to the amplitude corresponding to the interface is studied by testing on specimen containing repaired naturally delaminated cracks with crack widths about 1 mm, 3 mm and 5 mm. The impact-echo responses were compared with the drilling cores at the test positions. The results showed the cracks were not fully filled with epoxy when the peak amplitude corresponding to the interface dropped less than 20%. The peak corresponding to the thicker epoxy layer tends to be larger in amplitude. A field study was also performed on a column damaged by earthquake before and after repairing.« less

Influence of item distribution pattern and abundance on efficiency of benthic core sampling

USGS Publications Warehouse

Behney, Adam C.; O'Shaughnessy, Ryan; Eichholz, Michael W.; Stafford, Joshua D.

2014-01-01

ore sampling is a commonly used method to estimate benthic item density, but little information exists about factors influencing the accuracy and time-efficiency of this method. We simulated core sampling in a Geographic Information System framework by generating points (benthic items) and polygons (core samplers) to assess how sample size (number of core samples), core sampler size (cm2), distribution of benthic items, and item density affected the bias and precision of estimates of density, the detection probability of items, and the time-costs. When items were distributed randomly versus clumped, bias decreased and precision increased with increasing sample size and increased slightly with increasing core sampler size. Bias and precision were only affected by benthic item density at very low values (500–1,000 items/m2). Detection probability (the probability of capturing ≥ 1 item in a core sample if it is available for sampling) was substantially greater when items were distributed randomly as opposed to clumped. Taking more small diameter core samples was always more time-efficient than taking fewer large diameter samples. We are unable to present a single, optimal sample size, but provide information for researchers and managers to derive optimal sample sizes dependent on their research goals and environmental conditions.

Development of MPS Method for Analyzing Melt Spreading Behavior and MCCI in Severe Accidents

NASA Astrophysics Data System (ADS)

Yamaji, Akifumi; Li, Xin

2016-08-01

Spreading of molten core (corium) on reactor containment vessel floor and molten corium-concrete interaction (MCCI) are important phenomena in the late phase of a severe accident for assessment of the containment integrity and managing the severe accident. The severe accident research at Waseda University has been advancing to show that simulations with moving particle semi-implicit (MPS) method (one of the particle methods) can greatly improve the analytical capability and mechanical understanding of the melt behavior in severe accidents. MPS models have been developed and verified regarding calculations of radiation and thermal field, solid-liquid phase transition, buoyancy, and temperature dependency of viscosity to simulate phenomena, such as spreading of corium, ablation of concrete by the corium, crust formation and cooling of the corium by top flooding. Validations have been conducted against experiments such as FARO L26S, ECOKATS-V1, Theofanous, and SPREAD for spreading, SURC-2, SURC-4, SWISS-1, and SWISS-2 for MCCI. These validations cover melt spreading behaviors and MCCI by mixture of molten oxides (including prototypic UO2-ZrO2), metals, and water. Generally, the analytical results show good agreement with the experiment with respect to the leading edge of spreading melt and ablation front history of concrete. The MPS results indicate that crust formation may play important roles in melt spreading and MCCI. There is a need to develop a code for two dimensional MCCI experiment simulation with MPS method as future study, which will be able to simulate anisotropic ablation of concrete.

A GPR system for the high-resolution inspection of walls and structures

NASA Astrophysics Data System (ADS)

Manacorda, Guido; Simi, Alessandro; Barsacchi, Giorgio

2014-05-01

Nowadays GPR systems are used in a broad range of applications, including the non-destructive inspection of man-made concrete structures such as pillars and bridge decks. Concrete inspection involves several aspects including: location of reinforced bars in walls and floors, concrete condition assessment, concrete cover detection, etc. These surveys are very demanding as far as the system is concerned, because of the strict requirements in terms of resolution and accuracy. Specifically, a key GPR application concerns the condition assessment of a structure that has undergone rehabilitation (e.g. for the removal of architectural barriers or new openings); in this case, the current practice requires to re-check the stability of the entire structure that includes the identification of the number of rebars in reinforced concrete beams location of pre-tensioned cables and early detection of corrosion. This can be done by verification holes (coring) that is costly and intrusive practice or by using a pachometer, but this tool has a limited field of investigation (up to 7-8 cm from the surface). GPR can instead be a useful investigative tool especially when the surface of the beam is not accessible because it is covered by screed or floor. The need of detecting rebars with diameter in the millimeter range as well as the identification of small cavities and cracks, require the development of GPR antennas featuring linear phase and constant polarization, and capable to radiate a very short pulse (i.e. with a duration in the order of few hundreds of picosecond) with no ring-down in order to achieve a high range resolution. A novel 3 GHz center frequency antenna has been recently developed and tested; it has been found capable of providing a very clear image of the concrete internal structure that helps in locating targets and enables an early detection of damages, thus providing a fast and efficient maintenance of the structure itself. The Authors thank COST for funding COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

Lightweight Low Force Rotary Percussive Coring Tool for Planetary Applications

NASA Technical Reports Server (NTRS)

Hironaka, Ross; Stanley, Scott

2010-01-01

A prototype low-force rotary-percussive rock coring tool for use in acquiring samples for geological surveys in future planetary missions was developed. The coring tool could eventually enable a lightweight robotic system to operate from a relatively small (less than 200 kg) mobile or fixed platform to acquire and cache Mars or other planetary rock samples for eventual return to Earth for analysis. To gain insight needed to design an integrated coring tool, the coring ability of commercially available coring bits was evaluated for effectiveness of varying key parameters: weight-on-bit, rotation speed, percussive rate and force. Trade studies were performed for different methods of breaking a core at its base and for retaining the core in a sleeve to facilitate sample transfer. This led to a custom coring tool design which incorporated coring, core breakage, core retention, and core extraction functions. The coring tool was tested on several types of rock and demonstrated the overall feasibility of this approach for robotic rock sample acquisition.

Evaluation of the Influence of Specific Surface Treatments of RBA on a Set of Properties of Concrete.

PubMed

Ondova, Marcela; Sicakova, Alena

2016-03-03

High water absorption of recycled brick aggregate (RBA) is one of the most discussed parameters in terms of its application in the production of concrete-its influence on the amount of mixing water and, hence, the quality of the concrete, is usually considered negative. In this paper, different methods of decreasing the absorption of RBA and, consequently, the impact on the properties of concrete, are described. The RBA has been treated to decrease the water absorption capacity by impregnation approach using specific impregnators. Afterwards, the RBA samples have been dried at two different temperatures in the laboratory oven-20 and 90 °C. Concretes using 4/8 fraction of the treated RBA instead of natural aggregate (NA) have been mixed and tested. The effectiveness of the RBA treatments have been evaluated on the basis of their influence on the properties of the hardened concrete; by means of the following tests: flexural strength, compressive strength, capillarity, total water absorption capacity, depth of water penetration under pressure, and frost resistance. The method of ranking by ordinal scale has been used as it is suitable for the comparison of a large set of results, while results have been analyzed in terms of the most important technological parameter that influences the quality of the concrete-effective water content. Out of all the tested surface-treatments of RBA, treatment by sodium water glass has the best potential for reduction of the water/cement (w/c) ratio. When the effective w/c ratio is kept within standard limits, concretes containing treated RBA are possible to be specified for various exposure classes and manufacturing in practice. The experiment confirms that at a constant amount of mixing water, with decreasing water absorption of RBA, the effective amount of water in the concrete increases and, hence, the final properties of the concrete decrease (get worse). As the water absorption of the RBA declines, there is a potential for the reduction of the w/c ratio and improvement in the quality of the concrete.

Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Effects of retrieval and preservation

USGS Publications Warehouse

Kneafsey, T.J.; Lu, H.; Winters, W.; Boswell, R.; Hunter, R.; Collett, T.S.

2011-01-01

Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.

Field samples of hot mix as an acceptance procedure : final report.

DOT National Transportation Integrated Search

1983-12-01

Shifting the sampling site of asphalt concrete from the plant to the roadway necessitates a modification of the Marshall procedure. The effect of such as modification on the Marshall properties and resultant process levels in a Satistically Oriented ...

Water column and bed-sediment core samples collected from Brownlee Reservoir near Oxbow, Oregon, 2012

USGS Publications Warehouse

Fosness, Ryan L.; Naymik, Jesse; Hopkins, Candice B.; DeWild, John F.

2013-01-01

The U.S. Geological Survey, in cooperation with Idaho Power Company, collected water-column and bed-sediment core samples from eight sites in Brownlee Reservoir near Oxbow, Oregon, during May 5–7, 2012. Water-column and bed-sediment core samples were collected at each of the eight sites and analyzed for total mercury and methylmercury. Additional bed-sediment core samples, collected from three of the eight sites, were analyzed for pesticides and other organic compounds, trace metals, and physical characteristics, such as particle size. Total mercury and methylmercury were detected in each of the water column and bed-sediment core samples. Only 17 of the 417 unique pesticide and organic compounds were detected in bed-sediment core samples. Concentrations of most organic wastewater compounds detected in bed sediment were less than the reporting level. Trace metals detected were greater than the reporting level in all the bed-sediment core samples submitted for analysis. The particle size distribution of bed-sediment core samples was predominantly clay mixed with silt.

Abrasion-Erosion Evaluation of Concrete Mixtures for Stilling Basin Repairs, Kinzua Dam, Pennsylvania.

DTIC Science & Technology

1983-09-01

principal investigator. Mr. Steven A. Ragan prepared the concrete . mixtures; Mr. Dale Glass , Mr. Frank W. Dorsey, and Mr. Roger Buttner con- Vducted the...from the Buffalo Slag Co., Franklinville, New York. This fine aggregate is classified as a glacial sand and is composed primarily of limestone and...LAS SYMBOL NO.. PITT-8 S-1 TYPE OF MATERIAL Fine Aggregate LOCATION; Franklin, NY PRODUCER: Buffalo Slag Co. SAMPLED BY: Pittsburgh District Personnel

A Navy User’s Guide for Quality Assurance of New Concrete Construction

DTIC Science & Technology

2012-06-01

types and blends of cements, fly ash, silica fume, and blast furnace slag . During construction, concrete samples are taken to test and document the...chemical compositions provided by specific types and blends of cements, fly ash, silica fume, and blast furnace slag when used with specific aggregates...of portland cement and blast furnace slag . Before the 11 owner accepts the completed structure, all cracks transverse to the steel rebar in excess

Design and Properties of Asphalt Concrete Mixtures Using Renewable Bioasphalt Binder

NASA Astrophysics Data System (ADS)

Setyawan, A.; Djumari; Irfansyah, P. A.; Shidiq, A. M.; Wibisono, I. S.; Fauzy, M. N.; Hadi, F. N.

2017-02-01

The needs of petroleum asphalt as materials for pavement is very large, while the petroleum classified as natural resources that cannot be renewable. As a result of petroleum dwindling and prices tend to be more expensive. So that requiring other alternative materials as a substitute for conventional asphalt derived from biomass or often called bioasphalt. This study aims to know the volumetric and Marshall characteristics on Asphalt Cement ( AC ) using the Damar asphalt modification to substitute 60/70 penetration asphalt as a binder. The volumetric and Marshall characteristic are porosity, density, flow, stability, and Marshall quotient. The characteristic of asphalt concrete at optimum bitumen content are compared to the conditions from highway agency 1987 and the general specification of asphalt concrete Bina Marga 2010 the third revision. The research uses experimental method in the laboratory with the samples made using the dasphalt modification as binder and incorporating the aggregate gradation no. VII SNI 03-1737-1989. The research is using 15 samples divided into 5 contents of damar asphalt, they are 5%, 5,5%, 6%, 6,5%, dan 7%. Tests carried out using Marshall test equipment to get the value of flow and stability and then be searched the value of optimum damar asphalt content. The result of asphalt concrete analysis using dasphalt modification as binder gives the value of optimum dasphalt content at 5,242%. The most characteristics already met the requirements and specifications.

Turn Basin Construction

NASA Image and Video Library

2017-06-30

Across from the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, cement trucks stand by to support a construction project to upgrade the turn basin wharf. The work includes driving multiple precast concrete piles to a depth of about 70 feet to accommodate arrival of the core stage for the agency's Space Launch System (SLS) rocket. When the stage for NASA's SLS departs the Michoud Assembly Facility in New Orleans, it will be shipped by the agency's modified barge to the Launch Complex 39 turn basin.

Turn Basin Construction

NASA Image and Video Library

2017-06-30

Across from the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, cement is poured as part of a construction project to upgrade the turn basin wharf. The work includes driving multiple precast concrete piles to a depth of about 70 feet to accommodate arrival of the core stage for the agency's Space Launch System (SLS) rocket. When the stage for NASA's SLS departs the Michoud Assembly Facility in New Orleans, it will be shipped by the agency's modified barge to the Launch Complex 39 turn basin.

High-temperature gas-cooled reactor technology development program. Annual progress report for period ending December 31, 1982

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasten, P.R.; Rittenhouse, P.L.; Bartine, D.E.

1983-06-01

During 1982 the High-Temperature Gas-Cooled Reactor (HTGR) Technology Program at Oak Ridge National Laboratory (ORNL) continued to develop experimental data required for the design and licensing of cogeneration HTGRs. The program involves fuels and materials development (including metals, graphite, ceramic, and concrete materials), HTGR chemistry studies, structural component development and testing, reactor physics and shielding studies, performance testing of the reactor core support structure, and HTGR application and evaluation studies.

A practical approach for solving disposal of rubber waste: Leachability of heavy metals from foamed concrete containing rubber powder waste (RPW)

NASA Astrophysics Data System (ADS)

Kadir, Aeslina Abdul; Hassan, Mohd Ikhmal Haqeem; Sarani, Noor Amira; Yatim, Fatin Syahirah Mohamed; Jaini, Zainorizuan Mohd

2017-09-01

Enormous disposal of rubber wastes has become an issue with the facts that all tires have its own life span. Inefficient disposal method of RPW from used tire can cause environmental impact as the heavy metals content in tire can easily leach out thus causing contamination to the soil and waterways. The goals of this study is to identify the heavy metals content of rubber powder waste (RPW) and to determine the potential of leachability of heavy metals from foamed concrete containing different percentages of RPW. Therefore, this study is focused on the leachability of RPW incorporated in foamed concrete. Different percentages of RPW were incorporated in foamed concrete (0%, 6%, 12% and 18%) for the investigation. Leachability tests were done by using toxicity characteristic leaching procedure (TCLP) on crushed samples of foamed concrete incorporated with RPW and were analyzed by using inductive coupled plasma mass spectrometry (ICP-MS). The results from XRF indicated that RPW is high in metals such as Zn, Cu, Ba and Co. The highest concentration of heavy metals in raw RPW is Zn with 51403 ppm which is exceeded USEPA (2010) maximum contaminant level (MCL) of Zn with only 5 ppm. After RPW had been incorporated into a foamed concrete, the results demonstrated that the Zn, Cu, Ba and Co heavy metals were less leached and complied with USEPA standard. The incorporation of RPW into foamed concrete in this study demonstrated that it could be a potential alternative raw material for concrete thus enhancing the possibility of its reuse in safe and sustainable way.

Evaluation of tire reefs for enhancing aquatic communities in concrete-lined canals

USGS Publications Warehouse

Mueller, Gordon; Liston, Charles R.

1994-01-01

Large earthen canals in the arid southwest are being lined with concrete to reduce seepage and conserve limited water supplies. Lining reduces habitat and increases operational velocities (relative to unaltered streams), which are detrimental to aquatic communities. Fish communities that become reestablished in these waterways exhibit lower species diversity, densities, and biomass than they did in the former earthen canals. Placement of low-profile tire reefs in the Coachella Canal, California, and the Hayden-Rhodes Aqueduct, Arizona, reversed these trends. Comparative sampling revealed that invertebrate and fish densities were 3 and 20 times higher, respectively, in reef areas than in typical canal sections without reefs. Tire reefs are recommended as an effective means of enhancing aquatic communities in concrete canals.

Nondestructive evaluation of concrete structures by nonstationary thermal wave imaging

NASA Astrophysics Data System (ADS)

Mulaveesala, Ravibabu; Panda, Soma Sekhara Balaji; Mude, Rupla Naik; Amarnath, Muniyappa

2012-06-01

Reinforced concrete structures (RCS) have potential application in civil engineering and with the advent of nuclear engineering RCS to be capable enough to withstanding a variety of adverse environmental conditions. However, failures/loss of durability of designed structures due to premature reinforcement corrosion of rebar is a major constrain. Growing concern of safety of structure due to pre-mature deterioration has led to a great demand for development of non-destructive and non-contact testing techniques for monitoring and assessing health of RCS. This paper presents an experimental investigation of rebar corrosion by non-stationary thermal wave imaging. Experimental results have been proven, proposed approach is an effective technique for identification of corrosion in rebar in the concrete samples.

Preliminary Investigation of Acoustical Properties of Concrete Containing Oil Palm Shell as an Aggregate Replacement

NASA Astrophysics Data System (ADS)

Zanariah, J.; Zaiton, H.; Musli Nizam, Y.; Khairulzan, Y.; Dianah, M.; Nadirah, D.; Hanifi, O. Mohd

2018-03-01

Research has been so far focused extensively on mechanical properties of oil palm shell (OPS) concrete but less on sound properties. Thus, the objective of this study is to investigate whether concrete containing OPS can be applied in the field of road noise barrier. The acoustic properties of the samples were determined by using an impedance tube connected to a sound source. The noise reduction coefficient (NRC) and weighted sound absorption coefficient (αw) which is more commonly use in the road traffic noise barrier field were calculated according to BS EN ISO 11654:1997. Compressive strengths of samples were also determined by using compressive test. The results presented that the compressive strength of the OPS composites decreased as increased in w/c wit minimum of 20.44 N/mm2 at 28 days for w/c = 0.6 but still satisfactory for structural use. The sound absorption coefficient demonstrated that they were decreased as the w/c are higher with typical curve of two peaks at 315Hz and 1000Hz. All samples were then can be classified as class E as 0.5< αw < 0.25 and should be classified as L due to favourable deviation higher than 0.25 for 250 Hz.

Experimental study on infrared radiation temperature field of concrete under uniaxial compression

NASA Astrophysics Data System (ADS)

Lou, Quan; He, Xueqiu

2018-05-01

Infrared thermography, as a nondestructive, non-contact and real-time monitoring method, has great significance in assessing the stability of concrete structure and monitoring its failure. It is necessary to conduct in depth study on the mechanism and application of infrared radiation (IR) of concrete failure under loading. In this paper, the concrete specimens with size of 100 × 100 × 100 mm were adopted to carry out the uniaxial compressions for the IR tests. The distribution of IR temperatures (IRTs), surface topography of IRT field and the reconstructed IR images were studied. The results show that the IRT distribution follows the Gaussian distribution, and the R2 of Gaussian fitting changes along with the loading time. The abnormities of R2 and AE counts display the opposite variation trends. The surface topography of IRT field is similar to the hyperbolic paraboloid, which is related to the stress distribution in the sample. The R2 of hyperbolic paraboloid fitting presents an upward trend prior to the fracture which enables to change the IRT field significantly. This R2 has a sharp drop in response to this large destruction. The normalization images of IRT field, including the row and column normalization images, were proposed as auxiliary means to analyze the IRT field. The row and column normalization images respectively show the transverse and longitudinal distribution of the IRT field, and they have clear responses to the destruction occurring on the sample surface. In this paper, the new methods and quantitative index were proposed for the analysis of IRT field, which have some theoretical and instructive significance for the analysis of the characteristics of IRT field, as well as the monitoring of instability and failure for concrete structure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, D.W.; Heinrich, R.R.; Graczyk, D.G.

The ACL activities covered IFR fuel reprocessing, corium-concrete interactions, environmental samples, wastes, WIPP support, Advanced Photon Source, H-Tc superconductors, EBWR vessel, soils, illegal drug detection, quality control, etc.

Detecting the activation of a self-healing mechanism in concrete by acoustic emission and digital image correlation.

PubMed

Tsangouri, E; Aggelis, D G; Van Tittelboom, K; De Belie, N; Van Hemelrijck, D

2013-01-01

Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process.

Radiological characterization and evaluation of high volume bauxite residue alkali activated concretes.

PubMed

Croymans, Tom; Schroeyers, Wouter; Krivenko, Pavel; Kovalchuk, Oleksandr; Pasko, Anton; Hult, Mikael; Marissens, Gerd; Lutter, Guillaume; Schreurs, Sonja

2017-03-01

Bauxite residue, also known as red mud, can be used as an aggregate in concrete products. The study involves the radiological characterization of different types of concretes containing bauxite residue from Ukraine. The activity concentrations of radionuclides from the 238 U, 232 Th decay series and 40 K were determined for concrete mixture samples incorporating 30, 40, 50, 60, 75, 85 and 90% (by mass) of bauxite residue using gamma-ray spectrometry with a HPGe detector. The studied bauxite residue can, from a radiological point of view using activity concentration indexes developed by Markkanen, be used in concrete for building materials and in road construction, even in percentages reaching 90% (by mass). However, when also occupational exposure is considered it is recommended to incorporate less than 75% (by mass) of Ukrainian bauxite residue during the construction of buildings in order to keep the dose to workers below the dose criterion used by Radiation Protection (RP) 122 (0.3 mSv/a). Considering RP122 for evaluation of the total effective dose to workers no restrictions are required for the use of the Ukrainian bauxite residue in road construction. Copyright © 2016 Elsevier Ltd. All rights reserved.

Crumb Rubber Recycling in Enhancing Damping Properties of Concrete

NASA Astrophysics Data System (ADS)

Sugapriya, P.; Ramkrishnan, R.

2018-02-01

Damping plays a major role in the design of roadside structures that gets affected due to vibrations transmitted from moving traffic. In this study, fine aggregates were partially replaced with crumb rubber in concrete, at varying percentages of 5, 10, 15 and 20% by weight. Three different sets of concrete, mixed with crumb rubber were prepared using raw rubber, treated rubber and treated rubber with partial replacement of cement. Cement was partially replaced with Ultra-Fine Ground Granulated Blast furnace Slag (UFGGBS) for this study. Samples were cast, cured and tested for various properties on the 7th and 28th day. The damping ratio and frequency of the peak value from a number of waves in rubber incorporated beams were found out using a FFT Analyser along with its Strength, Damping and Sorptivity characteristics. SEM analysis was conducted to analyse the micro structural bonding between rubber and concrete. The mode shapes of pavement slabs were modelled and analysed using a FEM tool, ANSYS. From the results, the behaviour of the three sets of rubberized concrete were compared and analysed, and an optimum percentage for crumb rubber and UFGGBS was proposed to achieve best possible damping without compromising the strength properties.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bauer, Stephen J.; Flint, Gregory Mark

Accurate knowledge of thermophysical properties of concrete is considered extremely important for meaningful models to be developed of scenarios wherein the concrete is rapidly heated. Test of solid propellant burns on samples of concrete from Launch Complex 17 of the Cape Canaveral show spallation and fragmentation. In response to the need for accurate modeling scenarios of these observations, an experimental program to determine the permeability and thermal properties of the concrete was developed. Room temperature gas permeability measurements of Launch Complex 17 of the Cape Canaveral concrete dried at 50°C yield permeability estimates of 0.07mD (mean), and thermal properties (thermalmore » conductivity, diffusivity, and specific heat) were found to vary with temperatures from room temperature to 300°C. Thermal conductivity ranges from 1.7-1.9 W/mK at 50°C to 1.0-1.15 W/mK at 300°C, thermal diffusivity ranges from 0.75-0.96 mm 2/s at 50°C to 0.44-0.58 mm 2/s at 300°C, and specific heat ranges from 1.76-2.32 /m 3K to 2.00-2.50 /m 3K at 300°C.« less

Improving rubber concrete by waste organic sulfur compounds.

PubMed

Chou, Liang-Hisng; Lin, Chun-Nan; Lu, Chun-Ku; Lee, Cheng-Haw; Lee, Maw-Tien

2010-01-01

In this study, the use of crumb tyres as additives to concrete was investigated. For some time, researchers have been studying the physical properties of concrete to determine why the inclusion of rubber particles causes the concrete to degrade. Several methods have been developed to improve the bonding between rubber particles and cement hydration products (C-S-H) with the hope of creating a product with an improvement in mechanical strength. In this study, the crumb tyres were treated with waste organic sulfur compounds from a petroleum refining factory in order to modify their surface properties. Organic sulfur compounds with amphiphilic properties can enhance the hydrophilic properties of the rubber and increase the intermolecular interaction forces between rubber and C-S-H. In the present study, a colloid probe of C-S-H was prepared to measure these intermolecular interaction forces by utilizing an atomic force microscope. Experimental results showed that rubber particles treated with waste organic sulfur compounds became more hydrophilic. In addition, the intermolecular interaction forces increased with the adsorption of waste organic sulfur compounds on the surface of the rubber particles. The compressive, tensile and flexural strengths of concrete samples that included rubber particles treated with organic sulfur compound also increased significantly.

Durability of crystalline phase in concrete microstructure modified by the mineral powders: evaluation by nanoindentation tests

NASA Astrophysics Data System (ADS)

Rajczakowska, Magdalena; Łydżba, Dariusz

2016-03-01

This paper presents the nanoindentation investigation of the evolution of concrete microstructure modified by the Internal Crystallization Technology mineral powders. The samples under study were retrieved from a fragment of a circular concrete lining of the vertical mine shaft at a depth of approximately 1,000 m. Due to the aggressive environment and exposure to contaminated water, the internal surface of the structure was deteriorated, decreasing its strength significantly. The mineral powders were applied directly on the surface lining. The specimens were investigated one month, three months and one year after the application of the aforementioned substance in order to verify the time dependence of the strengthening processes and durability of the crystalline phase. The microstructural changes of concrete were assessed with the use of nanoindentation technique. The testing procedure involved including the previously cut specimens in the epoxy resin and grinding and polishing in order to reduce the surface roughness. As a result of the nanoindentation tests the hardness as well as Young's modulus of the material were evaluated. The results were then compared and statistically analyzed. As a consequence, the disintegration time of the crystalline network in the pores of concrete was identified.