Hybrid FRP-concrete bridge deck system final report I : development and system performance validation.

DOT National Transportation Integrated Search

2009-10-01

In this study, the concept of the hybrid FRP-concrete structural systems was applied to both bridge : superstructure and deck systems. Results from the both experimental and computational analysis for : both the hybrid bridge superstructure and deck ...

Evaluation of a KeyStone/Tensar geogrid retaining wall system : final report.

DOT National Transportation Integrated Search

1992-01-01

The KeyStone/Tensar Geogrid retaining wall system is an alternative to conventional reinforced concrete retaining wall structures. KeyStone concrete wall units, Tensar geogrid, and compacted soils are combined to form a reinforced soil mass that toge...

Development, characterization and applications of a non proprietary ultra high performance concrete for highway bridges : final report.

DOT National Transportation Integrated Search

2016-03-14

Ultra-high performance concrete (UHPC) is a new class of cementitious materials that have : exceptional mechanical and durability characteristics. UHPC is commercially available. : However, its cost for construction of highway structures is prohibiti...

Strategies to Increase the service life of concrete bridge decks : final report.

DOT National Transportation Integrated Search

2017-03-01

Corrosion of the steel in reinforced concrete bridge decks is a critical issue for structures that are exposed to chloride containing de-icing chemicals or marine salts. Oregon Department of Transportation (ODOT) has a large number of bridges that ar...

Retrofitting of Reinforced Concrete Beams using Reactive Powder Concrete (RPC)

NASA Astrophysics Data System (ADS)

Karthik, S.; Sundaravadivelu, Karthik

2017-07-01

Strengthening of existing damaged structures is one of the leading studies in civil engineering. The purpose of retrofitting is to structurally treat the member with an aim to restore the structure to its original strength. The focus of this project is to study the behaviour of damaged Reinforced Concrete beam retrofitted with Reactive Powder Concrete (RPC) Overlay. Reinforced concrete beams of length 1200 mm, width 100 mm and depth 200 mm were casted with M30 grade of concrete in the laboratory and cured for 28 days. One beam is taken as control and are tested under two point loading to find out ultimate load. Remaining beams are subjected to 90 % ultimate load of control beams. The partially damaged beams are retrofitted with Reactive Powder Concrete Overlay at the full tension face of the beam and side overlay depends upon the respectable retrofitting techniques with 10 mm and 20 mm thick layer to find optimum. Materials like steel fibres are added to enhance the ductility by eliminating coarse particle for homogeneity of the structure. Finally, the modes of failure for retrofitted beams are analysed experimentally under two point loading & compared the results with Control beam.

Validation of mechanical models for reinforced concrete structures: Presentation of the French project ``Benchmark des Poutres de la Rance''

NASA Astrophysics Data System (ADS)

L'Hostis, V.; Brunet, C.; Poupard, O.; Petre-Lazar, I.

2006-11-01

Several ageing models are available for the prediction of the mechanical consequences of rebar corrosion. They are used for service life prediction of reinforced concrete structures. Concerning corrosion diagnosis of reinforced concrete, some Non Destructive Testing (NDT) tools have been developed, and have been in use for some years. However, these developments require validation on existing concrete structures. The French project “Benchmark des Poutres de la Rance” contributes to this aspect. It has two main objectives: (i) validation of mechanical models to estimate the influence of rebar corrosion on the load bearing capacity of a structure, (ii) qualification of the use of the NDT results to collect information on steel corrosion within reinforced-concrete structures. Ten French and European institutions from both academic research laboratories and industrial companies contributed during the years 2004 and 2005. This paper presents the project that was divided into several work packages: (i) the reinforced concrete beams were characterized from non-destructive testing tools, (ii) the mechanical behaviour of the beams was experimentally tested, (iii) complementary laboratory analysis were performed and (iv) finally numerical simulations results were compared to the experimental results obtained with the mechanical tests.

Analysis of the connection of the timber-fiber concrete composite structure

NASA Astrophysics Data System (ADS)

Holý, Milan; Vráblík, Lukáš; Petřík, Vojtěch

2017-09-01

This paper deals with an implementation of the material parameters of the connection to complex models for analysis of the timber-fiber concrete composite structures. The aim of this article is to present a possible way of idealization of the continuous contact model that approximates the actual behavior of timber-fiber reinforced concrete structures. The presented model of the connection was derived from push-out shear tests. It was approved by use of the nonlinear numerical analysis, that it can be achieved a very good compliance between results of numerical simulations and results of the experiments by a suitable choice of the material parameters of the continuous contact. Finally, an application for an analytical calculation of timber-fiber concrete composite structures is developed for the practical use in engineering praxis. The input material parameters for the analytical model was received using data from experiments.

Field application of a thermal-sprayed titanium anode for cathodic protection of reinforcing steel in concrete : final report

DOT National Transportation Integrated Search

1999-01-01

This study provided the first field trial of a catalyzed, thermal-sprayed titanium anode for cathodic protection of steel reinforced concrete structures. Catalyzed titanium as an anode material offers the advantage of long life due to the inherent no...

Realization of FRC interior and exterior furniture

NASA Astrophysics Data System (ADS)

Šonka, Š.; Frantová, M.; Štemberk, P.; Havrda, J.; Janouch, P.

2017-09-01

This article deals with the implementation of fibre reinforced concrete for interior and exterior furniture. The use of fibre reinforced concrete for non-traditional and small structures brings some specifics in design and realization. These are, in particular, the design of a suitable mixture, the choice of the shape of the structure in relation to the technological possibilities of realization, the static effects and finally the actual production of the element.

Two innovative solutions based on fibre concrete blocks designed for building substructure

NASA Astrophysics Data System (ADS)

Pazderka, J.; Hájek, P.

2017-09-01

Using of fibers in a high-strength concrete allows reduction of the dimensions of small precast concrete elements, which opens up new ways of solution for traditional construction details in buildings. The paper presents two innovative technical solutions for building substructure: The special shaped plinth block from fibre concrete and the fibre concrete elements for new technical solution of ventilated floor. The main advantages of plinth block from fibre concrete blocks (compared with standard plinth solutions) is: easier and faster assembly, higher durability and thanks to the air cavity between the vertical part of the block, the building substructure reduced moisture level of structures under the waterproofing layer and a comprehensive solution to the final surface of building plinth as well as the surface of adjacent terrain. The ventilated floor based on fibre concrete precast blocks is an attractive structural alternative for tackling the problem of increased moisture in masonry in older buildings, lacking a functional waterproof layer in the substructure.

Smart acoustic emission system for wireless monitoring of concrete structures

NASA Astrophysics Data System (ADS)

Yoon, Dong-Jin; Kim, Young-Gil; Kim, Chi-Yeop; Seo, Dae-Cheol

2008-03-01

Acoustic emission (AE) has emerged as a powerful nondestructive tool to detect preexisting defects or to characterize failure mechanisms. Recently, this technique or this kind of principle, that is an in-situ monitoring of inside damages of materials or structures, becomes increasingly popular for monitoring the integrity of large structures. Concrete is one of the most widely used materials for constructing civil structures. In the nondestructive evaluation point of view, a lot of AE signals are generated in concrete structures under loading whether the crack development is active or not. Also, it was required to find a symptom of damage propagation before catastrophic failure through a continuous monitoring. Therefore we have done a practical study in this work to fabricate compact wireless AE sensor and to develop diagnosis system. First, this study aims to identify the differences of AE event patterns caused by both real damage sources and the other normal sources. Secondly, it was focused to develop acoustic emission diagnosis system for assessing the deterioration of concrete structures such as a bridge, dame, building slab, tunnel etc. Thirdly, the wireless acoustic emission system was developed for the application of monitoring concrete structures. From the previous laboratory study such as AE event patterns analysis under various loading conditions, we confirmed that AE analysis provided a promising approach for estimating the condition of damage and distress in concrete structures. In this work, the algorithm for determining the damage status of concrete structures was developed and typical criteria for decision making was also suggested. For the future application of wireless monitoring, a low energy consumable, compact, and robust wireless acoustic emission sensor module was developed and applied to the concrete beam for performance test. Finally, based on the self-developed diagnosis algorithm and compact wireless AE sensor, new AE system for practical AE diagnosis was demonstrated for assessing the conditions of damage and distress in concrete structures.

Ceramic ware waste as coarse aggregate for structural concrete production.

PubMed

García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

2015-01-01

The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

Evaluation of Shear Strength of RC Beams with Multiple Interfaces Formed before Initial Setting Using 3D Printing Technology

PubMed Central

Kim, Kyeongjin; Park, Sangmin; Jeong, Yoseok; Lee, Jaeha

2017-01-01

With the recent development of 3D printing technology, concrete materials are sometimes used in 3D printing. Concrete structures based on 3D printing have been characterized to have the form of multiple layer build-up. Unlike general concrete structures, therefore, the 3D-printed concrete can be regarded as an orthotropic material. The material property of the 3D-printed concrete’s interface between layers is expected to be far different from that of general concrete bodies since there are no aggregate interlocks and weak chemical bonding. Such a difference finally affects the structural performance of concrete structures even though the interfaces are formed before initial setting of the concrete. The current study mainly reviewed the changes in fracture energy (toughness) with respect to various environmental conditions of such interface. Changes in fracture energies of interfaces between concrete layers were measured using low-speed Crack Mouth Opening Displacement (CMOD) closed loop concrete fracture test. The experimental results indicated reduction in fracture energy as well as tensile strengths. To improve the tensile strength of interfaces, the use of bridging materials is suggested. Since it was assumed that reduction in fracture energy could be a cause of shear strength, to evaluate the reduced structural performance of concrete structure constructed with multiple interfaces by 3D printing technology, the shear strength of RC beam by 3D printing technology was predicted and compared with that of plain RC beam. Based on the fracture energy measured in this study, Modified Compression Field Theory (MCFT) theory-applied Vector 2 program was employed to predict the degree of reduction in shear strength without considering stirrups. Reduction factors were presented based on the obtained results to predict the reduction in shear strength due to interfaces before initial setting of the concrete.

Study on evaluation of corrosion condition of reinforcing bar embedded concrete using infrared thermal imaging camera

NASA Astrophysics Data System (ADS)

Ruiko, Watanabe; Toshiaki, Mizobuchi

2017-04-01

Rapid aging of many concrete structures, which have been developed during rapid economic growth period in Japan, has become a serious problem for us these days. And thus, there is an urgent need to prolong their service life expectancies. For this purpose, the deterioration of reinforcing bars in the concrete structures should be detected quickly and correctly at the early stages. Nevertheless, conventional testing methods such as destructive and nondestructive testing have disadvantages: partial damages on concrete structures; difficulty with quantitative evaluation, etc. Many preceding studies have examined to estimate the deterioration of reinforcing bars based on the temperature of the concrete specimen surfaces. According to those papers, the differences in corrosion degree of reinforcing bars have a certain effect on the temperature of concrete specimen surfaces. In this study, firstly, the quantitative evaluation of the corrosion degree was conducted with 3D scanner which could measure the volume, coverage area and cross-sectional area. Secondly, the surface of the concrete specimen was cooled down with liquid nitrogen, and thirdly, thermographic change was observed up until the air temperature. Finally, the surface of the concrete specimen was detected clearly by the thermal images. As a result, this study shows that the corrosion thickness tends to get bigger, following the uprising temperature of the concrete specimen surfaces. The same kind of tendency can be observed by the thermal images, too.

Probabilistic durability assessment of concrete structures in marine environments: Reliability and sensitivity analysis

NASA Astrophysics Data System (ADS)

Yu, Bo; Ning, Chao-lie; Li, Bing

2017-03-01

A probabilistic framework for durability assessment of concrete structures in marine environments was proposed in terms of reliability and sensitivity analysis, which takes into account the uncertainties under the environmental, material, structural and executional conditions. A time-dependent probabilistic model of chloride ingress was established first to consider the variations in various governing parameters, such as the chloride concentration, chloride diffusion coefficient, and age factor. Then the Nataf transformation was adopted to transform the non-normal random variables from the original physical space into the independent standard Normal space. After that the durability limit state function and its gradient vector with respect to the original physical parameters were derived analytically, based on which the first-order reliability method was adopted to analyze the time-dependent reliability and parametric sensitivity of concrete structures in marine environments. The accuracy of the proposed method was verified by comparing with the second-order reliability method and the Monte Carlo simulation. Finally, the influences of environmental conditions, material properties, structural parameters and execution conditions on the time-dependent reliability of concrete structures in marine environments were also investigated. The proposed probabilistic framework can be implemented in the decision-making algorithm for the maintenance and repair of deteriorating concrete structures in marine environments.

Low - Cost Shore Protection. Final Report on the Shoreline Erosion Control Demonstration Program (Section 54) 1981

DTIC Science & Technology

1981-08-01

rubble- mound breakwater ......................... . ... 66 Ŗ-6 Statistics and costs for nylon-sandbag breakwater ...... ................... .... 68 2-7...64 2-16 Rubble- mound and concrete-box breakwater sections ........... .................... 65 2-17...a series of low, fixed offshore breakwaters utilizing three structural devices: rubble mound , nylon sandbags, and precast concrete boxes, as shown in

Durability of a reinforced concrete designed for the construction of an intermediate-level radioactive waste disposal facility

NASA Astrophysics Data System (ADS)

Duffó, G. S.; Arva, E. A.; Schulz, F. M.; Vazquez, D. R.

2012-01-01

The National Atomic Energy Commission of the Argentine Republic is developing a nuclear waste disposal management programme that contemplates the design and construction of a facility for the final disposal of intermediate-level radioactive wastes. The repository is based on the use of multiple, independent and redundant barriers. The major components are made in reinforced concrete so, the durability of these structures is an important aspect for the facility integrity. This work presents an investigation performed on a reinforced concrete specifically designed for this purpose, to predict the service life of the intermediate level radioactive waste disposal facility from data obtained with several techniques. Results obtained with corrosion sensors embedded in a concrete prototype are also included. The information obtained will be used for the final design of the facility in order to guarantee a service life more or equal than the foreseen durability for this type of facilities.

Assessment of asphalt concrete reinforcement grid in flexible pavements : final report.

DOT National Transportation Integrated Search

2016-05-01

This report investigated the application of accepted methods of pavement structural evaluation to independently assess the potential structural benefit of asphalt geogrid reinforcement of an operational flexible highway pavement. The asphalt interlay...

Comprehensive benefits analysis of steel structure modular residence based on the entropy evaluation

NASA Astrophysics Data System (ADS)

Zhang, Xiaoxiao; Wang, Li; Jiang, Pengming

2017-04-01

Steel structure modular residence is the outstanding residential industrialization. It has many advantages, such as the low whole cost, high resource recovery, a high degree of industrialization. This paper compares the comprehensive benefits of steel structural in modular buildings with prefabricated reinforced concrete residential from economic benefits, environmental benefits, social benefits and technical benefits by the method of entropy evaluation. Finally, it is concluded that the comprehensive benefits of steel structural in modular buildings is better than that of prefabricated reinforced concrete residential. The conclusion of this study will provide certain reference significance to the development of steel structural in modular buildings in China.

Seismic damage identification using multi-line distributed fiber optic sensor system

NASA Astrophysics Data System (ADS)

Ou, Jinping; Hou, Shuang

2005-06-01

Determination of the actual nonlinear inelastic response mechanisms developed by civil structures such as buildings and bridges during strong earthquakes and post-earthquake damage assessment of these structures represent very difficult challenges for earthquake structural engineers. One of the main reasons is that the traditional sensor can't serve for such a long period to cover an earthquake and the seismic damage location in the structure can't be predicted in advance definitely. It is thought that the seismic damage of reinforced concrete (RC) structure can be related to the maximum response the structure, which can also be related to the cracks on the concrete. A distributed fiber optic sensor was developed to detect the cracks on the reinforced concrete structure under load. Fiber optic couples were used in the sensor system to extend the sensor system's capacity from one random point detection to more. An optical time domain reflectometer (OTDR) is employed for interrogation of the sensor signal. Fiber optic sensors are attached on the surface of the concrete by the epoxy glue. By choosing the strength of epoxy, the damage state of the concrete can be responded to the occurrence of the Fresnel scattering in the fiber optic sensor. Experiments involved monotonic loading to failure. Finally, the experimental results in terms of crack detection capability are presented and discussed.

Final Report: Self-Consolidating Concrete Construction for Modular Units

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

Gentry, Russell; Kahn, Lawrence; Kurtis, Kimberly

This report focuses on work completed on DE-NE0000667, Self-Consolidating Concrete for Modular Units, in connection with the Department of Energy Nuclear Energy Enabling Technologies (DOE-NEET) program. This project was completed in the School of Civil and Environmental Engineering at the Georgia Institute of Technology, with Westinghouse Corporation as the industrial partner. The primary objective of this project was to develop self-consolidating concrete (also termed “self-compacting concrete” or SCC) mixtures so that concrete placement can be made into steel plate composite (SC) modular structures without the need for continuous concrete placement. As part of the research, SCC mixtures were developed andmore » validated to ensure sufficient shear capacity across cold-joints, while minimizing shrinkage and temperature increase during curing to enhance concrete bonding with the steel plate construction found in modular units. The SCC mixtures developed were able to carry shearing forces across the cold-joint boundaries. This “self-roughening” was achieved by adding a tailored fraction of lightweight aggregate (LWA) to the concrete mix, some of which raised to the surface during curing, forming a rough surface on which subsequent concrete placements were made. The self-roughening behavior was validated through three sets of structural tests. Shear friction on small-scale specimens with cold joints was assessed using varying fractions of LWA and with varying amounts of external steel plate reinforcement. The results show that the shear friction coefficient, to be used with the provisions of ACI 318-14, Section 22.9, can be taken as 1.35. Mid-scale beam tests were completed to assess the cold-joint capacity in both in-plane and out-of-plane bending. The results showed that the self-roughened joints performed as well as monolithic joints. The final assessment was a full-scale test using a steel composite module supplied by Westinghouse and similar in construction to the steel composite modules being assembled at the Vogtle and V.C. Summer plant expansions. The final test showed that the roughened cold-joint showed excellent shear and flexural capacity, and substantial ductility, when used in conjunction with steel composite construction.« less

Optimisation of industrial wastes reuse as construction materials.

PubMed

Collivignarelli, C; Sorlini, S

2001-12-01

This study concerns the reuse of two inorganic wastes, foundry residues and fly ashes from municipal solid waste incineration, as "recycled aggregate" in concrete production. This kind of reuse was optimised by waste treatment with the following steps: waste washing with water; waste stabilisation-solidification treatment with inorganic reagents; final grinding of the stabilised waste after curing for about 10-20 days. Both the treated wastes were reused in concrete production with different mix-designs. Concrete specimens were characterised by means of conventional physical-mechanical tests (compression, elasticity modulus, shrinkage) and different leaching tests. Experimental results showed that a good structural and environmental quality of "recycled concrete" is due both to a correct waste treatment and to a correct mix-design for concrete mixture.

Improving resistance of high strength concrete (HSC) bridge beams to frost and defrosting salt attack by application of hydrophobic agent

NASA Astrophysics Data System (ADS)

Kolisko, Jiri; Balík, Lukáš; Kostelecka, Michaela; Pokorný, Petr

2017-09-01

HSC (High Strength Concrete) is increasingly used for bearing bridge structures nowadays. Bridge structures in the Czech Republic are exposed to severe conditions in winter time and durability of the concrete is therefore a crucial requirement. The high strength and low water absorption of HSC suggests that the material will have high durability. However, the situation may not be so straightforward. We carried out a study of the very poor durability of HSC concrete C70/85 used to produce prestresed beams 37.1 m in length to build a 6-span highway bridge. After the beams were cast, a production control test indicated some problems with the durability of the concrete. There was a danger that 42 of the beams would not be suitable for use. All participants in the bridge project finally decided, after extensive discussions, to attempt to improve the durability of the concrete by applying a hydrophobic agent. Paper will present the results of comparative tests of four hydrophobic agents in order to choose one for real application and describes this application on construction site.

Reliability assessment of slender concrete columns at the stability failure

NASA Astrophysics Data System (ADS)

Valašík, Adrián; Benko, Vladimír; Strauss, Alfred; Täubling, Benjamin

2018-01-01

The European Standard for designing concrete columns within the use of non-linear methods shows deficiencies in terms of global reliability, in case that the concrete columns fail by the loss of stability. The buckling failure is a brittle failure which occurs without warning and the probability of its formation depends on the columns slenderness. Experiments with slender concrete columns were carried out in cooperation with STRABAG Bratislava LTD in Central Laboratory of Faculty of Civil Engineering SUT in Bratislava. The following article aims to compare the global reliability of slender concrete columns with slenderness of 90 and higher. The columns were designed according to methods offered by EN 1992-1-1 [1]. The mentioned experiments were used as basis for deterministic nonlinear modelling of the columns and subsequent the probabilistic evaluation of structural response variability. Final results may be utilized as thresholds for loading of produced structural elements and they aim to present probabilistic design as less conservative compared to classic partial safety factor based design and alternative ECOV method.

Application of the self-diagnosis composite into concrete structure

NASA Astrophysics Data System (ADS)

Matsubara, Hideaki; Shin, Soon-Gi; Okuhara, Yoshiki; Nomura, Hiroshi; Yanagida, Hiroaki

2001-04-01

The function and performance of the self-diagnosis composites embedded in mortar/concrete blocks and concrete piles were investigated by bending tests and electrical resistance measurements. Carbon powder (CP) and carbon fiber (CF) were introduced in glass fiber reinforced plastics composites to obtain electrical conductivity. The CP composite has commonly good performances in various bending tests of block and pile specimens, comparing to the CF composite. The electrical resistance of the CP composite increases in a small strain to response remarkably micro-crack formation at about 200 (mu) strain and to detect well to smaller deformations before the crack formation. The CP composite possesses a continuous resistance change up to a large strain level near the final fracture of concrete structures reinforced by steel bars. The cyclic bending tests showed that the micro crack closed at unloading state was able to be evaluated from the measurement of residual resistance. It has been concluded that the self- diagnosis composite is fairly useful for the measurement of damage and fracture in concrete blocks and piles.

Aggregate Effect on the Concrete Cone Capacity of an Undercut Anchor under Quasi-Static Tensile Load

PubMed Central

Marcon, Marco; Ninčević, Krešimir; Boumakis, Ioannis; Czernuschka, Lisa-Marie

2018-01-01

In the last decades, fastening systems have become an essential part of the construction industry. Post-installed mechanical anchors are frequently used in concrete members to connect them with other load bearing structural members, or to attach appliances. Their performance is limited by the concrete related failure modes which are highly influenced by the concrete mix design. This paper aims at investigating the effect that different aggregates used in the concrete mix have on the capacity of an undercut anchor under tensile quasi-static loading. Three concrete batches were cast utilising three different aggregate types. For two concrete ages (28 and 70 days), anchor tensile capacity and concrete properties were obtained. Concrete compressive strength, fracture energy and elastic modulus are used to normalize and compare the undercut anchor concrete tensile capacity employing some of the most widely used prediction models. For a more insightful comparison, a statistical method that yields also scatter information is introduced. Finally, the height and shape of the concrete cones are compared by highly precise and objective photogrammetric means. PMID:29723972

Aggregate Effect on the Concrete Cone Capacity of an Undercut Anchor under Quasi-Static Tensile Load.

PubMed

Marcon, Marco; Ninčević, Krešimir; Boumakis, Ioannis; Czernuschka, Lisa-Marie; Wan-Wendner, Roman

2018-05-01

In the last decades, fastening systems have become an essential part of the construction industry. Post-installed mechanical anchors are frequently used in concrete members to connect them with other load bearing structural members, or to attach appliances. Their performance is limited by the concrete related failure modes which are highly influenced by the concrete mix design. This paper aims at investigating the effect that different aggregates used in the concrete mix have on the capacity of an undercut anchor under tensile quasi-static loading. Three concrete batches were cast utilising three different aggregate types. For two concrete ages (28 and 70 days), anchor tensile capacity and concrete properties were obtained. Concrete compressive strength, fracture energy and elastic modulus are used to normalize and compare the undercut anchor concrete tensile capacity employing some of the most widely used prediction models. For a more insightful comparison, a statistical method that yields also scatter information is introduced. Finally, the height and shape of the concrete cones are compared by highly precise and objective photogrammetric means.

Final Report: Self Consolidating Concrete Construction for Modular Units

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

Gentry, Russell; Kahn, Lawrence; Kurtis, Kimberly

This report outlines the development of a self-consolidating concrete (also termed “self-compacting concrete” or SCC) so that concrete placement can be made into steel plate composite (SC) modular structures without the need for continuous concrete placement. As part of the research, SCC mixtures were developed and validated to ensure sufficient shear capacity across cold-joints, while minimizing shrinkage and temperature increase during curing to enhance concrete bonding with the steel plate construction found in modular units. The self-roughening concrete produced as part of this research was assessed in SC structures at three scales: small-scale shear-friction specimens, mid-scale beams tested in in-planemore » and out-of-plane bending, and a full-scale validation test using an SC module produced by Westinghouse as part of the Plant Vogtle expansion. The experiments show that the self-roughening concrete can produce a cold-joint surface of 0.25 inches (6 mm) without external vibration during concrete placement. The experiments and subsequent analysis show that the shear friction provisions of ACI 318-14, Section 22.9 can be used to assess the shear capacity of the cold-joints in SC modular construction, and that friction coefficient of 1.35 is appropriate for use with these provisions.« less

A PERMEABLE ACTIVE AMENDMENT CONCRETE (PAAC) FOR CONTAMINANT REMEDIATION AND EROSION CONTROL

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

Knox, A.; Paller, M.; Dixon, K.

2012-06-29

The final project report for SEED SERDP ER - 2134 describes the development of permeable active amendment concrete (PAAC), which was evaluated through four tasks: 1) development of PAAC; 2) assessment of PAAC for contaminant removal; 3) evaluation of promising PAAC formulations for potential environmental impacts; and 4) assessment of the hydraulic, physical, and structural properties of PAAC. Conventional permeable concrete (often referred to as pervious concrete) is concrete with high porosity as a result of an extensive and interconnected void content. It is made from carefully controlled amounts of water and cementitious materials used to create a paste thatmore » forms a coating around aggregate particles. The mixture has a substantial void content (e.g., 15% - 25%) that results in a highly permeable structure that drains quickly. In PAAC, the aggregate material is partly replaced by chemically-active amendments that precipitate or adsorb contaminants in water that flows through the concrete interstices. PAAC combines the relatively high structural strength, ample void space, and water permeability of pervious concrete with the contaminant sequestration ability of chemically-active amendments to produce a new material with superior durability and ability to control contaminant mobility. The high surface area provided by the concrete interstices in PAAC provides significant opportunity for contaminants to react with the amendments incorporated into the concrete matrix. PAAC has the potential to immobilize a large variety of organic and inorganic contaminants by incorporating different active sequestering agents including phosphate materials (rock phosphate), organoclays, zeolite, and lime individually or in combinations.« less

Smart photonic coating for civil engineering field: for a future inspection technology on concrete bridge

NASA Astrophysics Data System (ADS)

Fudouzi, Hiroshi; Tsuchiya, Koichi; Todoroki, Shin-ichi; Hyakutake, Tsuyoshi; Nitta, Hiroyuki; Nishizaki, Itaru; Tanaka, Yoshikazu; Ohya, Takao

2017-04-01

Here we will propose the conceptual new idea of the inspection of concrete bridge using smart materials and mobile IoT system. We apply opal photonic crystal film to detect cracks on concrete infrastructures. High quality opal photonic crystal films were coated on black color PET sheet over 1000 cm2 area. The opal film sheet was cut and adhered to concrete or mortar test pieces by epoxy resin. In the tensile test, the structural color of the opal sheet was changed when the crack was formed. As a demonstration, we have installated the opal film sheet on the wall of the concrete bridge. Our final purpose is the color change will be recorded by portable CCD devices, and send to expert via IoT network.

Fiber-reinforced concretes with a high fiber volume fraction — a look in future. Can a design determine the fiber amount in concrete in real time in every part of a structure in production?

NASA Astrophysics Data System (ADS)

Tepfers, R.

2010-09-01

In near future, when the control of the load-bearing capacity of fiber-only-reinforced concrete members will be safely guaranteed, the deletion of the ordinary continuous steel reinforcing bars might be possible. For the time being, it is difficult to change the fiber amount during the casting with today's techniques. Therefore, the fiber concentration has to be determined by the maximum tensile stress in concrete structural members, resulting in an unnecessary fiber addition in compressed zones. However, if the right amount of fibers could be regulated and added to concrete in real time at the pump outlet, a future vision could be to design and produce a structure by using FEM-controlled equipment. The signals from calculation results could be transmitted to a concrete casting system for addition of a necessary amount of fibers to take care of the actual tensile stresses in the right position in the structure. The casting location could be determined by using a GPS for positioning the pump outlet for targeting the casting location horizontally and a laser vertically. The addition of fibers to concrete at the outlet of a concrete pump and proportioning them there according to the actual needs of the stress situation in a structure, given by a FEM analysis in real time, is a future challenge. The FEM analysis has to be based on material properties of fiber-only-reinforced concrete. This means that the resistance and stiffness of different-strength concrete members with a varying fiber content has to be determined in tests and conveyed to the FEM analysis. The FEM analysis has to be completed before the casting and controlled. Then it can be used as the base for adding a correct amount of fibers to concrete in every part of the structure. Thus, a system for introducing a correct amount of fibers into concrete has to be developed. The fibers have to be added at the outlet of concrete pump. Maybe a system to shotcrete concrete with electronically controlled fiber addition is to be preferred? The target point where the concrete comes to rest into a structure has to be electronically noted and sent to the FEM system. The FEM analysis should then immediately send back the information for the correct amount of fibers at that point. This requires the elaboration of an appropriate signal system, which should not be impossible. An integrated system for the design and production of concrete structures could be developed excluding the heavy and time-consuming work with steel reinforcing bars. The result could be: no evaluation of moments and shear forces from a FEM analysis for determining the bar reinforcement; no bar anchorage requirements and reinforcement detailing; no reinforcement drawings; no reinforcing bars; no heavy work with the reinforcement. Finally, investigations have to be performed concerning the demolition of fiber-reinforced concrete structures and the reuse of the material. The fragments of fiber-reinforced concrete might be sticky and cause problems for nature. The recirculation of material has also to be solved.

Proceedings of the Workshop on Measurement and Analysis of Structural Response in Concrete Armor Units Held in Vicksburg, Mississippi on 23-24 January 1985

DTIC Science & Technology

1988-02-01

57 Summary--"Comments from Dr. Hans Burcharth" ............81 "Strength of Armour Blocks...335 APPENDICES........................................................ 387 A--"Strength of Concrete Armour Units for Breakwaters"’ --Delft...STAT!STICS DESIGN WAVE CLIMATE PRELIMINARY DESIGN CALCULATION OF ARMOUR STABILIY ETC MODEL TESTS OF PRELIMINARY DESIGN FINAL DESIGN Figure 1. Ideal

The Shock and Vibration Digest. Volume 16, Number 9

DTIC Science & Technology

1984-09-01

behavior of the interface between dry Ottawa sand and concrete has been studied using a new device developed for Key Words: Underground structures, Concretes...Establishment, Ottawa , On- Reviews tario, Canada. Rept. No. NAE-AN-7, NRC-21276, -- 153 pp (Apr 1983) _ Recently developed analytical models for the...elements. The final phase of validation included simu- ,- 0 National Aeronautical Establishment, Ottawa , On- lation of dynamic tests of production

Final Report - Assessment of Potential Phosphate Ion-Cementitious Materials Interactions

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

Naus, Dan J; Mattus, Catherine H; Dole, Leslie Robert

The objectives of this limited study were to: (1) review the potential for degradation of cementitious materials due to exposure to high concentrations of phosphate ions; (2) provide an improved understanding of any significant factors that may lead to a requirement to establish exposure limits for concrete structures exposed to soils or ground waters containing high levels of phosphate ions; (3) recommend, as appropriate, whether a limitation on phosphate ion concentration in soils or ground water is required to avoid degradation of concrete structures; and (4) provide a "primer" on factors that can affect the durability of concrete materials andmore » structures in nuclear power plants. An assessment of the potential effects of phosphate ions on cementitious materials was made through a review of the literature, contacts with concrete research personnel, and conduct of a "bench-scale" laboratory investigation. Results of these activities indicate that: no harmful interactions occur between phosphates and cementitious materials unless phosphates are present in the form of phosphoric acid; phosphates have been incorporated into concrete as set retarders, and phosphate cements have been used for infrastructure repair; no standards or guidelines exist pertaining to applications of reinforced concrete structures in high-phosphate environments; interactions of phosphate ions and cementitious materials has not been a concern of the research community; and laboratory results indicate similar performance of specimens cured in phosphate solutions and those cured in a calcium hydroxide solution after exposure periods of up to eighteen months. Relative to the "primer," a separate NUREG report has been prepared that provides a review of pertinent factors that can affect the durability of nuclear power plant reinforced concrete structures.« less

Evaluation of grit-impregnated, epoxy coated prestressing strand on South Slough (Charleston) Bridge : final report.

DOT National Transportation Integrated Search

1995-04-01

The use of grit-impregnated, epoxy coated prestressing strand is a relatively new design strategy being used for corrosion abatement on new concrete structures. This application was chosen for the South Slough (Charleston) structure because it subjec...

Concrete Nanoscience and Nanotechnology: Definitions and Applications

NASA Astrophysics Data System (ADS)

Garboczi, E. J.

There are many improvements needed in concrete, especially for use in renewal and expansion of the world’s infrastructure. Nanomodification can help solve many of these problems. However, concrete has been slow to catch on to the nanotechnology revolution. There are several reasons for this lag in the nanoscience and nanotechnology of concrete (NNC). First is the lack of a complete basic understanding of chemical and physical mechanisms and structure at the nanometer length scale. Another reason is the lack of a broad understanding of what nanomodification means to concrete, which is a liquid-solid composite. NNC ideas need to profit from, but not be bound by, experience with other materials. As an illustration of these ideas, a specific application will be given of using nano-size molecules in solution to affect the viscosity of the concrete pore solution so that ionic diffusion is slowed. A molecular-based understanding would help move this project towards true nanotechnology. A final section of this paper lists some possibly fruitful focus areas for the nanoscience and nanotechnology of concrete.

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

Bech, H.; Haugsen, P.B.

The Norwegian Oil Company, Saga Petroleum a.s., is operator on two promising deep water blocks in the Norwegian sector of the North Sea. As a result, the company has introduced a new platform concept designed specifically for hostile and deep water areas. The platform idea is the result of a systematic innovation procedure. The first step was to analyze and describe the functions of the different structural elements on a general basis. Next was to analyze how these elements contributed to the total concept. The final development stage was to create a new solution. The resulting (hybrid platform design conceptmore » appears to offer a number of inherent deck layout and towout deck weight advantages). The concrete substructure is a lower unit consisting of a foundation with concrete skirts that will penetrate the soft soil in the seabed and a high concrete caisson extending up from the foundation, which is made up of seven cells with varying concrete thicknesses, terminating in domes. The upper steel platform section is a lattice-type jacket structure. There is a separate column for internal personnel access between the platform deck and the concrete caisson.« less

Smart concrete slabs with embedded tubular PZT transducers for damage detection

NASA Astrophysics Data System (ADS)

Gao, Weihang; Huo, Linsheng; Li, Hongnan; Song, Gangbing

2018-02-01

The objective of this study is to develop a new concept and methodology of smart concrete slab (SCS) with embedded tubular lead zirconate titanate transducer array for image based damage detection. Stress waves, as the detecting signals, are generated by the embedded tubular piezoceramic transducers in the SCS. Tubular piezoceramic transducers are used due to their capacity of generating radially uniform stress waves in a two-dimensional concrete slab (such as bridge decks and walls), increasing the monitoring range. A circular type delay-and-sum (DAS) imaging algorithm is developed to image the active acoustic sources based on the direct response received by each sensor. After the scattering signals from the damage are obtained by subtracting the baseline response of the concrete structures from those of the defective ones, the elliptical type DAS imaging algorithm is employed to process the scattering signals and reconstruct the image of the damage. Finally, two experiments, including active acoustic source monitoring and damage imaging for concrete structures, are carried out to illustrate and demonstrate the effectiveness of the proposed method.

Structural effects of radiation-induced volumetric expansion on unreinforced concrete biological shields

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

Le Pape, Y.

Limited literature (Pomaro et al., 2011, Mirhosseini et al., 2014, Salomoni et al., 2014 and Andreev and Kapliy, 2014) is available on the structural analysis of irradiated concrete biological shield (CBS), although extended operations of nuclear powers plants may lead to critical neutron exposure above 1.0 × 10 +19 n cm ₋2. To the notable exception of Andreev and Kapliy, available structural models do not account for radiation-induced volumetric expansion, although it was found to develop important linear dimensional change of the order of 1%, and, can lead to significant concrete damage (Le Pape et al., 2015). A 1D-cylindrical model of an unreinforced CBS accounting for temperature and irradiation effects is developed. Irradiated concrete properties are characterized probabilistically using the updated database collected by Oak Ridge National Laboratory (Field et al., 2015). The overstressed concrete ratio (OCR) of the CBS, i.e., the proportion of the wall thickness being subject to stresses beyond the resistance of concrete, is derived by deterministic and probabilistic analysis assuming that irradiated concrete behaves as an elastic materials. In the bi-axial compressive zone near the reactor cavity, the OCR is limited to 5.7%, i.e., 8.6 cm (3more » $$_2^1$$ in.), whereas, in the tension zone, the OCR extends to 72%, i.e., 1.08 m (42$$_2^1$$ in.). Finally, we find that these results, valid for a maximum neutron fluence on the concrete surface of 3.1 × 10 +19 n cm ₋2 (E > 0.1 MeV) and, obtained after 80 years of operation, give an indication of the potential detrimental effects of prolonged irradiation of concrete in nuclear power plants.« less

Structural effects of radiation-induced volumetric expansion on unreinforced concrete biological shields

DOE PAGES

Le Pape, Y.

2015-11-22

Limited literature (Pomaro et al., 2011, Mirhosseini et al., 2014, Salomoni et al., 2014 and Andreev and Kapliy, 2014) is available on the structural analysis of irradiated concrete biological shield (CBS), although extended operations of nuclear powers plants may lead to critical neutron exposure above 1.0 × 10 +19 n cm ₋2. To the notable exception of Andreev and Kapliy, available structural models do not account for radiation-induced volumetric expansion, although it was found to develop important linear dimensional change of the order of 1%, and, can lead to significant concrete damage (Le Pape et al., 2015). A 1D-cylindrical model of an unreinforced CBS accounting for temperature and irradiation effects is developed. Irradiated concrete properties are characterized probabilistically using the updated database collected by Oak Ridge National Laboratory (Field et al., 2015). The overstressed concrete ratio (OCR) of the CBS, i.e., the proportion of the wall thickness being subject to stresses beyond the resistance of concrete, is derived by deterministic and probabilistic analysis assuming that irradiated concrete behaves as an elastic materials. In the bi-axial compressive zone near the reactor cavity, the OCR is limited to 5.7%, i.e., 8.6 cm (3more » $$_2^1$$ in.), whereas, in the tension zone, the OCR extends to 72%, i.e., 1.08 m (42$$_2^1$$ in.). Finally, we find that these results, valid for a maximum neutron fluence on the concrete surface of 3.1 × 10 +19 n cm ₋2 (E > 0.1 MeV) and, obtained after 80 years of operation, give an indication of the potential detrimental effects of prolonged irradiation of concrete in nuclear power plants.« less

Corrosion behaviour of steel rebars embedded in a concrete designed for the construction of an intermediate-level radioactive waste disposal facility

NASA Astrophysics Data System (ADS)

Duffó, G. S.; Arva, E. A.; Schulz, F. M.; Vazquez, D. R.

2013-07-01

The National Atomic Energy Commission of the Argentine Republic is developing a nuclear waste disposal management programme that contemplates the design and construction of a facility for the final disposal of intermediate-level radioactive wastes. The repository is based on the use of multiple, independent and redundant barriers. The major components are made in reinforced concrete so, the durability of these structures is an important aspect for the facility integrity. This work presents an investigation performed on an instrumented reinforced concrete prototype specifically designed for this purpose, to study the behaviour of an intermediate level radioactive waste disposal facility from the rebar corrosion point of view. The information obtained will be used for the final design of the facility in order to guarantee a service life more or equal than the foreseen durability for this type of facilities.

Additional adjoint Monte Carlo studies of the shielding of concrete structures against initial gamma radiation. Final report

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

Beer, M.; Cohen, M.O.

1975-02-01

The adjoint Monte Carlo method previously developed by MAGI has been applied to the calculation of initial radiation dose due to air secondary gamma rays and fission product gamma rays at detector points within buildings for a wide variety of problems. These provide an in-depth survey of structure shielding effects as well as many new benchmark problems for matching by simplified models. Specifically, elevated ring source results were obtained in the following areas: doses at on-and off-centerline detectors in four concrete blockhouse structures; doses at detector positions along the centerline of a high-rise structure without walls; dose mapping at basementmore » detector positions in the high-rise structure; doses at detector points within a complex concrete structure containing exterior windows and walls and interior partitions; modeling of the complex structure by replacing interior partitions by additional material at exterior walls; effects of elevation angle changes; effects on the dose of changes in fission product ambient spectra; and modeling of mutual shielding due to external structures. In addition, point source results yielding dose extremes about the ring source average were obtained. (auth)« less

Simulation of fiber Bragg grating sensor for rebar corrosion

NASA Astrophysics Data System (ADS)

Geng, Jiang; Wu, Jin; Zhao, Xinming

2009-07-01

It is world widely concerned in the durability of reinforced concrete structures. Corrosion of rebar is one of the most important factors which can affect the durability of the concrete structures, and may result in damage to the structures in the form of expansion, cracking and eventually spalling of the cover concrete. In addition, the structural damage may be due to loss of bond between reinforcement and concrete and reduction of reinforcement cross-sectional area, and finally it may cause structure failure. With the advantages of linear reaction, small volume, high anti-erosion capability and automatic signal transmission, the smart sensors made of fiber bragg grating (FBG) to monitor strain, stress, temperature and local crack have got wide application in buildings, bridges and tunnels. FBG can be adhered to the surface of the structure, and also can be embedded into the inner of the structures when the project is being under construction to realize the real-time health monitoring. Based on volume expansion, the fiber bragg grating sensor for rebar corrosion is designed. The corrosion status of the structure can be obtained from the information provided by sensors. With the aid of the finite element software ANSYS, the simulation of the corrosion sensor was carried in this paper. The relationship between corrosion ratio and the shift of wavelength was established. According to the results of the simulation, there were differences between simulated results and measured results. The reason of the differences was also studied in this paper.

Thick Concrete Specimen Construction, Testing, and Preliminary Analysis

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

Clayton, Dwight A.; Hoegh, Kyle; Khazanovich, Lev

The purpose of the U.S. Department of Energy Office of Nuclear Energy’s Light Water Reactor Sustainability (LWRS) Program is to develop technologies and other solutions that can improve the reliability, sustain the safety, and extend the operating lifetimes of nuclear power plants (NPPs) beyond 60 years. Since many important safety structures in an NPP are constructed of concrete, inspection techniques must be developed and tested to evaluate the internal condition. In-service containment structures generally do not allow for the destructive measures necessary to validate the accuracy of these inspection techniques. This creates a need for comparative testing of the variousmore » nondestructive evaluation (NDE) measurement techniques on concrete specimens with known material properties, voids, internal microstructure flaws, and reinforcement locations. A preliminary report detailed some of the challenges associated with thick reinforced concrete sections and prioritized conceptual designs of specimens that could be fabricated to represent NPP concrete structures for using in NDE evaluation comparisons. This led to the construction of the concrete specimen presented in this report, which has sufficient reinforcement density and cross-sectional size to represent an NPP containment wall. Details on how a suitably thick concrete specimen was constructed are presented, including the construction materials, final nominal design schematic, as well as formwork and rigging required to safely meet the desired dimensions of the concrete structure. The report also details the type and methods of forming the concrete specimen as well as information on how the rebar and simulated defects were embedded. Details on how the resulting specimen was transported, safely anchored, and marked to allow access for systematic comparative NDE testing of defects in a representative NPP containment wall concrete specimen are also given. Data collection using the MIRA Ultrasonic NDE equipment and initial results are also presented along with a discussion of the preliminary findings. Comparative NDE of various defects in reinforced concrete specimens is a key component in identifying the most promising techniques and directing the research and development efforts needed to characterize concrete degradation in commercial NPPs. This requires access to the specimens for data collection using state-of-the-art technology. The construction of the specimen detailed in this report allows for an evaluation of how different NDE techniques may interact with the size and complexities of NPP concrete structures. These factors were taken into account when determining specimen size and features to ensure a realistic design. The lateral dimensions of the specimen were also chosen to mitigate unrealistic boundary effects that would not affect the results of field NPP concrete testing. Preliminary results show that, while the current methods are able to identify some of the deeper defects, improvements in data processing or hardware are necessary to be able to achieve the precision and reliability achieved in evaluating thinner and less heavily reinforced concrete structures.« less

Comparative analysis of structural concrete Quality Assurance practices on nine nuclear and three fossil fuel power plant construction projects. Final summary report

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

Willenbrock, J.H.; Thomas, H.R. Jr.; Burati, J.J. Jr.

1978-12-01

A summary of two reports, COO/4120-1 and COO/4120-2, is given. A comparative analysis was made of the Quality Assurance practices related to the structural concrete phase on nine nuclear and three fossil fuel power plant projects which are (or have been) under construction in the United States in the past ten years. For the nuclear projects the analysis identified the response of each Quality Assurance program to the applicable criteria of 10 CFR Part 50, Appendix B as well as to the pertinent regulatory requirements and industry standards. For the fossil projects the analysis identified the response of each Qualitymore » Assurance program to criteria similar to those which were applicable in the nuclear situation. The major emphasis was placed on the construction aspects of the structural concrete phase of each project. The engineering and design aspects were examined whenever they interfaced with the construction aspects.« less

Computer-Aided Construction at Designing Reinforced Concrete Columns as Per Ec

NASA Astrophysics Data System (ADS)

Zielińska, M.; Grębowski, K.

2015-02-01

The article presents the authors' computer program for designing and dimensioning columns in reinforced concrete structures taking into account phenomena affecting their behaviour and information referring to design as per EC. The computer program was developed with the use of C++ programming language. The program guides the user through particular dimensioning stages: from introducing basic data such as dimensions, concrete class, reinforcing steel class and forces affecting the column, through calculating the creep coefficient taking into account the impact of imperfection depending on the support scheme and also the number of mating members at load shit, buckling length, to generating the interaction curve graph. The final result of calculations provides two dependence points calculated as per methods of nominal stiffness and nominal curvature. The location of those points relative to the limit curve determines whether the column load capacity is assured or has been exceeded. The content of the study describes in detail the operation of the computer program and the methodology and phenomena which are indispensable at designing axially and eccentrically the compressed members of reinforced concrete structures as per the European standards.

Monitoring corrosion in reinforced concrete structures

NASA Astrophysics Data System (ADS)

Kung, Peter; Comanici, Maria I.

2014-06-01

Many defects can cause deterioration and cracks in concrete; these are results of poor concrete mix, poor workmanship, inadequate design, shrinkage, chemical and environmental attack, physical or mechanical damage, and corrosion of reinforcing steel (RS). We want to develop a suite of sensors and systems that can detect that corrosion is taking place in RS and inform owners how serious the problem is. By understanding the stages of the corrosion process, we can develop special a sensor that detects each transition. First, moisture ingress can be monitored by a fiber optics humidity sensor, then ingress of Chloride, which acts as a catalyst and accelerates the corrosion process by converting iron into ferrous compounds. We need a fiber optics sensor which can quantify Chloride ingress over time. Converting ferric to ferrous causes large volume expansion and cracks. Such pressure build-up can be detected by a fiber optic pressure sensor. Finally, cracks emit acoustic waves, which can be detected by a high frequency sensor made with phase-shifted gratings. This paper will discuss the progress in our development of these special sensors and also our plan for a field test by the end of 2014. We recommend that we deploy these sensors by visually inspecting the affected area and by identifying locations of corrosion; then, work with the designers to identify spots that would compromise the integrity of the structure; finally, drill a small hole in the concrete and insert these sensors. Interrogation can be done at fixed intervals with a portable unit.

Membrane protection for steel stringer tops : Yaquina Bay Bridge , Newport, Oregon : final report.

DOT National Transportation Integrated Search

1983-09-01

Direct coastal exposure imposes serious problems to structural and reinforcing steel in bridges. Corrosion causes expansion of the steel resulting in a variety of problems including spalling of reinforced concrete. This problem can become especially ...

Structural evaluation of LIC-310-0396 and FAY-35-17-6.82 box beams with advanced strand deterioration : draft final report - phase II.

DOT National Transportation Integrated Search

2011-09-01

This report describes the results from the testing of a full scale three span 43 year old adjacent prestressed concrete box beam bridge. This research is the second phase of the overall project entitled Structural Evaluation of LIC-310-0396 Box Be...

US-23 aggregate test road long-term performance evaluation : final report.

DOT National Transportation Integrated Search

2017-03-24

The US-23 Aggregate Test Road was constructed in 1992 with the main purpose to determine the influence of coarse : aggregate of varying frost susceptibility on long-term concrete durability. The pavement structure for the entire Test Road consists : ...

Galvanic Liquid Applied Coating Development for Protection of Steel in Concrete

NASA Technical Reports Server (NTRS)

Curran, Joseph John; Curran, Jerry; MacDowell, Louis

2004-01-01

Corrosion of reinforcing steel in concrete is a major problem affecting NASA facilities at Kennedy Space Center (KSC), other government agencies, and the general public. Problems include damage to KSC launch support structures, transportation and marine infrastructures, as well as building structures. A galvanic liquid applied coating was developed at KSC in order to address this problem. The coating is a non-epoxy metal rich ethyl silicate liquid coating. The coating is applied as a liquid from initial stage to final stage. Preliminary data shows that this coating system exceeds the NACE 100 millivolt shift criterion. The remainder of the paper details the development of the coating system through the following phases: Phase I: Development of multiple formulations of the coating to achieve easy application characteristics, predictable galvanic activity, long-term protection, and minimum environmental impact. Phase II: Improvement of the formulations tested in Phase I including optimization of metallic loading as well as incorporation of humectants for continuous activation. Phase III: Application and testing of improved formulations on the test blocks. Phase IV: Incorporation of the final formulation upgrades onto large instrumented structures (slabs).

Portland cement concrete pavement restoration : final summary report.

DOT National Transportation Integrated Search

1988-07-01

This final summary report is comprised of an Initial Construction Report; a Final Report; and two Interim Reports. These reports document the construction of Louisiana's Portland Cement Concrete Pavement Restoration project and its performance during...

Modeling of concrete cracking due to corrosion process of reinforcement bars

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

Bossio, Antonio, E-mail: antonio.bossio@unina.it; Monetta, Tullio, E-mail: monetta@unina.it; Bellucci, Francesco, E-mail: bellucci@unina.it

The reinforcement corrosion in Reinforced Concrete (RC) is a major reason of degradation for structures and infrastructures throughout the world leading to their premature deterioration before design life was attained. The effects of corrosion of reinforcement are: (i) the reduction of the cross section of the bars, and (ii) the development of corrosion products leading to the appearance of cracks in the concrete cover and subsequent cover spalling. Due to their intrinsic complex nature, these issues require an interdisciplinary approach involving both material science and structural design knowledge also in terms on International and National codes that implemented the conceptmore » of durability and service life of structures. In this paper preliminary FEM analyses were performed in order to simulate pitting corrosion or general corrosion aimed to demonstrate the possibility to extend the results obtained for a cylindrical specimen, reinforced by a single bar, to more complex RC members in terms of geometry and reinforcement. Furthermore, a mechanical analytical model to evaluate the stresses in the concrete surrounding the reinforcement bars is proposed. In addition, a sophisticated model is presented to evaluate the non-linear development of stresses inside concrete and crack propagation when reinforcement bars start to corrode. The relationships between the cracking development (mechanical) and the reduction of the steel section (electrochemical) are provided. Finally, numerical findings reported in this paper were compared to experimental results available in the literature and satisfactory agreement was found.« less

Stiffness of reinforced concrete walls resisting in-place shear -- Tier 2: Aging and durability of concrete used in nuclear power plants. Final report

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

Monteiro, P.J.M.; Moehle, J.P.

1995-12-01

Reinforced concrete walls are commonly used in power-plant construction to resist earthquake effects. Determination of wall stiffness is of particular importance for establishing design forces on attached equipment. Available experimental data indicate differences between the measured and calculated stiffness of walls in cases where concrete mechanical properties are well defined. Additional data indicate that in-situ concrete mechanical properties may differ significantly from those specified in design. The work summarized in this report was undertaken to investigate the mechanical properties of concrete considering aging and deterioration. Existing data on mechanical properties of concrete are evaluated, and new tests are carried outmore » on concrete cylinders batched for nuclear power plants and stored under controlled conditions for up to twenty years. It is concluded that concretes batched for nuclear power plants commonly have 28-day strength that exceeds the design value by at least 1000 psi. Under curing conditions representative of those in the interior of thick concrete elements, strength gain with time can be estimated conservatively using the expression proposed by ACI Committee 209, with strengths at 25 years being approximately 1.3 times the 28-day strength. Young`s modulus can be estimated using the expression given by ACI Committee 318. Variabilities in mechanical properties are identified. A review of concrete durability identified the main causes and results of concrete deterioration that are relevant for the class of concretes and structures commonly used in nuclear power plants. Prospects for identifying the occurrence and predicting the extent of deterioration are discussed.« less

Probabilistic design of fibre concrete structures

NASA Astrophysics Data System (ADS)

Pukl, R.; Novák, D.; Sajdlová, T.; Lehký, D.; Červenka, J.; Červenka, V.

2017-09-01

Advanced computer simulation is recently well-established methodology for evaluation of resistance of concrete engineering structures. The nonlinear finite element analysis enables to realistically predict structural damage, peak load, failure, post-peak response, development of cracks in concrete, yielding of reinforcement, concrete crushing or shear failure. The nonlinear material models can cover various types of concrete and reinforced concrete: ordinary concrete, plain or reinforced, without or with prestressing, fibre concrete, (ultra) high performance concrete, lightweight concrete, etc. Advanced material models taking into account fibre concrete properties such as shape of tensile softening branch, high toughness and ductility are described in the paper. Since the variability of the fibre concrete material properties is rather high, the probabilistic analysis seems to be the most appropriate format for structural design and evaluation of structural performance, reliability and safety. The presented combination of the nonlinear analysis with advanced probabilistic methods allows evaluation of structural safety characterized by failure probability or by reliability index respectively. Authors offer a methodology and computer tools for realistic safety assessment of concrete structures; the utilized approach is based on randomization of the nonlinear finite element analysis of the structural model. Uncertainty of the material properties or their randomness obtained from material tests are accounted in the random distribution. Furthermore, degradation of the reinforced concrete materials such as carbonation of concrete, corrosion of reinforcement, etc. can be accounted in order to analyze life-cycle structural performance and to enable prediction of the structural reliability and safety in time development. The results can serve as a rational basis for design of fibre concrete engineering structures based on advanced nonlinear computer analysis. The presented methodology is illustrated on results from two probabilistic studies with different types of concrete structures related to practical applications and made from various materials (with the parameters obtained from real material tests).

Development of a Drilling Fluid Drive Downhole Tractor in Oil Field

NASA Astrophysics Data System (ADS)

Fang, Delei; Shang, Jianzhong; Liu, Yiying; Wu, Wei; Luo, Zirong

2018-01-01

This paper proposes a drilling fluid drive downhole tractor, which has the advantages of compact structure, large traction, fast speed and high reliability. The overall mechanical structure of the tractor is introduced, the concrete structures including supporting structure and cushion mechanism are designed. And its all-hydraulic drive continuous propulsion principle is analyzed. Finally the simulation analysis of the tractor operation is carried out to prove that the traction motion scheme is feasible.

Sustainability and durability analysis of reinforced concrete structures

NASA Astrophysics Data System (ADS)

Horáková, A.; Broukalová, I.; Kohoutková, A.; Vašková, J.

2017-09-01

The article describes an assessment of reinforced concrete structures in terms of durability and sustainable development. There is a short summary of findings from the literature on evaluation methods for environmental impacts and also about corrosive influences acting on the reinforced concrete structure, about factors influencing the durability of these structures and mathematical models describing the corrosion impacts. Variant design of reinforced concrete structure and assessment of these variants in terms of durability and sustainability was performed. The analysed structure was a concrete ceiling structure of a parking house for cars. The variants differ in strength class of concrete and thickness of concrete slab. It was found that in terms of durability and sustainable development it is significantly preferable to use higher class of concrete. There are significant differences in results of concrete structures durability for different mathematical models of corrosive influences.

Accuracy analysis of point cloud modeling for evaluating concrete specimens

NASA Astrophysics Data System (ADS)

D'Amico, Nicolas; Yu, Tzuyang

2017-04-01

Photogrammetric methods such as structure from motion (SFM) have the capability to acquire accurate information about geometric features, surface cracks, and mechanical properties of specimens and structures in civil engineering. Conventional approaches to verify the accuracy in photogrammetric models usually require the use of other optical techniques such as LiDAR. In this paper, geometric accuracy of photogrammetric modeling is investigated by studying the effects of number of photos, radius of curvature, and point cloud density (PCD) on estimated lengths, areas, volumes, and different stress states of concrete cylinders and panels. Four plain concrete cylinders and two plain mortar panels were used for the study. A commercially available mobile phone camera was used in collecting all photographs. Agisoft PhotoScan software was applied in photogrammetric modeling of all concrete specimens. From our results, it was found that the increase of number of photos does not necessarily improve the geometric accuracy of point cloud models (PCM). It was also found that the effect of radius of curvature is not significant when compared with the ones of number of photos and PCD. A PCD threshold of 15.7194 pts/cm3 is proposed to construct reliable and accurate PCM for condition assessment. At this PCD threshold, all errors for estimating lengths, areas, and volumes were less than 5%. Finally, from the study of mechanical property of a plain concrete cylinder, we have found that the increase of stress level inside the concrete cylinder can be captured by the increase of radial strain in its PCM.

Concrete pavement quality control testing requirements needed for the super air meter : final report.

DOT National Transportation Integrated Search

2016-10-01

Concrete freeze-thaw durability is prominently linked to the air void system within the concrete. : Concrete pavements in Kansas undergo repetitive freeze-thaw cycles. Total air content measurements : currently used on fresh concrete do not provide a...

Simplified Calculation Model and Experimental Study of Latticed Concrete-Gypsum Composite Panels

PubMed Central

Jiang, Nan; Ma, Shaochun

2015-01-01

In order to address the performance complexity of the various constituent materials of (dense-column) latticed concrete-gypsum composite panels and the difficulty in the determination of the various elastic constants, this paper presented a detailed structural analysis of the (dense-column) latticed concrete-gypsum composite panel and proposed a feasible technical solution to simplified calculation. In conformity with mechanical rules, a typical panel element was selected and divided into two homogenous composite sub-elements and a secondary homogenous element, respectively for solution, thus establishing an equivalence of the composite panel to a simple homogenous panel and obtaining the effective formulas for calculating the various elastic constants. Finally, the calculation results and the experimental results were compared, which revealed that the calculation method was correct and reliable and could meet the calculation needs of practical engineering and provide a theoretical basis for simplified calculation for studies on composite panel elements and structures as well as a reference for calculations of other panels. PMID:28793631

Simplified Calculation Model and Experimental Study of Latticed Concrete-Gypsum Composite Panels.

PubMed

Jiang, Nan; Ma, Shaochun

2015-10-27

In order to address the performance complexity of the various constituent materials of (dense-column) latticed concrete-gypsum composite panels and the difficulty in the determination of the various elastic constants, this paper presented a detailed structural analysis of the (dense-column) latticed concrete-gypsum composite panel and proposed a feasible technical solution to simplified calculation. In conformity with mechanical rules, a typical panel element was selected and divided into two homogenous composite sub-elements and a secondary homogenous element, respectively for solution, thus establishing an equivalence of the composite panel to a simple homogenous panel and obtaining the effective formulas for calculating the various elastic constants. Finally, the calculation results and the experimental results were compared, which revealed that the calculation method was correct and reliable and could meet the calculation needs of practical engineering and provide a theoretical basis for simplified calculation for studies on composite panel elements and structures as well as a reference for calculations of other panels.

Evaluation of flyash in lean concrete base and continuously reinforced concrete pavements : final report.

DOT National Transportation Integrated Search

1991-07-01

Proposed research on this project included five main objectives: 1) To test and evaluate the physical characteristics of flyash concrete in comparions to non-flyash concrete. Tests will be conducted to see if flyash concrete meets OSHD specifications...

76 FR 34890 - Track Safety Standards; Concrete Crossties

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-15

...-0007, Notice No. 3] RIN 2130-AC01 Track Safety Standards; Concrete Crossties AGENCY: Federal Railroad... effective concrete crossties, for rail fastening systems connected to concrete crossties, and for automated inspections of track constructed with concrete crossties. The Track Safety Standards were amended via final...

A review of recent developments in parametric based acoustic emission techniques applied to concrete structures

NASA Astrophysics Data System (ADS)

Vidya Sagar, R.; Raghu Prasad, B. K.

2012-03-01

This article presents a review of recent developments in parametric based acoustic emission (AE) techniques applied to concrete structures. It recapitulates the significant milestones achieved by previous researchers including various methods and models developed in AE testing of concrete structures. The aim is to provide an overview of the specific features of parametric based AE techniques of concrete structures carried out over the years. Emphasis is given to traditional parameter-based AE techniques applied to concrete structures. A significant amount of research on AE techniques applied to concrete structures has already been published and considerable attention has been given to those publications. Some recent studies such as AE energy analysis and b-value analysis used to assess damage of concrete bridge beams have also been discussed. The formation of fracture process zone and the AE energy released during the fracture process in concrete beam specimens have been summarised. A large body of experimental data on AE characteristics of concrete has accumulated over the last three decades. This review of parametric based AE techniques applied to concrete structures may be helpful to the concerned researchers and engineers to better understand the failure mechanism of concrete and evolve more useful methods and approaches for diagnostic inspection of structural elements and failure prediction/prevention of concrete structures.

Assessment of concrete damage and strength degradation caused by reinforcement corrosion

NASA Astrophysics Data System (ADS)

Nepal, Jaya; Chen, Hua-Peng

2015-07-01

Structural performance deterioration of reinforced concrete structures has been extensively investigated, but very limited studies have been carried out to investigate the effect of reinforcement corrosion on time-dependent reliability with consideration of the influence of mechanical characteristics of the bond interface due to corrosion. This paper deals with how corrosion in reinforcement creates different types of defects in concrete structure and how they are responsible for the structural capacity deterioration of corrosion affected reinforced concrete structures during their service life. Cracking in cover concrete due to reinforcement corrosion is investigated by using rebar-concrete model and realistic concrete properties. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution due to reinforcement corrosion, which is examined by the experimental data available. The time-dependent reliability analysis is undertaken to calculate the life time structural reliability of corrosion damaged concrete structures by stochastic deterioration modelling of reinforced concrete. The results from the numerical example show that the proposed approach is capable of evaluating the damage caused by reinforcement corrosion and also predicting the structural reliability of concrete structures during their lifecycle.

Exploration of novel multifunctional open graded friction courses for in-situ highway runoff treatment July 1, 2014-June 30, 2016 : final research report.

DOT National Transportation Integrated Search

2014-07-01

Pervious Concrete Pavement (PCP), as one of open graded friction courses (OGFCs), has become attractive in roadway and parking lot constructions because of its economic, structural, and environmental advantages. It can facilitate the recharge of grou...

Assessment of high early strength limestone blended cement for next generation transportation structures : final report.

DOT National Transportation Integrated Search

2016-12-01

This research on Type IL cements for high early strength concretes demonstrated that Type IL cements satisfying AASHTO M 240 specifications may be used in place of Type I/II cements which satisfy AASHTO M 85 specifications for construction of transpo...

Lining seam elimination algorithm and surface crack detection in concrete tunnel lining

NASA Astrophysics Data System (ADS)

Qu, Zhong; Bai, Ling; An, Shi-Quan; Ju, Fang-Rong; Liu, Ling

2016-11-01

Due to the particularity of the surface of concrete tunnel lining and the diversity of detection environments such as uneven illumination, smudges, localized rock falls, water leakage, and the inherent seams of the lining structure, existing crack detection algorithms cannot detect real cracks accurately. This paper proposed an algorithm that combines lining seam elimination with the improved percolation detection algorithm based on grid cell analysis for surface crack detection in concrete tunnel lining. First, check the characteristics of pixels within the overlapping grid to remove the background noise and generate the percolation seed map (PSM). Second, cracks are detected based on the PSM by the accelerated percolation algorithm so that the fracture unit areas can be scanned and connected. Finally, the real surface cracks in concrete tunnel lining can be obtained by removing the lining seam and performing percolation denoising. Experimental results show that the proposed algorithm can accurately, quickly, and effectively detect the real surface cracks. Furthermore, it can fill the gap in the existing concrete tunnel lining surface crack detection by removing the lining seam.

Detection of active corrosion in reinforced and prestressed concrete: overview of NIST TIP project

NASA Astrophysics Data System (ADS)

Gonzalez-Nunez, M. A.; Nanni, A.; Matta, F.; Ziehl, P.

2011-04-01

The US transportation infrastructure has been receiving intensive public and private attention in recent years. The Federal Highway Administration estimates that 42 percent of the nearly 600,000 bridges in the Unites States are in need of structural or functional rehabilitation1. Corrosion of reinforcement steel is the main durability issue for reinforced and prestressed concrete structures, especially in coastal areas and in regions where de-icing salts are regularly used. Acoustic Emission (AE) has proved to be a promising method for detecting corrosion in steel reinforced and prestressed concrete members. This type of non-destructive test method primarily measures the magnitude of energy released within a material when physically strained. The expansive ferrous byproducts resulting from corrosion induce pressure at the steel-concrete interface, producing longitudinal and radial microcracks that can be detected by AE sensors. In the experimental study presented herein, concrete block specimens with embedded steel reinforcing bars and strands were tested under accelerated corrosion to relate the AE activity with the onset and propagation stages of corrosion. AE data along with half cell potential measurements and galvanic current were recorded to examine the deterioration process. Finally, the steel strands and bars were removed from the specimens, cleaned and weighed. The results were compared vis-à-vis Faraday's law to correlate AE measurements with degree of corrosion in each block.

Use of improved materials systems in marine piling : final report.

DOT National Transportation Integrated Search

1982-12-01

This report contains the results of a study to evaluate the feasibility of manufacturing precast, prestressed marine pile from polymer concrete, polymer impregnated concrete, internally sealed concrete and latex modified concrete. Included in the rep...

Ethical considerations for a better collaboration between architects and structural engineers: design of buildings with reinforced concrete frame systems in earthquake zones.

PubMed

Hurol, Yonca

2014-06-01

Architects design building structures, although structural design is the profession of structural engineers. Thus, it is better for architects and structural engineers to collaborate starting from the initial phases of the architectural design. However, this is not very common because of the contradictory design processes and value systems held within the two professions. This article provides a platform upon which architects and structural engineers can resolve the value conflicts between them by analysing phases of the structural design of reinforced concrete frame systems in architecture, the criteria of the structural design for each phase and determining the conflicting values for each criterion. The results shown in the article demonstrate that the architectural design of structures is a complex process, which is based on contradictory values and value systems. Finally, the article suggests to architects and structural engineers to use Value Sensitive Design and to choose an appropriate team leader in order to resolve the unethical conflict between them and to avoid any unreasonable decision making.

The Study on the Durability of Submerged Structure Displacement due to Concrete Failure

NASA Astrophysics Data System (ADS)

Mohd, M.; Zainon, O.; Rasib, A. W.; Majid, Z.

2016-09-01

Concrete structures that exposed to marine environments are subjected to multiple deterioration mechanisms. An overview of the existing technology for submerged concrete, pressure resistant, concrete structures which related such as cracks, debonds, and delamination are discussed. Basic knowledge related to drowning durability such as submerged concrete structures in the maritime environment are the durability of a concrete and the ability to resist to weathering, chemical attack, abrasion or other deterioration processes. The measuring techniques and instrumentation for geometrical monitoring of submerged structural displacements have traditionally been categorized into two groups according to the two main groups, namely as geodetic surveying and geotechnical structural measurements of local displacements. This paper aims to study the durability of submerged concrete displacement and harmful effects of submerged concrete structures.

Development of design parameters for mass concrete using finite element analysis : final report, February 2010.

DOT National Transportation Integrated Search

2010-02-01

A finite element model for analysis of mass concrete was developed in this study. To validate the developed model, large concrete blocks made with four different mixes of concrete, typical of use in mass concrete applications in Florida, were made an...

Use of steel fibres recovered from waste tyres as reinforcement in concrete: pull-out behaviour, compressive and flexural strength.

PubMed

Aiello, M A; Leuzzi, F; Centonze, G; Maffezzoli, A

2009-06-01

The increasing amount of waste tyres worldwide makes the disposition of tyres a relevant problem to be solved. In the last years over three million tons of waste tyres were generated in the EU states [ETRA, 2006. Tyre Technology International - Trends in Tyre Recycling. http://www.etra-eu.org]; most of them were disposed into landfills. Since the European Union Landfill Directive (EU Landfill, 1999) aims to significantly reduce the landfill disposal of waste tyres, the development of new markets for the tyres becomes fundamental. Recently some research has been devoted to the use of granulated rubber and steel fibres recovered from waste tyres in concrete. In particular, the concrete obtained by adding recycled steel fibres evidenced a satisfactory improvement of the fragile matrix, mostly in terms of toughness and post-cracking behaviour. As a consequence RSFRC (recycled steel fibres reinforced concrete) appears a promising candidate for both structural and non-structural applications. Within this context a research project was undertaken at the University of Salento (Italy) aiming to investigate the mechanical behaviour of concrete reinforced with RSF (recycled steel fibres) recovered from waste tyres by a mechanical process. In the present paper results obtained by the experimental work performed up to now are reported. In order to evaluate the concrete-fibres bond characteristics and to determine the critical fibre length, pull-out tests were initially carried out. Furthermore compressive strength of concrete was evaluated for different volume ratios of added RSF and flexural tests were performed to analyze the post-cracking behaviour of RSFRC. For comparison purposes, samples reinforced with industrial steel fibres (ISF) were also considered. Satisfactory results were obtained regarding the bond between recycled steel fibres and concrete; on the other hand compressive strength of concrete seems unaffected by the presence of fibres despite their irregular geometric properties. Finally, flexural tests furnished in some cases results comparable to those obtained when using ISF as concerns the post-cracking behaviour.

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.

Experimental evaluation and design of unfilled and concrete-filled FRP composite piles : Task 7 : final report : thesis.

DOT National Transportation Integrated Search

2015-05-01

The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP composite piles for load-bearing in bridges. This report covers Task 7, Final Report - Thesis. : This final report covers Tasks 1, 2, 3, 5 ...

76 FR 48802 - Certain Steel Concrete Reinforcing Bars From Turkey; Notice of Amended Final Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-09

... Reinforcing Bars From Turkey; Notice of Amended Final Results of Antidumping Duty Administrative Review AGENCY... (rebar) from Turkey. See Certain Steel Concrete Reinforcing Bars From Turkey; Final Results of... administrative review of rebar from Turkey as follows: Manufacturer/Producer/Exporter Margin Percentage Ekinciler...

A Sensor-Type PC Strand with an Embedded FBG Sensor for Monitoring Prestress Forces

PubMed Central

Kim, Sung Tae; Park, YoungHwan; Park, Sung Yong; Cho, Keunhee; Cho, Jeong-Rae

2015-01-01

Prestressed Concrete Wire and Strand (PC) strands are the most used materials to introduce prestress in a Pre-Stressed Concrete (PSC) structure. However, it is difficult to evaluate the final prestress force of the PC strand after prestressing or its residual prestress force after completion of the structure on site. This impossibility to assess eventual loss of prestress of the PC strand has resulted in a number of serious accidents and even in the collapse of several structures. This situation stresses the necessity to maintain the prestress force residual or after prestressing for the evaluation of the health of the concrete structure throughout its lifespan. Recently, several researchers have studied methods enabling one to verify the prestress force by inserting an optical fiber sensor inside the strand but failed to provide simple techniques for the fabrication of these devices to fulfill measurement performance from the design prestress to failure. Moreover, these methods require the additional installation of electrical resistance strain gages, displacement sensors and load cells on the outer surface of the structure for long-term precise measurement. This paper proposes a method enabling one to evaluate precisely and effectively the prestress force of the PC strand and intends to verify the applicability of the proposed method on actual concrete structures. To that end, an innovative PC strand is developed by embedding a Fiber Bragg Grating (FBG) sensor in the core wire of the PC strand so as to enable short term as well as long term monitoring. The measurement performance of the developed strand is then evaluated experimentally and the reliability of the monitoring data is assessed. PMID:25580903

A sensor-type PC strand with an embedded FBG sensor for monitoring prestress forces.

PubMed

Kim, Sung Tae; Park, YoungHwan; Park, Sung Yong; Cho, Keunhee; Cho, Jeong-Rae

2015-01-08

Prestressed Concrete Wire and Strand (PC) strands are the most used materials to introduce prestress in a Pre-Stressed Concrete (PSC) structure. However, it is difficult to evaluate the final prestress force of the PC strand after prestressing or its residual prestress force after completion of the structure on site. This impossibility to assess eventual loss of prestress of the PC strand has resulted in a number of serious accidents and even in the collapse of several structures. This situation stresses the necessity to maintain the prestress force residual or after prestressing for the evaluation of the health of the concrete structure throughout its lifespan. Recently, several researchers have studied methods enabling one to verify the prestress force by inserting an optical fiber sensor inside the strand but failed to provide simple techniques for the fabrication of these devices to fulfill measurement performance from the design prestress to failure. Moreover, these methods require the additional installation of electrical resistance strain gages, displacement sensors and load cells on the outer surface of the structure for long-term precise measurement. This paper proposes a method enabling one to evaluate precisely and effectively the prestress force of the PC strand and intends to verify the applicability of the proposed method on actual concrete structures. To that end, an innovative PC strand is developed by embedding a Fiber Bragg Grating (FBG) sensor in the core wire of the PC strand so as to enable short term as well as long term monitoring. The measurement performance of the developed strand is then evaluated experimentally and the reliability of the monitoring data is assessed.

Investigation of optimize graded concrete for Oklahoma : phase 1 : final report.

DOT National Transportation Integrated Search

2013-10-01

Optimized Graded Concrete has been a subject widely discussed through the history of concrete. Since aggregates make up over 70% of the volume in a mixture, gradation is critical to the strength, workability, and durability of concrete. In practice o...

Sub-Frequency Interval Approach in Electromechanical Impedance Technique for Concrete Structure Health Monitoring

PubMed Central

Yang, Yaowen; Divsholi, Bahador Sabet

2010-01-01

The electromechanical (EM) impedance technique using piezoelectric lead zirconate titanate (PZT) transducers for structural health monitoring (SHM) has attracted considerable attention in various engineering fields. In the conventional EM impedance technique, the EM admittance of a PZT transducer is used as a damage indicator. Statistical analysis methods such as root mean square deviation (RMSD) have been employed to associate the damage level with the changes in the EM admittance signatures, but it is difficult to determine the location of damage using such methods. This paper proposes a new approach by dividing the large frequency (30–400 kHz) range into sub-frequency intervals and calculating their respective RMSD values. The RMSD of the sub-frequency intervals (RMSD-S) will be used to study the severity and location of damage. An experiment is carried out on a real size concrete structure subjected to artificial damage. It is observed that damage close to the PZT changes the high frequency range RMSD-S significantly, while the damage far away from the PZT changes the RMSD-S in the low frequency range significantly. The relationship between the frequency range and the PZT sensing region is also presented. Finally, a damage identification scheme is proposed to estimate the location and severity of damage in concrete structures. PMID:22163548

Analysis, prediction, and case studies of early-age cracking in bridge decks

NASA Astrophysics Data System (ADS)

ElSafty, Adel; Graeff, Matthew K.; El-Gharib, Georges; Abdel-Mohti, Ahmed; Mike Jackson, N.

2016-06-01

Early-age cracking can adversely affect strength, serviceability, and durability of concrete bridge decks. Early age is defined as the period after final setting, during which concrete properties change rapidly. Many factors can cause early-age bridge deck cracking including temperature change, hydration, plastic shrinkage, autogenous shrinkage, and drying shrinkage. The cracking may also increase the effect of freeze and thaw cycles and may lead to corrosion of reinforcement. This research paper presents an analysis of causes and factors affecting early-age cracking. It also provides a tool developed to predict the likelihood and initiation of early-age cracking of concrete bridge decks. Understanding the concrete properties is essential so that the developed tool can accurately model the mechanisms contributing to the cracking of concrete bridge decks. The user interface of the implemented computer Excel program enables the user to input the properties of the concrete being monitored. The research study and the developed spreadsheet were used to comprehensively investigate the issue of concrete deck cracking. The spreadsheet is designed to be a user-friendly calculation tool for concrete mixture proportioning, temperature prediction, thermal analysis, and tensile cracking prediction. The study also provides review and makes recommendations on the deck cracking based mainly on the Florida Department of Transportation specifications and Structures Design Guidelines, and Bridge Design Manuals of other states. The results were also compared with that of other commercially available software programs that predict early-age cracking in concrete slabs, concrete pavement, and reinforced concrete bridge decks. The outcome of this study can identify a set of recommendations to limit the deck cracking problem and maintain a longer service life of bridges.

75 FR 47260 - Certain Steel Concrete Reinforcing Bars from Turkey: Notice of Amended Final Results Pursuant to...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-05

... Reinforcing Bars from Turkey: Notice of Amended Final Results Pursuant to Court Decision AGENCY: Import... concrete reinforcing bars (rebar) from Turkey. See Nucor Corporation, Gerdau Ameristeel, Inc., and... published its final results in the antidumping duty administrative review of rebar from Turkey covering the...

Latex modified fibrous concrete : experimental feature : final report.

DOT National Transportation Integrated Search

1985-03-01

In November 1980, a contractor requested permission to use a 1.5 inch thick Latex Modified Fibrous Concrete (LMFC) overlay in lieu of a 2.5 inch low slump concrete (Iowa System) or a 2.5 inch unreinforced latex modified concrete. The overlays were to...

Typical and darkened Portland cement concrete pavement: temperature, moisture, and roughness analyses : final report.

DOT National Transportation Integrated Search

2017-01-01

The objectives of this research were to 1) investigate the effects of lower concrete albedo on the thermal behavior of concrete pavement by directly comparing temperatures and moisture contents of typical and darkened concrete pavements and 2) invest...

Evaluation of thin epoxy system overlays for concrete bridge decks : final report.

DOT National Transportation Integrated Search

1991-12-01

Four overlay systems were applied to concrete bridge decks in north Louisiana in May 1995 to evaluate their performance as friction surface and also as concrete sealers. Dural Flexolith, Poly-Carb Flexogrid, and Con/Chem Con/Crete were placed on thre...

Ways to improve the technology of constructing concrete hydraulic structures

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

Osipov, A.D.

1985-05-01

The authors state that there is a need for a critical analysis of the established technology of constructing massive concrete structures and for the search for new, cheap, faster, and less labor-intensive designs when constructing concrete dams. Improvement of the technology of constructing concrete hydraulic structures is possible, they say, by introducing the following suggestions: construction of massive structures mainly from a very stiff, low-cement concrete mix compacted by the vibrating roller method; use of poured self-compacting concrete mixes when constructing reinforced-concrete structural elements of hydrostations, water intakes, tunnel linings, etc.; and by development of the technology of delivering stiffmore » concrete mixes by conveyors and their placement by rotary throwers when revetting slopes. This paper examines these elements in detail.« less

The size effect in corrosion greatly influences the predicted life span of concrete infrastructures.

PubMed

Angst, Ueli M; Elsener, Bernhard

2017-08-01

Forecasting the life of concrete infrastructures in corrosive environments presents a long-standing and socially relevant challenge in science and engineering. Chloride-induced corrosion of reinforcing steel in concrete is the main cause for premature degradation of concrete infrastructures worldwide. Since the middle of the past century, this challenge has been tackled by using a conceptual approach relying on a threshold chloride concentration for corrosion initiation ( C crit ). All state-of-the-art models for forecasting chloride-induced steel corrosion in concrete are based on this concept. We present an experiment that shows that C crit depends strongly on the exposed steel surface area. The smaller the tested specimen is, the higher and the more variable C crit becomes. This size effect in the ability of reinforced concrete to withstand corrosion can be explained by the local conditions at the steel-concrete interface, which exhibit pronounced spatial variability. The size effect has major implications for the future use of the common concept of C crit . It questions the applicability of laboratory results to engineering structures and the reproducibility of typically small-scale laboratory testing. Finally, we show that the weakest link theory is suitable to transform C crit from small to large dimensions, which lays the basis for taking the size effect into account in the science and engineering of forecasting the durability of infrastructures.

The size effect in corrosion greatly influences the predicted life span of concrete infrastructures

PubMed Central

Angst, Ueli M.; Elsener, Bernhard

2017-01-01

Forecasting the life of concrete infrastructures in corrosive environments presents a long-standing and socially relevant challenge in science and engineering. Chloride-induced corrosion of reinforcing steel in concrete is the main cause for premature degradation of concrete infrastructures worldwide. Since the middle of the past century, this challenge has been tackled by using a conceptual approach relying on a threshold chloride concentration for corrosion initiation (Ccrit). All state-of-the-art models for forecasting chloride-induced steel corrosion in concrete are based on this concept. We present an experiment that shows that Ccrit depends strongly on the exposed steel surface area. The smaller the tested specimen is, the higher and the more variable Ccrit becomes. This size effect in the ability of reinforced concrete to withstand corrosion can be explained by the local conditions at the steel-concrete interface, which exhibit pronounced spatial variability. The size effect has major implications for the future use of the common concept of Ccrit. It questions the applicability of laboratory results to engineering structures and the reproducibility of typically small-scale laboratory testing. Finally, we show that the weakest link theory is suitable to transform Ccrit from small to large dimensions, which lays the basis for taking the size effect into account in the science and engineering of forecasting the durability of infrastructures. PMID:28782038

Application of Crushed Concrete in Geotechnical Engineering - Selected Issues

NASA Astrophysics Data System (ADS)

Kawalec, Jacek; Kwiecien, Slawomir; Pilipenko, Anton; Rybak, Jarosław

2017-12-01

The reuse of building materials becomes an important issue in sustainable engineering. As the technical requirements for civil engineering structures changes with time and the life time is limited, the need of building new objects meets the necessity of recycling of the existing ones. In the case of steel structures, the possibility of recycling is obvious, also in the case of wooden constructions, the possibility of “burning” solves the problem. The concrete waste is generated mainly as a result of the demolition and reconstruction of residential and industrial buildings. These types of waste are basically made from crushed rocks and cement minerals and contain non-hydrated cement particles in its composition. Concrete poses a lot of problems mainly for two reasons. It is difficult to crush, heavy and hard to transport and demanding in reuse. Different fractions (particle sizes) may be used for different purposes. Starting from very fine particles which can be used in concrete production, through regular 16-300 mm fractions used to form new fills and fill the mats, up to very irregular mixtures used to form stone columns by means of Impulse Compaction or in Dynamic Replacement. The presented study juxtaposes authors experience with crushed concrete used in civil engineering, mainly in geotechnical projects. Authors’ experiences comprise the application of crushed concrete in the new concrete production in Russia, changing pulverized bridge into the fill of mesh sacks, or mattresses used as an effective way to protect the shoreline and the New Orleans East land bridge after Katrina storm (forming a new shoreline better able to withstand wave actions), and finally the use of very irregular concrete fractions to form stone columns in week soils on the example of railway and road projects in Poland. Selected case studies are presented and summarized with regard to social, technical and economic issues including energy consumption needed for proposed technologies and dynamic impact of ground transmitted vibrations and noise.

Improved specifications for hydraulic cement concrete : final report.

DOT National Transportation Integrated Search

1983-01-01

This is the final report of a study of the application of statistical concepts to specifications for hydraulic cement concrete as used in highway facilities. It reviews the general problems associated with the application of statistical techniques to...

TOPICAL REVIEW: Smart aggregates: multi-functional sensors for concrete structures—a tutorial and a review

NASA Astrophysics Data System (ADS)

Song, Gangbing; Gu, Haichang; Mo, Yi-Lung

2008-06-01

This paper summarizes the authors' recent pioneering research work in piezoceramic-based smart aggregates and their innovative applications in concrete civil structures. The basic operating principle of smart aggregates is first introduced. The proposed smart aggregate is formed by embedding a waterproof piezoelectric patch with lead wires into a small concrete block. The proposed smart aggregates are multi-functional and can perform three major tasks: early-age concrete strength monitoring, impact detection and structural health monitoring. The proposed smart aggregates are embedded into the desired location before the casting of the concrete structure. The concrete strength development is monitored by observing the high frequency harmonic wave response of the smart aggregate. Impact on the concrete structure is detected by observing the open-circuit voltage of the piezoceramic patch in the smart aggregate. For structural health monitoring purposes, a smart aggregate-based active sensing system is designed for the concrete structure. Wavelet packet analysis is used as a signal-processing tool to analyze the sensor signal. A damage index based on the wavelet packet analysis is used to determine the structural health status. To better describe the time-history and location information of damage, two types of damage index matrices are proposed: a sensor-history damage index matrix and an actuator-sensor damage index matrix. To demonstrate the multi-functionality of the proposed smart aggregates, different types of concrete structures have been used as test objects, including concrete bridge bent-caps, concrete cylinders and a concrete frame. Experimental results have verified the effectiveness and the multi-functionality of the proposed smart aggregates. The multi-functional smart aggregates have the potential to be applied to the comprehensive monitoring of concrete structures from their earliest stages and throughout their lifetime.

Multiscale Concrete Modeling of Aging Degradation

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

Hammi, Yousseff; Gullett, Philipp; Horstemeyer, Mark F.

In this work a numerical finite element framework is implemented to enable the integration of coupled multiscale and multiphysics transport processes. A User Element subroutine (UEL) in Abaqus is used to simultaneously solve stress equilibrium, heat conduction, and multiple diffusion equations for 2D and 3D linear and quadratic elements. Transport processes in concrete structures and their degradation mechanisms are presented along with the discretization of the governing equations. The multiphysics modeling framework is theoretically extended to the linear elastic fracture mechanics (LEFM) by introducing the eXtended Finite Element Method (XFEM) and based on the XFEM user element implementation of Ginermore » et al. [2009]. A damage model that takes into account the damage contribution from the different degradation mechanisms is theoretically developed. The total contribution of damage is forwarded to a Multi-Stage Fatigue (MSF) model to enable the assessment of the fatigue life and the deterioration of reinforced concrete structures in a nuclear power plant. Finally, two examples are presented to illustrate the developed multiphysics user element implementation and the XFEM implementation of Giner et al. [2009].« less

Light Water Reactor Sustainability Program: Survey of Models for Concrete Degradation

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

Spencer, Benjamin W.; Huang, Hai

Concrete is widely used in the construction of nuclear facilities because of its structural strength and its ability to shield radiation. The use of concrete in nuclear facilities for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. As such, when life extension is considered for nuclear power plants, it is critical to have predictive tools to address concerns related to aging processes of concrete structures and the capacity of structures subjected to age-related degradation. The goal of this report is to review and document the main aging mechanismsmore » of concern for concrete structures in nuclear power plants (NPPs) and the models used in simulations of concrete aging and structural response of degraded concrete structures. This is in preparation for future work to develop and apply models for aging processes and response of aged NPP concrete structures in the Grizzly code. To that end, this report also provides recommendations for developing more robust predictive models for aging effects of performance of concrete.« less

Statistical Analysis of Japanese Structural Damage Data

DTIC Science & Technology

1977-01-01

buildings and no ready correlation between I-beam and lattice work columns could be established. The complete listing of the buildings contained in the final...subclassification efforts in this structure class. Of the 90 buildings in the data base, two have such light lattice work steel columns that they would...more properly be clas- sified as Very Light Steel Frame Buildings; six have concrete panel walls; two have lattice steel columns that are filled with

Nanostructural Characteristics and Interfacial Properties of Polymer Fibers in Cement Matrix.

PubMed

Shalchy, Faezeh; Rahbar, Nima

2015-08-12

Concrete is the most used material in the world. It is also one of the most versatile yet complex materials that humans have used for construction. However, an important weakness of concrete (cement-based composites) is its low tensile properties. Therefore, over the past 30 years many studies were focused on improving its tensile properties using a variety of physical and chemical methods. One of the most successful attempts is to use polymer fibers in the structure of concrete to obtain a composite with high tensile strength and ductility. The advantages of polymer fiber as reinforcing material in concrete, both with regard to reducing environmental pollution and the positive effects on a country's economy, are beyond dispute. However, a thorough understanding of the mechanical behavior of fiber-reinforced concrete requires a knowledge of fiber/matrix interfaces at the nanoscale. In this study, a combination of atomistic simulations and experimental techniques has been used to study the nanostructure of fiber/matrix interfaces. A new model for calcium-silicate-hydrate (C-S-H)/fiber interfaces is also proposed on the basis of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. Finally, the adhesion energy between the C-S-H gel and three different polymeric fibers (poly(vinyl alcohol), nylon-6, and polypropylene) were numerically studied at the atomistic level because adhesion plays a key role in the design of ductile fiber-reinforced composites. The mechanisms of adhesion as a function of the nanostructure of fiber/matrix interfaces are further studied and discussed. It is observed that the functional group in the structure of polymer macromolecule affects the adhesion energy primarily by changing the C/S ratio of the C-S-H at the interface and by absorbing additional positive ions in the C-S-H structure.

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.

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...

Synthesis of Zinc Oxide Nanoparticles and Their Effect on the Compressive Strength and Setting Time of Self-Compacted Concrete Paste as Cementitious Composites

PubMed Central

Arefi, Mohammad Reza; Rezaei-Zarchi, Saeed

2012-01-01

In the present study, the mechanical properties of self-compacting concrete were investigated after the addition of different amounts of ZnO nanoparticles. The zinc oxide nanoparticles, with an average particle size of about 30 nm, were synthesized and their properties studied with the help of a scanning electron microscope (SEM) and X-ray diffraction. The prepared nanoparticles were partially added to self-compacting concrete at different concentrations (0.05, 0.1, 0.2, 0.5 and 1.0%), and the mechanical (flexural and split tensile) strength of the specimens measured after 7, 14, 21 and 28 days, respectively. The present results have shown that the ZnO nanoparticles were able to improve the flexural strength of self-compacting concrete. The increased ZnO content of more than 0.2% could increase the flexural strength, and the maximum flexural and split tensile strength was observed after the addition of 0.5% nanoparticles. Finally, ZnO nanoparticles could improve the pore structure of the self-compacted concrete and shift the distributed pores to harmless and less-harmful pores, while increasing mechanical strength. PMID:22605981

Synthesis of zinc oxide nanoparticles and their effect on the compressive strength and setting time of self-compacted concrete paste as cementitious composites.

PubMed

Arefi, Mohammad Reza; Rezaei-Zarchi, Saeed

2012-01-01

In the present study, the mechanical properties of self-compacting concrete were investigated after the addition of different amounts of ZnO nanoparticles. The zinc oxide nanoparticles, with an average particle size of about 30 nm, were synthesized and their properties studied with the help of a scanning electron microscope (SEM) and X-ray diffraction. The prepared nanoparticles were partially added to self-compacting concrete at different concentrations (0.05, 0.1, 0.2, 0.5 and 1.0%), and the mechanical (flexural and split tensile) strength of the specimens measured after 7, 14, 21 and 28 days, respectively. The present results have shown that the ZnO nanoparticles were able to improve the flexural strength of self-compacting concrete. The increased ZnO content of more than 0.2% could increase the flexural strength, and the maximum flexural and split tensile strength was observed after the addition of 0.5% nanoparticles. Finally, ZnO nanoparticles could improve the pore structure of the self-compacted concrete and shift the distributed pores to harmless and less-harmful pores, while increasing mechanical strength.

The influence of loading on the corrosion of steel in cracked ordinary Portland cement and high performance concretes

NASA Astrophysics Data System (ADS)

Jaffer, Shahzma Jafferali

Most studies that have examined chloride-induced corrosion of steel in concrete have focused on sound concrete. However, reinforced concrete is seldom uncracked and very few studies have investigated the influence of cracked concrete on rebar corrosion. Furthermore, the studies that have examined the relationship between cracks and corrosion have focused on unloaded or statically loaded cracks. However, in practice, reinforced concrete structures (e.g. bridges) are often dynamically loaded. Hence, the cracks in such structures open and close which could influence the corrosion of the reinforcing steel. Consequently, the objectives of this project were (i) to examine the effect of different types of loading on the corrosion of reinforcing steel, (ii) the influence of concrete mixture design on the corrosion behaviour and (iii) to provide data that can be used in service-life modelling of cracked reinforced concretes. In this project, cracked reinforced concrete beams made with ordinary Portland cement concrete (OPCC) and high performance concrete (HPC) were subjected to no load, static loading and dynamic loading. They were immersed in salt solution to just above the crack level at their mid-point for two weeks out of every four (wet cycle) and, for the remaining two weeks, were left in ambient laboratory conditions to dry (dry cycle). The wet cycle led to three conditions of exposure for each beam: (i) the non-submerged region, (ii) the sound, submerged region and (iii) the cracked mid-section, which was also immersed in the solution. Linear polarization resistance and galvanostatic pulse techniques were used to monitor the corrosion in the three regions. Potentiodynamic polarization, electrochemical current noise and concrete electrical resistance measurements were also performed. These measurements illustrated that (i) rebar corroded faster at cracks than in sound concrete, (ii) HPC was more protective towards the rebar than OPCC even at cracks and (iii) there was a minor effect of the type of loading on rebar corrosion within the period of the project. These measurements also highlighted the problems associated with corrosion measurements, for example, identifying the actual corroding area and the influence of the length of rebar. The numbers of cracks and crack-widths in each beam were measured after the beam's initial exposure to salt solution and, again, after the final corrosion measurements. HPC beams had more cracks than the OPCC. Also, final measurements illustrated increased crack-widths in dynamically loaded beams, regardless of the concrete type. The cracks in both statically and dynamically loaded OPCC and HPC beams bifurcated at the rebar level and propagated parallel to the rebar. This project also examined the extent of corrosion on the rebars and the distribution of corrosion products in the concrete and on the concrete walls of the cracks. Corrosion occurred only at cracks in the concrete and was spread over a larger area on the rebars in HPC than those in OPCC. The damage due to corrosion was superficial in HPC and crater-like in OPCC. Regardless of the concrete type, there was a larger distribution of corrosion products on the crack walls of the dynamically loaded beams. Corrosion products diffused into the cement paste and the paste-aggregate interface in OPCC but remained in the crack in HPC. The most voluminous corrosion product identified was ferric hydroxide. Elemental analysis of mill-scale on rebar which was not embedded in concrete or exposed to chlorides was compared to that of the bars that had been embedded in uncontaminated concrete and in cracked concrete exposed to chlorides. In uncontaminated concrete, mill-scale absorbed calcium and silicon. At a crack, a layer, composed of a mixture of cement paste and corrosion products, developed between the mill-scale and the substrate steel. Based on the results, it was concluded that (i) corrosion occurred on the rebar only at cracks in the concrete, (ii) corrosion was initiated at the cracks immediately upon exposure to salt solution, (ii) the type of loading had a minor influence on the corrosion rates of reinforcing steel and (iv) the use of polarized area led to a significant underestimation of the current density at the crack. It is recommended that the effect of cover-depth on (i) the time to initiation of corrosion and (ii) the corrosion current density in cracked concrete be investigated.

Type A polymer concrete overlay field trials : final report.

DOT National Transportation Integrated Search

1984-12-01

This report describes placement and subsequent performance of two methyl methacrylate polymer concrete overlays. Performance is evaluated as to: 1) the mixing and placement characteristics of the methyl methacrylate polymer concretes as overlay mater...

Evaluation of concrete patching materials : final report.

DOT National Transportation Integrated Search

1985-01-01

The project evaluated numerous repairs on portland cement concrete pavements and bridge decks made with a number of laboratory accepted, proprietary patching materials and portland cement concrete mixtures of different designs. It was ascertained tha...

Application of Composite Mechanics to Composites Enhanced Concrete Structures

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Gotsis, Pascal K.

2006-01-01

A new and effective method is described to design composites to repair damage or enhance the overload strength of concrete infrastructures. The method is based on composite mechanics which is available in computer codes. It is used to simulate structural sections made from reinforced concrete which are typical in infrastructure as well as select reinforced concrete structures. The structural sections are represented by a number of layers through the thickness where different layers are used in concrete, and for the composite. The reinforced concrete structures are represented with finite elements where the element stiffness parameters are from the structural sections which are represented by composite mechanics. The load carrying capability of the structure is determined by progressive structural fracture. Results show up to 40 percent improvements for damage and for overload enhancement with relatively small laminate thickness for the structural sections and up to three times for the composite enhanced select structures (arches and domes).

Development of high integrity, maximum durability concrete structures for LLW disposal facilities

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

Taylor, W.P.

1992-05-01

A number of disposal facilities for Low-Level Radioactive Wastes have been planned for the Savannah River Site. Design has been completed for disposal vaults for several waste classifications and construction is nearly complete or well underway on some facilities. Specific design criteria varies somewhat for each waste classification. All disposal units have been designed as below-grade concrete vaults, although the majority will be above ground for many years before being encapsulated with earth at final closure. Some classes of vaults have a minimum required service life of 100 years. All vaults utilize a unique blend of cement, blast furnace slagmore » and pozzolan. The design synthesizes the properties of the concrete mix with carefully planned design details and construction methodologies to (1) eliminate uncontrolled cracking; (2) minimize leakage potential; and (3) maximize durability. The first of these vaults will become operational in 1992. 9 refs.« less

Development of high integrity, maximum durability concrete structures for LLW disposal facilities

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

Taylor, W.P.

1992-01-01

A number of disposal facilities for Low-Level Radioactive Wastes have been planned for the Savannah River Site. Design has been completed for disposal vaults for several waste classifications and construction is nearly complete or well underway on some facilities. Specific design criteria varies somewhat for each waste classification. All disposal units have been designed as below-grade concrete vaults, although the majority will be above ground for many years before being encapsulated with earth at final closure. Some classes of vaults have a minimum required service life of 100 years. All vaults utilize a unique blend of cement, blast furnace slagmore » and pozzolan. The design synthesizes the properties of the concrete mix with carefully planned design details and construction methodologies to (1) eliminate uncontrolled cracking; (2) minimize leakage potential; and (3) maximize durability. The first of these vaults will become operational in 1992. 9 refs.« less

Bond-slip detection of concrete-encased composite structure using electro-mechanical impedance technique

NASA Astrophysics Data System (ADS)

Liang, Yabin; Li, Dongsheng; Parvasi, Seyed Mohammad; Kong, Qingzhao; Lim, Ing; Song, Gangbing

2016-09-01

Concrete-encased composite structure is a type of structure that takes the advantages of both steel and concrete materials, showing improved strength, ductility, and fire resistance compared to traditional reinforced concrete structures. The interface between concrete and steel profiles governs the interaction between these two materials under loading, however, debonding damage between these two materials may lead to severe degradation of the load transferring capacity which will affect the structural performance significantly. In this paper, the electro-mechanical impedance (EMI) technique using piezoceramic transducers was experimentally investigated to detect the bond-slip occurrence of the concrete-encased composite structure. The root-mean-square deviation is used to quantify the variations of the impedance signatures due to the presence of the bond-slip damage. In order to verify the validity of the proposed method, finite element model analysis was performed to simulate the behavior of concrete-steel debonding based on a 3D finite element concrete-steel bond model. The computed impedance signatures from the numerical results are compared with the results obtained from the experimental study, and both the numerical and experimental studies verify the proposed EMI method to detect bond slip of a concrete-encased composite structure.

Research progress of microbial corrosion of reinforced concrete structure

NASA Astrophysics Data System (ADS)

Li, Shengli; Li, Dawang; Jiang, Nan; Wang, Dongwei

2011-04-01

Microbial corrosion of reinforce concrete structure is a new branch of learning. This branch deals with civil engineering , environment engineering, biology, chemistry, materials science and so on and is a interdisciplinary area. Research progress of the causes, research methods and contents of microbial corrosion of reinforced concrete structure is described. The research in the field is just beginning and concerted effort is needed to go further into the mechanism of reinforce concrete structure and assess the security and natural life of reinforce concrete structure under the special condition and put forward the protective methods.

Portland-cement concrete rheology and workability : final report.

DOT National Transportation Integrated Search

2011-04-01

Methods for determining the workability of freshly mixed Portland-cement concrete with : slumps less than 5 1 mm (2 in) were investigated. Four potential methods to determine the : workability of concrete were proposed for evaluation and development....

Rapid setting concrete patching study : final report.

DOT National Transportation Integrated Search

1975-03-01

This investigation was prompted by the increasing number of concrete roadway failures which have required corrective action. A more permanent solution than the placing of hot or cold mixed asphalt compounds into concrete voids was deemed necessary. t...

75 FR 28557 - Pre-Stressed Concrete Steel Wire Strand from the People's Republic of China: Final Affirmative...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-21

...-stressed concrete (both pre-tensioned and post- tensioned) applications. The scope of this investigation... DEPARTMENT OF COMMERCE International Trade Administration [C-570-946] Pre-Stressed Concrete Steel... producers and exporters of pre-stressed concrete steel wire strand from the People's Republic of China (the...

Advanced Numerical Model for Irradiated Concrete

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

Giorla, Alain B.

In this report, we establish a numerical model for concrete exposed to irradiation to address these three critical points. The model accounts for creep in the cement paste and its coupling with damage, temperature and relative humidity. The shift in failure mode with the loading rate is also properly represented. The numerical model for creep has been validated and calibrated against different experiments in the literature [Wittmann, 1970, Le Roy, 1995]. Results from a simplified model are shown to showcase the ability of numerical homogenization to simulate irradiation effects in concrete. In future works, the complete model will be appliedmore » to the analysis of the irradiation experiments of Elleuch et al. [1972] and Kelly et al. [1969]. This requires a careful examination of the experimental environmental conditions as in both cases certain critical information are missing, including the relative humidity history. A sensitivity analysis will be conducted to provide lower and upper bounds of the concrete expansion under irradiation, and check if the scatter in the simulated results matches the one found in experiments. The numerical and experimental results will be compared in terms of expansion and loss of mechanical stiffness and strength. Both effects should be captured accordingly by the model to validate it. Once the model has been validated on these two experiments, it can be applied to simulate concrete from nuclear power plants. To do so, the materials used in these concrete must be as well characterized as possible. The main parameters required are the mechanical properties of each constituent in the concrete (aggregates, cement paste), namely the elastic modulus, the creep properties, the tensile and compressive strength, the thermal expansion coefficient, and the drying shrinkage. These can be either measured experimentally, estimated from the initial composition in the case of cement paste, or back-calculated from mechanical tests on concrete. If some are unknown, a sensitivity analysis must be carried out to provide lower and upper bounds of the material behaviour. Finally, the model can be used as a basis to formulate a macroscopic material model for concrete subject to irradiation, which later can be used in structural analyses to estimate the structural impact of irradiation on nuclear power plants.« less

Inspection of Nuclear Power Plant Containment Structures

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

Graves, H.L.; Naus, D.J.; Norris, W.E.

1998-12-01

Safety-related nuclear power plant (NPP) structures are designed to withstand loadings from a number of low-probability external and interval events, such as earthquakes, tornadoes, and loss-of-coolant accidents. Loadings incurred during normal plant operation therefore generally are not significant enough to cause appreciable degradation. However, these structures are susceptible to aging by various processes depending on the operating environment and service conditions. The effects of these processes may accumulate within these structures over time to cause failure under design conditions, or lead to costly repair. In the late 1980s and early 1990s several occurrences of degradation of NPP structures were discoveredmore » at various facilities (e.g., corrosion of pressure boundary components, freeze- thaw damage of concrete, and larger than anticipated loss of prestressing force). Despite these degradation occurrences and a trend for an increasing rate of occurrence, in-service inspection of the safety-related structures continued to be performed in a somewhat cursory manner. Starting in 1991, the U.S. Nuclear Regulatory Commission (USNRC) published the first of several new requirements to help ensure that adequate in-service inspection of these structures is performed. Current regulatory in-service inspection requirements are reviewed and a summary of degradation experience presented. Nondestructive examination techniques commonly used to inspect the NPP steel and concrete structures to identify and quantify the amount of damage present are reviewed. Finally, areas where nondestructive evaluation techniques require development (i.e., inaccessible portions of the containment pressure boundary, and thick heavily reinforced concrete sections are discussed.« less

Comparative analysis of structural concrete quality assurance practices on nine nuclear power plant construction projects. Final report

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

Willenbrock, J.H.; Thomas, H.R. Jr.; Burati, J.L. Jr.

1978-06-01

The basic objective of this research effort was to perform a comparative analysis of the Quality Assurance practices related to the structural concrete phase on nine nuclear power plant projects which are (or have been) under construction in the United States in the past ten years. This analysis identified the response of each Quality Assurance program to the applicable criteria of 10 CFR Part 50, Appendix B as well as to the pertinent regulatory requirements and industry standards. The major emphasis was placed on the construction aspects of the structural concrete phase of each project. The engineering and design aspectsmore » were examined whenever they interfaced with the construction aspects. For those aspects of the Quality Assurance system which can be considered managerial in nature (i.e., organizational relationships, types of Quality Assurance programs, corrective action procedures, etc.) an attempt has been made to present the alternative approaches that were identified. For those aspects of the Quality Assurance system which are technical in nature (i.e., the frequency of testing for slump, compressive strength, etc.) an attempt has been made to present a comparative analysis between projects and in relation to the recommended or mandated practices presented in the appropriate industry codes and standards.« less

Development of Non-Proprietary Ultra-High Performance Concrete : Final Report

DOT National Transportation Integrated Search

2017-12-01

Ultra-high performance concrete (UHPC) has mechanical and durability properties that far exceed those of conventional concrete. Particularly, UHPC has compressive and post-cracking tensile strengths of around 20 ksi and 0.72 ksi, respectively. Thus, ...

Protection of reinforced concrete bridge substructures using submerged bulk anodes : final report, January 25, 2009.

DOT National Transportation Integrated Search

2010-01-01

Reinforced concrete bridge substructures in Florida coastal waters have historically experienced deterioration as a consequence of embedded steel corrosion and resultant concrete cracking and spalling. Ultimately, this deterioration leads to added ma...

Development of design parameters for virtual cement and concrete testing : [summary].

DOT National Transportation Integrated Search

2013-12-01

At its most basic, concrete is made from cement : and aggregate, often Portland cement and gravel : (or in Florida, limestone). Varying ingredients and : their proportions directly influences the behavior : of the final cement and concrete products. ...

Fly ash in concrete : final report.

DOT National Transportation Integrated Search

1990-08-01

This study was initiated to develop information regarding the use of fly ash in portland cement concrete for state construction projects. : Concrete mixes containing 10%, 20%, 30%, 40% and 60% fly ash were evaluated in the laboratory in combination w...

Evaluation of various coarse aggregate concretes : final report.

DOT National Transportation Integrated Search

1983-10-01

This study was initiated to determine the properties of concrete using three types of coarse aggregate. The coarse aggregates evaluated in this study included silicious gravel, the standard aggregate for concrete in the state, with sandstone and lime...

Concrete debris assessment for road construction activities : final report.

DOT National Transportation Integrated Search

2016-08-01

Two distinct but related issues of importance to FDOT were investigated: (1) the possible impact of : recycled concrete aggregate (RCA) used as road base on the subsurface environment and (2) the : management of concrete grinding residuals (CGR) resu...

Performance and acceptance of self-consolidating concrete : final report

DOT National Transportation Integrated Search

2008-01-01

Self-consolidating concrete (SCC) is an important emerging material that can be used for many applications related to transportation infrastructure. SCC has an advantage over conventional concrete in that it can be easily placed without vibration or ...

Evaluating the strength of concrete structure on terrace houses

NASA Astrophysics Data System (ADS)

Hasbullah, Mohd. Amran; Yusof, Rohana; Rahman, Mohd Nazaruddin Yusoff @ Abdul

2016-08-01

The concrete structure is the main component to support the structure of the building, but when concrete has been used for an extended period hence, it needs to be evaluated to determine the current strength, durability and how long it can last. The poor quality of concrete structures will cause discomfort to the user and, the safety will be affected due to lack of concrete strength. If these issues are not monitored or not precisely known performance, and no further action done then, the concrete structure will fail and eventually it will collapse. Five units of terrace houses that are built less than 10 years old with extension or renovations and have cracks at Taman Samar Indah, Samarahan, Sarawak have been selected for this study. The instrument used in this research is Ultrasonic Pulse Velocity (UPV), with the objective to determine the current strength and investigate the velocity of a pulse at the concrete cracks. The data showed that the average velocity of the pulse is less than 3.0 km/s and has shown that the quality of the concrete in the houses too weak scale / doubt in the strength of concrete. It also indicates that these houses need to have an immediate repair in order to remain secure other concrete structures.

75 FR 1755 - Prestressed Concrete Steel Wire Strand From the People's Republic of China: Postponement of Final...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-13

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-945] Prestressed Concrete Steel Wire Strand From the People's Republic of China: Postponement of Final Determination AGENCY: Import Administration, International Trade Administration, Department of Commerce. DATES: Effective Date: January 13...

Design for FRP systems for strengthening concrete girders in shear : status letter.

DOT National Transportation Integrated Search

2010-09-24

This is to let you know that we have completed our NCHRP 12-75 project entitled DESIGN OF : FRP SYSTEMS FOR STRENGTHENING CONCRETE GIRDERS IN SHEAR and submitted the final : report on June 7, 2010. The report is undergoing final editorial revis...

Deterioration of concrete structures in coastal environment due to carbonation.

PubMed

Balaji, K V G D; Gopalaraju, S S S V; Trilochan, Jena

2010-07-01

Failure of existing concrete structures takes place due to lack of durability, and not due to less structural strength. One of the important aspects of durability is carbonation depth. The rate of carbonation in concrete is influenced by both its physical properties and exposure conditions. Rebar corrodes when carbonation reaches to a depth of concrete cover provided. In the present work, various concrete structures with different life periods and exposed to different weather conditions have been considered to study the carbonation effect. It is observed that the effect of carbonation is more in the structures located near to the sea coast and on windward face of the structure.

Evaluation of Advanced Signal Processing Techniques to Improve Detection and Identification of Embedded Defects

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

Clayton, Dwight A.; Santos-Villalobos, Hector J.; Baba, Justin S.

By the end of 1996, 109 Nuclear Power Plants were operating in the United States, producing 22% of the Nation’s electricity [1]. At present, more than two thirds of these power plants are more than 40 years old. The purpose of the U.S. Department of Energy Office of Nuclear Energy’s Light Water Reactor Sustainability (LWRS) Program is to develop technologies and other solutions that can improve the reliability, sustain the safety, and extend the operating lifetimes of nuclear power plants (NPPs) beyond 60 years [2]. The most important safety structures in an NPP are constructed of concrete. The structures generallymore » do not allow for destructive evaluation and access is limited to one side of the concrete element. Therefore, there is a need for techniques and technologies that can assess the internal health of complex, reinforced concrete structures nondestructively. Previously, we documented the challenges associated with Non-Destructive Evaluation (NDE) of thick, reinforced concrete sections and prioritized conceptual designs of specimens that could be fabricated to represent NPP concrete structures [3]. Consequently, a 7 feet tall, by 7 feet wide, by 3 feet and 4-inch-thick concrete specimen was constructed with 2.257-inch-and 1-inch-diameter rebar every 6 to 12 inches. In addition, defects were embedded the specimen to assess the performance of existing and future NDE techniques. The defects were designed to give a mix of realistic and controlled defects for assessment of the necessary measures needed to overcome the challenges with more heavily reinforced concrete structures. Information on the embedded defects is documented in [4]. We also documented the superiority of Frequency Banded Decomposition (FBD) Synthetic Aperture Focusing Technique (SAFT) over conventional SAFT when probing defects under deep concrete cover. Improvements include seeing an intensity corresponding to a defect that is either not visible at all in regular, full frequency content SAFT, or an improvement in contrast over conventional SAFT reconstructed images. This report documents our efforts in four fronts: 1) Comparative study between traditional SAFT and FBD SAFT for concrete specimen with and without Alkali-Silica Reaction (ASR) damage, 2) improvement of our Model-Based Iterative Reconstruction (MBIR) for thick reinforced concrete [5], 3) development of a universal framework for sharing, reconstruction, and visualization of ultrasound NDE datasets, and 4) application of machine learning techniques for automated detection of ASR inside concrete. Our comparative study between FBD and traditional SAFT reconstruction images shows a clear difference between images of ASR and non-ASR specimens. In particular, the left first harmonic shows an increased contrast and sensitivity to ASR damage. For MBIR, we show the superiority of model-based techniques over delay and sum techniques such as SAFT. Improvements include elimination of artifacts caused by direct arrival signals, and increased contrast and Signal to Noise Ratio. For the universal framework, we document a format for data storage based on the HDF5 file format, and also propose a modular Graphic User Interface (GUI) for easy customization of data conversion, reconstruction, and visualization routines. Finally, two techniques for ASR automated detection are presented. The first technique is based on an analysis of the frequency content using Hilbert Transform Indicator (HTI) and the second technique employees Artificial Neural Network (ANN) techniques for training and classification of ultrasound data as ASR or non-ASR damaged classes. The ANN technique shows great potential with classification accuracy above 95%. These approaches are extensible to the detection of additional reinforced, thick concrete defects and damage.« less

Correlation of rates of tritium migration through porous concrete

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

Fukada, S.; Katayama, K.; Takeishi, T.

In a nuclear facility when tritium leaks from a glovebox to room accidentally, an atmosphere detritiation system (ADS) starts operating, and HTO released is recovered by ADS. ADS starts when tritium activity in air becomes higher than its controlled level. Before ADS operates, the laboratory walls are the final enclosure facing tritium and are usually made of porous concrete coated with a hydrophobic paint. In the present study, previous data on the diffusivity and adsorption coefficient of concrete and paints are reviewed. Tritium penetrates and migrates into concrete by following 3 ways. First, gaseous HT or T{sub 2} easily penetratesmore » into porous concrete. Its diffusivity is almost equal to that of H{sub 2}. When a gaseous molecule diffuses through pores with a smaller diameter than a mean free path, its migration rate is described by the Knudsen diffusion formula. The second mechanism is H{sub 2}O vapor diffusion in pores. Concrete holds a lot of structural water. Therefore, H{sub 2}O or HTO vapor can diffuse inside concrete pores along with adsorption-desorption and isotopic exchange with structural water, which is the third mechanism. Literature shows that the diffusivity of HTO through the epoxy-resin paint is determined as D(HTO)=1.0*10{sup -16} m{sup 2}/s. We have used this data to set a model and we have applied it to estimate residual tritium in laboratory walls. We have considered 2 accidental cases and a normal case: first, ADS starts operating 1 hour after 100 Ci HTO is released in the room, secondly, ADS starts 24 hours after 100 Ci HTO release and thirdly, when the walls are exposed to HTO for 10 years of normal operation. It appears that the immediate start up of ADS is indispensable for safety.« less

On Deterioration Mechanism of Concrete Exposed to Freeze-Thaw Cycles

NASA Astrophysics Data System (ADS)

Trofimov, B. Ya; Kramar, L. Ya; Schuldyakov, K. V.

2017-11-01

At present, concrete and reinforced concrete are gaining ground in all sectors of construction including construction in the extreme north, on shelves, etc. Under harsh service conditions, the durability of reinforced concrete structures is related to concrete frost resistance. Frost resistance tests are accompanied by the accumulation of residual dilation deformations affected by temperature-humidity stresses, ice formation and other factors. Porosity is an integral part of the concrete structure which is formed as a result of cement hydration. The prevailing hypothesis of a deterioration mechanism of concrete exposed to cyclic freezing, i.e. the hypothesis of hydraulic pressure of unfrozen water in microcapillaries, does not take into account a number of phenomena that affect concrete resistance to frost aggression. The main structural element of concrete, i.e. hardened cement paste, contains various hydration products, such as crystalline, semicrystalline and gel-like products, pores and non-hydrated residues of clinker nodules. These structural elements in service can gain thermodynamic stability which leads to the concrete structure coarsening, decrease in the relaxation capacity of concrete when exposed to cycling. Additional destructive factors are leaching of portlandite, the difference in thermal dilation coefficients of hydration products, non-hydrated relicts, aggregates and ice. The main way to increase concrete frost resistance is to reduce the macrocapillary porosity of hardened cement paste and to form stable gel-like hydration products.

Investigation of Mechanism of Action of Modifying Admixtures Based on Products of Petrochemical Synthesis on Concrete Structure

NASA Astrophysics Data System (ADS)

Tukhareli, V. D.; Tukhareli, A. V.; Cherednichenko, T. F.

2017-11-01

The creation of composite materials for generating structural elements with the desired properties has always been and still remains relevant. The basis of a modern concrete technology is the creation of a high-quality artificial stone characterized by low defectiveness and structure stability. Improving the quality of concrete compositions can be achieved by using chemical admixtures from local raw materials which is a very promising task of modern materials’ science for creation of a new generation of concretes. The new generation concretes are high-tech, high-quality, multicomponent concrete mixes and compositions with admixtures that preserve the required properties in service under all operating conditions. The growing complexity of concrete caused by systemic effects that allow you to control the structure formation at all stages of the technology ensures the obtaining of composites with "directional" quality, compositions, structure and properties. The possibility to use the organic fraction of oil refining as a multifunctional hydrophobic-plasticizing admixture in the effective cement concrete is examined.

A reusable PZT transducer for monitoring initial hydration and structural health of concrete.

PubMed

Yang, Yaowen; Divsholi, Bahador Sabet; Soh, Chee Kiong

2010-01-01

During the construction of a concrete structure, strength monitoring is important to ensure the safety of both personnel and the structure. Furthermore, to increase the efficiency of in situ casting or precast of concrete, determining the optimal time of demolding is important for concrete suppliers. Surface bonded lead zirconate titanate (PZT) transducers have been used for damage detection and parameter identification for various engineering structures over the last two decades. In this work, a reusable PZT transducer setup for monitoring initial hydration of concrete and structural health is developed, where a piece of PZT is bonded to an enclosure with two bolts tightened inside the holes drilled in the enclosure. An impedance analyzer is used to acquire the admittance signatures of the PZT. Root mean square deviation (RMSD) is employed to associate the change in concrete strength with changes in the PZT admittance signatures. The results show that the reusable setup is able to effectively monitor the initial hydration of concrete and the structural health. It can also be detached from the concrete for future re-use.

A Reusable PZT Transducer for Monitoring Initial Hydration and Structural Health of Concrete

PubMed Central

Yang, Yaowen; Divsholi, Bahador Sabet; Soh, Chee Kiong

2010-01-01

During the construction of a concrete structure, strength monitoring is important to ensure the safety of both personnel and the structure. Furthermore, to increase the efficiency of in situ casting or precast of concrete, determining the optimal time of demolding is important for concrete suppliers. Surface bonded lead zirconate titanate (PZT) transducers have been used for damage detection and parameter identification for various engineering structures over the last two decades. In this work, a reusable PZT transducer setup for monitoring initial hydration of concrete and structural health is developed, where a piece of PZT is bonded to an enclosure with two bolts tightened inside the holes drilled in the enclosure. An impedance analyzer is used to acquire the admittance signatures of the PZT. Root mean square deviation (RMSD) is employed to associate the change in concrete strength with changes in the PZT admittance signatures. The results show that the reusable setup is able to effectively monitor the initial hydration of concrete and the structural health. It can also be detached from the concrete for future re-use. PMID:22399929

Concrete deck material properties : final report.

DOT National Transportation Integrated Search

2009-01-01

The two-fold focus of this study was (a) to develop an understanding of the mechanisms responsible for causing : cracking in the concrete; and (b) to study the influence of the local materials on the performance of NYSDOTs HP : concrete mixture. R...

Impact of aggregate gradation on properties of Portland cement concrete : final report.

DOT National Transportation Integrated Search

2013-10-15

Increasingly, aggregates in South Carolina are failing to meet the standard requirements for gradation for use in : portland cement concrete. The effect of such failed aggregate gradations on concrete properties and the : consequent effect on short- ...

Modeling of interaction between steel and concrete in continuously reinforced concrete pavements : final report.

DOT National Transportation Integrated Search

2016-01-01

Continuously reinforced concrete pavement (CRCP) contains continuous longitudinal reinforcement with no transverse : expansion within the early life of the pavement and can continue to develop cracks in the long-term. The : accurate modeling of CRCPs...

Microwave reflection measurements of the dielectric properties of concrete : final report.

DOT National Transportation Integrated Search

1983-01-01

The use of microwave reflection measurements to continuously and nondestructively monitor the hydration of concrete is described. The method relies upon the influence of the free-water content on the dielectric properties of the concrete. Use of the ...

Shear capacity assessment of corrosion-damaged reinforced concrete beams : final report.

DOT National Transportation Integrated Search

2003-12-01

This study investigated how the shear capacity of reinforced concrete bridge beams is affected by corrosion damage to the shear stirrups. It described the changes that occur in shear capacity and concrete cracking as shear stirrup corrosion progresse...

Development of Non-Proprietary Ultra High Performance Concrete : Final Presentation : November, 2017

DOT National Transportation Integrated Search

2017-11-01

Ultra-high performance concrete (UHPC) has mechanical and durability properties that far exceed those of conventional concrete. Particularly, UHPC has compressive and post-cracking tensile strengths of around 20 ksi and 0.72 ksi, respectively. Thus, ...

Review of a bituminous concrete statistical specification : final report.

DOT National Transportation Integrated Search

1971-01-01

The statistically oriented specification for bituminous concrete production reviewed in this report was used as a basis for acceptance of more than one million tons of bituminous concrete in 1970. Data obtained from this system were analyzed for grad...

Statistical methods for the quality control of steam cured concrete : final report.

DOT National Transportation Integrated Search

1971-01-01

Concrete strength test results from three prestressing plants utilizing steam curing were evaluated statistically in terms of the concrete as received and the effectiveness of the plants' steaming procedures. Control charts were prepared to show tren...

Data on optimum recycle aggregate content in production of new structural concrete.

PubMed

Paul, Suvash Chandra

2017-12-01

This data presented herein are the research summary of "mechanical behavior and durability performance of concrete containing recycled concrete aggregate" (Paul, 2011) [1]. The results reported in this article relate to an important parameter of optimum content of recycle concrete aggregate (RCA) in production of new concrete for both structural and non-structural applications. For the purpose of the research various types of physical, mechanical and durability tests are performed for concrete made with different percentages of RCA. Therefore, this data set can be a great help of the readers to understand the mechanism of RCA in relates to the concrete properties.

Performance and cost analysis of a structured concrete thermocline thermal energy storage system

NASA Astrophysics Data System (ADS)

Strasser, Matthew N.

Increasing global energy demands and diminishing fossil fuel resources have raised increased interest in harvesting renewable energy resources. Solar energy is a promising candidate, as sufficient irradiance is incident to the Earth to supply the energy demands of all of its inhabitants. At the utility scale, concentrating solar power (CSP) plants provide the most cost-efficient method of harnessing solar energy for conversion to electrical energy. A major roadblock to the large-scale implementation of CSP plants is the lack of thermal energy storage (TES) that would allow the continued production of electricity during the absence of constant irradiance. Sensible heat TES has been suggested as the most viable form of TES for CSP plants. Two-tank fluid TES systems have been incorporated at several CSP plants, significantly enhancing the performance of the plants. A single-tank thermocline TES system, requiring a reduced liquid media volume, has been suggested as a cost-reducing alternative. Unfortunately, the packed-aggregate bed of such TES system introduces the issue of thermal ratcheting and rupture of the tank's walls. To address this issue, it has been suggested that structured concrete be used in place of the aggregate bed. Potential concrete mix designs have been developed and tested for this application. Finite-difference-based numeric models are used to study the performance of packed-bed and structured concrete thermocline TES systems. Optimized models are developed for both thermocline configurations. The packed-bed thermocline model is used to determine whether or not assuming constant fluid properties over a temperature range is an acceptable assumption. A procedure is developed by which the cost of two-tank and single-tank thermocline TES systems in the capacity range of 100-3000 MWhe can be calculated. System Advisory Model is used to perform life-cycle cost and performance analysis of a central receiver plant incorporating four TES scenarios: no TES, two-tank TES, packed-bed thermocline TES, and structured concrete thermocline TES. Conclusions are drawn as to which form of TES provides the most viable option. Finally, concrete specimens cast from the aforementioned mix designs are tested in the presence of molten solar salt, and their applicability as structured filler material is assessed.

Evaluation of epoxy compounds as a material for patching and protecting concrete : final report.

DOT National Transportation Integrated Search

1971-01-01

The final report summarizes the results of a study of the use of epoxy compounds in the shallow surface repair and sealing of concrete bridge decks. The research effort concentrated on the use of epoxy resin systems as bonded overlays and included ev...

Special sensors for deformation measurements of different construction materials and structures

NASA Astrophysics Data System (ADS)

Glisic, Branko; Inaudi, Daniele; Kronenberg, Pascal; LLoret, Sandra; Vurpillot, Samuel

1999-05-01

SOFO is a fiber optic sensor system that allows the monitoring of micrometer deformations over measurement bases up to a few meters. It is particularly adapted to measure civil structures built with conventional civil engineering materials (concrete, steel and timber). It has been successfully tested in different types of structures such as bridges, tunnels and piles. The application of the system is however limited in some case when unusual materials are used in the construction and in other cases by the dimensions of standard SOFO sensors. To extend the domain of application of the current system, special sensors have been developed. In this paper we present four special SOFO sensors: long, membrane, thin and stiff sensors. The long sensor has a measurement basis of several tenths of meters and its purpose is the measurement of deformations in massive and large structures (dames, tunnels). The membrane sensor is for use on laminated materials (e.g. membrane roofing) and it is easy to install by simply gluing it to the structure to be monitored. Since standard sensors can not be used for thin mortar layers because of their cross- section, a thin sensor has been developed, too. Finally, the aim of the stiff sensor is to determine the hardening (solidification) time of concrete. This time is determined by comparing the deformations of a stiff and a standard sensor, closely placed in the concrete at the very early age. The design of these sensors is presented along with significant application examples.

Contrastive Numerical Investigations on Thermo-Structural Behaviors in Mass Concrete with Various Cements

PubMed Central

Zhou, Wei; Feng, Chuqiao; Liu, Xinghong; Liu, Shuhua; Zhang, Chao; Yuan, Wei

2016-01-01

This work is a contrastive investigation of numerical simulations to improve the comprehension of thermo-structural coupled phenomena of mass concrete structures during construction. The finite element (FE) analysis of thermo-structural behaviors is used to investigate the applicability of supersulfated cement (SSC) in mass concrete structures. A multi-scale framework based on a homogenization scheme is adopted in the parameter studies to describe the nonlinear concrete behaviors. Based on the experimental data of hydration heat evolution rate and quantity of SSC and fly ash Portland cement, the hydration properties of various cements are studied. Simulations are run on a concrete dam section with a conventional method and a chemo-thermo-mechanical coupled method. The results show that SSC is more suitable for mass concrete structures from the standpoint of temperature control and crack prevention. PMID:28773517

Contrastive Numerical Investigations on Thermo-Structural Behaviors in Mass Concrete with Various Cements.

PubMed

Zhou, Wei; Feng, Chuqiao; Liu, Xinghong; Liu, Shuhua; Zhang, Chao; Yuan, Wei

2016-05-20

This work is a contrastive investigation of numerical simulations to improve the comprehension of thermo-structural coupled phenomena of mass concrete structures during construction. The finite element (FE) analysis of thermo-structural behaviors is used to investigate the applicability of supersulfated cement (SSC) in mass concrete structures. A multi-scale framework based on a homogenization scheme is adopted in the parameter studies to describe the nonlinear concrete behaviors. Based on the experimental data of hydration heat evolution rate and quantity of SSC and fly ash Portland cement, the hydration properties of various cements are studied. Simulations are run on a concrete dam section with a conventional method and a chemo-thermo-mechanical coupled method. The results show that SSC is more suitable for mass concrete structures from the standpoint of temperature control and crack prevention.

The Effect of Different Shape and Perforated rHDPE in Concrete Structures on Flexural Strength

NASA Astrophysics Data System (ADS)

Yuhazri, MY; Hafiz, KM; Myia, YZA; Jia, CP; Sihombing, H.; Sapuan, SM; Badarulzaman, NA

2017-10-01

This research was carried out to develop a reinforcing structure from recycled HDPE plastic lubricant containers to be embedded in concrete structure. Different forms and shapes of recycled HDPE plastic are designed as reinforcement incorporate with cement. In this study, the reinforcing structure was prepared by washing, cutting, dimensioning and joining of the waste HDPE containers (direct technique without treatment on plastic surface). Then, the rHDPE reinforced concrete was produced by casting based on standard of procedure in civil engineering technique. Eight different shapes of rHDPE in concrete structure were used to determine the concrete’s ability in terms of flexural strength. Embedded round shape in solid and perforated of rHDPE in concrete system drastically improved flexural strength at 17.78 % and 13.79 %. The result would seem that the concrete with reinforcing rHDPE structure exhibits a more gradual or flexible properties than concrete beams without reinforcement that has the properties of fragile.

The effects of pressure dependent constitutive model to simulate concrete structures failure under impact loads

NASA Astrophysics Data System (ADS)

Mokhatar, S. N.; Sonoda, Y.; Kamarudin, A. F.; Noh, M. S. Md; Tokumaru, S.

2018-04-01

The main objective of this paper is to explore the effect of confining pressure in the compression and tension zone by simulating the behaviour of reinforced concrete/mortar structures subjected to the impact load. The analysis comprises the numerical simulation of the influences of high mass low speed impact weight dropping on concrete structures, where the analyses are incorporated with meshless method namely as Smoothed Particle Hydrodynamics (SPH) method. The derivation of the plastic stiffness matrix of Drucker-Prager (DP) that extended from Von-Mises (VM) yield criteria to simulate the concrete behaviour were presented in this paper. In which, the displacements for concrete/mortar structures are assumed to be infinitesimal. Furthermore, the influence of the different material model of DP and VM that used numerically for concrete and mortar structures are also discussed. Validation upon existing experimental test results is carried out to investigate the effect of confining pressure, it is found that VM criterion causes unreal impact failure (flexural cracking) of concrete structures.

Testing of concrete by laser ablation

DOEpatents

Flesher, Dann J.; Becker, David L.; Beem, William L.; Berry, Tommy C.; Cannon, N. Scott

1997-01-01

A method of testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed.

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).

Acoustic emission characterization of steel fibre reinforced concrete during bending

NASA Astrophysics Data System (ADS)

Aggelis, D. G.; Soulioti, D. V.; Sapouridis, N.; Barkoula, N. M.; Paipetis, A. S.; Matikas, T. E.

2010-04-01

The acoustic emission (AE) behaviour of steel fibre reinforced concrete is studied in this paper. The experiments were conducted in four-point bending with concurrent monitoring of AE signals. The sensors used, were of broadband response in order to capture a wide range of fracturing phenomena. The results indicate that AE parameters undergo significant changes much earlier than the final fracture of the specimens, even if the AE hit rate seems approximately constant. Specifically, the Ib-value which takes into account the amplitude distribution of the recent AE hits decreases when the load reaches about 60-70 % of its maximum value. Additionally, the average frequency of the signals decreases abruptly when a fracture incident occurs, indicating that matrix cracking events produce higher frequencies than fibre pull-out events. It is concluded that proper study of AE parameters enables the characterization of structural health of large structures in cases where remote monitoring is applied.

Early strength prediction of concrete based on accelerated curing methods : final report.

DOT National Transportation Integrated Search

1995-12-01

Concrete mix designs and components may currently be changed during the course of a project. The possible negative effects of such changes on concrete strength, are not determined under the current plant control/project control process. Also, the cur...

Effective field use of high-range, water-reduced concrete : final report.

DOT National Transportation Integrated Search

1981-01-01

This report describes the experience of the Virginia Department of Highways and Transportation with the use of high range, water reduced (HRWR) concrete. A description of the installation of the HRWR concrete in two pavements and four bridge decks, a...

Protective coatings on concrete surfaces : Madden Macryseal : experimental feature : final report.

DOT National Transportation Integrated Search

1985-02-01

The intrusion of salt-laden moisture into concrete bridge members has caused considerable damage to bridges along the Oregon coast. The increasing chloride ion content of the concrete fosters a galvanic corrosion cell. This results in the rapid corro...

Structural vulnerability assessment using reliability of slabs in avalanche area

NASA Astrophysics Data System (ADS)

Favier, Philomène; Bertrand, David; Eckert, Nicolas; Naaim, Mohamed

2013-04-01

Improvement of risk assessment or hazard zoning requires a better understanding of the physical vulnerability of structures. To consider natural hazard issue such as snow avalanches, once the flow is characterized, highlight on the mechanical behaviour of the structure is a decisive step. A challenging approach is to quantify the physical vulnerability of impacted structures according to various avalanche loadings. The main objective of this presentation is to introduce methodology and outcomes regarding the assessment of vulnerability of reinforced concrete buildings using reliability methods. Reinforced concrete has been chosen as it is one of the usual material used to build structures exposed to potential avalanche loadings. In avalanche blue zones, structures have to resist to a pressure up to 30kPa. Thus, by providing systematic fragility relations linked to the global failure of the structure, this method may serve the avalanche risk assessment. To do so, a slab was numerically designed. It represented the avalanche facing wall of a house. Different configuration cases of the element in stake have been treated to quantify numerical aspects of the problem, such as the boundary conditions or the mechanical behaviour of the structure. The structure is analysed according to four different limit states, semi-local and global failures are considered to describe the slab behaviour. The first state is attained when cracks appear in the tensile zone, then the two next states are described consistent with the Eurocode, the final state is the total collapse of the structure characterized by the yield line theory. Failure probability is estimated in accordance to the reliability framework. Monte Carlo simulations were conducted to quantify the fragility to different loadings. Sensitivity of models in terms of input distributions were defined with statistical tools such as confidence intervals and Sobol's indexes. Conclusion and discussion of this work are established to well determine contributions, limits and future needs or developments of the research. First of all, this study provides spectrum of fragility curves of reinforced concrete structures which could be used to improve risk assessment. Second, the influence of the failure criterion picked up in this survey are discussed. Then, the weight of the statistical distribution choice is analysed. Finally, the limit between vulnerability and fragility relations is set up to establish the boundary use of our approach.

Corrosion detection and evolution monitoring in reinforced concrete structures by the use of fiber Bragg grating sensor

NASA Astrophysics Data System (ADS)

Ali-Alvarez, S.; Ferdinand, P.; Magne, S.; Nogueira, R. P.

2013-04-01

Corrosion of reinforced bar (rebar) in concrete structures represents a major issue in civil engineering works, being its detection and evolution a challenge for the applied research. In this work, we present a new methodology to corrosion detection in reinforced concrete structures, by combining Fiber Bragg Grating (FBG) sensors with the electrochemical and physical properties of rebar in a simplified assembly. Tests in electrolytic solutions and concrete were performed for pitting and general corrosion. The proposed Structural Health Monitoring (SHM) methodology constitutes a direct corrosion measurement potentially useful to implement or improve Condition-Based Maintenance (CBM) program for civil engineering concrete structures.

Degradation and mechanism of the mechanics and durability of reinforced concrete slab in a marine environment

NASA Astrophysics Data System (ADS)

Wu, Sheng-xing; Liu, Guan-guo; Bian, Han-bing; Lv, Wei-bo; Jiang, Jian-hua

2016-04-01

An experimental research was conducted to determine the corrosion and bearing capacity of a reinforced concrete (RC) slab at different ages in a marine environment. Results show that the development of corrosion-induced cracks on a slab in a marine environment can be divided into three stages according to crack morphology at the bottom of the slab. In the first stage, cracks appear. In the second stage, cracks develop from the edges to the middle of the slab. In the third stage, longitudinal and transverse corrosion-induced cracks coexist. The corrosion ratio of reinforcements nonlinearly increases with the age, and the relationship between the corrosion ratio of the reinforcements and the corrosion-induced crack width of the concrete is established. The flexural capacity of the corroded RC slab nonlinearly decreases with the age, and the model for the bearing capacity factor of the corroded RC slab is established. The mid-span deflection of the corroded RC slab that corresponds to the yield of the reinforcements linearly increases with the increase in corrosion ratio. Finally, the mechanisms of corrosion morphology and the degradation of the mechanical properties of an RC slab in a marine environment are discussed on the basis of the basic theories of steel corrosion in concrete and concrete structure design.

Gamma-ray spectrometry method used for radioactive waste drums characterization for final disposal at National Repository for Low and Intermediate Radioactive Waste--Baita, Romania.

PubMed

Done, L; Tugulan, L C; Dragolici, F; Alexandru, C

2014-05-01

The Radioactive Waste Management Department from IFIN-HH, Bucharest, performs the conditioning of the institutional radioactive waste in concrete matrix, in 200 l drums with concrete shield, for final disposal at DNDR - Baita, Bihor county, in an old exhausted uranium mine. This paper presents a gamma-ray spectrometry method for the characterization of the radioactive waste drums' radionuclides content, for final disposal. In order to study the accuracy of the method, a similar concrete matrix with Portland cement in a 200 l drum was used. © 2013 The Authors. Published by Elsevier Ltd All rights reserved.

Review of concrete biodeterioration in relation to nuclear waste.

PubMed

Turick, Charles E; Berry, Christopher J

2016-01-01

Storage of radioactive waste in concrete structures is a means of containing wastes and related radionuclides generated from nuclear operations in many countries. Previous efforts related to microbial impacts on concrete structures that are used to contain radioactive waste showed that microbial activity can play a significant role in the process of concrete degradation and ultimately structural deterioration. This literature review examines the research in this field and is focused on specific parameters that are applicable to modeling and prediction of the fate of concrete structures used to store or dispose of radioactive waste. Rates of concrete biodegradation vary with the environmental conditions, illustrating a need to understand the bioavailability of key compounds involved in microbial activity. Specific parameters require pH and osmotic pressure to be within a certain range to allow for microbial growth as well as the availability and abundance of energy sources such as components involved in sulfur, iron and nitrogen oxidation. Carbon flow and availability are also factors to consider in predicting concrete biodegradation. The microbial contribution to degradation of the concrete structures containing radioactive waste is a constant possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters. Parameters to focus on for modeling activities and possible options for mitigation that would minimize concrete biodegradation are discussed and include key conditions that drive microbial activity on concrete surfaces. Copyright © 2015. Published by Elsevier Ltd.

100 years of concrete pavements in Iowa : final report, March 2009.

DOT National Transportation Integrated Search

2009-03-01

Portland cement concrete (PCC) pavements have given excellent service history for : Iowa. The first concrete pavement was placed in Le Mars in 1904 and was in service : until 1968. The Eddyville Cemetery Road placed in 1909 is still in service today....

Rapid curing and strength relationships of concrete : final report.

DOT National Transportation Integrated Search

1985-05-01

The rapid rate of construction has created a need to have information on the strength of concrete at the earliest possible time. Having to wait 28 days before the strength can be determined can cause serious problems if inferior concrete had been use...

The protection effectiveness of waterproof membrane systems on bridge decks in Louisiana : final report.

DOT National Transportation Integrated Search

1978-12-01

The effects of de-icing salts on concrete and reinforcing steel is well documented, and efficient methods of protection from the penetrating chloride ions have long been sought. Concrete bridge decks need the protection, and waterproofing the concret...

Design and test properties of super water reducers in Portland cement concrete : final report.

DOT National Transportation Integrated Search

1980-12-01

Recently, new concrete admixtures (super water reducers) have been developed and marketed by private industry. These admixtures permit the mixing and placement of very low water-cement ratio (0.32 to 0.38) concretes at conventional consistencies (slu...

Underwater Concrete Inspection Equipment

DTIC Science & Technology

1991-04-01

nondestructive testing of con- crete waterfront structures. One instrument is a magnetic rebar locator that locates rebar in concrete structures and measures the...amount of con- crete cover over the rebar . Another instrument is a rebound hammer that measures the surface hardness of the concrete . The third...development of three specialized instruments for the underwater nondestructive testing or concrete waterfront structures. One instrument is a magnetic rebar

The effect of crack width on the service life of reinforced concrete structures

NASA Astrophysics Data System (ADS)

Van Hung, Nguyen; Viet Hung, Vu; Viet, Tran Bao

2018-04-01

Reinforced concrete has become a widely used construction material around the world. Nowadays, the assessment of deterioration and life expectancy of reinforced concrete structure is very important and necessary as concrete is a complex material with brittle failure. Under the effect of load and over time, cracks occur in the structure, significantly reducing its performance and durability. Therefore, a number of models for predicting the penetration of chloride ions into the concrete were proposed to assess the durability of the structure. In the study performed by T B Viet (2016) [1], the author proposed a new theoretical model, especially considering the effects of macro and micro cracking on the diffusion coefficient of chloride ion in the cracked concrete. The following experimental results, in term of electrical indication of concrete’s ability to resist chloride ion penetration, are used to calculate the lifespan of a reinforced concrete structure according to Dura Crete approach [8] with different crack widths to evaluate the accuracy and reliability of the above model in the range of concrete compressive strength of 30-70MPa.

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.

Testing of concrete by laser ablation

DOEpatents

Flesher, D.J.; Becker, D.L.; Beem, W.L.; Berry, T.C.; Cannon, N.S.

1997-01-07

A method is disclosed for testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed. 1 fig.

Evaluation of a nuclear gage for controlling the consolidation of fresh concrete : final report.

DOT National Transportation Integrated Search

1981-01-01

Evaluated was an approach to controlling the consolidation of in-place portland cement concrete on the basis of densities obtained with a Troxler 3411 nuclear gage. The gage was used in the backscatter mode on low-slump concrete bridge deck overlays ...

Evaluation of a Highway Bridge Constructed Using High Strength Lightweight Concrete Bridge Girders : final report.

DOT National Transportation Integrated Search

2011-04-01

The use of high performance concretes to provide longer bridge spans has been limited due to the capacity of existing infrastructure to handle the load of the girders during transportation. The use of High Strength Lightweight Concrete (HSLW) can pro...

Determination of need for water soaking period in measurement of concrete volume of permeable voids : final report.

DOT National Transportation Integrated Search

2016-10-01

Water permeability of concrete is one of the key factors concerning many concrete deterioration : problems. It is often evaluated indirectly by measuring the volume of permeable voids through the KT-73 : (2012) testing procedures. These procedures in...

Bond slip detection of concrete-encased composite structure using shear wave based active sensing approach

NASA Astrophysics Data System (ADS)

Zeng, Lei; Parvasi, Seyed Mohammad; Kong, Qingzhao; Huo, Linsheng; Lim, Ing; Li, Mo; Song, Gangbing

2015-12-01

Concrete-encased composite structure exhibits improved strength, ductility and fire resistance compared to traditional reinforced concrete, by incorporating the advantages of both steel and concrete materials. A major drawback of this type of structure is the bond slip introduced between steel and concrete, which directly reduces the load capacity of the structure. In this paper, an active sensing approach using shear waves to provide monitoring and early warning of the development of bond slip in the concrete-encased composite structure is proposed. A specimen of concrete-encased composite structure was investigated. In this active sensing approach, shear mode smart aggregates (SAs) embedded in the concrete act as actuators and generate desired shear stress waves. Distributed piezoceramic transducers installed in the cavities of steel plates act as sensors and detect the wave response from shear mode SAs. Bond slip acts as a form of stress relief and attenuates the wave propagation energy. Experimental results from the time domain analysis clearly indicate that the amplitudes of received signal by lead zirconate titanate sensors decreased when bond slip occurred. In addition, a wavelet packet-based analysis was developed to compute the received signal energy values, which can be used to determine the initiation and development of bond slip in concrete-encased composite structure. In order to establish the validity of the proposed method, a 3D finite element analysis of the concrete-steel bond model is further performed with the aid of the commercial finite element package, Abaqus, and the numerical results are compared with the results obtained in experimental study.

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...

Prediction model for carbonation depth of concrete subjected to freezing-thawing cycles

NASA Astrophysics Data System (ADS)

Xiao, Qian Hui; Li, Qiang; Guan, Xiao; Xian Zou, Ying

2018-03-01

Through the indoor simulation test of the concrete durability under the coupling effect of freezing-thawing and carbonation, the variation regularity of concrete neutralization depth under freezing-thawing and carbonation was obtained. Based on concrete carbonation mechanism, the relationship between the air diffusion coefficient and porosity in concrete was analyzed and the calculation method of porosity in Portland cement concrete and fly ash cement concrete was investigated, considering the influence of the freezing-thawing damage on the concrete diffusion coefficient. Finally, a prediction model of carbonation depth of concrete under freezing-thawing circumstance was established. The results obtained using this prediction model agreed well with the experimental test results, and provided a theoretical reference and basis for the concrete durability analysis under multi-factor environments.

Modeling of the attenuation of stress waves in concrete based on the Rayleigh damping model using time-reversal and PZT transducers

NASA Astrophysics Data System (ADS)

Tian, Zhen; Huo, Linsheng; Gao, Weihang; Li, Hongnan; Song, Gangbing

2017-10-01

Wave-based concrete structural health monitoring has attracted much attention. A stress wave experiences significant attenuation in concrete, however there is a lack of a unified method for predicting the attenuation coefficient of the stress wave. In this paper, a simple and effective absorption attenuation model of stress waves in concrete is developed based on the Rayleigh damping model, which indicates that the absorption attenuation coefficient of stress waves in concrete is directly proportional to the square of the stress wave frequency when the damping ratio is small. In order to verify the theoretical model, related experiments were carried out. During the experiments, a concrete beam was designed in which the d33-model piezoelectric smart aggregates were embedded to detect the propagation of stress waves. It is difficult to distinguish direct stress waves due to the complex propagation paths and the reflection and scattering of stress waves in concrete. Hence, as another innovation of this paper, a new method for computing the absorption attenuation coefficient based on the time-reversal method is developed. Due to the self-adaptive focusing properties of the time-reversal method, the time-reversed stress wave focuses and generates a peak value. The time-reversal method eliminates the adverse effects of multipaths, reflection, and scattering. The absorption attenuation coefficient is computed by analyzing the peak value changes of the time-reversal focused signal. Finally, the experimental results are found to be in good agreement with the theoretical model.

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.

Influence of processing factors over concrete strength.

NASA Astrophysics Data System (ADS)

Kara, K. A.; Dolzhenko, A. V.; Zharikov, I. S.

2018-03-01

Construction of facilities of cast in-situ reinforced concrete poses additional requirements to quality of material, peculiarities of the construction process may sometimes lead to appearance of lamination planes and inhomogeneity of concrete, which reduce strength of the material and structure as a whole. Technology compliance while working with cast in-situ concrete has a significant impact onto the concrete strength. Such process factors as concrete curing, vibration and compaction of the concrete mixture, temperature treatment, etc., when they are countered or inadequately followed lead to a significant reduction in concrete strength. Here, the authors experimentally quantitatively determine the loss of strength in in-situ cast concrete structures due to inadequate following of process requirements, in comparison with full compliance.

Concreteness Effects and Syntactic Modification in Written Composition.

ERIC Educational Resources Information Center

Sadoski, Mark; Goetz, Ernest T.

1998-01-01

Investigates whether concreteness was related to a key characteristic of written composition--the cumulative sentence with a final modifier--which has been consistently associated with higher quality writing. Supports the conceptual-peg hypothesis of dual coding theory, with concrete verbs providing the pegs on which cumulative sentences are…

78 FR 68090 - Steel Concrete Reinforcing Bar from Mexico and Turkey

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-13

...)] Steel Concrete Reinforcing Bar from Mexico and Turkey Determinations On the basis of the record \\1... injured by reason of imports from Mexico and Turkey of steel concrete reinforcing bar, provided for in... L. Aranoff dissenting with regard to subject imports from Mexico. Commencement of Final Phase...

75 FR 28560 - Prestressed Concrete Steel Wire Strand From the People's Republic of China: Final Determination...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-21

... Wire Strand From the People's Republic of China: Final Determination of Sales at Less Than Fair Value... Steel Wire Strand From the People's Republic of China: Preliminary Determination of Sales at Less Than... Antidumping Duty Investigation of Prestressed Concrete Steel Wire Strand From the People's Republic of China...

75 FR 22552 - Certain Steel Concrete Reinforcing Bars from Turkey; Notice of Amended Final Results Pursuant to...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-29

... Reinforcing Bars from Turkey; Notice of Amended Final Results Pursuant to Court Decisions AGENCY: Import... certain steel concrete of reinforcing bars (rebar) from Turkey. See Habas Sinai ve Tibbi Gazlar Istihsal... Turkey for the period of review (POR) of April 1, 2003, through March 31, 2004. See Certain Steel...

Creep and cracking of concrete hinges: insight from centric and eccentric compression experiments.

PubMed

Schlappal, Thomas; Schweigler, Michael; Gmainer, Susanne; Peyerl, Martin; Pichler, Bernhard

2017-01-01

Existing design guidelines for concrete hinges consider bending-induced tensile cracking, but the structural behavior is oversimplified to be time-independent. This is the motivation to study creep and bending-induced tensile cracking of initially monolithic concrete hinges systematically. Material tests on plain concrete specimens and structural tests on marginally reinforced concrete hinges are performed. The experiments characterize material and structural creep under centric compression as well as bending-induced tensile cracking and the interaction between creep and cracking of concrete hinges. As for the latter two aims, three nominally identical concrete hinges are subjected to short-term and to longer-term eccentric compression tests. Obtained material and structural creep functions referring to centric compression are found to be very similar. The structural creep activity under eccentric compression is significantly larger because of the interaction between creep and cracking, i.e. bending-induced cracks progressively open and propagate under sustained eccentric loading. As for concrete hinges in frame-like integral bridge construction, it is concluded (i) that realistic simulation of variable loads requires consideration of the here-studied time-dependent behavior and (ii) that permanent compressive normal forces shall be limited by 45% of the ultimate load carrying capacity, in order to avoid damage of concrete hinges under sustained loading.

Geopolymer concrete for structural use: Recent findings and limitations

NASA Astrophysics Data System (ADS)

Nuruddin, M. F.; Malkawi, A. B.; Fauzi, A.; Mohammed, B. S.; Almattarneh, H. M.

2016-06-01

Geopolymer binders offer a possible solution for several problems that facing the current cement industry. These binders exhibit similar or better engineering properties compared to cement and can utilize several types of waste materials. This paper presents the recent research progress regarding the structural behaviour of reinforced geopolymer concrete members including beams, columns and slabs. The reported results showed that the structural behaviour of the reinforced geopolymer concrete members is similar to the known behaviour of the ordinary reinforced concrete members. In addition, the currently available standards have been conservatively used for analysis and designing of reinforced geopolymer concrete structures. On the other hand, the main hurdles facing the spread of geopolymer concrete was the absence of standards and the concerns about the long-term properties. Other issues included the safety, cost and liability.

Rational and Safe Design of Concrete Transportation Structures for Size Effect and Multi-Decade Sustainability

DOT National Transportation Integrated Search

2012-10-01

The overall goal of this project was to improve the safety and sustainability in the design of large : prestressed concrete bridges and other transportation structures. The safety of large concrete : structures, including bridges, has been insufficie...

Principles and Applications of Ultrasonic-Based Nondestructive Methods for Self-Healing in Cementitious Materials

PubMed Central

Ahn, Eunjong; Kim, Hyunjun; Sim, Sung-Han; Shin, Sung Woo; Shin, Myoungsu

2017-01-01

Recently, self-healing technologies have emerged as a promising approach to extend the service life of social infrastructure in the field of concrete construction. However, current evaluations of the self-healing technologies developed for cementitious materials are mostly limited to lab-scale experiments to inspect changes in surface crack width (by optical microscopy) and permeability. Furthermore, there is a universal lack of unified test methods to assess the effectiveness of self-healing technologies. Particularly, with respect to the self-healing of concrete applied in actual construction, nondestructive test methods are required to avoid interrupting the use of the structures under evaluation. This paper presents a review of all existing research on the principles of ultrasonic test methods and case studies pertaining to self-healing concrete. The main objective of the study is to examine the applicability and limitation of various ultrasonic test methods in assessing the self-healing performance. Finally, future directions on the development of reliable assessment methods for self-healing cementitious materials are suggested. PMID:28772640

Guided wave propagation and spectral element method for debonding damage assessment in RC structures

NASA Astrophysics Data System (ADS)

Wang, Ying; Zhu, Xinqun; Hao, Hong; Ou, Jinping

2009-07-01

A concrete-steel interface spectral element is developed to study the guided wave propagation along the steel rebar in the concrete. Scalar damage parameters characterizing changes in the interface (debonding damage) are incorporated into the formulation of the spectral finite element that is used for damage detection of reinforced concrete structures. Experimental tests are carried out on a reinforced concrete beam with embedded piezoelectric elements to verify the performance of the proposed model and algorithm. Parametric studies are performed to evaluate the effect of different damage scenarios on wave propagation in the reinforced concrete structures. Numerical simulations and experimental results show that the method is effective to model wave propagation along the steel rebar in concrete and promising to detect damage in the concrete-steel interface.

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.

Factor Structure of the Piagetian Stage of Concrete Operations.

ERIC Educational Resources Information Center

Klausmeier, Herbert J.; Sipple, Thomas S.

1982-01-01

The Piagetian developmental stage of concrete operational thought and the theoretical groupement structures underlying children's performance of 12 concrete operations tasks are discussed. Tasks were shown to develop in five related sets. Three factor structures were found in this longitudinal study. (Author/CM)

Acoustic emission monitoring of concrete columns and beams strengthened with fiber reinforced polymer sheets

NASA Astrophysics Data System (ADS)

Ma, Gao; Li, Hui; Zhou, Wensong; Xian, Guijun

2012-04-01

Acoustic emission (AE) technique is an effective method in the nondestructive testing (NDT) field of civil engineering. During the last two decades, Fiber reinforced polymer (FRP) has been widely used in repairing and strengthening concrete structures. The damage state of FRP strengthened concrete structures has become an important issue during the service period of the structure and it is a meaningful work to use AE technique as a nondestructive method to assess its damage state. The present study reports AE monitoring results of axial compression tests carried on basalt fiber reinforced polymer (BFRP) confined concrete columns and three-point-bending tests carried on BFRP reinforced concrete beams. AE parameters analysis was firstly utilized to give preliminary results of the concrete fracture process of these specimens. It was found that cumulative AE events can reflect the fracture development trend of both BFRP confined concrete columns and BFRP strengthened concrete beams and AE events had an abrupt increase at the point of BFRP breakage. Then the fracture process of BFRP confined concrete columns and BFRP strengthened concrete beams was studied through RA value-average frequency analysis. The RA value-average frequency tendencies of BFRP confined concrete were found different from that of BFRP strengthened concrete beams. The variation tendency of concrete crack patterns during the loading process was revealed.

Nuclear reactor containment structure with continuous ring tunnel at grade

DOEpatents

Seidensticker, Ralph W.; Knawa, Robert L.; Cerutti, Bernard C.; Snyder, Charles R.; Husen, William C.; Coyer, Robert G.

1977-01-01

A nuclear reactor containment structure which includes a reinforced concrete shell, a hemispherical top dome, a steel liner, and a reinforced-concrete base slab supporting the concrete shell is constructed with a substantial proportion thereof below grade in an excavation made in solid rock with the concrete poured in contact with the rock and also includes a continuous, hollow, reinforced-concrete ring tunnel surrounding the concrete shell with its top at grade level, with one wall integral with the reinforced concrete shell, and with at least the base of the ring tunnel poured in contact with the rock.

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.

Methodology for assessing the probability of corrosion in concrete structures on the basis of half-cell potential and concrete resistivity measurements.

PubMed

Sadowski, Lukasz

2013-01-01

In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential E corr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures.

Fibre Concrete 2017

NASA Astrophysics Data System (ADS)

2017-09-01

9th international conference on fibre reinforced concretes (FRC), textile reinforced concretes (TRC) and ultra-high performance concretes (UHPC) Preface The Fibre Concrete Conference series is held biennially to provide a platform to share knowledge on fibre reinforced concretes, textile concretes and ultra-high performance concretes regarding material properties and behaviour, technology procedures, topics of long-term behaviour, creep, durability; sustainable aspects of concrete including utilisation of waste materials in concrete production and recycling of concrete. The tradition of Fibre Concrete Conferences started in eighties of the last century. Nowadays the conference is organized by the Department of Concrete and Masonry Structures of the Czech Technical University in Prague, Faculty of Civil Engineering. The 9th International Conference Fibre Concrete 2017 had 109 participants from 27 countries all over the world. 55 papers were presented including keynote lectures of Professor Bažant, Professor Bartoš and Dr. Broukalová. The conference program covered wide range of topics from scientific research to practical applications. The presented contributions related to performance and behaviour of cement based composites, their long-term behaviour and durability, sustainable aspects, advanced analyses of structures from these composites and successful applications. This conference was organized also to honour Professor Zděnek P. Bažant on the occasion of his jubilee and to appreciate his merits and discoveries in the field of fibre reinforced composites, structural mechanics and engineering.

Development and construction of low-cracking high-performance concrete (LC-HPC) bridge decks : free shrinkage, moisture optimization and concrete production : final report.

DOT National Transportation Integrated Search

2009-08-01

The development and evaluation of low-cracking high-performance concrete (LC-HPC) for use in bridge decks : is described based on laboratory test results and experience gained during the construction of 14 bridges. This report : emphasizes the materi...

Final report : Polymer concrete overlay on Beulah Road Bridge : condition of overlay after one year in service.

DOT National Transportation Integrated Search

1983-01-01

An evaluation of the thin polymer concrete overlay placed on the Beulah Road bridge indicates that the overlay is securely bonded to the base concrete and is providing low permeability and high skid resistance after 1 year of service life. The lane c...

Evaluation of several types of curing and protective materials for concrete : final report on part I : laboratory and outdoor exposure studies preliminary to field trials.

DOT National Transportation Integrated Search

1970-01-01

Concern for improving the durability of concrete has focused renewed attention on all aspects of concrete technology. Numerous proprietary products which are claimed to improve durability have been marketed as protective coatings, curing agents or co...

Study on Detailing Design of Precast Concrete Frame Structure

NASA Astrophysics Data System (ADS)

Lida, Tian; Liming, Li; Kang, Liu; Jiao, Geng; Ming, Li

2018-03-01

Taking a certain precast concrete frame structure as an example, this paper introduces the general procedures and key points in detailing design of emulative cast-in-place prefabricated structure from the aspects of structural scheme, precast element layout, shop drawing design and BIM 3D modelling. This paper gives a practical solution for the detailing design of precast concrete frame structure under structural design codes in China.

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 %.

Performance of Hydrophobisation Techniques in Case of Reinforced Concrete Structures

NASA Astrophysics Data System (ADS)

Błaszczyński, Tomasz; Osesek, Mateusz; Gwozdowski, Błażej; Ilski, Mirosław

2017-10-01

Concrete is, unchangeably, one of the most frequently applied building materials, also in the case of bridges, overpasses or viaducts. Along with the aging of such structures, the degradation of concrete, which may accelerate the corrosion of reinforcing steel and drastically decrease the load-bearing capacity of the structure, becomes an important issue. The paper analyzes the possibilities of using deep hydrophobisation in repairing reinforced concrete engineering structures. The benefits of properly securing reinforced concrete structures from the damaging effects of UV radiation, the influence of harmful gases, or progression of chlorine induced corrosion have been presented, especially in regards to bridge structures. The need to calculate the costs of carrying out investments along with the expected costs of maintaining such structures, as well as the high share of costs connected with logistics, has also been indicated in the total costs of repair works.

Fundamental period of Italian reinforced concrete buildings: comparison between numerical, experimental and Italian code simplified values

NASA Astrophysics Data System (ADS)

Ditommaso, Rocco; Carlo Ponzo, Felice; Auletta, Gianluca; Iacovino, Chiara; Nigro, Antonella

2015-04-01

Aim of this study is a comparison among the fundamental period of reinforced concrete buildings evaluated using the simplified approach proposed by the Italian Seismic code (NTC 2008), numerical models and real values retrieved from an experimental campaign performed on several buildings located in Basilicata region (Italy). With the intention of proposing simplified relationships to evaluate the fundamental period of reinforced concrete buildings, scientists and engineers performed several numerical and experimental campaigns, on different structures all around the world, to calibrate different kind of formulas. Most of formulas retrieved from both numerical and experimental analyses provides vibration periods smaller than those suggested by the Italian seismic code. However, it is well known that the fundamental period of a structure play a key role in the correct evaluation of the spectral acceleration for seismic static analyses. Generally, simplified approaches impose the use of safety factors greater than those related to in depth nonlinear analyses with the aim to cover possible unexpected uncertainties. Using the simplified formula proposed by the Italian seismic code the fundamental period is quite higher than fundamental periods experimentally evaluated on real structures, with the consequence that the spectral acceleration adopted in the seismic static analysis may be significantly different than real spectral acceleration. This approach could produces a decreasing in safety factors obtained using linear and nonlinear seismic static analyses. Finally, the authors suggest a possible update of the Italian seismic code formula for the simplified estimation of the fundamental period of vibration of existing RC buildings, taking into account both elastic and inelastic structural behaviour and the interaction between structural and non-structural elements. Acknowledgements This study was partially funded by the Italian Civil Protection Department within the project DPC-RELUIS 2014 - RS4 ''Seismic observatory of structures and health monitoring''. References R. Ditommaso, M. Vona, M. R. Gallipoli and M. Mucciarelli (2013). Evaluation and considerations about fundamental periods of damaged reinforced concrete buildings. Nat. Hazards Earth Syst. Sci., 13, 1903-1912, 2013. www.nat-hazards-earth-syst-sci.net/13/1903/2013. doi:10.5194/nhess-13-1903-2013

CF60 Concrete Composition Design and Application on Fudiankou Xijiang Super Large Bridge

NASA Astrophysics Data System (ADS)

Qiu, Yi Mei; Wen, Sen Yuan; Chen, Jun Xiang

2018-06-01

Guangxi Wuzhou City Ring Road Fudiankou Xijiang super large bridge CF60 concrete is a new multi-phase composite high-performance concrete, this paper for the Fudiankou Xijiang bridge structure and characteristics of the project, in accordance with the principle of local materials and technical specification requirements, combined with the site conditions of CF60 engineering high performance concrete component materials, proportion and the technical performance, quantify the main physical and mechanical performance index. Analysis main influencing factors of the technical indicators, reasonable adjustment of concrete mix design parameters, and the use of technical means of admixture and multi-function composite admixture of concrete, obtain the optimal proportion of good work, process, mechanical properties stability and durability of engineering properties, recommend and verification of concrete mix; to explore the CF60 high performance concrete Soil in the Fudiankou Xijiang bridge application technology, detection and tracking the quality of concrete construction, concrete structure during the construction of the key technology and control points is proposed, evaluation of CF60 high performance concrete in the actual engineering application effect and benefit to ensure engineering quality of bridge structure and service life, and super long span bridge engineering construction to provide basis and reference.

CRITICAL MECHANICAL PROPERTIES OF STRUCTURAL LIGHT-WEIGHT CONCRETE AND THE EFFECTS OF THESE PROPERTIES ON THE DESIGN OF THE PAVEMENT STRUCTURE.

DOT National Transportation Integrated Search

1965-01-01

In this study, critical mechanical properties of structural lightweight concrete were determined and utilized in the evaluation of a design of concrete pavements. Also presented are the critical mechanical properties resulting from unrestrained and r...

77 FR 35956 - Appalachian Power Company; Notice of Application Accepted for Filing, Soliciting Motions To...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-15

...) screened intake structures; (3) a concrete powerhouse containing three turbine-generator units with a total... structures; (3) a concrete powerhouse containing three turbine-generator units with a total installed... by a log boom; (2) screened intake structures; (3) a concrete powerhouse containing three turbine...

Fundamental Study on the Development of Structural Lightweight Concrete by Using Normal Coarse Aggregate and Foaming Agent

PubMed Central

Lee, Han-Seung; Ismail, Mohamed A.; Woo, Young-Je; Min, Tae-Beom; Choi, Hyun-Kook

2014-01-01

Structural lightweight concrete (SLWC) has superior properties that allow the optimization of super tall structure systems for the process of design. Because of the limited supply of lightweight aggregates in Korea, the development of structural lightweight concrete without lightweight aggregates is needed. The physical and mechanical properties of specimens that were cast using normal coarse aggregates and different mixing ratios of foaming agent to evaluate the possibility of creating structural lightweight concrete were investigated. The results show that the density of SLWC decreases as the dosage of foaming agent increases up to a dosage of 0.6%, as observed by SEM. It was also observed that the foaming agent induced well separated pores, and that the size of the pores ranged from 50 to 100 μm. Based on the porosity of concrete specimens with foaming agent, compressive strength values of structural lightweight foam concrete (SLWFC) were obtained. It was also found that the estimated values from proposed equations for compressive strength and modulus of elasticity of SLWFC, and values obtained by actual measurements were in good agreement. Thus, this study confirms that new structural lightweight concrete using normal coarse aggregates and foaming agent can be developed successfully. PMID:28788691

A corrosion monitoring system for existing reinforced concrete structures.

DOT National Transportation Integrated Search

2015-05-01

This study evaluated a multi-parameter corrosion monitoring system for existing reinforced concrete structures in chloride-laden service environments. The system was fabricated based on a prototype concrete corrosion measurement system that : had bee...

Monitoring of Beachsaver Reef with Filter Blanket and Double-T Sill at Cape May Point, New Jersey, Section 227 Demonstration Site; First Year Monitoring - 2002-2003

DTIC Science & Technology

2005-07-01

evaluate the functional, structural, and economic performance of the patented Beachsaver Reef prefabricated concrete submerged breakwater and the less...expensive prefabricated concrete structure called a Double-T sill. This demonstration project was developed through a cooperative effort of the U.S...patented Beachsaver Reef prefabricated concrete submerged breakwater and a less expensive, prefabricated concrete structure called a Double-T sill. Data

Comparison of embedded, surface bonded and reusable piezoelectric transducers for monitoring of concrete structures

NASA Astrophysics Data System (ADS)

Sabet Divsholi, Bahador; Yang, Yaowen

2011-04-01

Piezoelectric lead zirconate titanate (PZT) transducers have been used for health monitoring of various structures over the last two decades. There are three methods to install the PZT transducers to structures, namely, surface bonded, reusable setup and embedded PZTs. The embedded PZTs and reusable PZT setups can be used for concrete structures during construction. On the other hand, the surface bonded PZTs can be installed on the existing structures. In this study, the applicability and limitations of each installation method are experimentally studied. A real size concrete structure is cast, where the surface bonded, reusable setup and embedded PZTs are installed. Monitoring of concrete hydration and structural damage is conducted by the electromechanical impedance (EMI), wave propagation and wave transmission techniques. It is observed that embedded PZTs are suitable for monitoring the hydration of concrete by using both the EMI and the wave transmission techniques. For damage detection in concrete structures, the embedded PZTs can be employed using the wave transmission technique, but they are not suitable for the EMI technique. It is also found that the surface bonded PZTs are sensitive to damage when using both the EMI and wave propagation techniques. The reusable PZT setups are able to monitor the hydration of concrete. However they are less sensitive in damage detection in comparison to the surface bonded PZTs.

Evaluation on Compression Properties of Different Shape and Perforated rHDPE in Concrete Structures

NASA Astrophysics Data System (ADS)

Yuhazri, M. Y.; Hafiz, K. M.; Myia, Y. Z. A.; Jia, C. P.; Sihombing, H.; Sapuan, S. M.; Badarulzaman, N. A.

2017-10-01

The purpose of this study was to develop a concrete structure by incorporating waste HDPE plastic as the main reinforcement material and cement as the matrix via standard casting technique. There are eight different shapes of rHDPE reinforcing structure were used to investigate the compression properties of produced concrete composites. Experimental result shown that the highest shape in compressive strength of rHDPE reinforcing structure were the concrete with the addition of X-perforated beam (18.22 MPa), followed by X-beam (17.7 MPa), square perforated tube (17.54 MPa), round tube (17.42 MPa) and round perforated tube (16.69 MPa). In terms of their compressive behavior, the average concrete containing rHDPE reinforcement was successfully improved by 6 % of the mechanical characteristic compared to control concrete. It is shown that the addition of waste plastic as reinforcement structure can provide better compressive strength based on their shape and pattern respectively.

Surface Chloride Levels in Colorado Structural Concrete

DOT National Transportation Integrated Search

2018-01-01

This project focused on the chloride-induced corrosion of reinforcing steel in structural concrete. The primary goal of this project is to analyze the surface chloride concentration level of the concrete bridge decks throughout Colorado. The study in...

Fatigue testing of wood-concrete composite beams.

DOT National Transportation Integrated Search

2013-05-01

Currently, wood-concrete composite structural members are usually applied in building structures. There are a relatively small number (in the low 100s) of known bridge applications involving wood-concrete composites. A problem with using these novel ...

Usage of Crushed Concrete Fines in Decorative Concrete

NASA Astrophysics Data System (ADS)

Pilipenko, Anton; Bazhenova, Sofia

2017-10-01

The article is devoted to the questions of usage of crushed concrete fines from concrete scrap for the production of high-quality decorative composite materials based on mixed binder. The main problem in the application of crushed concrete in the manufacture of decorative concrete products is extremely low decorative properties of crushed concrete fines itself, as well as concrete products based on them. However, crushed concrete fines could have a positive impact on the structure of the concrete matrix and could improve the environmental and economic characteristics of the concrete products. Dust fraction of crushed concrete fines contains non-hydrated cement grains, which can be opened in screening process due to the low strength of the contact zone between the hydrated and non-hydrated cement. In addition, the screening process could increase activity of the crushed concrete fines, so it can be used as a fine aggregate and filler for concrete mixes. Previous studies have shown that the effect of the usage of the crushed concrete fines is small and does not allow to obtain concrete products with high strength. However, it is possible to improve the efficiency of the crushed concrete fines as a filler due to the complex of measures prior to mixing. Such measures may include a preliminary mechanochemical activation of the binder (cement binder, iron oxide pigment, silica fume and crushed concrete fines), as well as the usage of polycarboxylate superplasticizers. The development of specific surface area of activated crushed concrete fines ensures strong adhesion between grains of binder and filler during the formation of cement stone matrix. The particle size distribution of the crushed concrete fines could achieve the densest structure of cement stone matrix and improve its resistance to environmental effects. The authors examined the mechanisms of structure of concrete products with crushed concrete fines as a filler. The results of studies of the properties of the crushed concrete fines were provided. It is shown that the admixture of the crushed concrete fines has little effect on the colour characteristics of the decorative concrete products. The preferred options to improve the surfaces of decorative concrete are also proposed.

Methodology for Assessing the Probability of Corrosion in Concrete Structures on the Basis of Half-Cell Potential and Concrete Resistivity Measurements

PubMed Central

2013-01-01

In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential E corr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures. PMID:23766706

Application of Natural Mineral Additives in Construction

NASA Astrophysics Data System (ADS)

Linek, Malgorzata; Nita, Piotr; Wolka, Paweł; Zebrowski, Wojciech

2017-12-01

The article concerns the idea of using selected mineral additives in the pavement quality concrete composition. The basis of the research paper was the modification of cement concrete intended for airfield pavements. The application of the additives: metakaolonite and natural zeolite was suggested. Analyses included the assessment of basic physical properties of modifiers. Screening analysis, assessment of micro structure and chemical microanalysis were conducted in case of these materials. The influence of the applied additives on the change of concrete mix parameters was also presented. The impact of zeolite and metakaolinite on the mix density, oxygen content and consistency class was analysed. The influence of modifiers on physical and mechanical changes of the hardened cement concrete was discussed (concrete density, compressive strength and bending strength during fracturing) in diversified research periods. The impact of the applied additives on the changes of internal structure of cement concrete was discussed. Observation of concrete micro structure was conducted using the scanning electron microscope. According to the obtained lab test results, parameters of the applied modifiers and their influence on changes of internal structure of cement concrete are reflected in the increase of mechanical properties of pavement quality concrete. The increase of compressive and bending strength in case of all analysed research periods was proved.

Parametric Study of Fire Performance of Concrete Filled Hollow Steel Section Columns with Circular and Square Cross-Section

NASA Astrophysics Data System (ADS)

Nurfaidhi Rizalman, Ahmad; Tahir, Ng Seong Yap Mahmood Md; Mohammad, Shahrin

2018-03-01

Concrete filled hollow steel section column have been widely accepted by structural engineers and designers for high rise construction due to the benefits of combining steel and concrete. The advantages of concrete filled hollow steel section column include higher strength, ductility, energy absorption capacity, and good structural fire resistance. In this paper, comparison on the fire performance between circular and square concrete filled hollow steel section column is established. A three-dimensional finite element package, ABAQUS, was used to develop the numerical model to study the temperature development, critical temperature, and fire resistance time of the selected composite columns. Based on the analysis and comparison of typical parameters, the effect of equal cross-sectional size for both steel and concrete, concrete types, and thickness of external protection on temperature distribution and structural fire behaviour of the columns are discussed. The result showed that concrete filled hollow steel section column with circular cross-section generally has higher fire resistance than the square section.

206. Big Witch Road grade separation structure. This concrete box ...

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

206. Big Witch Road grade separation structure. This concrete box culvert, built in 1950, is unusual in that the culvert's concrete bottom extends beyond the structure to the ends of its perpendicular wing walls. Facing northeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

Experimental Study and Reactive Transport Modeling of Boric Acid Leaching of Concrete

NASA Astrophysics Data System (ADS)

Pabalan, R. T.; Chiang, K.-T. K.

2013-07-01

Borated water leakage through spent fuel pools (SFPs) at pressurized water reactors is a concern because it could cause corrosion of reinforcement steel in the concrete structure, compromise the integrity of the structure, or cause unmonitored releases of contaminated water to the environment. Experimental data indicate that pH is a critical parameter that determines the corrosion susceptibility of rebar in borated water and the degree of concrete degradation by boric acid leaching. In this study, reactive transport modeling of concrete leaching by borated water was performed to provide information on the solution pH in the concrete crack or matrix and the degree of concrete degradation at different locations of an SFP concrete structure exposed to borated water. Simulations up to 100 years were performed using different boric acid concentrations, crack apertures, and solution flow rates. Concrete cylinders were immersed in boric acid solutions for several months and the mineralogical changes and boric acid penetration in the concrete cylinder were evaluated as a function of time. The depths of concrete leaching by boric acid solution derived from the reactive transport simulations were compared with the measured boric acid penetration depth.

Probabilistic Analysis of Structural Member from Recycled Aggregate Concrete

NASA Astrophysics Data System (ADS)

Broukalová, I.; Šeps, K.

2017-09-01

The paper aims at the topic of sustainable building concerning recycling of waste rubble concrete from demolition. Considering demands of maximising recycled aggregate use and minimising of cement consumption, composite from recycled concrete aggregate was proposed. The objective of the presented investigations was to verify feasibility of the recycled aggregate cement based fibre reinforced composite in a structural member. Reliability of wall from recycled aggregate fibre reinforced composite was assessed in a probabilistic analysis of a load-bearing capacity of the wall. The applicability of recycled aggregate fibre reinforced concrete in structural applications was demonstrated. The outcomes refer to issue of high scatter of material parameters of recycled aggregate concretes.

Damage detection and quantification in a structural model under seismic excitation using time-frequency analysis

NASA Astrophysics Data System (ADS)

Chan, Chun-Kai; Loh, Chin-Hsiung; Wu, Tzu-Hsiu

2015-04-01

In civil engineering, health monitoring and damage detection are typically carry out by using a large amount of sensors. Typically, most methods require global measurements to extract the properties of the structure. However, some sensors, like LVDT, cannot be used due to in situ limitation so that the global deformation remains unknown. An experiment is used to demonstrate the proposed algorithms: a one-story 2-bay reinforce concrete frame under weak and strong seismic excitation. In this paper signal processing techniques and nonlinear identification are used and applied to the response measurements of seismic response of reinforced concrete structures subject to different level of earthquake excitations. Both modal-based and signal-based system identification and feature extraction techniques are used to study the nonlinear inelastic response of RC frame using both input and output response data or output only measurement. From the signal-based damage identification method, which include the enhancement of time-frequency analysis of acceleration responses and the estimation of permanent deformation using directly from acceleration response data. Finally, local deformation measurement from dense optical tractor is also use to quantify the damage of the RC frame structure.

The use of synthetic blended fibers to reduce cracking risk in high performance concrete.

DOT National Transportation Integrated Search

2014-09-01

Transportation departments have observed varying degrees of cracking in their concrete structures. Cracking of high performance reinforced concrete structures, in particular bridge decks, is of paramount concern to Pacific Northwest Departments of Tr...

Long-term strength properties of HVFA concretes

NASA Astrophysics Data System (ADS)

Špak, M.; Bašková, R.

2015-01-01

Fly ash from coal burning is used as active addition for concrete in Middle-Europe region for several decades. The intensity of its utilization increases still. In the role of supplementary cement addition it serves as binder, whereby it helps to reduce final price of concrete as well as improves both the rheological properties of fresh concrete and several characteristics of hardened concrete. Fly ash presents the co-product of energetic industry. Its production increases together with growth of energy consumption. These factors bring the opportunity and requirement of production of concretes with high volume of fly ash based addition. Thus, significant economic, environmental, technological and technical benefits can be achieved by using of high amount of fly ash for concrete production.

Peculiarities of Thermal Treatment of Monolithic Reinforced Concrete Structures

NASA Astrophysics Data System (ADS)

Kuchin, V. N.; Shilonosova, N. V.

2017-11-01

A mathematical program has been developed that allows one to determine the parameters of heat treatment of monolithic structures. One of the quality indicators of monolithic reinforced concrete structures is the level of temperature stresses arising in the process of heat treatment and further operation of structures. In winter at heat treatment the distribution of temperatures along the cross-section of the structure is uneven. A favorable thermo-stressed state in a concrete massif occurs when using the preheating method, providing the concrete temperature in the center of the structure is greater than at the periphery. In this case, after the strength is set and the temperature is later equalized along the cross-section, the central part of the structure tends to decrease its dimensions more but the extreme zones prevent it. Therefore, the center is in a state of tension, and the extreme zones on the periphery are compressed. In compressed concrete there is a lesser chance of cracks or defects. The temperature gradient over the section of the structure, the stress in the concrete and its strength are determined. When calculating the temperature and strength fields, the stress level was determined - a value equal to the ratio of the tensile stresses in the section under consideration to the tensile strength of the concrete in this section at the same time. The nature of the change in stress level is determined by the massive structure and power of the formwork heaters. It is shown that under unfavorable conditions the stress level is close to the critical value. The greatest temperature gradient occurs in the outer layers adjacent to the heating formwork. A technology for concrete conditioning is proposed which makes it possible to reduce the temperature stresses along the cross-section of the structure. The time for concrete conditioning in the formwork is reduced. In its turn, it further reduces labor costs and the cost of concrete work along with the cost of heat treatment. The authors conduct the technical and economic comparison of heat treatment options for the structures. The duration of monolithic structures erection with the use of combined heat treatment decreases in comparison with the method of peripheral heating. The economic effect consists of the reduction of the cost to organize and perform temperature control, insulation, electricity.

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.

Overview of ORNL/NRC programs addressing durability of concrete structures

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

Naus, D.J.; Oland, C.B.

1994-06-01

The role of reinforced concrete relative to its applications as either safety-related structures in nuclear power or engineered barriers of low-level radioactive waste disposal facilities is described. Factors that can affect the long-term durability of reinforced concrete are identified. Overviews are presented of the Structural Aging Program, which is addressing the aging management of safety-related concrete structures in nuclear power plants, and the Permeability Test Methods and Data Program, which is identifying pertinent data and information for use in performance assessments of engineered barriers for low-level radioactive waste disposal.

Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete

PubMed Central

Liu, Jun; Qiu, Qiwen; Xing, Feng; Pan, Dong

2014-01-01

This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively) were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride transport, apparent water permeability and pore structure. The results demonstrate that incorporation of fly ash, for the early test period, promotes the chloride ingress at the surface layer of concrete but substituting proportions of fly ash may have little impact on it. With the process of chloride immersion, the chloride concentration at the surface layer of concrete with or without fly ash was found to be nearly the same. In addition, it is suggested that the water permeability at the concrete surface area is closely related to the fly ash contents as well as the chloride exposure time. Pore structure was characterized by means of mercury intrusion porosimetry (MIP) test and the scanning electron microscopy (SEM) images. The modification of pore structure of concrete submersed in distilled water is determined by the pozzolanic reaction of fly ash and the calcium leaching effect. The pozzolanic reaction was more dominant at the immersion time of 180 days while the calcium leaching effect became more evident after 270 days. PMID:28788677

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

A Nonlocal Peridynamic Plasticity Model for the Dynamic Flow and Fracture of Concrete.

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

Vogler, Tracy; Lammi, Christopher James

A nonlocal, ordinary peridynamic constitutive model is formulated to numerically simulate the pressure-dependent flow and fracture of heterogeneous, quasi-brittle ma- terials, such as concrete. Classical mechanics and traditional computational modeling methods do not accurately model the distributed fracture observed within this family of materials. The peridynamic horizon, or range of influence, provides a characteristic length to the continuum and limits localization of fracture. Scaling laws are derived to relate the parameters of peridynamic constitutive model to the parameters of the classical Drucker-Prager plasticity model. Thermodynamic analysis of associated and non-associated plastic flow is performed. An implicit integration algorithm is formu-more » lated to calculate the accumulated plastic bond extension and force state. The gov- erning equations are linearized and the simulation of the quasi-static compression of a cylinder is compared to the classical theory. A dissipation-based peridynamic bond failure criteria is implemented to model fracture and the splitting of a concrete cylinder is numerically simulated. Finally, calculation of the impact and spallation of a con- crete structure is performed to assess the suitability of the material and failure models for simulating concrete during dynamic loadings. The peridynamic model is found to accurately simulate the inelastic deformation and fracture behavior of concrete during compression, splitting, and dynamically induced spall. The work expands the types of materials that can be modeled using peridynamics. A multi-scale methodology for simulating concrete to be used in conjunction with the plasticity model is presented. The work was funded by LDRD 158806.« less

Final Report Inspection of Aged/Degraded Containments Program.

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

Naus, Dan J; Ellingwood, B R; Oland, C Barry

2005-09-01

The Inspection of Aged/Degraded Containments Program had primary objectives of (1) understanding the significant factors relating corrosion occurrence, efficacy of inspection, and structural capacity reduction of steel containments and liners of reinforced concrete containments; (2) providing the United States Nuclear Regulatory Commission (USNRC) reviewers a means of establishing current structural capacity margins or estimating future residual structural capacity margins for steel containments, and concrete containments as limited by liner integrity; (3) providing recommendations, as appropriate, on information to be requested of licensees for guidance that could be utilized by USNRC reviewers in assessing the seriousness of reported incidences of containmentmore » degradation; and (4) providing technical assistance to the USNRC (as requested) related to concrete technology. Primary program accomplishments have included development of a degradation assessment methodology; reviews of techniques and methods for inspection and repair of containment metallic pressure boundaries; evaluation of high-frequency acoustic imaging, magnetostrictive sensor, electromagnetic acoustic transducer, and multimode guided plate wave technologies for inspection of inaccessible regions of containment metallic pressure boundaries; development of a continuum damage mechanics-based approach for structural deterioration; establishment of a methodology for reliability-based condition assessments of steel containments and liners; and fragility assessments of steel containments with localized corrosion. In addition, data and information assembled under this program has been transferred to the technical community through review meetings and briefings, national and international conference participation, technical committee involvement, and publications of reports and journal articles. Appendix A provides a listing of program reports, papers, and publications; and Appendix B contains a listing of program-related presentations.« less

Investigation of low compressive strengths of concrete in paving, precast and structural concrete

DOT National Transportation Integrated Search

2000-08-01

This research examines the causes for a high incidence of catastrophically low compressive strengths, primarily on structural concrete, during the 1997 construction season. The source for the low strengths was poor aggregate-paste bond associated wit...

Evaluation of deterioration of structural concrete due to chloride intrusion and other damaging mechanisms.

DOT National Transportation Integrated Search

2015-09-01

Kentucky's bridges continue to age and experience distress. The intrusion of chlorides into : concrete remains the primary mechanism for deterioration. It leads to reinforcing steel corrosion : that damages the adjoining concrete structure. This stud...

Development of shrinkage limits and testing protocols for ODOT high performance concrete.

DOT National Transportation Integrated Search

2013-12-01

ODOT has observed varying degrees of cracking in their concrete structures. Cracking of high performance reinforced : concrete structures, in particular bridge decks, is of paramount concern to ODOT. Cracking at early ages (especially within : the fi...

Mechanical performance of porous concrete pavement containing nano black rice husk ash

NASA Astrophysics Data System (ADS)

Ibrahim, M. Y. Mohd; Ramadhansyah, P. J.; Rosli, H. Mohd; Ibrahim, M. H. Wan

2018-01-01

This paper presents an experimental research on the performance of nano black rice husk ash on the porous concrete pavement properties. The performance of the porous concrete pavement mixtures was investigated based on their compressive strength, flexural strength, and splitting tensile strength. The results indicated that using nano material from black rice husk ash improved the mechanical properties of porous concrete pavement. In addition, the result of compressive, flexural, and splitting tensile strength was increased with increasing in curing age. Finally, porous concrete pavement with 10% replacement levels exhibited an excellent performance with good strength compared to others.

Frequency selection for coda wave interferometry in concrete structures.

PubMed

Fröjd, Patrik; Ulriksen, Peter

2017-09-01

This study contributes to the establishment of frequency recommendations for use in coda wave interferometry structural health monitoring (SHM) systems for concrete structures. To this end, codas with widely different central frequencies were used to detect boreholes with different diameters in a large concrete floor slab, and to track increasing damage in a small concrete beam subjected to bending loads. SHM results were obtained for damage that can be simulated by drilled holes on the scale of a few mm or microcracks due to bending. These results suggest that signals in the range of 50-150kHz are suitable in large concrete structures where it is necessary to account for the high attenuation of high-frequency signals. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Final Environmental Assessment for the Military Housing Privatization Initiative (MHPI), Dyess Air Force Base, Texas

DTIC Science & Technology

2011-07-01

drainageway for the flightline have been lined with concrete for a fuel-spill retention system . One unnamed tributary, which flows into Lake Totten on... potential , and erodibility all determine the ability of the ground to support man-made structures and facilities, to provide a landscaped environment...following effects : • Potential for increased likelihood of a release of hazardous materials (e.g., asbestos or lead from building demolition activities

Molecular Survey of Concrete Sewer Biofilm Microbial Communities

EPA Science Inventory

Although bacteria are implicated in deteriorating concrete structures, there is very little information on the composition of concrete microbial communities. To this end, we studied different concrete biofilms by performing sequence analysis of 16S rDNA concrete clone libraries. ...

Digital Image Correlation of Concrete Slab at University of Tennessee, Knoxville

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

Mahadevan, Sankaran; Agarwal, Vivek; Pham, Binh T.

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. Some degradation mechanisms of concrete manifest themselves via swelling or by other shape deformation of the concrete. Specifically, degradation of concrete structure damaged by ASR is viewed as one of the dominant factors impacting the structural integrity of aging nuclear power plants. 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 maintenancemore » decisions. Number of nondestructive examination techniques (i.e., thermography, digital image correlation, mechanical deformation measurements, nonlinear impact resonance (DIC) acoustic spectroscopy, and vibro-acoustic modulation) is used to detect the damage caused by ASR. DIC techniques have been increasing in popularity, especially in micro- and nano-scale mechanical testing applications due to its relative ease of implementation and use. Advances in computer technology and digital cameras help this method moving forward. To ensure the best outcome of the DIC system, important factors in the experiment are identified. They include standoff distance, speckle size, speckle pattern, and durable paint. These optimal experimental options are selected basing on a thorough investigation. The resulting DIC deformation map indicates that this technique can be used to generate data related to degradation assessment of concrete structure damaged by the impact of ASR.« less

Fiber-Reinforced Concrete For Hardened Shelter Construction

DTIC Science & Technology

1993-02-01

reduced cost and weight versus the symmetrically rebar reinforced beam design using normal-weight, standard-strength concrete currently used by the...while possibly reducing their cost and weight. Emphasis is placed on modular construction using prefabricated fiber- and rebar -reinforced concrete ...fiber- and rebar -reinforced concrete structural members into U.S. Air Force hardened structure designs. vii (The reverse of this page is blank) PREFACE

Identifying incompatible combinations of concrete materials : volume I, final report.

DOT National Transportation Integrated Search

2006-08-01

Unexpected interactions between otherwise acceptable ingredients in portland cement concrete are becoming increasingly common as cementitious systems become more and more complex and demands on the systems are more rigorous. Such incompatibilities ar...

Polymer concrete overlay test program : final report.

DOT National Transportation Integrated Search

1981-12-01

The results in this report were obtained during the test program which began in 1973. Physical properties of various polymer concretes are listed. They include compressive strength, splitting tensile strength, bond strength, the modulus of elasticity...

Crumb rubber modified asphalt concrete in Oregon : final report.

DOT National Transportation Integrated Search

2002-03-01

Since 1993, the Oregon Department of Transportation (ODOT) has been monitoring performance of seventeen rubber modified : asphalt and asphalt concrete sections constructed on Oregon highways. The study originated in response to the Intermodal Surface...

Placement of low-slump concrete : final report.

DOT National Transportation Integrated Search

1981-01-01

Low-slump concrete is being used on bridge decks mainly to prevent or minimize spalling and delaminations resulting from corrosion of the reinforcing steel. Other beneficial effects reported include high strength and durability. This study investigat...

Grooving of concrete pavements : final report.

DOT National Transportation Integrated Search

1973-08-01

This project was initiated by the Louisiana Department of Highways in cooperation with the Federal Highway Administration to determine whether transverse diamond cut grooves of a certain style (Christensen Style 7) placed in hardened concrete in seve...

Laboratory investigation of the use of volcanic ash in concrete : final report.

DOT National Transportation Integrated Search

2016-09-01

Supplementary cementitious materials (SCMs) are commonly used in KDOT concrete pavements and : bridge decks to improve strength and permeability characteristics. The supplementary cementitious materials : allowed under current KDOT specifications are...

55th Annual Fuze Conference

DTIC Science & Technology

2011-05-26

concrete plate and compact soil Confirmation: Complete Success both tests The TDD functioned as programmed; traces show entry and exit from each...concrete target and difference in deceleration levels between concrete and soil configuration The final exit & fire signals were generated as planned...Technical Data Package • Determine Process Capability • FMEA Manufacturing • Determine process capability • Cp = ( USL -LSL)/(6*Sigma) • Cpl

75 FR 38977 - Pre-Stressed Concrete Steel Wire Strand from the People's Republic of China: Notice of Amended...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-07

... Wire Strand from the People's Republic of China: Notice of Amended Final Affirmative Countervailing... issuing a countervailing duty order on pre-stressed concrete steel wire strand (PC strand) from the People... determination of material injury to a U.S. industry. See Pre-Stressed Concrete Steel Wire Strand from the People...

Factors that influence the efficiency of electrochemical chloride extraction during corrosion mitigation in reinforced concrete structures.

DOT National Transportation Integrated Search

2006-01-01

Electrochemical chloride extraction (ECE) is an electrochemical bridge restoration method for mitigating corrosion in reinforced concrete structures. ECE does this by moving chlorides away from the reinforcement and out of the concrete while simultan...

Modeling of porous concrete elements under load

NASA Astrophysics Data System (ADS)

Demchyna, B. H.; Famuliak, Yu. Ye.; Demchyna, Kh. B.

2017-12-01

It is known that cell concretes are almost immediately destroyed under load, having reached certain critical stresses. Such kind of destruction is called a "catastrophic failure". Process of crack formation is one of the main factors, influencing process of concrete destruction. Modern theory of crack formation is mainly based on the Griffith theory of destruction. However, the mentioned theory does not completely correspond to the structure of cell concrete with its cell structure, because the theory is intended for a solid body. The article presents one of the possible variants of modelling of the structure of cell concrete and gives some assumptions concerning the process of crack formation in such hollow, not solid environment.

Analisis parametrico de las variables que influyen en el comportamiento adherente de las armaduras pretesas en el hormigon

NASA Astrophysics Data System (ADS)

Arbelaez Jaramillo, Cesar Augusto

Prestressed concrete technique through the use of prestressed reinforcement is extended in the precast concrete industry. This technique consists on casting a concrete element over a previously prestressed reinforcement, proceeding to release once the concrete has reached a determined strength so the prestressed stress introduced to the reinforcement be transmitted, by bond, to concrete. The bond behaviour of prestressed reinforcement includes two phenomena: prestress transmission from the reinforcement to concrete and anchorage of the reinforcement. This bond behaviour is characterized by mean of two lengths: transmission length and anchorage length. The good design of these lengths is a basic and fundamental aspect in the project of precast prestressed concrete elements to guaranty the appropriate transmission of prestress and to allow the anchorage of the reinforcement along the structural element service life. The influence of the parameters related to the concrete dosage on the transmission and anchorage lengths of prestressing strands have been analyzed. The ECADA test method has been applied. With this method the operations of transmission of prestress and anchorage of the reinforcement are sequentially done. The transmission and anchorage lengths are determined from the force control supported by the reinforcement testing series of specimens with different embedment lengths. The differentiation of the concepts of anchorage length without slips and with slips has been proposed. The relationship of the parameters of dosage with the bond stress and the registered slips during the processes of transmission and anchorage has been studied. Expressions to value the slips distribution of the reinforcement in the transmission zone and in the anchorage zone have been proposed. A study on the determination of the transmission length from the free reinforcement slip end has been done and the viability to experimentally determine the transmission length from the slips sequence in the pull-out end as a function of the embedment length has been verified. The experimental results have been compared with results and predictions from other authors and standards, and an expression to calculate the transmission length have been proposed. Finally, the bond behaviour of self-compacting concretes has been compared with the bond behaviour of traditional concretes.

Effect of mineral additives on structure and properties of concrete for pavements

NASA Astrophysics Data System (ADS)

Sobol, Khrystyna; Markiv, Taras; Hunyak, Oleksii

2017-12-01

Concrete pavements is an attractive alternative to asphalt pavements because of its lower cost and higher durability. Major contribution to sustainable development can be made by partial replacement of cement in concrete pavement with supplementary cementitious materials of different nature and origin. In this paper, the effect of natural zeolite and perlite additives in complex with chemical admixtures on the structure and properties of concrete for pavement was studied. Compressive and flexural strength test was used to study the mechanical behavior of designed concrete under load. Generally, the compressive strength of both control concrete and concrete containing mineral additives levels at the later ages of hardening. The microstructure analysis of concrete with mineral additives of different nature activity showed the formation of additional amount of hydration products such as tobermorite type calcium hydrosilicate which provide self-reinforcement of hardening concrete system.

Studies concerning the durability of concrete vaults for intermediate level radioactive waste disposal: Electrochemical monitoring and corrosion aspects

NASA Astrophysics Data System (ADS)

Duffó, G. S.; Farina, S. B.; Arva, E. A.; Giordano, C. M.; Lafont, C. J.

2006-11-01

The Argentine Atomic Energy Commission (CNEA) is responsible of the development of a management nuclear waste disposal programme. This programme contemplates the design and construction of a facility for the final disposal of intermediate-level radioactive waste. The proposed concept is the near-surface monolithic repository similar to those in operation in El Cabril, Spain. The design of this type of repository is based on the use of multiple, independent and redundant barriers. Since the vault and cover are major components of the engineered barriers, the durability of these concrete structures is an important aspect for the facilities integrity. This work presents a laboratory and field investigation performed for the last 6 years on reinforced concrete specimens, in order to predict the service life of the intermediate level radioactive waste disposal vaults from data obtained from electrochemical techniques. On the other hand, the development of sensors that allow on-line measurements of rebar corrosion potential and corrosion current density; incoming oxygen flow that reaches the metal surface; concrete electrical resistivity and chloride concentration is shown. Those sensors, properly embedded in a new full scale vault (nowadays in construction), will allow the monitoring of the corrosion process of the steel rebars embedded in thestructure.

Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

PubMed Central

Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

2014-01-01

Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion. PMID:24558346

Monitoring corrosion of steel bars in reinforced concrete structures.

PubMed

Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

2014-01-01

Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion.

Online Monitoring of Concrete Structures in Nuclear Power Plants: Interim Report

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

Mahadevan, Sankaran; Cai, Guowei; Agarwal, Vivek

The existing fleet of nuclear power plants in the United States have initial operating licenses of 40 years, and many of these plants have applied for and received license extensions. As plant structures, systems, and components age, their useful life—considering both structural integrity and performance—is reduced as a result of deterioration of the materials. Assessment and management of aging concrete structures in nuclear plants require a more systematic approach than simple reliance on existing code-based design margins of safety. Structural health monitoring is required to produce actionable information regarding structural integrity that supports operational and maintenance decisions. The online monitoringmore » of concrete structures project conducted under the Advanced Instrumentation, Information, and Control Technologies Pathway of the Light Water Reactor Sustainability program at Idaho National Laboratory is seeking to develop and demonstrate capabilities for concrete structures health monitoring. Through this research project, several national laboratories and Vanderbilt University propose to develop a framework of research activities for the health monitoring of nuclear power plant concrete structures that includes the integration of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report briefly discusses activities in this project during October-December, 2014. The most significant activity during this period was the organizing of a two-day workshop on research needs in online monitoring of concrete structures, hosted by Vanderbilt University in November 2014. Thirty invitees from academia, industry and government participated in the workshop. The presentations and discussions at the workshop surveyed current activities related to concrete structures deterioration modeling and monitoring, and identified the challenges, knowledge gaps, and opportunities for advancing the state of the art; these discussions are summarized in this report« less

Primer on Durability of Nuclear Power Plant Reinforced Concrete Structures - A Review of Pertinent Factors

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

Naus, Dan J

The objective of this study was to provide a primer on the environmental effects that can affect the durability of nuclear power plant concrete structures. As concrete ages, changes in its properties will occur as a result of continuing microstructural changes (i.e., slow hydration, crystallization of amorphous constituents, and reactions between cement paste and aggregates), as well as environmental influences. These changes do not have to be detrimental to the point that concrete will not be able to meet its performance requirements. Concrete, however, can suffer undesirable changes with time because of improper specifications, a violation of specifications, or adversemore » performance of its cement paste matrix or aggregate constituents under either physical or chemical attack. Contained in this report is a discussion on concrete durability and the relationship between durability and performance, a review of the historical perspective related to concrete and longevity, a description of the basic materials that comprise reinforced concrete, and information on the environmental factors that can affect the performance of nuclear power plant concrete structures. Commentary is provided on the importance of an aging management program.« less

Radiation effects in concrete for nuclear power plants Part I: Quantification of radiation exposure and radiation effects

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

Field, Kevin G; Pape, Yann Le; Remec, Igor

A large fraction of light water reactor (LWR) construction utilizes concrete, including safety-related structures such as the biological shielding and containment building. Concrete is an inherently complex material, with the properties of concrete structures changing over their lifetime due to the intrinsic nature of concrete and influences from local environment. As concrete structures within LWRs age, the total neutron fluence exposure of the components, in particular the biological shield, can increase to levels where deleterious effects are introduced as a result of neutron irradiation. This work summarizes the current state of the art on irradiated concrete, including a review ofmore » the current literature and estimates the total neutron fluence expected in biological shields in typical LWR configurations. It was found a first-order mechanism for loss of mechanical properties of irradiated concrete is due to radiation-induced swelling of aggregates, which leads to volumetric expansion of the concrete. This phenomena is estimated to occur near the end of life of biological shield components in LWRs based on calculations of estimated peak neutron fluence in the shield after 80 years of operation.« less

Investigation of best practices for maintenance of concrete bridge railings : [tech summary].

DOT National Transportation Integrated Search

2015-01-01

The development of bio lms on concrete structures has a negative impact on aesthetics as well as on the performance and integrity : of concrete structures. Bio lms develop and grow easily when the right conditions are present, such as high rela...

Development of structural health monitoring and early warning system for reinforced concrete system

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

Iranata, Data, E-mail: iranata-data@yahoo.com, E-mail: data@ce.its.ac.id; Wahyuni, Endah; Murtiadi, Suryawan

Many buildings have been damaged due to earthquakes that occurred recently in Indonesia. The main cause of the damage is the large deformation of the building structural component cannot accommodate properly. Therefore, it is necessary to develop the Structural Health Monitoring System (SHMS) to measure precisely the deformation of the building structural component in the real time conditions. This paper presents the development of SHMS for reinforced concrete structural system. This monitoring system is based on deformation component such as strain of reinforcement bar, concrete strain, and displacement of reinforced concrete component. Since the deformation component has exceeded the limitmore » value, the warning message can be sent to the building occupies. This warning message has also can be performed as early warning system of the reinforced concrete structural system. The warning message can also be sent via Short Message Service (SMS) through the Global System for Mobile Communications (GSM) network. Hence, the SHMS should be integrated with internet modem to connect with GSM network. Additionally, the SHMS program is verified with experimental study of simply supported reinforced concrete beam. Verification results show that the SHMS has good agreement with experimental results.« less

An evaluation of concrete recycling and reuse practices

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

Nakhjiri, K.S.; MacKinney, J.

1997-02-01

Nuclear facilities operated by the Department of Energy (DOE), Department of Defense (DOD), and NRC licensees contain many concrete structures that are contaminated with radioactivity. Dismantling these structures will result in significant quantities of waste materials, both contaminated and uncontaminated. Bartlett estimates the total volume of waste from demolition of concrete structures to be on the order of 4 million cubic meters, but that only 20,000 cubic meters would be contaminated with radioactivity. Other studies suggest that as much as 5% of the concrete in these facilities would be contaminated with radioactivity. While the actual quantity of contaminated material shouldmore » be fixed with greater precision, the fact that so much uncontaminated concrete exists (over 95% of the total 4 million cubic meters) suggests that a program that recycles concrete could produce substantial savings for both government agencies (DOE, DOD) and private companies (NRC licensees). This paper presents a fundamental discussion of (1) various methods of processing concrete, (2) demolition methods, especially those compatible with recycling efforts, and (3) state-of-the-art concrete dismantlement techniques.« less

NDE application of ultrasonic tomography to a full-scale concrete structure.

PubMed

Choi, Hajin; Popovics, John S

2015-06-01

Newly developed ultrasonic imaging technology for large concrete elements, based on tomographic reconstruction, is presented. The developed 3-D internal images (velocity tomograms) are used to detect internal defects (polystyrene foam and pre-cracked concrete prisms) that represent structural damage within a large steel reinforced concrete element. A hybrid air-coupled/contact transducer system is deployed. Electrostatic air-coupled transducers are used to generate ultrasonic energy and contact accelerometers are attached on the opposing side of the concrete element to detect the ultrasonic pulses. The developed hybrid testing setup enables collection of a large amount of high-quality, through-thickness ultrasonic data without surface preparation to the concrete. The algebraic reconstruction technique is used to reconstruct p-wave velocity tomograms from the obtained time signal data. A comparison with a one-sided ultrasonic imaging method is presented for the same specimen. Through-thickness tomography shows some benefit over one-sided imaging for highly reinforced concrete elements. The results demonstrate that the proposed through-thickness ultrasonic technique shows great potential for evaluation of full-scale concrete structures in the field.

Scaling and saturation laws for the expansion of concrete exposed to sulfate attack.

PubMed

Monteiro, Paulo J M

2006-08-01

Reinforced concrete structures exposed to aggressive environments often require repair or retrofit even though they were designed to last >50 years. This statement is especially true for structures subjected to sulfate attack. It is critical that fundamental models of life prediction be developed for durability of concrete. Based on experimental results obtained over a 40-year period, scaling and saturation laws were formulated for concrete exposed to sulfate solution. These features have not been considered in current models used to predict life cycle of concrete exposed to aggressive environment. The mathematical analysis shows that porous concrete made with high and moderate water-to-cement ratios develops a definite scaling law after an initiation time. The scaling coefficient depends on the cement composition but does not depend on the original water-to-cement ratio. Dense concrete made with low water-to-cement ratios develops a cyclic saturation curve. An index for "potential of damage" is created to allow engineers to design concrete structures with better precision and cement chemists to develop portland cements with optimized composition.

Investigation on dynamic performance of concrete column crumb rubber steel and fiber concrete

NASA Astrophysics Data System (ADS)

Siti Nurul Nureda, M. Z.; Mariyana, A. K.; Khiyon, M. Iqbal; Rahman, M. S. Abdul; Nurizaty, Z.

2017-11-01

In general the Normal Concrete (NC) are by quasi-brittle failure, where, the nearly complete loss of loading capacity, once failure is initiated especially under dynamic loadings. The significance of this study is to improve the damping properties of concrete structure by utilization of the recycled materials from waste tires to be used in concrete as structural materials that improve seismic performance. In this study, the concrete containing 10% of fine crumb rubber and 1 % volume fraction of steel fiber from waste tires is use to investigate the dynamic performance (natural frequency and damping ratio).A small scale column were fabricated from Treated Crumb Rubber and Steel Fiber Concrete (TCRSFC) and NC were cast and cured for 28 days to investigate the dynamic performance. Based on analysis, dynamic modulus, damping ratio and natural frequency of TCRSFC has improved considerably by 5.18%, 109% and 10.94% when compared with NC. The TCRSFC producing concrete with the desired properties as well as to introduce the huge potential as dynamic resistance structure from severe damage especially prevention on catastrophic failure.

Bi-directional evolutionary structural optimization for strut-and-tie modelling of three-dimensional structural concrete

NASA Astrophysics Data System (ADS)

Shobeiri, Vahid; Ahmadi-Nedushan, Behrouz

2017-12-01

This article presents a method for the automatic generation of optimal strut-and-tie models in reinforced concrete structures using a bi-directional evolutionary structural optimization method. The methodology presented is developed for compliance minimization relying on the Abaqus finite element software package. The proposed approach deals with the generation of truss-like designs in a three-dimensional environment, addressing the design of corbels and joints as well as bridge piers and pile caps. Several three-dimensional examples are provided to show the capabilities of the proposed framework in finding optimal strut-and-tie models in reinforced concrete structures and verifying its efficiency to cope with torsional actions. Several issues relating to the use of the topology optimization for strut-and-tie modelling of structural concrete, such as chequerboard patterns, mesh-dependency and multiple load cases, are studied. In the last example, a design procedure for detailing and dimensioning of the strut-and-tie models is given according to the American Concrete Institute (ACI) 318-08 provisions.

Evaluation of fiber reinforced concrete : final report.

DOT National Transportation Integrated Search

1991-05-01

This study was conducted to evaluate the physical properties of plastic and hardened fiber reinforced concrete using three basic types of fibers: steel, fiberglass and polypropylene. Fibers have been shown to increase flexural and tensile strength, d...

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...

Evaluation of concrete pavement patching techniques.

DOT National Transportation Integrated Search

1989-01-01

This final report presents the results of a study undertaken to improve in concrete pavement patching techniques. Activities included an evaluation of the suitability of the impact hammer and maturity calculations for determining when a patch is read...

Roller-compacted concrete pavements.

DOT National Transportation Integrated Search

2010-09-01

Roller-compacted concrete (RCC) gets its name from the heavy vibratory steel drum and rubber-tired rollers used to help compact it into its final form. RCC has similar strength properties and consists of the same basic ingredients as conventional con...

Evaluation of concrete pavements with materials-related distress : final report.

DOT National Transportation Integrated Search

2010-03-02

An evaluation of cores sampled from six concrete pavements was performed. Factors : contributing to pavement distress observed in the field were determined, including expansive : alkali-silica reactivity and freeze-thaw deterioration related to poor ...

The economy of preventive maintenance of concrete bridges : final report.

DOT National Transportation Integrated Search

2016-03-01

The most economical approach to maintain existing concrete bridges is by adopting an active preventive maintenance : approach. An in-depth investigation of the combined deterioration effects of various deterioration mechanisms is needed : to establis...

Blast Design of Reinforced Concrete and Masonry Components Retrofitted with FRP

DTIC Science & Technology

2010-07-01

1 BLAST DESIGN OF REINFORCED CONCRETE AND MASONRY COMPONENTS RETROFITTED WITH FRP Marlon L. Bazan, Ph.D. and Charles J. Oswald, P.E., Ph.D...as an alternative to traditional methods for strengthening and retrofitting concrete and masonry structures to resist blast loads. The development...and experimental validation of a methodology for modeling the response of blast loaded concrete and masonry structural components retrofitted with FRP

Sensitivity study on durability variables of marine concrete structures

NASA Astrophysics Data System (ADS)

Zhou, Xin'gang; Li, Kefei

2013-06-01

In order to study the influence of parameters on durability of marine concrete structures, the parameter's sensitivity analysis was studied in this paper. With the Fick's 2nd law of diffusion and the deterministic sensitivity analysis method (DSA), the sensitivity factors of apparent surface chloride content, apparent chloride diffusion coefficient and its time dependent attenuation factor were analyzed. The results of the analysis show that the impact of design variables on concrete durability was different. The values of sensitivity factor of chloride diffusion coefficient and its time dependent attenuation factor were higher than others. Relative less error in chloride diffusion coefficient and its time dependent attenuation coefficient induces a bigger error in concrete durability design and life prediction. According to probability sensitivity analysis (PSA), the influence of mean value and variance of concrete durability design variables on the durability failure probability was studied. The results of the study provide quantitative measures of the importance of concrete durability design and life prediction variables. It was concluded that the chloride diffusion coefficient and its time dependent attenuation factor have more influence on the reliability of marine concrete structural durability. In durability design and life prediction of marine concrete structures, it was very important to reduce the measure and statistic error of durability design variables.

Study on Flexural Behaviour of Ternary Blended Reinforced Self Compacting Concrete Beam with Conventional RCC Beam

NASA Astrophysics Data System (ADS)

Marshaline Seles, M.; Suryanarayanan, R.; Vivek, S. S.; Dhinakaran, G.

2017-07-01

The conventional concrete when used for structures having dense congested reinforcement, the problems such as external compaction and vibration needs special attention. In such case, the self compacting concrete (SCC) which has the properties like flow ability, passing and filling ability would be an obvious answer. All those SCC flow behavior was governed by EFNARC specifications. In present study, the combination type of SCC was prepared by replacing cement with silica fume (SF) and metakaolin (MK) along with optimum dosages of chemical admixtures. From the fresh property test, cube compressive strength and cylinder split tensile strength, optimum ternary mix was obtained. In order to study the flexural behavior, the optimum ternary mix was taken in which beam specimens of size 1200 mm x 100 mm x 200 mm was designed as singly reinforced section according to IS: 456-2000, Limit state method. Finally the comparative experimental analysis was made between conventional RCC and SCC beams of same grade in terms of flexural strength namely yield load & ultimate load, load- deflection curve, crack size and pattern respectively.

Microstructural and Microanalytical Study on Concrete Exposed to the Sulfate Environment

NASA Astrophysics Data System (ADS)

Qing, Fang; Beixing, Li; Jiangang, Yin; Xiaolu, Yuan

2017-11-01

Microstructural properties have been examined to investigate the effect of mineral admixtures on the sulfate resistance of concrete. Concrete and cement paste specimens made with ordinary Portland cement (OPC) or ordinary Portland cement incorporating 20% fly ash (FA) or 30% ground blast furnace slag (GBFS), were made and exposed to 250 cycles of the cyclic sulfate environment. Microstructural and Microanalytical study was conducted by means of x-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and mercury intrusion porosimetry (MIP). Results indicate that the pore structure of concrete after sulfate exposure possesses the fractal feature. The OPC concrete presents more complex pore internal surface, higher porosity and less micro-pores than the concrete incorporating fly ash and GBFS. Portlandite in OPC concrete and OPC-FA concrete is mainly converted to gypsum; while for OPC-GBFS concrete, both gypsum and ettringite are formed. In the cyclic sulfate environment, repeated hydration and dehydration of sulfates produce the expansive stress in pores, aggravating the demolishment of concrete structure.

Application of smart BFRP bars with distributed fiber optic sensors into concrete structures

NASA Astrophysics Data System (ADS)

Tang, Yongsheng; Wu, Zhishen; Yang, Caiqian; Wu, Gang; Zhao, Lihua; Song, Shiwei

2010-04-01

In this paper, the self-sensing and mechanical properties of concrete structures strengthened with a novel type of smart basalt fiber reinforced polymer (BFRP) bars were experimentally studied, wherein the sensing element is Brillouin scattering-based distributed optical fiber sensing technique. First, one of the smart bars was applied to strengthen a 2m concrete beam under a 4-points static loading manner in the laboratory. During the experiment, the bar can measure the inner strain changes and monitor the randomly distributed cracks well. With the distributed strain information along the bar, the distributed deformation of the beam can be calculated, and the structural health can be monitored and evaluated as well. Then, two smart bars with a length of about 70m were embedded into a concrete airfield pavement reinforced by long BFRP bars. In the field test, all the optical fiber sensors in the smart bars survived the whole concrete casting process and worked well. From the measured data, the concrete cracks along the pavement length can be easily monitored. The experimental results also confirmed that the bars can strengthen the structures especially after the yielding of steel bars. All the results confirm that this new type of smart BFRP bars show not only good sensing performance but also mechanical performance in the concrete structures.

Experimental Investigation on Pore Structure Characterization of Concrete Exposed to Water and Chlorides

PubMed Central

Liu, Jun; Tang, Kaifeng; Qiu, Qiwen; Pan, Dong; Lei, Zongru; Xing, Feng

2014-01-01

In this paper, the pore structure characterization of concrete exposed to deionised water and 5% NaCl solution was evaluated using mercury intrusion porosity (MIP), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of calcium leaching, fly ash incorporation, and chloride ions on the evolution of pore structure characteristics were investigated. The results demonstrate that: (i) in ordinary concrete without any fly ash, the leaching effect of the cement products is more evident than the cement hydration effect. From the experimental data, Ca(OH)2 is leached considerably with the increase in immersion time. The pore structure of concrete can also be affected by the formation of an oriented structure of water in concrete materials; (ii) incorporation of fly ash makes a difference for the performance of concrete submersed in solutions as the total porosity and the pore connectivity can be lower. Especially when the dosage of fly ash is up to 30%, the pores with the diameter of larger than 100 nm show significant decrease. It demonstrates that the pore properties are improved by fly ash, which enhances the resistance against the calcium leaching; (iii) chlorides have a significant impact on microstructure of concrete materials because of the chemical interactions between the chlorides and cement hydrates. PMID:28788204

Fundamental and assessment of concrete structure monitoring by using acoustic emission technique testing: A review

NASA Astrophysics Data System (ADS)

Desa, M. S. M.; Ibrahim, M. H. W.; Shahidan, S.; Ghadzali, N. S.; Misri, Z.

2018-04-01

Acoustic emission (AE) technique is one of the non-destructive (NDT) testing, where it can be used to determine the damage of concrete structures such as crack, corrosion, stability, sensitivity, as structure monitoring and energy formed within cracking opening growth in the concrete structure. This article gives a comprehensive review of the acoustic emission (AE) technique testing due to its application in concrete structure for structural health monitoring (SHM). Assessment of AE technique used for structural are reviewed to give the perception of its structural engineering such as dam, bridge and building, where the previous research has been reviewed based on AE application. The assessment of AE technique focusing on basic fundamental of parametric and signal waveform analysis during analysis process and its capability in structural monitoring. Moreover, the assessment and application of AE due to its function have been summarized and highlighted for future references

Modeling of fracture of protective concrete structures under impact loads

NASA Astrophysics Data System (ADS)

Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

2015-10-01

This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

Microbial healing of cracks in concrete: a review.

PubMed

Joshi, Sumit; Goyal, Shweta; Mukherjee, Abhijit; Reddy, M Sudhakara

2017-11-01

Concrete is the most widely used construction material of the world and maintaining concrete structures from premature deterioration is proving to be a great challenge. Early age formation of micro-cracking in concrete structure severely affects the serviceability leading to high cost of maintenance. Apart from conventional methods of repairing cracks with sealants or treating the concrete with adhesive chemicals to prevent the cracks from widening, a microbial crack-healing approach has shown promising results. The unique feature of the microbial system is that it enables self-healing of concrete. The effectiveness of microbially induced calcium carbonate precipitation (MICCP) in improving durability of cementitious building materials, restoration of stone monuments and soil bioclogging is discussed. Main emphasis has been laid on the potential of bacteria-based crack repair in concrete structure and the applications of different bacterial treatments to self-healing cracks. Furthermore, recommendations to employ the MICCP technology at commercial scale and reduction in the cost of application are provided in this review.

Fiber reinforcement of concrete structures

DOT National Transportation Integrated Search

2002-09-01

Deterioration of concrete structures due to steel corrosion is a matter of considerable concern since the repairing of these structures proved to be a costly process. Repair and rehabilitation of the civil structures needs an enduring repair material...

Construction vibration attenuation with distance and its effect on the quality of early-age concrete.

DOT National Transportation Integrated Search

2011-06-01

Damage to structures due to vibrations from pile driving operations is of great concern to engineers. This : research has stemmed from the need to address potential damage to concrete-filled pipe piles and recently : placed concrete structures that c...

Performance of high performance concrete (HPC) in low pH and sulfate environment.

DOT National Transportation Integrated Search

2013-05-01

The goal of this research is to determine the impact of low pH and sulfate environment on high-performance concrete (HPC) and if the current structural and materials specifications provide adequate protections for concrete structures to meet the 75-y...

Strength and durability of concrete: Effects of cement paste-aggregate interfaces. Part 1: Theoretical study on influence of interfacial transition zone on properties of concrete materials; Final report

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

Zhang, Y.; Chen, W.F.

1998-08-01

This research was based on a two-part basic research investigation studying the effects of cement paste-aggregate interfaces (or interfacial transition zones-ITZ) on strength and durability of concrete. Part 1 dealt with the theoretical study and Part 2 dealt with the experimental.

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.

Outdoor thermal monitoring of large scale structures by infrared thermography integrated in an ICT based architecture

NASA Astrophysics Data System (ADS)

Dumoulin, Jean; Crinière, Antoine; Averty, Rodolphe

2015-04-01

An infrared system has been developed to monitor transport infrastructures in a standalone configuration. Results obtained on bridges open to traffic allows to retrieve the inner structure of the decks. To complete this study, experiments were carried out over several months to monitor two reinforced concrete beams of 16 m long and 21 T each. Detection of a damaged area over one of the two beams was made by Pulse Phase Thermography approach. Measurements carried out over several months. Finally, conclusion on the robustness of the system is proposed and perspectives are presented.

29 CFR 1926.704 - Requirements for precast concrete.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 8 2010-07-01 2010-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural framing...

Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures.

PubMed

Zhan, Yijian; Meschke, Günther

2017-07-08

The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense.

Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures

PubMed Central

Zhan, Yijian

2017-01-01

The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense. PMID:28773130

High-performance concrete : applying life-cycle cost analysis and developing specifications.

DOT National Transportation Integrated Search

2016-12-01

Numerous studies and transportation agency experience across the nation have established that highperformance concrete (HPC) technology improves concrete quality and extends the service life of concrete structures at risk of chlorideinduced cor...

Quality control of fireproof coatings for reinforced concrete structures

NASA Astrophysics Data System (ADS)

Gravit, Marina; Dmitriev, Ivan; Ishkov, Alexander

2017-10-01

The article analyzes methods of quality inspection of fireproof coatings (work flow, measuring, laboratory, etc.). In modern construction there is a problem of lack of distinct monitoring for the fire protection testing. There is a description of this testing for reinforced concrete structures. The article shows the results of calculation quality control of hatches as an example of fireproof coating for reinforced concrete structures.

Energy use in repairs by cover concrete replacement or silane treatment for extending service life of chloride-exposed concrete structures

NASA Astrophysics Data System (ADS)

Petcherdchoo, A.

2018-05-01

In this study, the service life of repaired concrete structures under chloride environment is predicted. This prediction is performed by considering the mechanism of chloride ion diffusion using the partial differential equation (PDE) of the Fick’s second law. The one-dimensional PDE cannot simply be solved, when concrete structures are cyclically repaired with cover concrete replacement or silane treatment. The difficulty is encountered in solving position-dependent chloride profile and diffusion coefficient after repairs. In order to remedy the difficulty, the finite difference method is used. By virtue of numerical computation, the position-dependent chloride profile can be treated position by position. And, based on the Crank-Nicolson scheme, a proper formulation embedded with position-dependent diffusion coefficient can be derived. By using the aforementioned idea, position- and time-dependent chloride ion concentration profiles for concrete structures with repairs can be calculated and shown, and their service life can be predicted. Moreover, the use of energy in different repair actions is also considered for comparison. From the study, it is found that repairs can control rebar corrosion and/or concrete cracking depending on repair actions.

The evaluation of pavement patching materials in Oregon : final report.

DOT National Transportation Integrated Search

1980-11-01

This report describes the installation and evaluation of trial pavement patching materials in Oregon. The patches were placed in Portland cement concrete and bituminous concrete pavements and evaluated for periods ranging from four to twelve months. ...

Asphaltic concrete overlays of rigid and flexible pavements : final report.

DOT National Transportation Integrated Search

1980-10-01

This study evaluated the effect of a given thickness of asphaltic concrete overlay in rehabilitating 53 test sections conforming to the experiment design. This factorial design specified various levels of traffic intensity and overlay thickness for b...

Correlation of construction quality criteria with performance of asphaltic concrete pavements : final report.

DOT National Transportation Integrated Search

1987-08-01

This report is concerned with the detemination of the relationship between asphaltic concrete suface course specifications and the level of performance of pavements constructed under these specifications. The relationship was investigated through com...

Investigation of nuclear asphalt content gauge : final report.

DOT National Transportation Integrated Search

1995-07-01

The introduction of new aggregate sources to Louisiana in the mid 1980s has presented problems in asphalt concrete mix design and construction. Absorptive aggregates such as reclaimed portland cement concrete and some stones now being supplied have m...

An evaluation of dense graded asphalt-rubber concrete in Minnesota. Final report

DOT National Transportation Integrated Search

1991-11-01

The Minnesota Department of Transportation is continually investigating ways to improve the cold temperature performance of its asphalt concrete pavements. One reported method is to modify the asphalt binder with ground reclaimed automobile and truck...

Pozzolan cement study : final report.

DOT National Transportation Integrated Search

1979-12-01

An experimental section using Type 1P cement concrete was poured on an active construction project in south Louisiana, near Franklin. A comparison in quality was made between this section and the normal Type 1(B) cement concrete poured on the remaind...

Quality control of recycled asphaltic concrete : final report.

DOT National Transportation Integrated Search

1982-07-01

This study examined the variations found in recycled asphaltic concrete mix based upon plant quality control data and verification testing. The data was collected from four recycled hot-mix projects constructed in 1981. All plant control and acceptan...

Internally sealed concrete for bridge deck protection : final report.

DOT National Transportation Integrated Search

1983-01-01

This study investigated the characteristics of internally sealed concrete through tests on specimens fabricated in the laboratory to determine its properties and an installation in a bridge deck to assess the controls needed during construction and i...

Polypropylene fiber reinforced concrete detention ponds : final report.

DOT National Transportation Integrated Search

1995-09-01

In 1991, two Durafiber polypropylene fiber reinforced concrete lined detention ponds were constructed. The detention ponds are located on the north side of the 181st Avenue Interchange, on the Columbia River Highway (I-84), approximately ten miles ea...

Evaluation of synthetic fabrics for the reduction of reflective cracking : final report.

DOT National Transportation Integrated Search

1975-04-01

This research was undertaken to evaluate the effectiveness of two synthetic fabrics in relieving stress and reducing or eliminating reflection cracking in the asphaltic concrete overlay of existing distressed concrete pavements. : The polypropylene f...

Concrete patching guide : final report.

DOT National Transportation Integrated Search

2003-09-01

Maintenance personnel often select a material for patching concrete based on what they have used in the past. However, each patching job has particular demands, which may be different from what was required in past applications. Also, the list of ava...

Route 139 rehabilitation : Pulaski Skyway contract 2 : final report.

DOT National Transportation Integrated Search

2017-06-01

After being outside and exposed to the elements during many years of service, concrete and the reinforcement within begins to deteriorate and corrode, which affects the performance of concrete bridge balustrades, especially those built in the 1930...

Texturing of concrete pavements : final report.

DOT National Transportation Integrated Search

1979-08-01

During the month of June, 1973, the plastic concrete surface of a section of Interstate 10 in the Baton Rouge area was textured using several different texturing techniques, such as burlap drag, brooms and metal tines. The purpose of this experimenta...

Evaluation of full depth asphaltic concrete pavements : final report.

DOT National Transportation Integrated Search

1982-10-01

the aim of this study was to evaluate the full depth asphaltic concrete pavement design concept by observing the performance characteristics of two 13-inch pavements constructed in 1970. Pavement performance measurements, over an 11-year period, incl...

Impact of coarse aggregate gradation on PCC performance properties : final report.

DOT National Transportation Integrated Search

2013-10-15

Increasingly, aggregates in South Carolina are failing to meet the standard requirements for gradation for use in : portland cement concrete. The effect of such failed aggregate gradations on concrete properties and the : consequent effect on short- ...

A comment on the use of polymer-impregnated concrete in bridge decks to achieve a reduction in material volume and first cost.

DOT National Transportation Integrated Search

1975-01-01

Three 180', simple span, composite plate girder structures were designed to approximate the material requirements and first cost associated with a polymer-impregnated concrete as compared to those for a conventional concrete bridge deck. The structur...

Damage evaluation of reinforced concrete frame based on a combined fiber beam model

NASA Astrophysics Data System (ADS)

Shang, Bing; Liu, ZhanLi; Zhuang, Zhuo

2014-04-01

In order to analyze and simulate the impact collapse or seismic response of the reinforced concrete (RC) structures, a combined fiber beam model is proposed by dividing the cross section of RC beam into concrete fiber and steel fiber. The stress-strain relationship of concrete fiber is based on a model proposed by concrete codes for concrete structures. The stress-strain behavior of steel fiber is based on a model suggested by others. These constitutive models are implemented into a general finite element program ABAQUS through the user defined subroutines to provide effective computational tools for the inelastic analysis of RC frame structures. The fiber model proposed in this paper is validated by comparing with experiment data of the RC column under cyclical lateral loading. The damage evolution of a three-dimension frame subjected to impact loading is also investigated.

Numerical simulation of deformation and fracture of space protective shell structures from concrete and fiber concrete under pulse loading

NASA Astrophysics Data System (ADS)

Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

2015-11-01

This paper presents results of numerical simulation of interaction between aircraft Boeing 747-400 and protective shell of nuclear power plant. The shell is presented as complex multilayered cellular structure comprising layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was held three-dimensionally using the author's algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. The dynamics of stress-strain state and fracture of structure were studied. Destruction is described using two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of shell cellular structure—cells start to destruct in unloading wave, originating after output of compression wave to the free surfaces of cells.

Structural-functional integrated concrete with macro-encapsulated inorganic PCM

NASA Astrophysics Data System (ADS)

Mohseni, Ehsan; Tang, Waiching; Wang, Zhiyu

2017-09-01

Over the last few years the application of thermal energy storage system incorporating phase change materials (PCMs) to foster productivity and efficiency of buildings energy has grown rapidly. In this study, a structural-functional integrated concrete was developed using macro-encapsulated PCM-lightweight aggregate (LWA) as partial replacement (25 and 50% by volume) of coarse aggregate in control concrete. The PCM-LWA was prepared by incorporation of an inorganic PCM into porous LWAs through vacuum impregnation. The mechanical and thermal performance of PCM-LWA concrete were studied. The test results revealed that though the compressive strength of concrete with PCM-LWA was lower than the control concrete, but ranged from 22.02 MPa to 42.88 MPa which above the minimum strength requirement for structural application. The thermal performance test indicated that macro-encapsulated PCM-LWA has underwent the phase change transition reducing the indoor temperature.

Management of the aging of critical safety-related concrete structures in light-water reactor plants

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

Naus, D.J.; Oland, C.B.; Arndt, E.G.

1990-01-01

The Structural Aging Program has the overall objective of providing the USNRC with an improved basis for evaluating nuclear power plant safety-related structures for continued service. The program consists of a management task and three technical tasks: materials property data base, structural component assessment/repair technology, and quantitative methodology for continued-service determinations. Objectives, accomplishments, and planned activities under each of these tasks are presented. Major program accomplishments include development of a materials property data base for structural materials as well as an aging assessment methodology for concrete structures in nuclear power plants. Furthermore, a review and assessment of inservice inspection techniquesmore » for concrete materials and structures has been complete, and work on development of a methodology which can be used for performing current as well as reliability-based future condition assessment of concrete structures is well under way. 43 refs., 3 tabs.« less

Preface

NASA Astrophysics Data System (ADS)

L'Hostis, Valérie; Foct, François; Féron, Damien

2006-11-01

The reinforced concrete is widely used in the construction of nuclear power plants, of nuclear facilities and structures for long-term storage and the disposal of radioactive waste. Indeed this kind of material is used for many purposes, including support, containment, and environmental protection for different types of facilities: e.g. surface structures, shallow subsurface vaults and deep underground repositories. These structures are required to besafe and reliable in challenging and varying environments for periods of time that can potentially range up to several hundred years. During their operational life, these structures will in all likelihood be subjected to a number of environmental stresses or ageing factors that may adversely affect their performance and result in shortened service lives. The detection and assessment of the magnitude as well as the rate of occurrence of any environmental factor-related degradation are key factors in maintaining the capability of these structures to meet their operational requirements. As the knowledge base for modern concretes, such as would be used in fuel cycle-related facilities, is relatively new (i.e. about, 100 years versus the required 200 to 500 or more years), additional inputs are required in several areas to ensure that these structures will continue to meet their design requirements throughout their operational life. Within this context, the international Workshop entitled "NUCPERF 2006, Corrosion and Long Term Performance of Concrete in NPP and Waste Facilities" (EFC Event 284) was held at Cadarache (France), on 27-30 March 2006. Its purpose was to bring together scientists and engineers from various countries that are developing nuclear power generation and/or waste disposal programmes. A special focus has been made on the discussion on R& D progress with regard to concrete degradation and corrosion of steel reinforcements in order to reach a consensus on R& D needs to further develop cooperative programmes. The sessions of the workshop covered the following areas, from fundamental aspects to technically relevant industrial applications: - Present and Future Expectations on regulations, design codes and R& D programmes; - Experimental Studies mainly focused on corrosion of embedded steels and its mechanical consequences, reactive agents transport and chemical degradation of concrete; - Phenomenological Modelling of the different mechanisms involved in reinforced concrete degradation (corrosion, transport, mechanics, etc.); - Service Life Models focused on the assessment of reinforced concrete structures and life cycle analysis; - Feedback Experience use of field experiences and archaeological artefacts for the phenomenological understanding and modelling; - Monitoring and Repair on-site corrosion evaluation, repairing techniques performance... The organisation and the success of this Workshop have been made possible thanks to CEA (Commissariat à l'Énergie Atomique) and EDF (Électricité de France) which co-organised this event. It was co-sponsored by EFC/WP4 (European Federation of Corrosion, Nuclear corrosion working party) and OECD/NEA (Nuclear Energy Agency) which the editors want to warmly thank for their active scientific and practical contributions. The editors would also like to thank the authors who presented papers of outstanding scientific content and who responded enthusiastically to the discussions and questions raised during the Workshop, the programme committee, who had to make the tricky selection of the presented papers, and finally the reviewers of the papers presented in this special issue. This Workshop was a forum to exchange state-of-the-art knowledge on corrosion and long-term performance of concrete in nuclear power plants and waste facilities. The editors hope that the scientific results gathered in these proceedings will be useful to scientists and engineers in the field of reinforced concrete materials for nuclear applications. Valérie L'Hostis, François Foct and Damien Féron Editors of this Special Issue

Lattice Modeling of Early-Age Behavior of Structural Concrete.

PubMed

Pan, Yaming; Prado, Armando; Porras, Rocío; Hafez, Omar M; Bolander, John E

2017-02-25

The susceptibility of structural concrete to early-age cracking depends on material composition, methods of processing, structural boundary conditions, and a variety of environmental factors. Computational modeling offers a means for identifying primary factors and strategies for reducing cracking potential. Herein, lattice models are shown to be adept at simulating the thermal-hygral-mechanical phenomena that influence early-age cracking. In particular, this paper presents a lattice-based approach that utilizes a model of cementitious materials hydration to control the development of concrete properties, including stiffness, strength, and creep resistance. The approach is validated and used to simulate early-age cracking in concrete bridge decks. Structural configuration plays a key role in determining the magnitude and distribution of stresses caused by volume instabilities of the concrete material. Under restrained conditions, both thermal and hygral effects are found to be primary contributors to cracking potential.

Modeling of fracture of protective concrete structures under impact loads

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

Radchenko, P. A., E-mail: radchenko@live.ru; Batuev, S. P.; Radchenko, A. V.

This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength propertiesmore » of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.« less

Lattice Modeling of Early-Age Behavior of Structural Concrete

PubMed Central

Pan, Yaming; Prado, Armando; Porras, Rocío; Hafez, Omar M.; Bolander, John E.

2017-01-01

The susceptibility of structural concrete to early-age cracking depends on material composition, methods of processing, structural boundary conditions, and a variety of environmental factors. Computational modeling offers a means for identifying primary factors and strategies for reducing cracking potential. Herein, lattice models are shown to be adept at simulating the thermal-hygral-mechanical phenomena that influence early-age cracking. In particular, this paper presents a lattice-based approach that utilizes a model of cementitious materials hydration to control the development of concrete properties, including stiffness, strength, and creep resistance. The approach is validated and used to simulate early-age cracking in concrete bridge decks. Structural configuration plays a key role in determining the magnitude and distribution of stresses caused by volume instabilities of the concrete material. Under restrained conditions, both thermal and hygral effects are found to be primary contributors to cracking potential. PMID:28772590

Biocalcification by halophilic bacteria for remediation of concrete structures in marine environment.

PubMed

Bansal, Roohi; Dhami, Navdeep Kaur; Mukherjee, Abhijit; Reddy, M Sudhakara

2016-11-01

Microbial carbonate precipitation has emerged as a promising technology for remediation and restoration of concrete structures. Deterioration of reinforced concrete structures in marine environments is a major concern due to chloride-induced corrosion. In the current study, halophilic bacteria Exiguobacterium mexicanum was isolated from sea water and tested for biomineralization potential under different salt stress conditions. The growth, urease and carbonic anhydrase production significantly increased under salt stress conditions. Maximum calcium carbonate precipitation was recorded at 5 % NaCl concentration. Application of E. mexicanum on concrete specimens significantly increased the compressive strength (23.5 %) and reduced water absorption about five times under 5 % salt stress conditions compared to control specimens. SEM and XRD analysis of bacterial-treated concrete specimens confirmed the precipitation of calcite. The present study results support the potential of this technology for improving the strength and durability properties of building structures in marine environments.

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.

Fighting Corrosion

NASA Technical Reports Server (NTRS)

2004-01-01

Reinforced concrete structures such as bridges, parking decks, and balconies are designed to have a service life of over 50 years. All too often, however, many structures fall short of this goal, requiring expensive repairs and protection work earlier than anticipated. The corrosion of reinforced steel within the concrete infrastructure is a major cause for this premature deterioration. Such corrosion is a particularly dangerous problem for the facilities at NASA s Kennedy Space Center. Located near the Atlantic Ocean in Florida, Kennedy is based in one of the most corrosive-prone areas in the world. In order to protect its launch support structures, highways, pipelines, and other steel-reinforced concrete structures, Kennedy engineers developed the Galvanic Liquid Applied Coating System. The system utilizes an inorganic coating material that slows or stops the corrosion of reinforced steel members inside concrete structures. Early tests determined that the coating meets the criteria of the National Association of Corrosion Engineers for complete protection of steel rebar embedded in concrete. Testing is being continued at the Kennedy's Materials Science Beach Corrosion Test Site.

Impact load-induced micro-structural damage and micro-structure associated mechanical response of concrete made with different surface roughness and porosity aggregates

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

Erdem, Savas, E-mail: evxse1@nottingham.ac.uk; Dawson, Andrew Robert; Thom, Nicholas Howard

2012-02-15

The relationship between the nature of micro damage under impact loading and changes in mechanical behavior associated with different microstructures is studied for concretes made with two different coarse aggregates having significant differences mainly in roughness and porosity - sintered fly ash and uncrushed gravel. A range of techniques including X-ray diffraction, digital image analysis, mercury porosimetry, X-ray computed tomography, laser surface profilometry and scanning electron microscopy were used to characterize the aggregates and micro-structures. The concrete prepared with lightweight aggregates was stronger in compression than the gravel aggregate concrete due to enhanced hydration as a result of internal curing.more » In the lightweight concrete, it was deduced that an inhomogeneous micro-structure led to strain incompatibilities and consequent localized stress concentrations in the mix, leading to accelerated failure. The pore structure, compressibility, and surface texture of the aggregates are of paramount importance for the micro-cracking growth.« less

Use of recycled fine aggregate in concretes with durable requirements.

PubMed

Zega, Claudio Javier; Di Maio, Angel Antonio

2011-11-01

The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete. Copyright © 2011 Elsevier Ltd. All rights reserved.

Evaluation of treatment options for ASR-affected concrete : final report, December 11, 2009.

DOT National Transportation Integrated Search

2009-12-11

This research project was undertaken to evaluate the potential of using surface treatments including lithium nitrate, : sodium tartarate, siloxanes, silane, and boiled linseed oil to mitigate or slow the rate of concrete deterioration : associated wi...

Overview of latex modified concrete overlays : final report.

DOT National Transportation Integrated Search

1984-01-01

Twelve bridges with latex modified concrete (LMC) overlays ranging in age from new to 13 years were studied and their general condition found to be good. The half-cell and chloride data were inconclusive because background data were not available for...

Hot plant recycling of asphaltic concrete : final report.

DOT National Transportation Integrated Search

1980-05-01

This report covers the design, construction and evaluation of two hot mix recycling projects. One project recycled two inches of existing dense-asphaltic concrete through a modified batch plant. The second project recycled a total of five inches of e...

Evaluation of Louisiana's statistically based quality control and acceptance specifications for asphaltic concrete : final report.

DOT National Transportation Integrated Search

1998-09-01

In 1971, the Louisiana Department of Transportation and Development initiated a statistically based specification system for asphaltic concrete using historically generated data. A Materials Test Data (MATT) reporting system was also started to archi...

Laboratory evaluation of 100 percent fly ash cementitious systems : final report 573.

DOT National Transportation Integrated Search

2016-12-01

Long-lasting, durable concrete is a must have for Departments of Transportation (DOTs) in todays construction and economic climate. Many entities are : turning to alternative concrete mixtures to ensure long-term durability such as ternary mixt...

Experimental validation of bracing recommendations for long-span concrete girders : final report.

DOT National Transportation Integrated Search

2012-12-01

During bridge construction, flexible support conditions provided by steel-reinforced neoprene bearing pads supporting precast, prestressed concrete girders may allow the girders to become unstable, rolling about an axis parallel to the span of the gi...

Nitrogen dioxide sequestration using demolished concrete and its potential application in transportation infrastructure development : final report.

DOT National Transportation Integrated Search

2016-04-01

Achieving environmental sustainability of the US transportation infrastructure via more environmentally sound construction is not a trivial task. Our : proposal, which addresses this critical area, is aiming at transforming concrete, the material of ...

Antistripping additives in lieu of mineral fillers in asphaltic concrete mixtures : final report.

DOT National Transportation Integrated Search

1975-04-01

The major objective of the study was to determine the feasibility of specifying antistripping additives in lieu of mineral fillers in asphaltic concrete mixtures using Marshall Test and visual observation of stripping characteristics as criteria. : T...

In-Vehicle Safety Advisory And Warning System (Ivsaws), Volume II: Final Report

DOT National Transportation Integrated Search

2001-04-01

Methods for determining the workability of freshly mixed portland-cement concrete with slumps less than 51 mm (2 in) were investigated. Four potential methods to determine the workability of concrete were proposed for evaluation and development. The ...

Evaluation of recycled asphaltic concrete : final report.

DOT National Transportation Integrated Search

1977-01-01

This report describes a project in which approximately 6,200 tons (5,630 Mg) of asphaltic concrete were recycled through a conventional asphalt batch plant. During the construction of the project, a buildup of asphalt-coated fines occurred in the dry...

To What Degree Does Handling Concrete Molecular Models Promote the Ability to Translate and Coordinate between 2D and 3D Molecular Structure Representations? A Case Study with Algerian Students

ERIC Educational Resources Information Center

Mohamed-Salah, Boukhechem; Alain, Dumon

2016-01-01

This study aims to assess whether the handling of concrete ball-and-stick molecular models promotes translation between diagrammatic representations and a concrete model (or vice versa) and the coordination of the different types of structural representations of a given molecular structure. Forty-one Algerian undergraduate students were requested…

Long-Term, Deep Ocean Test of Concrete Spherical Structures - Results after 13 Years.

DTIC Science & Technology

1985-07-01

corrosion of reinforcing steel are problems, even though the concrete becomes saturated with seawater. Uncoated concrete has a very low rate of permeation... concrete matrix nor corrosion of reinforcing steel are problems, even though the concrete becomes saturated with seawater. Uncoated concrete I has a...which concrete protects the steel against corrosion in the deep ocean environ- ment. The ocean depth range for the spheres corresponds to predicled

Use of improved structural materials systems in marine piling : interim report.

DOT National Transportation Integrated Search

1982-09-01

This report contains the results of a study to evaluate the feasibility of manufacturing precast, prestressed marine pile from polymer concrete, polymer impregnated concrete, internally sealed concrete and latex modified concrete. Included in the rep...

Acoustic emission techniques applied to conventionally reinforced concrete bridge girders.

DOT National Transportation Integrated Search

2008-09-01

Reinforced concrete (RC) bridges generally operate at service-level loads except during discrete overload events that can reduce the integrity of the structure by initiating concrete cracks, widening or extending of existing concrete cracks, as well ...

Improving Fatigue Strength of polymer concrete using nanomaterials.

DOT National Transportation Integrated Search

2016-11-30

Polymer concrete (PC) is that type of concrete where the cement binder is replaced with polymer. PC is often used to improve friction and protect structural substrates in reinforced concrete and orthotropic steel bridges. However, its low fatigue per...

Characterization of Navajo Sandstone concretions: Mars comparison and criteria for distinguishing diagenetic origins

NASA Astrophysics Data System (ADS)

Potter, Sally L.; Chan, Marjorie A.; Petersen, Erich U.; Dyar, M. Darby; Sklute, Elizabeth

2011-01-01

The eolian Jurassic Navajo Sandstone spheroidal hydrous ferric oxide (HFO) concretions are divided into two size classes: macro-concretions of > 5 mm diameter and micro-concretions of < 5 mm diameter. Three internal structural end-members of macro-concretions are described as rind, layered, and solid. Two end-members of micro-concretions are rind and solid. Chemical and mineralogical gradients (μm- to mm-scale) are identified with QEMSCAN (Quantitative Elemental Mineralogy using a SCANning electron microscope) and visible to near infrared (VNIR) reflectance spectroscopy. Three HFO phases are identified using VNIR reflectance spectroscopy. An amorphous HFO phase is typically located in the rinds. Goethite is present along interior edges of rinds and throughout the interiors of layered and solid concretions. Hematite is present in the centers of rind concretions. A synthesis of petrographic, mineralogical and chemical analyses suggests that concretions grow pervasively (as opposed to radially expanding). Our model proposes that concretions precipitate initially as an amorphous HFO that sets the radius and retains some original porosity. Subsequent precipitation fills remaining pore space with younger mineral phases. Inward digitate cement crystal growth corroborates concretion growth from a set radius toward the centers. Internal structure is modified during late stage precipitation that diffuses reactants through semi-permeable rinds and overprints the interiors with younger cements. Physical characterization of textures and minerals provides diagnostic criteria for understanding how similar concretions ("blueberries") form in Meridiani Planum, Mars. The analogous Navajo Sandstone concretions show similar characteristics of in situ self-organized spacing, spheroidal geometries, internal structures, conjoined forms, and precursor HFO phases that dehydrate to goethite or hematite. These characteristics indicate a common origin via groundwater diagenesis.

Effects of climate and corrosion on concrete behaviour

NASA Astrophysics Data System (ADS)

Ismail, Mohammad; Egba, Ernest Ituma

2017-11-01

Corrosion of steel is a damaging agent that reduces the functional and structural responsibilities of reinforced concrete structures. Accordingly, reinforced concrete members in the environments that are prone to concrete carbonation or chloride attack coupled with high temperature and relative humidity suffer from accelerated corrosion of reinforcing material. Also, literature proves that climate influences corrosion of concrete, and suggests investigation of impact of corrosion on concrete based on climate zone. Therefore, this paper presents the effects of climate and corrosion on concrete behavior, using bond strength of concrete as a case study. Concrete specimens were prepared form concrete mix that was infested with 3.5 kgm-3 of sodium chloride to accelerate corrosion. The specimens were cured sodium chloride solution 3.5% by weight of water for 28 days before placing them in the exposure conditions. Pull-out tests were conducted at time intervals for one year to measure the impact of exposure condition and corrosion on bond strength of concrete. The results show reduction of bond strength of concrete by 32%, 28% and 8% after one year of subjection of the specimens to the unsheltered natural climate, sheltered natural climate, and laboratory ambient environment respectively. The findings indicate that the climate influences corrosion, which reduces the interlocking bond between the reinforcing bar and the adjacent concrete.

Palm Oil Fuel Ash (POFA) and Eggshell Powder (ESP) as Partial Replacement for Cement in Concrete

NASA Astrophysics Data System (ADS)

Ezdiani Mohamad, Mazizah; Mahmood, Ali A.; Min, Alicia Yik Yee; Nur Nadhira A., R.

2018-03-01

This study is an attempt to partially replace Ordinary Portland cement (OPC) in concrete with palm oil fuel ash (POFA) and eggshell powder (ESP). The mix proportions of POFA and ESP were varied at 10% of cement replacement and compared with OPC concrete as control specimen. The fineness of POFA is characterized by passing through 300 μm sieve and ESP by passing through 75 μm sieve. Compressive strength testing was conducted on concrete specimens to determine the optimum mix proportion of POFA and ESP. Generally the compressive strength of OPC concrete is higher compared to POFA-ESP concrete. Based on the results of POFA-ESP concrete overall, it shows that the optimum mix proportion of concrete is 6%POFA:4% ESP achieved compressive strength of 38.60 N/mm2 at 28 days. The compressive strength of OPC concrete for the same period was 42.37 N/mm2. Higher water demand in concrete is needed due to low fineness of POFA that contributing to low compressive strength of POFA-ESP concrete. However, the compressive strength and workability of the POFA-ESP concrete were within the ranges typically encountered in regular concrete mixtures indicating the viability of this replacement procedure for structural and non-structural applications.

Experimental Study on Welded Headed Studs Used In Steel Plate-Concrete Composite Structures Compared with Contactless Method of Measuring Displacement

NASA Astrophysics Data System (ADS)

Kisała, Dawid; Tekieli, Marcin

2017-10-01

Steel plate-concrete composite structures are a new innovative design concept in which a thin steel plate is attached to the reinforced concrete beam by means of welded headed studs. The comparison between experimental studies and theoretical analysis of this type of structures shows that their behaviour is dependent on the load-slip relationship of the shear connectors used to ensure sufficient bond between the concrete and steel parts of the structure. The aim of this paper is to describe an experimental study on headed studs used in steel plate-concrete composite structures. Push-out tests were carried out to investigate the behaviour of shear connectors. The test specimens were prepared according to standard push-out tests, however, instead of I-beam, a steel plate 16 mm thick was used to better reflect the conditions in the real structure. The test specimens were produced in two batches using concrete with significantly different compressive strength. The experimental study was carried out on twelve specimens. Besides the traditional measurements based on LVDT sensors, optical measurements based on the digital image correlation method (DIC) and pattern tracking methods were used. DIC is a full-field contactless optical method for measuring displacements in experimental testing, based on the correlation of the digital images taken during test execution. With respect to conventional methods, optical measurements offer a wider scope of results and can give more information about the material or construction behaviour during the test. The ultimate load capacity and load-slip curves obtained from the experiments were compared with the values calculated based on Eurocodes, American and Chinese design specifications. It was observed that the use of the relationships developed for the traditional steel-concrete composite structures is justified in the case of ultimate load capacity of shear connectors in steel plate-concrete composite structures.

New Surface-Treatment Technique of Concrete Structures Using Crack Repair Stick with Healing Ingredients

PubMed Central

Ahn, Tae-Ho; Kim, Hong-gi; Ryou, Jae-Suk

2016-01-01

This study focused on the development of a crack repair stick as a new repair method along with self-healing materials that can be used to easily repair the cracks in a concrete structure at the construction site. In developing this new repair technique, the self-healing efficiency of various cementitious materials was considered. Likewise, a crack repair stick was developed to apply to concrete structures with 0.3 mm or lower crack widths. The crack repair stick was made with different materials, such as cement, an expansive material (C12A7), a swelling material, and calcium carbonate, to endow it with a self-healing property. To verify the performance of the crack repair stick for concrete structures, two types of procedures (field experiment and field absorption test) were carried out. As a result of such procedures, it was concluded that the developed crack repair stick could be used on concrete structures to reduce repair expenses and for the improved workability, usability, and serviceability of such structures. On the other hand, to evaluate the self-healing performance of the crack repair stick, various tests were conducted, such as the relative dynamic modulus of elasticity test, the water tightness test, the water permeability test, observation via a microscope, and scanning electron microscope (SEM) analysis. From the results, it is found that water leakage can be prevented and that the durability of a concrete structure can be improved through self-healing. Also, it was verified that the cracks were perfectly closed after 28 days due to application of the crack repair stick. These results indicate the usability of the crack repair stick for concrete structures, and its self-healing efficiency. PMID:28773776

An Experimental Study on Shrinkage Strains of Normal-and High-Strength Concrete-Filled Frp Tubes

NASA Astrophysics Data System (ADS)

Vincent, Thomas; Ozbakkaloglu, Togay

2017-09-01

It is now well established that concrete-filled fiber reinforced polymer (FRP) tubes (CFFTs) are an attractive construction technique for new columns, however studies examining concrete shrinkage in CFFTs remain limited. Concrete shrinkage may pose a concern for CFFTs, as in these members the curing of concrete takes place inside the FRP tube. This paper reports the findings from an experimental study on concrete shrinkage strain measurements for CFFTs manufactured with normal- and high-strength concrete (NSC and HSC). A total of 6 aramid FRP (AFRP)-confined concrete specimens with circular cross-sections were manufactured, with 3 specimens each manufactured using NSC and HSC. The specimens were instrumented with surface and embedded strain gauges to monitor shrinkage development of exposed concrete and concrete sealed inside the CFFTs, respectively. All specimens were cylinders with a 152 mm diameter and 305 mm height, and their unconfined concrete strengths were 44.8 or 83.2 MPa. Analysis of the shrinkage measurements from concrete sealed inside the CFFTs revealed that embedment depth and concrete compressive strength only had minor influences on recorded shrinkage strains. However, an analysis of shrinkage measurements from the exposed concrete surface revealed that higher amounts of shrinkage can occur in HSC. Finally, it was observed that shrinkage strains are significantly higher for concrete exposed at the surface compared to concrete sealed inside the CFFTs.

Study on the strength characteristics of High strength concrete with Micro steel fibers

NASA Astrophysics Data System (ADS)

Gowdham, K.; Sumathi, A.; Saravana Raja Mohan, K.

2017-07-01

The study of High Strength Concrete (HSC) has become interesting as concrete structures grow taller and larger. The usage of HSC in structures has been increased worldwide and has begun to make an impact in India. Ordinary cementitious materials are weak under tensile loads and fiber reinforced cementitious composites (FRCCs) have been developed to improve this weak point. High Strength concrete containing Alccofine as mineral admixture and reinforced with micro steel fibers were cast and tested to study the mechanical properties. The concrete were designed to have compressive strength of 60 MPa. Mixtures containing 0% and 10% replacement of cement by Alccofine and with 1%, 2% and 3% of micro steel fibers by weight of concrete were prepared. Mixtures incorporating Alccofine with fibers developed marginal increase in strength properties at all curing days when compared to control concrete.

Enamel coated steel reinforcement for improved durability and life-cycle performance of concrete structures: microstructure, corrosion, and deterioration

NASA Astrophysics Data System (ADS)

Tang, Fujian

This study is aimed (a) to statistically characterize the corrosion-induced deterioration process of reinforced concrete structures (concrete cracking, steel mass loss, and rebar-concrete bond degradation), and (b) to develop and apply three types of enamel-coated steel bars for improved corrosion resistance of the structures. Commercially available pure enamel, mixed enamel with 50% calcium silicate, and double enamel with an inner layer of pure enamel and an outer layer of mixed enamel were considered as various steel coatings. Electrochemical tests were respectively conducted on steel plates, smooth bars embedded in concrete, and deformed bars with/without concrete cover in 3.5 wt.% NaCl or saturated Ca(OH)2 solution. The effects of enamel microstructure, coating thickness variation, potential damage, mortar protection, and corrosion environment on corrosion resistance of the steel members were investigated. Extensive test results indicated that corrosion-induced concrete cracking can be divided into four stages that gradually become less correlated with corrosion process over time. The coefficient of variation of crack width increases with the increasing level of corrosion. Corrosion changed the cross section area instead of mechanical properties of steel bars. The bond-slip behavior between the corroded bars and concrete depends on the corrosion level and distribution of corrosion pits. Although it can improve the chemical bond with concrete and steel, the mixed enamel coating is the least corrosion resistant. The double enamel coating provides the most consistent corrosion performance and is thus recommended to coat reinforcing steel bars for concrete structures applied in corrosive environments. Corrosion pits in enamel-coated bars are limited around damage locations.

Development of a Tomography Technique for Assessment of the Material Condition of Concrete Using Optimized Elastic Wave Parameters.

PubMed

Chai, Hwa Kian; Liu, Kit Fook; Behnia, Arash; Yoshikazu, Kobayashi; Shiotani, Tomoki

2016-04-16

Concrete is the most ubiquitous construction material. Apart from the fresh and early age properties of concrete material, its condition during the structure life span affects the overall structural performance. Therefore, development of techniques such as non-destructive testing which enable the investigation of the material condition, are in great demand. Tomography technique has become an increasingly popular non-destructive evaluation technique for civil engineers to assess the condition of concrete structures. In the present study, this technique is investigated by developing reconstruction procedures utilizing different parameters of elastic waves, namely the travel time, wave amplitude, wave frequency, and Q-value. In the development of algorithms, a ray tracing feature was adopted to take into account the actual non-linear propagation of elastic waves in concrete containing defects. Numerical simulation accompanied by experimental verifications of wave motion were conducted to obtain wave propagation profiles in concrete containing honeycomb as a defect and in assessing the tendon duct filling of pre-stressed concrete (PC) elements. The detection of defects by the developed tomography reconstruction procedures was evaluated and discussed.

An experiment on the use of disposable plastics as a reinforcement in concrete beams

NASA Technical Reports Server (NTRS)

Chowdhury, Mostafiz R.

1992-01-01

Illustrated here is the concept of reinforced concrete structures by the use of computer simulation and an inexpensive hands-on design experiment. The students in our construction management program use disposable plastic as a reinforcement to demonstrate their understanding of reinforced concrete and prestressed concrete beams. The plastics used for such an experiment vary from plastic bottles to steel reinforced auto tires. This experiment will show the extent to which plastic reinforcement increases the strength of a concrete beam. The procedure of using such throw-away plastics in an experiment to explain the interaction between the reinforcement material and concrete, and a comparison of the test results for using different types of waste plastics are discussed. A computer analysis to simulate the structural response is used to compare the test results and to understand the analytical background of reinforced concrete design. This interaction of using computers to analyze structures and to relate the output results with real experimentation is found to be a very useful method for teaching a math-based analytical subject to our non-engineering students.

Shear design expressions for concrete filled steel tube and reinforced concrete filled tube components.

DOT National Transportation Integrated Search

2016-06-01

Concrete-filled steel tubes (CFSTs) and reinforced concrete-filled steel tubes (RCFSTs) are increasingly : used in transportation structures as piers, piles, caissons or other foundation components. While the axial : and flexural properties of CFTs h...

Development of a real-time vibrator tracking system for intelligent concrete consolidation.

DOT National Transportation Integrated Search

2014-01-01

Proper consolidation of concrete is critical to the long-term strength of concrete bridge structures. Vibration : is a commonly used method to make concrete owable and to remove the excessive entrapped air, therefore : contributing to proper concr...

Molecular Survey of Concrete Biofilm Microbial Communities

EPA Science Inventory

Although several studies have shown that bacteria can deteriorate concrete structures, there is very little information on the composition of concrete microbial communities. To this end, we studied different microbial communities associated with concrete biofilms using 16S rRNA g...

Experimental sensitivity analysis of subsoil-slab behaviour regarding degree of fibre-concrete slab reinforcement

NASA Astrophysics Data System (ADS)

Hrubesova, E.; Lahuta, H.; Mohyla, M.; Quang, T. B.; Phi, N. D.

2018-04-01

The paper is focused on the sensitivity analysis of behaviour of the subsoil – foundation system as regards the variant properties of fibre-concrete slab resulting into different relative stiffness of the whole cooperating system. The character of slab and its properties are very important for the character of external load transfer, but the character of subsoil cannot be neglected either because it determines the stress-strain behaviour of the all system and consequently the bearing capacity of structure. The sensitivity analysis was carried out based on experimental results, which include both the stress values in soil below the foundation structure and settlements of structure, characterized by different quantity of fibres in it. Flat dynamometers GEOKON were used for the stress measurements below the observed slab, the strains inside slab were registered by tensometers, the settlements were monitored geodetically. The paper is focused on the comparison of soil stresses below the slab for different quantity of fibres in structure. The results obtained from the experimental stand can contribute to more objective knowledge of soil – slab interaction, to the evaluation of real carrying capacity of the slab, to the calibration of corresponding numerical models, to the optimization of quantity of fibres in the slab, and finally, to higher safety and more economical design of slab.

Interior view of coffee processing structure No. 1, showing concrete ...

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

Interior view of coffee processing structure No. 1, showing concrete reservoirs on floor, view towards the west - Finca Silem, Coffee Processing Structure No. 1, Highway 139, Kilometer 9.3, Maraguez, Ponce Municipio, PR

Generation of Rayleigh waves into mortar and concrete samples.

PubMed

Piwakowski, B; Fnine, Abdelilah; Goueygou, M; Buyle-Bodin, F

2004-04-01

The paper deals with a non-destructive method for characterizing the degraded cover of concrete structures using high-frequency ultrasound. In a preliminary study, the authors emphasized on the interest of using higher frequency Rayleigh waves (within the 0.2-1 MHz frequency band) for on-site inspection of concrete structures with subsurface damage. The present study represents a continuation of the previous work and aims at optimizing the generation and reception of Rayleigh waves into mortar and concrete be means of wedge transducers. This is performed experimentally by checking the influence of the wedge material and coupling agent on the surface wave parameters. The selection of the best combination wedge/coupling is performed by searching separately for the best wedge material and the best coupling material. Three wedge materials and five coupling agents were tested. For each setup the five parameters obtained from the surface wave measurement i.e. the frequency band, the maximal available central frequency, the group velocity error and its standard deviation and finally the error in velocity dispersion characteristic were investigated and classed as a function of the wedge material and the coupling agent. The selection criteria were chosen so as to minimize the absorption of both materials, the randomness of measurements and the systematic error of the group velocity and of dispersion characteristic. Among the three tested wedge materials, Teflon was found to be the best. The investigation on the coupling agent shows that the gel type materials are the best solutions. The "thick" materials displaying higher viscosity were found as the worst. The results show also that the use of a thin plastic film combined with the coupling agent even increases the bandwidth and decreases the uncertainty of measurements.

Experimental Study on Permeability of Concrete

NASA Astrophysics Data System (ADS)

Yang, Honglu; Liu, Rentai; Zheng, Zhuo; Liu, Haojie; Gao, Yan; Liu, Yankai

2018-01-01

To study the influencing factors on permeability of pervious concrete, by adding inorganic organic composite materials obtained experimental results show that different aggregate size, aggregate cement ratio of different, different water cement ratio on the permeability performance. The permeability of the concrete was tested by using the self - made permeable device. The experimental results showed that the permeation coefficient of the experiment was obtained and the factors influencing the permeability of the concrete were compared and analyzed. At the same time, the porosity of pervious concrete was measured, the influence of various variables on porosity was studied, and the influence of various factors on the permeability of voids was found. Finally, through comprehensive analysis of a variety of factors, the optimal water cement ratio is 0.28. At this time, the pervious performance of concrete is optimal.

Evaluation of Rocky Point Viaduct Concrete Beam : Final Report

DOT National Transportation Integrated Search

2000-06-01

This study was intended to determine why it was necessary to replace the Rocky Point Viaduct after a period of service that was much shorter than that of many other reinforced concrete bridges on the Oregon coast; to identify construction practices t...

Freeze-thaw resistance of concrete with marginal air content : final report

DOT National Transportation Integrated Search

2006-12-01

Freeze-thaw resistance is a key durability factor for concrete pavements. Recommendations for the air : void system parameters are normally: 6 1 percent total air, and spacing factor less than 0.20 : millimeters. However, it was observed that some...

Remaining life of reinforced concrete beams with diagonal-tension cracks : final report.

DOT National Transportation Integrated Search

2004-04-01

This report covers the initial efforts of a research study investigating the remaining capacity and life of cast-in-place reinforced concrete deck-girder (RCDG) bridges with diagonal tension cracks. A database of 442 bridges constructed from 1947 to ...

Polymer concrete bridge deck overlays : Deschutes River Bridge (Biggs) and Maupin Bridge (Maupin) : final report.

DOT National Transportation Integrated Search

1995-07-01

This report documents the construction and performance of two thin polymer concrete (with polyester/styrene resins) bridge deck overlays. The overlays were constructed in Biggs and Maupin, Oregon in June 1993. : Several problems were encountered duri...

Polymer concrete overlay test program : Lebanon Ditch Bridge : final report.

DOT National Transportation Integrated Search

1983-01-01

This report presents information on the installation of a thin polymer concrete overlay and the evaluation of its durability after a 15-month in-service period. The project was performed by the Oregon State Highway Division under the sponsorship of t...

Evaluation of the gyratory compactor for use in designing asphaltic concrete mixtures : final report.

DOT National Transportation Integrated Search

1966-12-01

The primary objective of this study was to evaluate the gyratory kneading compactor and to investigate the possibilities and capabilities of this type of equipment. : Curves were developed for six different asphaltic concrete mixes with varying compa...

Survey of Virginia aggregates for chloride contents : final report.

DOT National Transportation Integrated Search

1980-01-01

A major cause of concrete bridge deck deterioration is the corrosion of the reinforcing steel which, in turn, is caused by the presence of extremely high concentrations of chloride ions in the concrete. It was believed that the chloride came almost e...

Problems in achieving density in asphaltic concrete : final report.

DOT National Transportation Integrated Search

1979-01-01

This investigation was undertaken in an attempt to identify the causes of low densities in asphaltic concrete placed on 9 projects. The most prevalent cause, which accounted for the difficulties on 5 of the 9 projects, appeared to be improper mix des...

Evaluation of bent caps in reinforced concrete deck girder bridges, part 2 : final report.

DOT National Transportation Integrated Search

2008-09-01

This report describes research conducted to enable evaluation of existing vintage bent cap beams in reinforced concrete : deck girder bridges. The report is organized into two parts: 1) flexural anchorage capacity response and prediction of : reduced...

Evaluation of bent caps in reinforced concrete deck girder bridges, part 1 : final report.

DOT National Transportation Integrated Search

2008-09-01

This report describes research conducted to enable evaluation of existing vintage bent cap beams in reinforced concrete : deck girder bridges. The report is organized into two parts: 1) flexural anchorage capacity response and prediction of : reduced...

A correlation of various smoothness measuring systems for asphaltic concrete surfaces : final report.

DOT National Transportation Integrated Search

1974-06-01

The primary purpose of this research effort was to assess the presently specified smoothness criteria for new construction of asphaltic concrete surfaces using various rolling straightedges and roadmeters. This assessment was to be based on the corre...

Design and evaluation of high strength concrete for girders : final report.

DOT National Transportation Integrated Search

1980-05-01

The scope of the study was to make concrete mixes in the laboratory using a partial factorial, with three cement contents, two coarse aggregates and three fine-to-coarse aggregate ratios. The mixes showing the best properties and highest compressive ...

Evaluation of data generated by statistically oriented end-result specifications : final report.

DOT National Transportation Integrated Search

1979-01-01

This report is concerned with the review of data generated on projects let under the statistically oriented end-result specifications (ERS) on asphaltic concrete and Portland cement concrete. The review covered analysis of data for determination of p...

Application of titanium alloy bars for strengthening reinforced concrete bridge girders (part a: shear) : final report.

DOT National Transportation Integrated Search

2017-07-04

Large numbers of conventionally reinforced concrete bridges (RC) were constructed during the interstate highway expansion of the 1950s and remain in the national inventory. Coincidently, deformed steel reinforcing bars were standardized. The stand...

Finite Element Analysis of Deep Wide-Flanged Pre-stressed Girders : Draft Final Report

DOT National Transportation Integrated Search

2011-06-01

Hundreds of prestressed concrete girders are used each year for building bridges in Wisconsin. : The prestress transfer from the prestressing strands to concrete takes place at the girder ends. : Characteristic cracks form in this end region during o...

Steel slag in hot mix asphalt concrete : final report

DOT National Transportation Integrated Search

2000-04-01

In September 1994, steel slag test and control sections were constructed in Oregon to evaluate the use of steel slag in hot mix asphalt concrete (HMAC). This report covers the construction and five-year performance of a pavement constructed with 30% ...

Review and specification for shrinkage cracks of bridge decks : final report.

DOT National Transportation Integrated Search

2016-12-01

An existing standard method ASTM C157 is used to determine the length change or free shrinkage of an unrestrained concrete specimen. However, in bridge decks, the concrete is actually under restrained conditions, and thus free shrinkage test methods ...

Structural Effects of Reinforced Concrete Beam Due to Corrosion

NASA Astrophysics Data System (ADS)

Noh, Hamidun Mohd; Idris, Nur'ain; Noor, Nurazuwa Md; Sarpin, Norliana; Zainal, Rozlin; Kasim, Narimah

2018-03-01

Corrosion of steel in reinforced concrete is one of the main issues among construction stakeholders. The main consequences of steel corrosion include loss of cross section of steel area, generation of expansive pressure which caused cracking of concrete, spalling and delaminating of the concrete cover. Thus, it reduces the bond strength between the steel reinforcing bar and concrete, and deteriorating the strength of the structure. The objective of this study is to investigate the structural effects of corrosion damage on the performance of reinforced concrete beam. A series of corroded reinforced concrete beam with a corrosion rate of 0%, 20% and 40% of rebar corrosion is used in parametric study to assess the influence of different level of corrosion rate to the structural performance. As a result, the used of interface element in the finite element modelling predicted the worst case of corrosion analysis since cracks is induced and generate at this surface. On the other hand, a positive linear relationship was sketched between the increase of expansive pressure and the corrosion rate. Meanwhile, the gradient of the graph is decreased with the increase of steel bar diameter. Furthermore, the analysis shows that there is a significant effect on the load bearing capacity of the structure where the higher corrosion rate generates a higher stress concentration at the mid span of the beam. This study could predict the residual strength of reinforced concrete beam under the corrosion using the finite element analysis. The experimental validation is needed on the next stage to investigate the quantitative relation between the corrosion rate and its influence on the mechanical properties.

Evaluation of Blast Resistance of Fiber Reinforced Composite Specimens under Contact Blast Load

NASA Astrophysics Data System (ADS)

Janota, O.; Foglar, M.

2017-09-01

This paper presents results of experimental programme which took place in 2014, 2015 and 2016. Experiments were focused on the resistance of full scale concrete panels subjected to contact blast loading. Specimens were loaded by contact blast by plastic explosive. All specimens were reinforced concrete slabs made of fiber concrete. Basalt mesh and textile sheets were added to some of the experiments for creating more heterogeneous material to achieve better resistance of the specimens. Evaluation of experiments was mainly focused on the damaged area on the contact side and soffit of the specimens. Dependency of the final damage of concrete panels on the weight of explosive and concrete strength was assessed.

Monitoring of temperature fatigue failure mechanism for polyvinyl alcohol fiber concrete using acoustic emission sensors.

PubMed

Li, Dongsheng; Cao, Hai

2012-01-01

The applicability of acoustic emission (AE) techniques to monitor the mechanism of evolution of polyvinyl alcohol (PVA) fiber concrete damage under temperature fatigue loading is investigated. Using the temperature fatigue test, real-time AE monitoring data of PVA fiber concrete is achieved. Based on the AE signal characteristics of the whole test process and comparison of AE signals of PVA fiber concretes with different fiber contents, the damage evolution process of PVA fiber concrete is analyzed. Finally, a qualitative evaluation of the damage degree is obtained using the kurtosis index and b-value of AE characteristic parameters. The results obtained using both methods are discussed.

Monitoring of Temperature Fatigue Failure Mechanism for Polyvinyl Alcohol Fiber Concrete Using Acoustic Emission Sensors

PubMed Central

Li, Dongsheng; Cao, Hai

2012-01-01

The applicability of acoustic emission (AE) techniques to monitor the mechanism of evolution of polyvinyl alcohol (PVA) fiber concrete damage under temperature fatigue loading is investigated. Using the temperature fatigue test, real-time AE monitoring data of PVA fiber concrete is achieved. Based on the AE signal characteristics of the whole test process and comparison of AE signals of PVA fiber concretes with different fiber contents, the damage evolution process of PVA fiber concrete is analyzed. Finally, a qualitative evaluation of the damage degree is obtained using the kurtosis index and b-value of AE characteristic parameters. The results obtained using both methods are discussed. PMID:23012555

Failure of underground concrete structures subjected to blast loadings

NASA Technical Reports Server (NTRS)

Ross, C. A.; Nash, P. T.; Griner, G. R.

1979-01-01

The response and failure of two edges of free reinforced concrete slabs subjected to intermediate blast loadings are examined. The failure of the reinforced concrete structures is defined as a condition where actual separation or fracture of the reinforcing elements has occurred. Approximate theoretical methods using stationary and moving plastic hinge mechanisms with linearly varying and time dependent loadings are developed. Equations developed to predict deflection and failure of reinforced concrete beams are presented and compared with the experimental results.

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

Monitoring of Concrete Structures Using Ofdr Technique

NASA Astrophysics Data System (ADS)

Henault, J. M.; Salin, J.; Moreau, G.; Delepine-Lesoille, S.; Bertand, J.; Taillade, F.; Quiertant, M.; Benzarti, K.

2011-06-01

Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as bridges, dikes, nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a centimeter scale spatial resolution over hundred of meters and with a level of precision equal to 1 μstrain and 0.1 °C. Several sensing cables are designed with different materials targeting to last for decades in a concrete aggressive environment and to ensure an optimal transfer of temperature and strain from the concrete matrix to the optical fiber. Tests were carried out by embedding various sensing cables into plain concrete specimens and representative-scale reinforced concrete structural elements. Measurements were performed with an OFDR instrument; meanwhile, mechanical solicitations were imposed to the concrete element. Preliminary experiments are very promising since measurements performed with distributed sensing system are comparable to values obtained with conventional sensors used in civil engineering and with the Strength of Materials Modelling. Moreover, the distributed sensing system makes it possible to detect and localize cracks appearing in concrete during the mechanical loading.

Influence of reinforcement mesh configuration for improvement of concrete durability

NASA Astrophysics Data System (ADS)

Pan, Chong-gen; Jin, Wei-liang; Mao, Jiang-hong; Zhang, Hua; Sun, Li-hao; Wei, Dong

2017-10-01

Steel bar in concrete structures under harsh environmental conditions, such as chlorine corrosion, seriously affects its service life. Bidirectional electromigration rehabilitation (BIEM) is a new method of repair technology for reinforced concrete structures in such chloride corrosion environments. By applying the BIEM, chloride ions can be removed from the concrete and the migrating corrosion inhibit can be moved to the steel surface. In conventional engineering, the concrete structure is often configured with a multi-layer steel mesh. However, the effect of the BIEM in such structures has not yet been investigated. In this paper, the relevant simulation test is carried out to study the migration law of chloride ions and the migrating corrosion inhibitor in a concrete specimen with complex steel mesh under different energizing modes. The results show that the efficiency of the BIEM increases 50% in both the monolayer steel mesh and the double-layer steel mesh. By using the single-sided BIEM, 87% of the chloride ions are removed from the steel surface. The different step modes can affect the chloride ion removal. The chloride ions within the range of the reinforcement protective cover are easier to be removed than those in the concrete between the two layers of steel mesh. However, the amount of migrating corrosion inhibitor is larger in the latter circumstances.

Evaluation of concrete bridge mix designs for control of cracking, phase I.

DOT National Transportation Integrated Search

2014-11-01

Cracking of concrete is a common problem with concrete structures such as bridge decks, pavements and bridge : rail. The Agency of Transportation (VTrans) has recently invested in higher performing concrete mixes that are : more impervious and has hi...

Utilization of construction and agricultural waste in Malaysia for development of Green Concrete: A Review

NASA Astrophysics Data System (ADS)

Tambichik, M. A.; Mohamad, N.; Samad, A. A. A.; Bosro, M. Z. M.; Iman, M. A.

2018-04-01

Green Concrete (GC) is defined as a concrete that utilize a waste material for at least one of its component. The production of GC has been increasing due to the drawback of conventional concrete that create many environmental problems. In Malaysia, the amount of waste generates from agricultural and construction industries were increasing every year. Hence, one of the solutions to reduce the impact of conventional concrete and limited landfill spaces due to excessive waste is by utilizing it in concrete. This paper reviews the possible use of construction waste (Recycle Concrete Aggregate) and agricultural waste (Palm Oil Fuel Ash, Rice Husk Ash and Palm Oil Fibre) as partial replacement for the basic material in a concrete to produce an innovative Green Concrete. The optimum replacement level for each type of waste was also been review. Green Concrete also has the potential to reduce environmental pollution and solve the depletion of natural sources. The result from this review shows that the addition of agricultural waste or construction waste in concrete indicate positive and satisfactory strength when compared to normal concrete. Finally, a mass production of Green Concrete can fulfil the Construction Industry Transformation Plan (CITP) 2016-2020 made by CIDB that emphasizes on a construction system which is environmentally sustainable.

Reusing recycled aggregates in structural concrete

NASA Astrophysics Data System (ADS)

Kou, Shicong

The utilization of recycled aggregates in concrete can minimize environmental impact and reduce the consumption of natural resources in concrete applications. The aim of this thesis is to provide a scientific basis for the possible use of recycled aggregates in structure concrete by conducting a comprehensive programme of laboratory study to gain a better understanding of the mechanical, microstructure and durability properties of concrete produced with recycled aggregates. The study also explored possible techniques to of improve the properties of recycled aggregate concrete that is produced with high percentages (≧ 50%) of recycled aggregates. These techniques included: (a) using lower water-to-cement ratios in the concrete mix design; (b) using fly ash as a cement replacement or as an additional mineral admixture in the concrete mixes, and (c) precasting recycled aggregate concrete with steam curing regimes. The characteristics of the recycled aggregates produced both from laboratory and a commercially operated pilot construction and demolition (C&D) waste recycling plant were first studied. A mix proportioning procedure was then established to produce six series of concrete mixtures using different percentages of recycled coarse aggregates with and without the use of fly ash. The water-to-cement (binder) ratios of 0.55, 0.50, 0.45 and 0.40 were used. The fresh properties (including slump and bleeding) of recycled aggregate concrete (RAC) were then quantified. The effects of fly ash on the fresh and hardened properties of RAC were then studied and compared with those RAC prepared with no fly ash addition. Furthermore, the effects of steam curing on the hardened properties of RAC were investigated. For micro-structural properties, the interfacial transition zones of the aggregates and the mortar/cement paste were analyzed by SEM and EDX-mapping. Moreover, a detailed set of results on the fracture properties for RAC were obtained. Based on the experimental results, a number of recommendations were made on how to optimize the use of recycled aggregates for structural concrete production. The results demonstrate that one of the practical ways to utilize a higher percentage of recycled aggregates in concrete is "precasting" with the use of fly ash and an initial steam curing stage immediately after casting.

A multiscale model for predicting the viscoelastic properties of asphalt concrete

NASA Astrophysics Data System (ADS)

Garcia Cucalon, Lorena; Rahmani, Eisa; Little, Dallas N.; Allen, David H.

2016-08-01

It is well known that the accurate prediction of long term performance of asphalt concrete pavement requires modeling to account for viscoelasticity within the mastic. However, accounting for viscoelasticity can be costly when the material properties are measured at the scale of asphalt concrete. This is due to the fact that the material testing protocols must be performed recursively for each mixture considered for use in the final design.

Analysis of cracked RC beams under vibration

NASA Astrophysics Data System (ADS)

Capozucca, R.; Magagnini, E.

2017-05-01

Among the methods of monitoring of integrity, vibration analysis is more convenient as non-destructive testing (NDT) method. Many aspects regarding the vibration monitoring of the structural integrity of damaged RC elements have not been completely analysed in literature. The correlation between the development of the crack pattern on concrete surface under bending loadings, as well as the width and depth of cracks, and the variation of dynamic parameters on a structural element is an important aspects that has to be more investigated. This paper deals with cracked RC beams controlled by NDT based on natural vibration, which may be correlated to damage degree due to cracking of concrete under severe state of loading. An experimental investigation on the assessment of RC beams in different scale under loading has been done through dynamic tests in different constraint conditions of edges measuring frequency values and frequency variation. Envelope of Frequency Response Functions (FRFs) are shown and the changes of natural frequency values are related to the damage degree of RC beams subjected to static tests. Finally, a comparison between data obtained by finite element analysis and experimental results is shown.

Earthquake simulator tests and associated study of an 1/6-scale nine-story RC model

NASA Astrophysics Data System (ADS)

Sun, Jingjiang; Wang, Tao; Qi, Hu

2007-09-01

Earthquake simulator tests of a 1/6-scale nine-story reinforced concrete frame-wall model are described in the paper. The test results and associated numerical simulation are summarized and discussed. Based on the test data, a relationship between maximum inter-story drift and damage state is established. Equations of variation of structural characteristics (natural frequency and equivalent stiffness) with overall drifts are derived by data fitting, which can be used to estimate structural damage state if structural characteristics can be measured. A comparison of the analytical and experimental results show that both the commonly used equivalent beam and fiber element models can simulate the nonlinear seismic response of structures very well. Finally, conclusions associated with seismic design and damage evaluation of RC structures are presented.

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

Rashid, A.; Nygaard, C.

The use of concrete in marine environment has gained tremendous popularity in the past decade and is continued to be a very popular material for marine industry in the world today. It has a very diversified use from large offshore platforms and floating structures in the North Sea, Canada and South America to offshore loading terminals and junction platforms in shallow waters in the marshes of southern Louisiana in the Gulf of Mexico. Also, precast concrete sections are extensively used all over the world in the construction of marine structures. Because of their large variety of shapes and sizes, theymore » can be tailored to fit multiple applications in marine environment. The added quality control in the fabrication yard and the ease of installation by lifting makes them a very attractive option. The use of precast concrete sections is gaining a lot of popularity in South America. A lot of fabrication yards are manufacturing these sections locally. There are hundreds of offshore concrete platforms utilizing these sections in Lake Maracaibo, Venezuela. The paper discusses the use of concrete for offshore structures including floaters. It describes some general concepts and advantages to be gained by the use of concrete (precast and cast-in-place) in marine environment. It also discusses some general design considerations required for the use of different types of precast concrete sections that can be utilized for oil and gas platforms and loading terminals. Lastly the paper describes some typical examples of concrete platforms built out of concrete piles, precast concrete girders and beam sections and concrete decking.« less

Triaxial constitutive model for plain and reinforced concrete behavior

NASA Astrophysics Data System (ADS)

Kang, Hong Duk

Inelastic failure analysis of concrete structures has been one of the central issues in concrete mechanics. Especially, the effect of confinement has been of great importance to capture the transition from brittle to ductile fracture of concrete under triaxial loading scenarios. Moreover, it has been a difficult task to implement numerically material descriptions which are susceptible to loss of stability and localization. Consequently, it has been a challenge to develop comprehensive material formulations of concrete, which consider the full spectrum of loading histories which the material in a real structure is subjected to. A new triaxial constitutive model of concrete is presented that not only describes the hardening/softening behavior of concrete in tension and low confined compression, but also captures the transition from brittle to ductile failure under high confinement. The concrete model is based on a loading surface that is Csp1-continuous, and that closes smoothly in equitriaxial compression, while the deviatoric trace expands from a triangular to a circular shape with increasing confinement. The plastic potential has a different curvature from the plastic loading function for non-associativity in order to reduce excessive inelastic dilatancy. In the thesis, the results of deformation and localization analyses for various loading histories are presented in the constitutive study. In addition, studies of associativity and non-associativity, and two-invariant versus three-invariant formulations are performed. At the structural level the triaxial concrete model is used to predict the nonlinear response behavior of a reinforced concrete column subject to axial and lateral loadings.

Experimental Investigation of the Mechanical and Durability Properties of Crumb Rubber Concrete.

PubMed

Liu, Hanbing; Wang, Xianqiang; Jiao, Yubo; Sha, Tao

2016-03-07

Recycling waste tire rubber by incorporating it into concrete has become the preferred solution to dispose of waste tires. In this study, the effect of the volume content of crumb rubber and pretreatment methods on the performances of concrete was evaluated. Firstly, the fine aggregate and mixture were partly replaced by crumb rubber to produce crumb rubber concrete. Secondly, the mechanical and durability properties of crumb rubber concrete with different replacement forms and volume contents had been investigated. Finally, the crumb rubber after pretreatment by six modifiers was introduced into the concrete mixture. Corresponding tests were conducted to verify the effectiveness of pretreatment methods as compared to the concrete containing untreated crumb rubber. It was observed that the mechanical strength of crumb rubber concrete was reduced, while durability was improved with the increasing of crumb rubber content. 20% replacement of fine aggregate and 5% replacement of the total mixture exhibited acceptable properties for practical applications. In addition, the results indicated that the modifiers had a positive impact on the mechanical and durability properties of crumb rubber concrete. It avoided the disadvantage of crumb rubber concrete having lower strength and provides a reference for the production of modified crumb rubber concrete.

Experimental Investigation of the Mechanical and Durability Properties of Crumb Rubber Concrete

PubMed Central

Liu, Hanbing; Wang, Xianqiang; Jiao, Yubo; Sha, Tao

2016-01-01

Recycling waste tire rubber by incorporating it into concrete has become the preferred solution to dispose of waste tires. In this study, the effect of the volume content of crumb rubber and pretreatment methods on the performances of concrete was evaluated. Firstly, the fine aggregate and mixture were partly replaced by crumb rubber to produce crumb rubber concrete. Secondly, the mechanical and durability properties of crumb rubber concrete with different replacement forms and volume contents had been investigated. Finally, the crumb rubber after pretreatment by six modifiers was introduced into the concrete mixture. Corresponding tests were conducted to verify the effectiveness of pretreatment methods as compared to the concrete containing untreated crumb rubber. It was observed that the mechanical strength of crumb rubber concrete was reduced, while durability was improved with the increasing of crumb rubber content. 20% replacement of fine aggregate and 5% replacement of the total mixture exhibited acceptable properties for practical applications. In addition, the results indicated that the modifiers had a positive impact on the mechanical and durability properties of crumb rubber concrete. It avoided the disadvantage of crumb rubber concrete having lower strength and provides a reference for the production of modified crumb rubber concrete. PMID:28773298

Design and testing of tubular polymeric capsules for self-healing of concrete

NASA Astrophysics Data System (ADS)

Araújo, M.; Van Tittelboom, K.; Feiteira, J.; Gruyaert, E.; Chatrabhuti, S.; Raquez, J.-M.; Šavija, B.; Alderete, N.; Schlangen, E.; De Belie, N.

2017-10-01

Polymeric healing agents have proven their efficiency to heal cracks in concrete in an autonomous way. However, the bottleneck for valorisation of self-healing concrete with polymeric healing agents is their encapsulation. In the present work, the suitability of polymeric materials such as poly(methyl methacrylate) (PMMA), polystyrene (PS) and poly(lactic acid) (PLA) as carriers for healing agents in self-healing concrete has been evaluated. The durability of the polymeric capsules in different environments (demineralized water, salt water and simulated concrete pore solution) and their compatibility with various healing agents have been assessed. Next, a numerical model was used to simulate capsule rupture when intersected by a crack in concrete and validated experimentally. Finally, two real-scale self-healing concrete beams were made, containing the selected polymeric capsules (with the best properties regarding resistance to concrete mixing and breakage upon crack formation) or glass capsules and a reference beam without capsules. The self-healing efficiency was determined after crack creation by 3-point-bending tests.

Use of neoprene pads in testing concrete cylinders : final report.

DOT National Transportation Integrated Search

1982-01-01

This study investigated the feasibility of using neoprene pads confined by steel end caps instead of sulfur-mortar caps in compressive strength tests on concrete cylinders. The 1/2 in. (13 mm) thick neoprene pads had a 50 durometer hardness and were ...

A pavement management system for concrete roadways in Virginia : phase I : condition ratings : final report.

DOT National Transportation Integrated Search

1988-01-01

This report traces the development of a rating system proposed by the author and reviewed by a subcommittee of the Pavement Management Research Advisory Committee for use in evaluating the service condition of Virginia's Portland cement concrete pave...

High Strength Reinforcing Steel Bars : Concrete Shear Friction Interface : final report : Part A.

DOT National Transportation Integrated Search

2017-03-01

High-strength steel (HSS) reinforcement, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) steel reinf...

High strength reinforcing steel bars : concrete shear friction interface : final report : Part A.

DOT National Transportation Integrated Search

2017-03-01

High-strength steel (HSS) reinforcement, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) steel reinf...

Characterization of Chloride thresholds in Florida coastal concrete bridge substructures : final report, February 11, 2009.

DOT National Transportation Integrated Search

2009-02-11

Sea water induced reinforcing steel corrosion often results in high maintenance costs and can be service life limiting for concrete bridge substructure elements in marine environments. In the present research, a novel piling type specimen assembly an...

Testing Notched Ends of Prestressed Concrete Box Beams: Final Letter Report on Projects 1479 and 1340

DOT National Transportation Integrated Search

1994-12-01

Prestressed concrete box beams incorporated in a bridge project under construction in the Houston District encountered cracking in the notched (dapped) ends during fabrication. Because the members in question are trapezoidal in section and have inter...

Latex modified fiber reinforced concrete bridge deck overlay : final report.

DOT National Transportation Integrated Search

1995-11-01

In an attempt to increase the tensile strength of LMC and reduce cracking, steel fibers were added to a LMC mix. The results are what is termed as "latex-modified, fiber-reinforced concrete" (LMFRC). LMFRC was placed on Hayden Bridge as an experiment...

Evaluation of recycled hot mix asphalt concrete on Route 220 : final report.

DOT National Transportation Integrated Search

1985-01-01

This report describes the performance of an approximately 8-mi section of roadway on which the rod two layers of asphalt concrete were milled, recycled through a conventional asphalt batch plant, and relaid. The recycled mix consisted of about 40% re...

75 FR 8113 - Prestressed Concrete Steel Wire Strand From China

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-23

... INTERNATIONAL TRADE COMMISSION [Investigation Nos. 701-TA-464 and 731-TA-1160 (Final)] Prestressed Concrete Steel Wire Strand From China AGENCY: United States International Trade Commission. ACTION: Revised schedule for the subject investigations. DATES: Effective Date: February 16, 2010. FOR FURTHER INFORMATION...

Evaluation of waste concrete road materials for use in oyster aquaculture - Phase 3.

DOT National Transportation Integrated Search

2016-08-01

This project was the final phase of a three-phase project. The primary objective was to determine the suitability of recycled concrete aggregate (RCA) from road projects as a bottom conditioning material for on-bottom oyster aquaculture in the Chesap...

Cost effective bridge deck reconstruction in Kansas using high-density concrete overlays and asphalt membrane overlays : final report.

DOT National Transportation Integrated Search

2009-08-01

In 1976 the Federal Highway Administration (FHWA) approved federal aid funding for experimental : installations of corrosion protection for reinforcing steel in existing concrete bridge decks. Sixteen of the sixty-nine : Kansas bridges with Cost Effe...

Relationship of fatigue to the tensile stiffness of asphaltic concrete : final report on phase 1, laboratory investigation.

DOT National Transportation Integrated Search

1972-01-01

The correlation between asphaltic concrete tensile stiffness and fatigue life was determined in the laboratory. Constant strain fatigue tests were utilized and indirect tensile tests were selected because of their simplicity and applicability. Four a...

Evaluation of dowel bar inserter practices in PCC pavements with magnetic tomography technology : final report.

DOT National Transportation Integrated Search

2016-12-01

Dowel Bar Inserters (DBI) are automated mechanical equipment that position dowel bars in Portland Cement Concrete (PCC) after concrete is placed. Compared to the alternative approach, which is using dowel baskets, DBIs offer advantages in cost and sp...

Low cracking concretes for the closure pours and overlays of the Dunlap Creek Bridge : final report.

DOT National Transportation Integrated Search

2017-10-01

Joints, wide cracks, and poor-quality concretes facilitate the intrusion of chlorides, causing corrosion in bridge decks and substructures. In this study, joints were replaced with closure pours (link slabs) consisting of low permeability fiber-reinf...

Evaluation of Portland Cement concretes containing ground granulated blast furnace slag : final report.

DOT National Transportation Integrated Search

2002-05-01

A two part laboratory experimental program was conducted to evaluate strength and durability of various concrete mix : designs. In Part I of the study, the influence of using Grade 120 ground granulated blast furnace slag (GGBFS) on the : strength an...

Research on seismic behavior and filling effect of a new CFT column-CFT beam frame structure

NASA Astrophysics Data System (ADS)

Wang, Ying; Shima, Hiroshi

2009-12-01

Concrete filled-steel tube (CFT) structure is popularly used in practical structures nowadays. Self-compacting concrete (SCC) was employed to construct a new CFT column-CFT beam frame structure (hereinafter cited as new CFT frame structure) in this research. Three specimens, two CFT column-CFT beam joints and one hollow steel column-I beam joint were tested to investigate seismic behavior of the new CFT frame structure. The experimental results showed that SCC can be successfully compacted into the new CFT frame structure joints in the lab, and the joints provided adequate seismic behavior. In order to further assess filling effect of SCC in the long steel tube, scale column-beam subassembly made of acrylics plate was employed and concrete visual model experiment was done. The results showed that the concrete was able to be successfully cast into the subassembly which indicated that the new CFT frame structure is possible to be constructed in the real building.

Research on seismic behavior and filling effect of a new CFT column-CFT beam frame structure

NASA Astrophysics Data System (ADS)

Wang, Ying; Shima, Hiroshi

2010-03-01

Concrete filled-steel tube (CFT) structure is popularly used in practical structures nowadays. Self-compacting concrete (SCC) was employed to construct a new CFT column-CFT beam frame structure (hereinafter cited as new CFT frame structure) in this research. Three specimens, two CFT column-CFT beam joints and one hollow steel column-I beam joint were tested to investigate seismic behavior of the new CFT frame structure. The experimental results showed that SCC can be successfully compacted into the new CFT frame structure joints in the lab, and the joints provided adequate seismic behavior. In order to further assess filling effect of SCC in the long steel tube, scale column-beam subassembly made of acrylics plate was employed and concrete visual model experiment was done. The results showed that the concrete was able to be successfully cast into the subassembly which indicated that the new CFT frame structure is possible to be constructed in the real building.

Influence of Axial Load on Electromechanical Impedance (EMI) of Embedded Piezoceramic Transducers in Steel Fiber Concrete.

PubMed

Wang, Zhijie; Chen, Dongdong; Zheng, Liqiong; Huo, Linsheng; Song, Gangbing

2018-06-01

With the advantages of high tensile, bending, and shear strength, steel fiber concrete structures have been widely used in civil engineering. The health monitoring of concrete structures, including steel fiber concrete structures, receives increasing attention, and the Electromechanical Impedance (EMI)-based method is commonly used. Structures are often subject to changing axial load and ignoring the effect of axial forces may introduce error to Structural Health Monitoring (SHM), including the EMI-based method. However, many of the concrete structure monitoring algorithms do not consider the effects of axial loading. To investigate the influence of axial load on the EMI of a steel fiber concrete structure, concrete specimens with different steel fiber content (0, 30, 60, 90, 120) (kg/m³) were casted and the Lead Zirconate Titanate (PZT)-based Smart Aggregate (SA) was used as the EMI sensor. During tests, the step-by-step loading procedure was applied on different steel fiber content specimens, and the electromechanical impedance values were measured. The Normalized root-mean-square deviation Index (NI) was developed to analyze the EMI information and evaluate the test results. The results show that the normalized root-mean-square deviation index increases with the increase of the axial load, which clearly demonstrates the influence of axial load on the EMI values for steel fiber concrete and this influence should be considered during a monitoring or damage detection procedure if the axial load changes. In addition, testing results clearly reveal that the steel fiber content, often at low mass and volume percentage, has no obvious influence on the PZT's EMI values. Furthermore, experiments to test the repeatability of the proposed method were conducted. The repeating test results show that the EMI-based indices are repeatable and there is a great linearity between the NI and the applied loading.

(Durability of building materials and components)

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

Naus, D.J.

1990-11-27

The traveler participated in the fourth meeting of RILEM 100-TSL, Techniques for Service Life Prediction,'' and The Fifth International Conference on Durability of Building Materials and Components.'' In addition, the traveler met with staff members at Taywood Engineering Ltd., Electricite de France, and AEA Technology. The meeting pertained to performance of concrete materials in nuclear power plant structures, time variation of concrete material properties, methods for evaluating concrete structures, and modeling to predict the effects of degradation factors on concrete materials. As many of the concrete structures in general civil engineering applications as well as nuclear power plant applications inmore » Europe are aging, there is increasing emphasis on assessing the durability of these structures. Information was provided of direct application to the Structural Aging Program which would not have been available without these visits. Of equal, or possibly more importance, was the individual contacts established at the organizations visited. Each organization was extremely interested in both the approach and scope of the Structural Aging Program and requested that they be informed of progress. The initial steps were taken to cooperate with several of these researchers and this should help the Structural Aging Program keep abreast of related European activities. In summary, information obtained during this trip will benefit the ongoing Structural Aging Program by informing Oak Ridge National Laboratory (ORNL) of the extensive European research programs addressing the durability of concrete structures, and also by forming and strengthening acquaintances with counterparts in other countries, thus enhancing the basis for possible international cooperation.« less

Assessment of the Uretek process on continuously reinforced concrete pavement, jointed concrete pavement, and bridge approach slabs : technical assistance report.

DOT National Transportation Integrated Search

2004-12-01

This study evaluates the rehabilitation method utilizing the injection of Uretek (polyurethane) into the pavement structures on continuously reinforced concrete pavement (CRCP), jointed concrete pavement (JCP), and bridge approach slabs. The polyuret...

A simplified method for prediction of long-term prestress loss in post-tensioned concrete bridges.

DOT National Transportation Integrated Search

2006-07-01

Creep and shrinkage of concrete and relaxation of prestressing steel cause time-dependent changes in : the stresses and strains of concrete structures. These changes result in continuous reduction in the : concrete compression stresses and in the ten...

Implementation of ASTM C157: testing of length change of hardened concrete : technical summary.

DOT National Transportation Integrated Search

2016-09-01

The Kansas Department of Transportation (KDOT) has a history of using : tests such as concrete strength, permeability, and air void structure as design : and acceptance criteria on concrete paving and bridge deck projects. In 2012, : the KDOT Concret...

Concrete Infrastructure Corrosion

NASA Astrophysics Data System (ADS)

Waanders, F. B.; Vorster, S. W.

2003-06-01

It is well known that many reinforced concrete structures are at risk of deterioration due to chloride ion contamination of the concrete or atmospheric carbon dioxide dissolving in water to form carbonic acid, which reacts with the concrete and the reinforcing steel. The environment within the concrete will determine the corrosion product layers, which might, inter alia, contain the oxides and/or hydroxides of iron. Tensile forces resulting from volume changes during their formation lead to the cracking and delamination of the concrete. In the present investigation the handrail of an outside staircase suffered rebar corrosion during 30 year's service, leading to severe delamination damage to the concrete structure. The railings had been sealed into the concrete staircase using a polysulphide sealant, Thiokol®. The corrosion products were identified by means of Mössbauer and SEM analyses, which indicated that the corrosion product composition varied from the original steel surface to the outer layers, the former being mainly iron oxides and the latter iron oxyhydroxide.

Clogging in permeable concrete: A review.

PubMed

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

2017-05-15

Permeable concrete (or "pervious concrete" in North America) is used to reduce local flooding in urban areas and is an important sustainable urban drainage system. However, permeable concrete exhibits reduction in permeability due to clogging by particulates, which severely limits service life. This paper reviews the clogging mechanism and current mitigating strategies in order to inform future research needs. The pore structure of permeable concrete and characteristics of flowing particulates influence clogging, which occurs when particles build-up and block connected porosity. Permeable concrete requires regular maintenance by vacuum sweeping and pressure washing, but the effectiveness and viability of these methods is questionable. The potential for clogging is related to the tortuosity of the connected porosity, with greater tortuosity resulting in increased potential for clogging. Research is required to develop permeable concrete that can be poured on-site, which produces a pore structure with significantly reduced tortuosity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Forward problem studies of electrical resistance tomography system on concrete materials

NASA Astrophysics Data System (ADS)

Ang, Vernoon; Rahiman, M. H. F.; Rahim, R. A.; Aw, S. R.; Wahab, Y. A.; Thomas W. K., T.; Siow, L. T.

2017-03-01

Electrical resistance tomography (ERT) is well known as non-invasive imaging technique, inexpensive, radiation free, visualization measurements of the multiphase flows and frequently applied in geophysical, medical and Industrial Process Tomography (IPT) applications. Application of ERT in concrete is a new exploration field, which can be used in monitoring and detecting the health and condition of concrete without destroying it. In this paper, ERT model under the condition of concrete is studied in which the sensitivity field model is produced and simulated by using COMSOL software. The affects brought by different current injection values with different concrete conductivity are studied in detail. This study able to provide the important direction for the further study of inverse problem in ERT system. Besides, the results of this technique hopefully can open a new exploration in inspection method of concrete structures in order to maintain the health of the concrete structure for civilian safety.

I-SonReb: an improved NDT method to evaluate the in situ strength of carbonated concrete

NASA Astrophysics Data System (ADS)

Breccolotti, Marco; Bonfigli, Massimo F.

2015-10-01

Concrete strength evaluated in situ by means of the conventional SonReb method can be highly overestimated in presence of carbonation. This latter, in fact, is responsible for the physical and chemical alteration of the outer layer of concrete. As most of the existing concrete structures are subjected to carbonation, it is of high importance to overcome this problem. In this paper, an Improved SonReb method (I-SonReb) for carbonated concretes is proposed. It relies on the definition of a correction coefficient of the measured Rebound index as a function of the carbonated concrete cover thickness, an additional parameter to be measured during in situ testing campaigns. The usefulness of the method has been validated showing the improvement in the accuracy of concrete strength estimation from two sets of NDT experimental data collected from investigations on real structures.

Studying of influence of fiber reinforcing at fine-grained concrete applying in transport construction

NASA Astrophysics Data System (ADS)

Begunov, Oleg; Alexandrova, Olga; Solovyov, Vadim

2017-10-01

We observed causes of using fiber in nowadays construction industry and its influence on a final product properties, where the fine-grained concrete basing of repairing dry construction mix was used as a base. However, in Russia we do not have such experience. If we’re talking about changes occurring in the fine-grained concrete all of its are known about it, either in concrete, but in dry-construction mixes changes may have another purpose. Advantages and disadvantages of using fiber were oblieved also in that article. The main subject of this research is the influence of fiber on a mechanical properties of fine-grained concrete. The most attention is paid to estimate the influence of a concrete’s properties by metal fibers: casting time (initial and final), workability and strength (tensile strength and compressive strength) in this article. The most popular different type of metal fiber compares for its length and width and the optimum quantity of metal component chooses, which will indicate the maximum possible affirmative result of its using. Dependences comparing properties of fine-grained properties with fiber’s type, measurements and quantity which show the evident result of researching are 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.

Evaluation of Modern Navies’ Damage Control and Firefighting Training using Simulator Platforms

DTIC Science & Technology

2011-09-01

Figure 18 below is a two-story concrete structure including holes in bulkheads, ruptured pipelines, and almost all situations that can cause flooding...the four simulators address Class A, B, and C fires. The first one—the “Basic Firefighting Trainer”—is a single-story concrete structure with four...Figure 19—is a three-story concrete structure that houses berthing facilities, engine rooms, storage compartments and electrical and engine room mock

Relationship between critical mechanical properties and age for structural lightweight concrete.

DOT National Transportation Integrated Search

1964-02-25

The necessity to use structural lightweight concrete has created : a need for investigations into its critical mechanical properties that : affect the design and performance of structures. The primary critical : properties were found to be direct ten...

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

Effect of a viscoelastic admixture on transient vibration in a concrete and steel floor

NASA Astrophysics Data System (ADS)

Moiseev, Neil

1992-02-01

The typical concrete and steel building structure has very little inherent damping, resulting in a very large Q, a measure of the sharpness of the amplitude response at resonance. Some damping effects are provided through the inertia and friction provided by a building''s full height partitions, hung ceilings, furniture, and suspended ducts and piping. These items have an effect on the very low amplitude vibration that affects sensitive laboratory equipment and the processes used in the microelectronic industry. This paper presents studies of transient vibration of floors in two existing buildings. The floors have been treated by adding a two inch thick concrete topping to the structural floor. This additional layer of concrete was treated by using a viscoelastic damping admixture in place of some of the water used to form the concrete. The admixture can dramatically reduce the Q of concrete from the normal 200 to between 20 and 50, depending on the amount of admixture used per yard of concrete. The measured velocity and frequency of the transient vibration excited by footfalls is compared to the predicted velocity and frequency of the same floor structure without the damping admixture. A formula to predict the peak transient vibration velocity due to footfalls for a concrete floor with a viscoelastic admixture is proposed.

Events as power source: wireless sustainable corrosion monitoring.

PubMed

Sun, Guodong; Qiao, Guofu; Zhao, Lin; Chen, Zhibo

2013-12-17

This study presents and implements a corrosion-monitoring wireless sensor platform, EPS (Events as Power Source), which monitors the corrosion events in reinforced concrete (RC) structures, while being powered by the micro-energy released from the corrosion process. In EPS, the proposed corrosion-sensing device serves both as the signal source for identifying corrosion and as the power source for driving the sensor mote, because the corrosion process (event) releases electric energy; this is a novel idea proposed by this study. For accumulating the micro-corrosion energy, we integrate EPS with a COTS (Commercial Off-The-Shelf) energy-harvesting chip that recharges a supercapacitor. In particular, this study designs automatic energy management and adaptive transmitted power control polices to efficiently use the constrained accumulated energy. Finally, a set of preliminary experiments based on concrete pore solution are conducted to evaluate the feasibility and the efficacy of EPS.

Load drop evaluation for TWRS FSAR

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

Julyk, L.J.; Ralston, G.L.

1996-09-30

Operational or remediation activities associated with existing underground high-level waste storage tank structures at the Hanford Site often require the installation/removal of various equipment items. To gain tank access for installation or removal of this equipment, large concrete cover blocks must be removed and reinstalled in existing concrete pits above the tanks. An accidental drop of the equipment or cover blocks while being moved over the tanks that results in the release of contaminants to the air poses a potential risk to onsite workers or to the offsite public. To minimize this potential risk, the use of critical lift hoistingmore » and rigging procedures and restrictions on lift height are being considered during development of the new tank farm Basis for Interim Operation and Final Safety Analysis Report. The analysis contained herein provides information for selecting the appropriate lift height restrictions for these activities.« less

Aging management program of the reactor building concrete at Point Lepreau Generating Station

NASA Astrophysics Data System (ADS)

Aldea, C.-M.; Shenton, B.; Demerchant, M. M.; Gendron, T.

2011-04-01

In order for New Brunswick Power Nuclear (NBPN) to control the risks of degradation of the concrete reactor building at the Point Lepreau Generating Station (PLGS) the development of an aging management plan (AMP) was initiated. The intention of this plan was to determine the requirements for specific structural components of concrete of the reactor building that require regular inspection and maintenance to ensure the safe and reliable operation of the plant. The document is currently in draft form and presents an integrated methodology for the application of an AMP for the concrete of the reactor building. The current AMP addresses the reactor building structure and various components, such as joint sealant and liners that are integral to the structure. It does not include internal components housed within the structure. This paper provides background information regarding the document developed and the strategy developed to manage potential degradation of the concrete of the reactor building, as well as specific programs and preventive and corrective maintenance activities initiated.

Thermo-mechanical simulations of early-age concrete cracking with durability predictions

NASA Astrophysics Data System (ADS)

Havlásek, Petr; Šmilauer, Vít; Hájková, Karolina; Baquerizo, Luis

2017-09-01

Concrete performance is strongly affected by mix design, thermal boundary conditions, its evolving mechanical properties, and internal/external restraints with consequences to possible cracking with impaired durability. Thermo-mechanical simulations are able to capture those relevant phenomena and boundary conditions for predicting temperature, strains, stresses or cracking in reinforced concrete structures. In this paper, we propose a weakly coupled thermo-mechanical model for early age concrete with an affinity-based hydration model for thermal part, taking into account concrete mix design, cement type and thermal boundary conditions. The mechanical part uses B3/B4 model for concrete creep and shrinkage with isotropic damage model for cracking, able to predict a crack width. All models have been implemented in an open-source OOFEM software package. Validations of thermo-mechanical simulations will be presented on several massive concrete structures, showing excellent temperature predictions. Likewise, strain validation demonstrates good predictions on a restrained reinforced concrete wall and concrete beam. Durability predictions stem from induction time of reinforcement corrosion, caused by carbonation and/or chloride ingress influenced by crack width. Reinforcement corrosion in concrete struts of a bridge will serve for validation.

Workability enhancement of geopolymer concrete through the use of retarder

NASA Astrophysics Data System (ADS)

Umniati, B. Sri; Risdanareni, Puput; Zein, Fahmi Tarmizi Zulfikar

2017-09-01

Geopolymer concrete is a type of concrete manufactured without the addition of cement. In geopolymer concrete, along with an activator, cement as the concrete binder can be replaced by the fly ash. This will reduce global demand on cement, and therefore will reduce CO2 emission due to cement production. Thus, geopolymer concrete is commonly known as an eco-friendly concrete. Geopolymer concrete also offers a solution concerning with the utilization of the fly ash waste. However, despite of its environmental advantages, geopolymer concrete has a drawback, namelygeopolymer concrete set quickly, thus reducing its workability. This research aimed to increase the workability of geopolymer concrete by using retarder admixture (Plastocrete RT6 Plus). Retarder used varies within 0.2%, 0.4% and 0.6% of fly ash mass. As a control, geopolymer concrete without retarder (0%) were also made. Activator used in this research was Na2SiO3 mixed with NaOH 10 M solution, with ratio of 1:5. The results showed an optimum composition of geopolymer concrete with 0.6% retarder, where initial setting time occured after 6.75 hours, and the final setting time reached after 9.5 hours. Moreover, the slump of the geopolymer concrete was 8.8 cm, and the slump flow was 24 cm. The compressive strength of the geopolymer concrete at 28 days was 47.21 MPa. The experiment showed that the more retarder added, the setting time of the geopolymer concrete will be increased, thus increasing its workability.

Image enhancement for on-site X-ray nondestructive inspection of reinforced concrete structures.

PubMed

Pei, Cuixiang; Wu, Wenjing; Ueaska, Mitsuru

2016-11-22

The use of portable and high-energy X-ray system can provide a very promising approach for on-site nondestructive inspection of inner steel reinforcement of concrete structures. However, the noise properties and contrast of the radiographic images for thick concrete structures do often not meet the demands. To enhance the images, we present a simple and effective method for noise reduction based on a combined curvelet-wavelet transform and local contrast enhancement based on neighborhood operation. To investigate the performance of this method for our X-ray system, we have performed several experiments with using simulated and experimental data. With comparing to other traditional methods, it shows that the proposed image enhancement method has a better performance and can significantly improve the inspection performance for reinforced concrete structures.

VIEW OF GUN EMPLACEMENT AND THE TABLELIKE CAST CONCRETE STRUCTURE ...

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

VIEW OF GUN EMPLACEMENT AND THE TABLE-LIKE CAST CONCRETE STRUCTURE SHOWING THE SPALLED AREA ON ITS EAST SIDE (LEFT) WHERE THE SECOND PROJECTING ARM WAS BROKEN OFF. NOTE THE SLOPED CONCRETE PAD IN THE BACKGROUND. VIEW FACING SOUTHWEST - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, East Gun Emplacement, Ford Island, Pearl City, Honolulu County, HI

Research notes : polymer concrete bridge deck overlays : Deschutes River Bridge (Biggs), Maupin Bridge (Maupin) : final report.

DOT National Transportation Integrated Search

1995-07-01

This report documents the construction and performance of two thin polymer concrete (with polyester/styrene resins) bridge deck overlays. The overlays were constructed in Biggs and Maupin, Oregon in June 1993. Construction of the overlays was less th...

Strength and durability of near-surface mounted CFRP bars for shear strengthening reinforced concrete bridge girders : final report appendices.

DOT National Transportation Integrated Search

2012-03-01

During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candida...

Final report evaluation of bond retainage in Portland cement concrete overlays using infrared thermography and ground penetrating radar.

DOT National Transportation Integrated Search

1989-01-01

When concrete deterioration begins to occur in highway pavement, : repairs become necessary to assure the rider safety, extend its : useful life and restore its riding qualities. One rehabilitation : technique used to restore the pavement to acceptab...

Field evaluation of a new aluminum alloy as a sacrificial anode for steel embedded in concrete

DOT National Transportation Integrated Search

1998-04-01

This is the final report for a study to evaluate the use of sacrificial cathodic protection for reinforced and prestressed concrete bridge members. Cathodic protection (CP) using impressed current is an accepted and common method used to provide corr...

Determination of the cement content of hardened concrete by selective solution : final report.

DOT National Transportation Integrated Search

1972-01-01

The method of selective solution by methanolic maleic acid, developed by Tabikh et. al for the determination of cement content in hardened concrete, was evaluated. It was found to be relatively simple and inexpensive, and is accurate to within 1 pe...

Economic impact of multi-span, prestressed concrete girder bridges designed as simple span versus continuous span : final report.

DOT National Transportation Integrated Search

2016-10-01

The objective of this study was to determine the economic impact of designing pre-tensioned prestressed concrete beam (PPCB) : bridges utilizing the continuity developed in the bridge deck as opposed to the current Iowa Department of Transportation (...

Acoustic emission testing of in-service conventionally reinforced concrete deck girder superstructures on highway bridges : final report.

DOT National Transportation Integrated Search

2008-09-01

Three reports were produced from research sponsored by the Oregon Department of Transportation on acoustic emission (AE). The first describes the evaluation of AE techniques applied to two reinforced concrete (RC) bridge girders, which were loaded to...

The use of fiber reinforcement in latex modified concrete overlay : final report.

DOT National Transportation Integrated Search

2016-12-01

The requirement to quickly reopen highways in North Carolina has motivated the increased use of rapid-setting concrete in overlays. The addition of polymer latex to the material has been used to increase the service life of the overlays. The latex mo...

Implementation of the use of higher micro-fines in concrete pavements final report.

DOT National Transportation Integrated Search

2009-12-01

The main purpose of this project was to implement previous research performed on concrete utilizing micro-fines : in a field test. The project can be divided into three main parts: First, predetermined materials that were local to : the field trial s...

Dynamic evaluation of a pinned anchoring system for New York state's temporary concrete barriers : final report, September 8, 2009.

DOT National Transportation Integrated Search

2009-09-08

Temporary concrete barrier (TCB) systems are utilized in many circumstances, including for placement adjacent to vertical : dropoffs. Free-standing TCB systems are known to have relatively large deflections when impacted, which may be undesirable whe...

Study of lime vs. no lime in cold in-place recycled asphalt concrete pavements : final report.

DOT National Transportation Integrated Search

1991-09-01

The resilient characteristics of cold in-place recycled asphalt concrete with and without lime were examined. Six core samples were obtained from a site two months after construction; six months later, six additional core samples were obtained from t...

Environmental durability of reinforced concrete deck girders strengthened for shear with surface-bonded carbon fiber-reinforced polymer : final report.

DOT National Transportation Integrated Search

2009-05-01

This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort ...

Strength and durability of near-surface mounted CFRP bars for shear strengthening reinforced concrete bridge girders : final report.

DOT National Transportation Integrated Search

2012-03-01

During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candida...

Environmental durability of reinforced concrete deck girders strengthened for shear with surface bonded carbon fiber-reinforced polymer : final report.

DOT National Transportation Integrated Search

2009-05-01

This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced : concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effor...

Modulus of elasticity, creep and shrinkage of concrete, phase II : part 1, creep study, final report.

DOT National Transportation Integrated Search

2009-10-01

A laboratory testing program was performed to evaluate the physical and mechanical properties of typical Class II, IV, V, and VI concrete mixtures made with a Miami Oolite limestone, a Georgia granite, and a lightweight aggregate Stalite, including c...

Measures to reduce construction time of high-rise buildings

NASA Astrophysics Data System (ADS)

Kolchedantsev, Leonid; Adamtsevich, Aleksey; Stupakova, Olga; Drozdov, Alexander

2018-03-01

The organizational and technological solutions for high-rise buildings construction efficiency increase are considered, primarily - decrease of typical floor construction time and improvement of bearing structures concrete quality. The essence of offered technology is: a concrete mixing station and a polygon mainly for load-bearing wall panels with starter bars casting are located on the building site; for reinforced concrete components manufacturing and butt joints grouting the warmed-up concrete mixtures are used. The results of researches and elaborations carried out by the SPSUACE in area of a preliminary warming-up of concrete mixtures are presented. The possibility and feasibility of their usage in high-rise buildings and of excess height buildings construction including cast-in-place and precast execution are shown. The essence of heat-vibro treating of concrete mixture is revealed as a kind of prior electroresistive curing, and the achieved results are: accelerated concrete strength gain, power inputs decrease, concrete quality improvement. It is shown that the location of a concrete mixing station on the building site enables to broaden possibilities of the "thermos" method use and to avoid concrete mixtures warming up in medium-mass structures erection (columns, girders) during the high-rise buildings construction. It is experimentally proved that the splice between precast elements encased with warmed-up concrete mixture is equal with conjugated elements in strength.

Experimental Study on Voided Reinforced Concrete Beams with Polythene Balls

NASA Astrophysics Data System (ADS)

Sivaneshan, P.; Harishankar, S.

2017-07-01

The primary component in any structure is concrete, that exist in buildings and bridges. In present situation, a serious problems faced by construction industry is exhaustive use of raw materials. Recent times, various methods are being adopted to limit the use of concrete. In structural elements like beams, polythene balls can be induced to reduce the usage of concrete. A simply supported reinforced concrete beam has two zones, one above neutral axis and other below neutral axis. The region below neutral axis is in tension and above neutral axis is in compression. As concrete is weak in tension, steel reinforcements are provided in tension zone. The concrete below the neutral axis acts as a stress transfer medium between the compression zone and tension zone. The concrete above the neutral axis takes minimum stress so that we could partially replace the concrete above neutral axis by creating air voids using recycled polythene balls. Polythene balls of varying diameters of 75 mm, 65 mm and 35 mm were partially replaced in compression zone. Hence the usage of concrete in beams and self-weight of the beams got reduced considerably. The Load carrying capacity, Deflection of beams and crack patterns were studied and compared with conventional reinforced concrete beams.

27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, ...

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

27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, A SHORT DISTANCE WEST OF D STREET ABOUT ONE-QUARTER MILE SOUTH OF 9TH AVENUE (SECTION 26). - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

Infrastructure Retrofit Design via Composite Mechanics

NASA Technical Reports Server (NTRS)

Chamis, Christos, C.; Gotsis,Pascal K.

1998-01-01

Select applications are described to illustrate the concept for retrofitting reinforced concrete infrastructure with fiber reinforced plastic laminates. The concept is first illustrated by using an axially loaded reinforced concrete column. A reinforced concrete arch and a dome are then used to illustrate the versatility of the concept. Advanced methods such as finite element structural analysis and progressive structural fracture are then used to evaluate the retrofitting laminate adequacy. Results obtains show that retrofits can be designed to double and even triple the as-designed load of the select reinforced concrete infrastructures.

Balanced improvement of high performance concrete material properties with modified graphite nanomaterials

NASA Astrophysics Data System (ADS)

Peyvandi, Amirpasha

Graphite nanomaterials offer distinct features for effective reinforcement of cementitious matrices in the pre-crack and post-crack ranges of behavior. Thoroughly dispersed and well-bonded nanomaterials provide for effective control of the size and propagation of defects (microcracks) in matrix, and also act as closely spaced barriers against diffusion of moisture and aggressive solutions into concrete. Modified graphite nanomaterials can play multi-faceted roles towards enhancing the mechanical, physical and functional attributes of concrete materials. Graphite nanoplatelets (GP) and carbon nanofibers (CNF) were chosen for use in cementitious materials. Experimental results highlighted the balanced gains in diverse engineering properties of high-performance concrete realized by introduction of graphite nanomaterials. Nuclear Magnetic Resonance (NMR) spectroscopy was used in order to gain further insight into the effects of nanomaterials on the hydration process and structure of cement hydrates. NMR exploits the magnetic properties of certain atomic nuclei, and the sensitivity of these properties to local environments to generate data which enables determination of the internal structure, reaction state, and chemical environment of molecules and bulk materials. 27 Al and 29Si NMR spectroscopy techniques were employed in order to evaluate the effects of graphite nanoplatelets on the structure of cement hydrates, and their resistance to alkali-silica reaction (ASR), chloride ion diffusion, and sulfate attack. Results of 29Si NMR spectroscopy indicated that the percent condensation of C-S-H in cementitious paste was lowered in the presence of nanoplatelets at the same age. The extent of chloride diffusion was assessed indirectly by detecting Friedel's salt as a reaction product of chloride ions with aluminum-bearing cement hydrates. Graphite nanoplatelets were found to significantly reduce the concentration of Friedel's salt at different depths after various periods of exposure to chloride solutions, pointing at the benefits of nanoplatelets towards enhancement of concrete resistance to chloride ion diffusion. It was also found that the intensity of Thaumasite, a key species marking sulfate attack on cement hydrates, was lowered with the addition of graphite nanoplatelets in concrete exposed to sulfate solutions. Experimental evaluations were conducted on scaled-up production of concrete nanocomposite in precast concrete plants. Full-scale reinforced concrete pipes and beams were produced using concrete nanocomposites. Durability and structural tests indicated that the use of graphite nanoplatelets, alone or in combination with synthetic (PVA) fibers, produced significant gains in the durability characteristics, and also benefited the structural performance of precast reinforced concrete products. The material and scaled-up structural investigations conducted in the project concluded that lower-cost graphite nanomaterials (e.g., graphite nanoplatelets) offer significant potentials as multi-functional additives capable of enhancing the barrier, durability and mechanical performance of concrete materials. The benefits of graphite nanomaterials tend to be more pronounced in higher-performance concrete materials.

Doubling the Life of Concrete Structures

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

Pesic, Batric; Raja, Krishnan; Xi, Yumping

Overall objective of the project was to study the fundamental properties of concrete (with and without steel reinforcement) with respect to chemical and physical parameters that can influence its structural integrity.

Dynamics of layered reinforced concrete beam on visco-elastic foundation with different resistances of concrete and reinforcement to tension and compression

NASA Astrophysics Data System (ADS)

Nemirovsky, Y. V.; Tikhonov, S. V.

2018-03-01

Originally, fundamentals of the theory of limit equilibrium and dynamic deformation of building metal and reinforced concrete structures were created by A. A. Gvozdev [1] and developed by his followers [4, 5, 6, 7, 11, 12]. Forming the basis for the calculation, the model of an ideal rigid-plastic material has enabled to determine in many cases the ultimate load bearing capacity and upper (kinematically possible) or lower (statically valid) values for a wide class of different structures with quite simple methods. At the same time, applied to concrete structures the most important property of concrete to significantly differently resist tension and compression was not taken into account [10]. This circumstance was considered in [3] for reinforced concrete beams under conditions of quasistatic loading. The deformation is often accompanied by resistance of the environment in construction practice [8, 9]. In [2], the dynamics of multi-layered concrete beams on visco-elastic foundation under the loadings of explosive type is considered. In this work we consider the case which is often encountered in practical applications when the loadings weakly change in time.

Influence of Blended Cements with Calcareous Fly Ash on Chloride Ion Migration and Carbonation Resistance of Concrete for Durable Structures.

PubMed

Glinicki, Michał A; Jóźwiak-Niedźwiedzka, Daria; Gibas, Karolina; Dąbrowski, Mariusz

2016-01-02

The objective of this paper is to examine the possible use of new blended cements containing calcareous fly ash in structural concrete, potentially adequate for structural elements of nuclear power plants. The investigation included five new cements made with different contents of non-clinker constituents: calcareous fly ash, siliceous fly ash, ground granulated blastfurnace slag, and a reference cement-ordinary Portland cement. The influence of innovative cements on the resistance of concrete to chloride and carbonation exposure was studied. Additionally, an evaluation of the microstructure was performed using optical microscopy on concrete thin sections. Test results revealed a substantial improvement of the resistance to chloride ion penetration into concrete containing blended cements. The resistance was higher for increased clinker replacement levels and increased with curing time. However, concrete made with blended cements exhibited higher depth of carbonation than the Portland cement concrete, except the Portland-fly ash cement with 14.3% of calcareous fly ash. The thin sections analysis confirmed the values of the carbonation depth obtained from the phenolphthalein test. Test results indicate the possible range of application for new cements containing calcareous fly ash.

Influence of Blended Cements with Calcareous Fly Ash on Chloride Ion Migration and Carbonation Resistance of Concrete for Durable Structures

PubMed Central

Glinicki, Michał A.; Jóźwiak-Niedźwiedzka, Daria; Gibas, Karolina; Dąbrowski, Mariusz

2016-01-01

The objective of this paper is to examine the possible use of new blended cements containing calcareous fly ash in structural concrete, potentially adequate for structural elements of nuclear power plants. The investigation included five new cements made with different contents of non-clinker constituents: calcareous fly ash, siliceous fly ash, ground granulated blastfurnace slag, and a reference cement—ordinary Portland cement. The influence of innovative cements on the resistance of concrete to chloride and carbonation exposure was studied. Additionally, an evaluation of the microstructure was performed using optical microscopy on concrete thin sections. Test results revealed a substantial improvement of the resistance to chloride ion penetration into concrete containing blended cements. The resistance was higher for increased clinker replacement levels and increased with curing time. However, concrete made with blended cements exhibited higher depth of carbonation than the Portland cement concrete, except the Portland-fly ash cement with 14.3% of calcareous fly ash. The thin sections analysis confirmed the values of the carbonation depth obtained from the phenolphthalein test. Test results indicate the possible range of application for new cements containing calcareous fly ash. PMID:28787821

Research Status on Bonding Behavior of Prefabricated Concrete Shear Wall

NASA Astrophysics Data System (ADS)

Wang, Donghui; Liu, Xudong; Wang, Sheng; Li, Shanshan

2018-03-01

Prefabricated shear wall structure adapts to the development and requirements of China’s residential industrialization. The key to the prefabricated concrete shear wall structure is the connection between the prefabricated members, where the reliability of the connection of the concrete joint is related to the overall performance and seismic effect of the structure. In this paper, the microstructures of the joint surface and shear properties are analysed, and the formula for calculating the shear strength of the joint is obtained.

Kaiser and Felicity effects and their application for evaluation of concrete by acoustic emission method

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

Nesvijski, E.; Nesvijski, T.

1996-12-31

Concrete as one of the main construction materials, which is used for building of industrial and civil structures, highways, bridges, etc. requires periodical evaluation of its properties by different nondestructive methods. Application of acoustic emission (AE) for these purposes occupies a modest place among other nondestructive methods. But the AE methods proved to be very effective for testing of concrete and reinforced concrete elements and structures under load. This work is devoted to an important, from methodological point of view, problem connected with two opposite effects: of Kaiser and of Felicity, and their application for evaluation of concrete by themore » AE method.« less

Determination of the neutralization depth of concrete under the aggressive environment influence

NASA Astrophysics Data System (ADS)

Morzhukhina, Anastasia; Nikitin, Stanislav; Akimova, Elena

2018-03-01

Aggressive environments have a significant impact on destruction of many reinforced concrete structures, such as high-rise constructions or chemical plants. For example, some high-rise constructions are equipped with a swimming pool, so they are exposed to chloride ions in the air. Penetration of aggressive chemical substances into the body of concrete contributes to acceleration of reinforced concrete structure corrosion that in turn leads to load bearing capacity loss and destruction of the building. The article considers and analyzes the main technologies for calculating penetration depth of various aggressive substances into the body of concrete. The calculation of corrosion depth was made for 50-year service life.

Transfer and development length of prestressing tendons in full-scale AASHTO prestressed concrete girders using self-consolidating concrete.

DOT National Transportation Integrated Search

2009-03-01

Self-consolidating concrete (SCC) is a highly workable concrete that flows through densely reinforced or : complex structural elements under its own weight. The benefits of using SCC include: a) Reducing labor costs : by eliminating the need for mech...

The cost of concreteness: the effect of nonessential information on analogical transfer.

PubMed

Kaminski, Jennifer A; Sloutsky, Vladimir M; Heckler, Andrew F

2013-03-01

Most theories of analogical transfer focus on similarities between the learning and transfer domains, where transfer is more likely between domains that share common surface features, similar elements, or common interpretations of structure. We suggest that characteristics of the learning instantiation alone can give rise to different levels of transfer. We propose that concreteness of the learning instantiation can hinder analogical transfer of well-defined structured concepts, such as mathematical concepts. We operationalize the term concreteness as the amount of information communicated through a specific instantiation of a concept. The 5 reported experiments with undergraduate students tested the hypothesis by presenting participants with the concept of a commutative mathematical group of order 3. The experiments varied the level of concreteness of the training instantiation and measured transfer of learning to a new instantiation. The results support the hypothesis, demonstrating better transfer from more generic instantiations (i.e., ones that communicate minimal extraneous information) than from more concrete instantiations. Specifically, concreteness was found to create an obstacle to successful structural alignment across domains, whereas generic instantiations led to spontaneous structural alignment. These findings have important implications for the theory of learning and transfer and practical implications for the design of educational material. Although some concreteness may activate prior knowledge and perhaps offer a leg up in the learning process, this benefit may come at the cost of transfer.

Embedded micro-sensor for monitoring pH in concrete structures

NASA Astrophysics Data System (ADS)

Srinivasan, Rengaswamy; Phillips, Terry E.; Bargeron, C. Brent; Carlson, Micah A.; Schemm, Elizabeth R.; Saffarian, Hassan M.

2000-04-01

Three major causes of corrosion of steel in concrete are chloride ions (Cl-), temperature (T) and acidity (pH). Under normal operating temperatures and with pH above 13, steel does not undergo pitting corrosion. In presence of Cl-, if the pH decreases below 12, the probability of pitting increases. Acid rain and atmospheric carbon dioxide cause the pH to drop in concrete, often leading to corrosion of the structure with the concomitant cost of repair or replacement. Currently, the pH level in concrete is estimated through destructive testing of the structures. Glass ISFET, and other pH sensors that need maintenance and calibration cannot be embedded in concrete. In this paper, we describe an inexpensive solid state pH sensor that can be embedded in concrete, to detect pH changes at the early stages. It employs a chemical reagent, trinitrobenzenesulfonic acid (TNBS) that exhibits changes in optical properties in the 12 - 14 pH range, and is held in a film of a sol-gel/TNBS composite on an optically transparent surface. A simple LED/filter/photodiode transducer monitors pH-induced changes in TNBS. Such a device needs no periodic calibration or maintenance. The optical window, the light-source and sensor can be easily housed and encapsulated in a chemically inert structure, and embedded in concrete.

Experimental collaboration for thick concrete structures with alkali-silica reaction

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

Ezell, N Dianne Bull; Hayes, Nolan W.; Lenarduzzi, Roberto

Alkali-Silica Reaction (ASR) is a reaction that occurs over time in concrete between alkaline cement paste and reactive, non-crystalline silica in aggregates. An expansive gel is formed within the aggregates which results in micro-cracks in aggregates and adjacent cement paste. The reaction requires the presence of water and has been predominantly detected in groundwater-impacted portions of below grade structures, with limited impact to exterior surfaces in above grade structures. ASR can potentially affect concrete properties and performance characteristics such as compressive strength, modulus of elasticity, shear strength, and tensile strength. Since ASR degradation often takes significant amounts of time, developingmore » ASR detection techniques is important to the sustainability and extended operation lifetimes of nuclear power plants (NPPs). The University of Tennessee, Knoxville (UTK) in collaboration with Oak Ridge National Laboratory (ORNL) designed and built an experiment representative of typical NPP structures to study ASR in thick concrete structures.« less

Experimental collaboration for thick concrete structures with alkali-silica reaction

NASA Astrophysics Data System (ADS)

Ezell, N. Dianne Bull; Hayes, Nolan; Lenarduzzi, Roberto; Clayton, Dwight; Ma, Z. John; Le Pape, Sihem; Le Pape, Yann

2018-04-01

Alkali-Silica Reaction (ASR) is a reaction that occurs over time in concrete between alkaline cement paste and reactive, non-crystalline silica in aggregates. An expansive gel is formed within the aggregates which results in micro-cracks in aggregates and adjacent cement paste. The reaction requires the presence of water and has been predominantly detected in groundwater-impacted portions of below grade structures, with limited impact to exterior surfaces in above grade structures. ASR can potentially affect concrete properties and performance characteristics such as compressive strength, modulus of elasticity, shear strength, and tensile strength. Since ASR degradation often takes significant amounts of time, developing ASR detection techniques is important to the sustainability and extended operation lifetimes of nuclear power plants (NPPs). The University of Tennessee, Knoxville (UTK) in collaboration with Oak Ridge National Laboratory (ORNL) designed and built an experiment representative of typical NPP structures to study ASR in thick concrete structures.

Material and Structural Performance Evaluations of Hwangtoh Admixtures and Recycled PET Fiber-Added Eco-Friendly Concrete for CO2 Emission Reduction

PubMed Central

Koo, Bon-Min; Kim, Jang-Ho Jay; Kim, Sung-Bae; Mun, Sungho

2014-01-01

In order to reduce carbon dioxide (CO2) emissions and produce an eco-friendly construction material, a type of concrete that uses a minimal amount of cement, yet still retains equivalent properties to ordinary cement concrete, has been developed and studied all over the world. Hwangtoh, a type of red clay broadly deposited around the world, has traditionally been considered an eco-friendly construction material, with bonus advantages of having health and cost benefits. Presently, Hwangtoh is not commonly used as a modern construction material due to properties such as low strength and high rates of shrinkage cracking. Recent studies, however, have shown that Hwangtoh can be used as a mineral admixture to improve the strength of concrete. In addition, polyethylene terephthalate (PET) fibers recycled from PET bottle waste can be used to control shrinkage cracks in Hwangtoh concrete. Therefore, in this study, performance verification is conducted on newly developed Hwangtoh concrete mixed with short recycled PET fibers. The results show that Hwangtoh concrete has compressive strength, elastic modulus, and pH properties that are similar to these features in ordinary cement concrete. The properties of carbonation depth and creep strain of Hwangtoh concrete, however, are larger and smaller, respectively, than in ordinary cement concrete. According to flexural tests, reinforced concrete (RC) specimens cast with Hwangtoh admixtures (with and without PET fibers) possess similar or better capacities than ordinary RC specimens. The addition of PET fibers significantly improves the structural ductility of RC specimens under normal environmental conditions. However, the implementations of the concrete in aggressive environment must be carefully considered, since a previous study result indicates degradation of its durability performance in aggressive environments, such as seawater [1]. The results of this study validate the possibility of using eco-friendly Hwangtoh concrete reinforced with recycled PET fibers as a structural material for modern construction. PMID:28788171

Material and Structural Performance Evaluations of Hwangtoh Admixtures and Recycled PET Fiber-Added Eco-Friendly Concrete for CO₂ Emission Reduction.

PubMed

Koo, Bon-Min; Kim, Jang-Ho Jay; Kim, Sung-Bae; Mun, Sungho

2014-08-19

In order to reduce carbon dioxide (CO₂) emissions and produce an eco-friendly construction material, a type of concrete that uses a minimal amount of cement, yet still retains equivalent properties to ordinary cement concrete, has been developed and studied all over the world. Hwangtoh, a type of red clay broadly deposited around the world, has traditionally been considered an eco-friendly construction material, with bonus advantages of having health and cost benefits. Presently, Hwangtoh is not commonly used as a modern construction material due to properties such as low strength and high rates of shrinkage cracking. Recent studies, however, have shown that Hwangtoh can be used as a mineral admixture to improve the strength of concrete. In addition, polyethylene terephthalate (PET) fibers recycled from PET bottle waste can be used to control shrinkage cracks in Hwangtoh concrete. Therefore, in this study, performance verification is conducted on newly developed Hwangtoh concrete mixed with short recycled PET fibers. The results show that Hwangtoh concrete has compressive strength, elastic modulus, and pH properties that are similar to these features in ordinary cement concrete. The properties of carbonation depth and creep strain of Hwangtoh concrete, however, are larger and smaller, respectively, than in ordinary cement concrete. According to flexural tests, reinforced concrete (RC) specimens cast with Hwangtoh admixtures (with and without PET fibers) possess similar or better capacities than ordinary RC specimens. The addition of PET fibers significantly improves the structural ductility of RC specimens under normal environmental conditions. However, the implementations of the concrete in aggressive environment must be carefully considered, since a previous study result indicates degradation of its durability performance in aggressive environments, such as seawater [1]. The results of this study validate the possibility of using eco-friendly Hwangtoh concrete reinforced with recycled PET fibers as a structural material for modern construction.

GRIZZLY Model of Multi-Reactive Species Diffusion, Moisture/Heat Transfer and Alkali-Silica Reaction for Simulating Concrete Aging and Degradation

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

Huang, Hai; Spencer, Benjamin W.; Cai, Guowei

Concrete is widely used in the construction of nuclear facilities because of its structural strength and its ability to shield radiation. The use of concrete in nuclear power plants for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. As such, when life extension is considered for nuclear power plants, it is critical to have accurate and reliable predictive tools to address concerns related to various aging processes of concrete structures and the capacity of structures subjected to age-related degradation. The goal of this report is to document themore » progress of the development and implementation of a fully coupled thermo-hydro-mechanical-chemical model in GRIZZLY code with the ultimate goal to reliably simulate and predict long-term performance and response of aged NPP concrete structures subjected to a number of aging mechanisms including external chemical attacks and volume-changing chemical reactions within concrete structures induced by alkali-silica reactions and long-term exposure to irradiation. Based on a number of survey reports of concrete aging mechanisms relevant to nuclear power plants and recommendations from researchers in concrete community, we’ve implemented three modules during FY15 in GRIZZLY code, (1) multi-species reactive diffusion model within cement materials; (2) coupled moisture and heat transfer model in concrete; and (3) anisotropic, stress-dependent, alkali-silica reaction induced swelling model. The multi-species reactive diffusion model was implemented with the objective to model aging of concrete structures subjected to aggressive external chemical attacks (e.g., chloride attack, sulfate attack, etc.). It considers multiple processes relevant to external chemical attacks such as diffusion of ions in aqueous phase within pore spaces, equilibrium chemical speciation reactions and kinetic mineral dissolution/precipitation. The moisture/heat transfer module was implemented to simulate long-term spatial and temporal evolutions of the moisture and temperature fields within concrete structures at both room and elevated temperatures. The ASR swelling model implemented in GRIZZLY code can simulate anisotropic expansions of ASR gel under either uniaxial, biaxial and triaxial stress states, and can be run simultaneously with the moisture/heat transfer model and coupled with various elastic/inelastic solid mechanics models that were implemented in GRIZZLY code previously. This report provides detailed descriptions of the governing equations, constitutive equations and numerical algorithms of the three modules implemented in GRIZZLY during FY15, simulation results of example problems and model validation results by comparing simulations with available experimental data reported in the literature. The close match between the experiments and simulations clearly demonstrate the potential of GRIZZLY code for reliable evaluation and prediction of long-term performance and response of aged concrete structures in nuclear power plants.« less

Department of the Navy. FY 1994/FY 1995 Biennial Budget Estimates. Military Construction Program. FY 1994

DTIC Science & Technology

1992-01-01

3 are severely deteriorated. The concrete deck and supporting wood -pile structure are nearing the end of their life cycle. Both piers are to be...PROPOSED CONSTRUCTION One-story building with concrete foundation walls, load bearing masonry walls, and concrete floors; roof with wood truss framing...concrete building addition; concrete foundation and slab on grade; wood truss roof; 750 KVA. 3 phase transformer; utilities; concrete and storm drain. 11

General setting from alley, office to left, concrete structure in ...

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

General setting from alley, office to left, concrete structure in center foreground, garage/shop to right, view to northeast - Former Umatilla Project Headquarters Buildings, Hermiston, Umatilla County, OR

Non-destructive testing for the structures and civil infrastructures characterization

NASA Astrophysics Data System (ADS)

Capozzoli, L.; Rizzo, E.

2012-04-01

This work evaluates the ability of non-conventional NDT techniques such as GPR, geoelectrical method and conventional ones such as infrared thermography (IRT) and sonic test for the characterization of building structures in laboratory and in-situ. Moreover, the integration of the different techniques were evaluated in order to reduce the degree of uncertainties associated. The presence of electromagnetic, resistivity or thermal anomalies in the behavior may be related to the presence of defects, crack, decay or moisture. The research was conducted in two phases: the first phase was performed in laboratory and the second one mainly in the field work. The laboratory experiments proceeded to calibrate the geophysical techniques GPR and geoelectrical method on building structures. A multi-layer structure was reconstructed in laboratory, in order to simulate a back-bridge: asphalt, reinforced concrete, sand and gravel layers. In the deep sandy layer, PVC, aluminum and steel pipes were introduced. This structure has also been brought to crack in a predetermined area and hidden internal fractures were investigated. GPR has allowed to characterize the panel in a non-invasive mode; radar maps were developed using various algorithms during post-process about 2D maps and 3D models with aerial acquisition of 400 MHz, 900MHz, 1500MHz, 2000MHz. Geoelectrical testing was performed with a network of 25 electrodes spaced at mutual distance of 5 cm. Two different configurations were used dipole-dipole and pole-dipole approaches. In the second phase, we proceeded to the analysis of pre-tensioned concrete in order to detect the possible presence of criticality in the structure. For this purpose by GPR 2GHz antenna, a '70 years precast bridge characterized by a high state of decay was studied; then were also analyzed a pillar and a beam of recent production directly into the processing plant. Moreover, results obtained using GPR were compared with those obtained through the use of infrared thermography and sonic testing. Finally, we investigated a radiant floor by GPR (900 MHz to 2000 MHz antennas) and long-wave infrared camera. Non-destructive diagnostic techniques allow to investigate a building structure in reinforced concrete or masonry without altering the characteristics of the element investigated. For this reason, geo-electrical and electromagnetic surveys of masonry are a suitable non-destructive tool for the diagnosis of a deteriorated concrete structure. Moreover, the integration of different NDT techniques (conventional and no-conventional) is a very powerful to maximize the capabilities and to compensate for the limitations of each method.

Esthetic enhancement of concrete structures using ferro-cement panels.

DOT National Transportation Integrated Search

1974-01-01

An investigation of ferro-cement indicates that when used in colored panels, such panels can be used to enhance the appearance of concrete structures. The panels are simply made, light in weight, and easily attached to either old or new structures. W...

Development of an NCHRP report 350 TL-3 New Jersey shape 50-inch portable concrete barrier : final report, June 2006.

DOT National Transportation Integrated Search

2006-06-01

For roadside work-zones in areas that have opposing traffic flow, safety is enhanced if the temporary barriers incorporate a "glare-shield" that blocks headlight glare from opposing traffic. Currently-available 32-inch portable concrete barriers requ...

Experimental evaluation and design of unfilled and concrete-filled FRP composite piles : Task 4B : material & construction specifications : final report.

DOT National Transportation Integrated Search

2015-07-01

The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP composite piles for load-bearing in bridges. This report covers Task 4B, Materials and Construction Specifications. : This technical report...

Final report on a cold climate permeable interlocking concrete pavement test facility at the University of New Hampshire Stormwater Center.

DOT National Transportation Integrated Search

2013-05-01

University of New Hampshire Stormwater Center (UNHSC) completed a two year field verification study of a permeable interlocking concrete pavement (PICP) stormwater management system. The purpose of this study was to evaluate the cold climate function...

Evaluation of warm mix technologies for use in asphalt rubber - asphaltic concrete friction courses (AR\\0x2010ACFC) : final report.

DOT National Transportation Integrated Search

2016-07-01

The objective of this research project was to determine whether warm mix asphalt (WMA) technologies can be : used by the Arizona Department of Transportation (ADOT) for the production of an asphalt rubberasphaltic : concrete friction course (AR...

Development of a wireless MEMS multifunction sensor system and field demonstration of embedded sensors for monitoring concrete pavements, volume II

DOT National Transportation Integrated Search

2016-08-01

This two-pronged study evaluated the performance of commercial off-the-shelf (COTS) micro-electromechanical sensors and systems (MEMS) embedded in concrete pavement (Final Report Volume I) and developed a wireless MEMS multifunctional sensor system f...

FRP reinforcement for concrete : performance assessment and new construction volume I : Sierrita De La Cruz Creek bridge : final report.

DOT National Transportation Integrated Search

2016-07-01

Glass fiber reinforced polymer (GFRP) composites are emerging as a feasible economical solution to eliminate the corrosion problem of steel reinforcements in the concrete industry. Confirmation of GFRP long-term durability is crucial to extend its ap...

Design and construction of a bonded fiber concrete overlay of CRCP : final report.

DOT National Transportation Integrated Search

1992-01-01

The purpose of this study was to evaluate a bonded steel fiber reinforced concrete overlay on an existing 8-inch CRC pavement on Interstate 10 south of Baton Rough, LA. The project objectives were to provide an overlay with a high probability for lon...

Feasibility of development of a nuclear density gage for determining the density of plastic concrete at a particular stratum : final report.

DOT National Transportation Integrated Search

1981-05-01

Development of a nuclear density gage for determining the degree of consolidation of plastic concrete in selected horizontal layers was determined to be feasible. A commercially available, with some modifications, two-probe density gage (detector in ...

Quality control analysis : part V : review of data generated by statistical specifications on asphaltic concrete : final report.

DOT National Transportation Integrated Search

1975-12-01

The primary objective of this study was to review the data generated by projects governed by statistically oriented system of specifications for the control and acceptance of asphaltic concrete and to recommend any revisions that may be deemed necess...

Laboratory evaluation of influence of operational tolerance (acceptance criterion) on performance of hot-mix asphalt concrete.

DOT National Transportation Integrated Search

2010-06-01

The performance of flexible pavements relies heavily on the final quality of the hot-mix asphalt concrete (HMAC) as it : is produced and placed in the field. To account for production and construction variability while ensuring the quality of the : H...

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...

In-service performance evaluation and monitoring of a hybrid composite beam bridge system : final report.

DOT National Transportation Integrated Search

2017-10-01

The hybrid composite beam (HCB) technology has been presented as a system for short and medium span beam bridges as an alternative to traditional materials such as concrete and steel. An HCB consists of a concrete tied arch encased in a fiber reinfor...

Quantify the energy and environmental effects of using recycled asphalt and recycled concrete for pavement construction phase I : final report.

DOT National Transportation Integrated Search

2009-08-01

The objective of this study is to quantify the energy and environment impacts from using recycled materials : for highway construction. Specifically, when recycled asphalt pavement is re-used for producing hot mix : asphalt or when recycled concrete ...

Experimental evaluation and design of unfilled and concrete-filled FRP composite piles : Task 5 : laminate durability testing : final report.

DOT National Transportation Integrated Search

2015-05-01

The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP composite piles for load-bearing in bridges. This report covers Task 5, Laminate Durability Testing. : Mechanical properties of the FRP mat...

Evaluation of long-term pavement performance and noise characteristics of the next generation concrete surface : final report.

DOT National Transportation Integrated Search

2014-01-01

This report documents the performance of the first Next Generation Concrete Surface (NGCS) built by the : Washington State Department of Transportation (WSDOT). A 1,500 foot test section was installed on the : eastbound lanes of I-82 near Sunnyside, ...

Precast concrete deck panel performance on long span, high traffic volume bridges : final report.

DOT National Transportation Integrated Search

2006-02-01

The NHDOT prohibited the use of partial depth precast deck panels on its long span, high traffic volume bridges until it could investigate if the precast : slabs and the concrete overpour were acting in a composite manner. The NHDOT also wanted to en...

Cost-effective and rapid concrete repair techniques.

DOT National Transportation Integrated Search

2016-02-08

Concrete is a principal component of many transportation structures. While highly durable, a : variety of processes degrade and damage concrete. Replacement is expensive. Many cases : warrant repair instead of replacement. Since many damage processes...

Influence of length-to-diameter ratio on shrinkage of basalt fiber concrete

NASA Astrophysics Data System (ADS)

Ruijie, MA; Yang, Jiansen; Liu, Yuan; Zheng, Xiaojun

2017-09-01

In order to study the shrinkage performance of basalt concrete, using the shrinkage rate as index, the work not only studied the influence of different length-to-diameter ratio (LDR) on plastic shrinkage and drying shrinkage of basalt fiber concrete, but also analyzed the action mechanism. The results show that when the fiber content is 0.1%, the LDR of 800 and 1200 take better effects on reducing plastic shrinkage, however the fiber content is 0.3%, that of LDR 600 is better. To improve drying shrinkage, the fiber of LDR 800 takes best effect. In the concrete structure, the adding basalt fibers form a uniform and chaotic supporting system, optimize the pore and the void structure of concrete, make the material further compacted, reduce the water loss, so as to decrease the shrinkage of concrete effectively.