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Sample records for hot mix asphalt

  1. Emissions Reductions Associated with the Use of Warm-Mix Asphalt as Compared to Hot-Mix Asphalt

    DTIC Science & Technology

    2014-06-01

    gas, light fuel oils, or waste fuel oils and its sulfur content (NPI 1999). In counter-flow drum-mix plants, the liquid asphalt , aggregate, and...ER D C/ G SL T R- 14 -1 9 Emissions Reductions Associated with the Use of Warm-Mix Asphalt as Compared to Hot-Mix Asphalt G eo te ch ni...Reductions Associated with the Use of Warm-Mix Asphalt as Compared to Hot-Mix Asphalt Mariely Mejías-Santiago Geotechnical and Structures

  2. User's guide: Hot-mix recycling of asphalt concrete pavements

    NASA Astrophysics Data System (ADS)

    Shoenberger, James E.

    1993-05-01

    This guide provides the technical information required to implement the application of hot-mix recycling of asphalt concrete pavements. Included are details on application, benefits/advantages, limitations/disadvantages, and costs associated with this technology. Information is provided on three demonstration sites at Fort Gillem, Georgia; Fort Leavenworth, Kansas; and Fort Benjamin Harrison, Indiana. Also provided is information concerning funding, procurement, maintenance, and performance monitoring. A fact sheet on recycling, contract specification example, and references are provided in the appendices.

  3. Production variability analysis of hot-mixed asphalt concrete containing reclaimed asphalt pavement. Final research report

    SciTech Connect

    Solaimanian, M.; Kennedy, T.W.

    1995-02-01

    A research project was undertaken to evaluate the production and construction variability of Hot Mix Asphalt Concrete (HMAC) containing high quantities of reclaimed asphalt pavement (RAP) material. Four construction projects were selected for this purpose. Two of the projects used 35 percent RAP material (both type-C mixes), while the other two used 40 percent (a type-B mix) and 50 percent (a type-D mix) of the RAP material, respectively. The projects differed in sizes, with total construction tonnage ranging from 10.9 million kg to 27.2 million kg (12,000 to 30,000 tons). In all cases, dedicated stockpiles of RAP material were used. Analysis was performed on the results obtained from the tests. The gradation and asphalt content deviations, air voids, penetration and viscosities, and stabilities, were included in the analysis. Pay adjustment factors were determined for gradation and asphalt content deviation, as well as for air voids (based on TxDOT Specification 3007). In general, these high-percent RAP projects indicated a variability higher than that of a typical HMAC without RAP. The pay adjustment factors for gradation and asphalt content deviation were lower than typical values. The construction gradations were finer than the job-mix formula target gradations, possibly a result of aggregate crushing during the milling operation.

  4. A review of changes in composition of hot mix asphalt in the United States.

    PubMed

    Mundt, Diane J; Marano, Kristin M; Nunes, Anthony P; Adams, Robert C

    2009-11-01

    This review researched the materials, methods, and practices in the hot mix asphalt industry that might impact future exposure assessments and epidemiologic research on road paving workers. Since World War II, the U.S. interstate highway system, increased traffic volume, transportation speeds, and vehicle axle loads have necessitated an increase in demand for hot mix asphalt for road construction and maintenance, while requiring a consistent road paving product that meets state-specific physical performance specifications. We reviewed typical practices in hot mix asphalt paving in the United States to understand the extent to which materials are and have been added to hot mix asphalt to meet specifications and how changes in practices and technology could affect evaluation of worker exposures for future research. Historical documents were reviewed, and industry experts from 16 states were interviewed to obtain relevant information on industry practices. Participants from all states reported additive use, with most being less than 2% by weight. Crumb rubber and recycled asphalt pavement were added in concentrations approximately 10% per unit weight of the mix. The most frequently added materials included polymers and anti-stripping agents. Crumb rubber, sulfur, asbestos, roofing shingles, slag, or fly ash have been used in limited amounts for short periods of time or in limited geographic areas. No state reported using coal tar as an additive to hot mix asphalt or as a binder alternative in hot mix pavements for high-volume road construction. Coal tar may be present in recycled asphalt pavement from historical use, which would need to be considered in future exposure assessments of pavers. Changes in hot mix asphalt production and laydown emission control equipment have been universally implemented over time as the technology has become available to reduce potential worker exposures. This work is a companion review to a study undertaken in the petroleum refining

  5. Effect of gilsonite-modified asphalt on hot-mix asphaltic concrete mixes used in District 12, Houston, Texas

    SciTech Connect

    Wong, C.; Ho, M.K.

    1990-06-01

    Gilsonite is a naturally occurring black hydrocarbon from Utah with a high asphaltene content and an unusual amount of nitrogen compounds. Because of its composition, it is believed that the addition of gilsonite will increase the viscosity, stability, water susceptibility and durability of the asphalt mix. The District 12 laboratory conducted tests on two hot mix designs using gilsonite-modified asphalts. A control batch and batches containing 4%, 6% and 8% gilsonite by weight of asphalt were tested. The appropriate gilsonite-aggregate mixtures were molded and evaluated for stability, specific gravity, indirect tensile strength and water susceptibility. From the results of the laboratory tests, it was evident that gilsonite-modified asphalt mixes did increase dry and wet tensile strength but did not increase H veem stability. Since there is no overwhelming proof of gilsonite's ability as an anti-stripping agent, it has been recommended that gilsonite be used with an anti-stripping agent to combat stripping and rutting. It is further recommended that the field performance of gilsonite be evaluated before approval is given for its use.

  6. Engineering characterisation of epoxidized natural rubber-modified hot-mix asphalt.

    PubMed

    Al-Mansob, Ramez A; Ismail, Amiruddin; Yusoff, Nur Izzi Md; Rahmat, Riza Atiq O K; Borhan, Muhamad Nazri; Albrka, Shaban Ismael; Azhari, Che Husna; Karim, Mohamed Rehan

    2017-01-01

    Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR-asphalt mixes prepared using the wet process. Mechanical testing on the ENR-asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR-asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR-asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress.

  7. Engineering characterisation of epoxidized natural rubber-modified hot-mix asphalt

    PubMed Central

    Al-Mansob, Ramez A.; Ismail, Amiruddin; Yusoff, Nur Izzi Md.; Rahmat, Riza Atiq O. K.; Borhan, Muhamad Nazri; Albrka, Shaban Ismael; Azhari, Che Husna; Karim, Mohamed Rehan

    2017-01-01

    Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR–asphalt mixes prepared using the wet process. Mechanical testing on the ENR–asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR–asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR–asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress. PMID:28182724

  8. Evaluation of the benefits of adding waste fiberglass roofing shingles to Hot-Mix asphalt. Final report

    SciTech Connect

    Abdulshafi, O.; Kedzierski, B.; Fitch, M.G.; Mukhtar, H.

    1997-07-03

    The decreased availability of landfills, growing concern over waste disposal, and rising cost of asphalt cement, resulted in an increased interest in incorporating waste asphalt roofing shingles in the production of asphalt concrete mixes. This project addressed Hot-Mix, surface course asphalt concrete mixes produced with an addition of waste fiberglass asphalt roofing shingles that were obtained from the shingle manufacturing process. A total of twenty-six asphalt concrete mixes were studied. The variables included: aggregate type, shingle producers, level of shingle addition (0, 5, 10, and 15%), and type of shingle size reduction. Properties of the produced asphalt concrete mixes were evaluated based on the results of applicable tests that were performed.

  9. Evaluation of steel slag coarse aggregate in hot mix asphalt concrete.

    PubMed

    Ahmedzade, Perviz; Sengoz, Burak

    2009-06-15

    This paper presents the influences of the utilization of steel slag as a coarse aggregate on the properties of hot mix asphalt. Four different asphalt mixtures containing two types of asphalt cement (AC-5; AC-10) and coarse aggregate (limestone; steel slag) were used to prepare Marshall specimens and to determine optimum bitumen content. Mechanical characteristics of all mixtures were evaluated by Marshall stability, indirect tensile stiffness modulus, creep stiffness, and indirect tensile strength tests. The electrical sensitivity of the specimens were also investigated in accordance with ASTM D257-91. It was observed that steel slag used as a coarse aggregate improved the mechanical properties of asphalt mixtures. Moreover, volume resistivity values demonstrated that the electrical conductivity of steel slag mixtures were better than that of limestone mixtures.

  10. Evaluation of properties of recycled asphalt concrete hot mix

    SciTech Connect

    Brown, E.R.

    1983-01-01

    This study was undertaken to evaluate the laboratory performance of recycled asphalt concrete mixtures and to compare these results to those measured for conventional asphalt concrete mixtures. To make these comparisons, samples of aged asphalt concrete were obtained from three locations where recycling was planned. These samples were blended with new aggregate and new asphalt materials to produce six different recycled mixtures. Two aggregate types, a crushed gravel and a crushed limestone, were used to produce two conventional mixtures and to blend with the reclaimed asphalt pavement to produce the six recycled mixtures. Three asphalt materials which were obtained to produce the various mixtures being evaluated consisted of AC-20 for preparing the conventional mixtures and AC-5 and a recycling agent for preparing the recycled mixtures. The Shell BISAR computer program was used to predict the stesses and strains for two typical pavement sections under a given loading conditions. The computed stresses and strains were then analyzed along with the laboratory fatigue tests to predict the fatigue performance of the various mixtures. The results of this study indicated a satisfactory comparison between laboratory performance of recycled mixtures and conventional mixtures. Fatigue analysis indicated that the conventional mixtures would provide the greatest fatigue resistance in thick asphalt concrete layers at lower temperatures while the recycled mixtures would provide the greatest fatigue resistance in thin asphalt layers at higher temperatures.

  11. Design and Properties of Thin Surfacing Hot Mix Asphalt Containing Crumb Rubber as Partial Aggregate Replacement

    NASA Astrophysics Data System (ADS)

    Setyawan, Ary; Febrianto, Nugroho; Sarwono, Djoko

    2017-07-01

    Road damage caused as a result of the traffic load and environment. One method to improve the road condition is from an overlay. But the new layer on the top of the pavement structure is thick enough and elevate the surface of the pavement, so it will cause some impact on the user safety and engineering. The use of a thin layer of hot mix asphalt is an alternative to anticipate the thickness problem. Crumb rubber is a waste material that has a flexible nature, these materials are used as an aggregate replacement in the hot mix asphalt thin layer. The research was conducted to find the optimum bitumen content and optimum crumb rubber content on asphalt mixtures by the Marshall procedure. Finally, it was concluded that the addition of crumb rubber in a thin layer of hot mix asphalt indicates the better the interlocking between aggregates so that gave the better Marshall stability, the higher the flow rate, the lower the marshall quotient, reduce the void ratio. The results show that the addition of crumb rubber content as an aggregate replacement leads to the use of less optimum bitumen content.

  12. Construction and testing of crumb rubber modified hot mix asphalt pavement. Interim report

    SciTech Connect

    Albritton, G.E.; Gatlin, G.R.

    1996-08-01

    This study was structured towards addressing that portion of ISTEA which directs the individual states to conduct studies on the recyclability of crumb rubber modified hot mix asphalt (CRMHMA), and the technical performance of CRMHMA pavement by monitoring the construction and evaluating the performance of highway test sections in which CRMHA is removed by cold milling and recycled into new HMA through a hot mix asphalt plant. This project is to be constructed in two phases, the CRMHMA will be built in the first phase and approximately one year later it will be recycled. This report deals with the first phase in which the objective was to further document the construction, engineering characteristics, and performace of CRMHMA.

  13. The Effect of Dustler on Reducing Stripping Failure in Hot Mix Asphalt Mixture

    NASA Astrophysics Data System (ADS)

    Baizura Hamid, Nor; Ezree Abdullah, Mohd; Erwan Sanik, Mohd; Mokhtar, Mardiha; Kaamin, Masiri; Syazwani Saari, Nur

    2017-08-01

    Hot mix asphalt (HMA) is one type of premix widely used in road construction worldwide. Aggregates for HMA are usually classified by size as coarse aggregates, fine aggregates, or mineral fillers. Moisture damage or stripping is one of the major concerns in HMA industry. The existence of water in asphalt pavement is often one of the major factors affecting the durability of HMA. The water- induced damage in HMA layers may be associated with two mechanisms a loss of adhesion and loss of cohesion. The main focus of this study based on these two objectives which is to develop HMA that involves used of dustler in asphalt mixture and to investigate the performance of dustler against stripping failure. The asphalt mixture of combination virgin aggregate and this waste material was studied. The percentages of dustler used in this study were 0.5%, 1.0% and 2.0% respectively. The method used in this study was Superpave mix design method. From the laboratory test, the indirect tensile strength (ITS) test was conducted to show the stripping performance. The result from that test showed that the value of ITS for dry sample is higher compared to wet sample for all percentages. The moisture sensitivity was determined through tensile strength ratio (TSR) test. From the results, it showed that the percentages of dustler were fulfilled the minimum requirement of AASHTO T283 which is 80% minimum requirement of moisture susceptibility. The highest value of TSR is 0.5% of dustler sample which is 98.55% compared to 1.0% of dustler sample, control sample and 2.0% of dustler sample. So, it can be concluded that dustler inhibits great potential on reducing stripping failure in hot mix asphalt.

  14. Laboratory and field evaluation of hot mix asphalt with high contents of reclaimed asphalt pavement

    NASA Astrophysics Data System (ADS)

    Van Winkle, Clinton Isaac

    Currently in Iowa, the amount of RAP materials allowed for the surface layer is limited to 15% by weight. The objective of this project was to develop quality standards for inclusion of RAP content higher than 15% in asphalt mixtures. To meet Superpave mix design requirements, it was necessary to fractionate the RAP materials. Based on the extensive sieve-by-sieve analysis of RAP materials, the optimum sieve size to fractionate RAP materials was identified. To determine if the higher percentage of RAP materials than 15% can be used in Iowa's state highway, three test sections with 30.0%, 35.5% and 39.2% of RAP materials were constructed on Highway 6 in Iowa City. The construction of the field test sections was monitored and the cores were obtained to measure field densities of test sections. Field mixtures collected from test sections were compacted in the laboratory in order to test the moisture sensitivity using a Hamburg Wheel Tracking Device. The binder was extracted from the field mixtures with varying amounts of RAP materials and tested to determine the effects of RAP materials on the PG grade of a virgin binder. Field cores were taken from the various mix designs to determine the percent density of each test section. A condition survey of the test sections was then performed to evaluate the short-term performance.

  15. Noise characteristics of hot mix asphalt and Portland cement concrete pavements in United States

    NASA Astrophysics Data System (ADS)

    Hanson, Douglas I.

    2005-09-01

    In today's society, traffic noise is a serious problem that generally is considered an environmental pollution because it lowers the standard of living. Research in Europe and in the United States has indicated that it is possible to build pavement surfaces that will reduce the level of noise generated on roadways. In January of 2002 the National Center for Asphalt Technology initiated a research study with the objective to develop safe, quiet and durable asphalt pavement surfaces. As a part of that study over 300 pavement surfaces [both Portland Cement Concrete (PCCP) and Hot Mix Asphalt (HMA)] throughout the United States have been tested using a close-proximity noise trailer. The study has shown that in general PCCP surfaces have a higher noise level than HMA surfaces. But, it has also shown that by properly choosing the surface texture of the PCCP surface significant reductions in the noise level of a PCCP surface can be achieved. The study has shown that it is possible to construct low-noise HMA mixes and that in general the smaller the nominal maximum size for those mixes (regards whether they are dense graded, SMA or OFGC mixes) the lower the noise level.

  16. Experimental testing of hot mix asphalt mixture made of recycled aggregates.

    PubMed

    Rafi, Muhammad Masood; Qadir, Adnan; Siddiqui, Salman Hameed

    2011-12-01

    The migration of population towards big cities generates rapid construction activities. These activities not only put pressure on natural resources but also produce construction, renovation and demolition waste. There is an urgent need to find out ways to handle this waste owing to growing environmental concerns. This can reduce pressure on natural resources as well. This paper presents the results of experimental studies which were carried out on hot mix asphalt mixture samples. These samples were manufactured by adding recycled aggregates (RA) with natural crushed stone aggregates (CSA). Three levels of addition of RA were considered in the presented studies. RA were obtained from both the concrete waste of construction, renovation and demolition activities and reclaimed asphalt pavement. Separate samples were manufactured with the coarse and fine aggregate fractions of both types of RA. Samples made with CSA were used as control specimens. The samples were prepared and tested using the Marshall method. The performance of the samples was investigated in terms of density-void and stability/flow analysis and was compared with the performance criteria as given by National Highway Authority for wearing course material in Pakistan. Based on this data optimum asphalt contents were determined. All the samples made by adding up to 50% RA conform to the specification requirements of wearing course material as given by National Highway Authority in terms of optimum asphalt contents, voids in mineral aggregates and stability/flow. A statistical analysis of variation of these samples confirmed that addition is also possible statistically.

  17. Development of a rapid test method for asphalt concrete content determination in hot-mix paving mixtures

    NASA Astrophysics Data System (ADS)

    Chavez, J. J. M.

    1984-01-01

    A rapid test method was developed for the determination of asphalt cement content in hot-mix bituminous paving mixtures. It is based on the extraction of asphalt cement from mixtures with trichloroethylene and subsequent measurement of the transmittance of light through the extracted solution. A good correlation was found between the results obtained using the rapid test and those obtained using the standard test (ASTM D-2172, Method E1) for samples tested in the field at asphalt mix plants. The test uses a portable spectrophotometer and a metal can for extraction. The asphalt content can be determined in less than ten minutes. The possibility of using the rapid test on materials containing emulsified asphalt, slag aggregate, unusually high amounts of fine material and recycled material was also studied.

  18. Evaluation of Properties of Recycled Asphalt Concrete Hot Mix.

    DTIC Science & Technology

    1984-02-01

    the literature, it is difti ult to compare test results among the various laboratories. Whitcomb evaluated a simplified method of mix design for...proposed ASTM test method under jurisdiction of ASTM Subcom- mittee D04.20). A nomograph was used to select the type of recycling agent needed to...in viscosity with aging. The thin-film oven test and rolling thin-film oven test have been used in durability tests . These two test methods are used

  19. Contributions crumb rubber in hot mix asphalt to the resilient modulus

    NASA Astrophysics Data System (ADS)

    Ariyapijati, Raden Hendra; Hadiwardoyo, Sigit Pranowo; Sumabrata, R. Jachrizal

    2017-06-01

    Pavement on the structure of the surface layer receives direct load from the vehicles. Road surfaces are designed to withstand the wear from vehicle loads. Therefore, we need a way to improve the durability of the pavement. Road damage may reduce the life of roads and increase the maintenance costs. The retention rate of road surface material is affected by the environmental conditions, one of them is temperature. To overcome the issues related to temperature, material additives are added to the asphalt mixture. These additive materials would change the binding properties of bitumen and the characteristics of strain and stress before the damage due to repeated traffic loading. Crumb rubber (CR) is a type of polymer additives and thermoplastic elastomers are obtained from scrap tires and rubber waste that is utilized in order to preserve the environment. This study investigated the contribution of the crumb rubber in terms of the value of resilient modulus and resistance to deformation. Hot mix asphalt used was asphalt Pen 60/70, coarse aggregate, fine aggregate and filler. Crumb rubber was made from scrap tire rubber, in the form of fine powder with sieve no. 30 (0.6 mm). CR additive was added to the base asphalt at several rates of 5%, 10%, 15%, and 20% at a temperature of 177° C. The test data used the indirect tensile test with a tool UMATTA at temperatures of 25°, 35°, and 45° C. The test results showed that the levels of crumb rubber on the asphalt decreased the penetration rate, increased the bitumen softening point, and improved the resistance to permanent deformation. The addition of additive materials was evidenced to improve the penetration index, reduce the temperature sensitivity, and increase the viscosity. Subsequently, it can extend the temperature range of viscoelasticity. The contributions of crumb rubber in hot mix asphalt included the increase of the recoverable deformation and the decrease of the value of resilient modulus. This study

  20. Effects of asphalt rejuvenator on thermal and mechanical properties on oxidized hot mixed asphalt pavements

    NASA Astrophysics Data System (ADS)

    Farace, Nicholas A.; Buttlar, William G.; Reis, Henrique

    2016-04-01

    The utilization of asphalt rejuvenator, and its effectiveness for restoring thermal and mechanical properties was investigated via Disk-shaped Compact Tension (DC(T)) and acoustic emission (AE) testing for determining mechanical properties and embrittlement temperatures of the mixtures. During the DC(T) testing the fracture energies and peak loads were used to measure the resistance of the rejuvenated asphalt to low temperature cracking. The AE testing monitored the acoustic emission activity while the specimens were cooled from room temperature to -40 °C to estimate the temperature at which thermal cracking began (i.e. the embrittlement temperature). First, a baseline response was obtained by obtaining the mechanical and thermal response of virgin HMA samples and HMA samples that had been exposed to oxidative aging for 36 hours at 135°C. The results showed the virgin samples had much higher peak loads and fracture energies than the 36 hours aged samples. Acoustic Emission showed similar results with the virgin samples having embrittlement temperatures 10 °C cooler than the 36 hours aged specimens. Then, overaged for 36 hours specimens were treated different amounts of rejuvenator (10%, 15%, and 20% by weight of binder content) and left to dwell for increased amount of time periods varying from one to eight weeks. It was observed that the AE results showed an improvement of embrittlement temperature with increasing with the dwell times. The 8 weeks specimens had cooler embrittlement temperatures than the virgin specimens. Finally, the low temperature effects on fracture energy and peak load of the rejuvenated asphalt was investigated. Rejuvenator was applied (10% by weight of binder) to specimens aged 36 hours at 135 °C, and the dwell time was varied from 1 to 4 weeks. The results showed that the peak loads were restored to levels of the virgin specimens, and the fracture energies improved to levels beyond that of the virgin specimens. The results also showed a

  1. Value-added utilisation of recycled concrete in hot-mix asphalt

    SciTech Connect

    Wong, Yiik Diew; Sun, Darren Delai . E-mail: ddsun@ntu.edu.sg; Lai, Dickson

    2007-07-01

    The feasibility of partial substitution of granite aggregate in hot-mix asphalt (HMA) with waste concrete aggregate was investigated. Three hybrid HMA mixes incorporating substitutions of granite fillers/fines with 6%, 45% untreated, and 45% heat-treated concrete were evaluated by the Marshall mix design method; the optimum binder contents were found to be 5.3%, 6.5% and 7.0% of grade Pen 60/70 bitumen, respectively. All three hybrid mixes satisfied the Marshall criteria of the Singapore Land Transport Authority (LTA) W3B wearing course specification. The hybrid mix with 6% concrete fillers gave comparable resilient modulus and creep resistance as the conventional W3B mix, while hybrid mixes with higher concrete substitutions achieved better performance. X-ray diffraction (XRD) showed the distinct presence of free lime in the heat-treated concrete, while the scanning electron microscope (SEM) provided an in-depth perspective of the concrete grains in the HMA matrix. The results suggest feasible use of waste concrete as partial aggregate substitution in HMA.

  2. Value-added utilisation of recycled concrete in hot-mix asphalt.

    PubMed

    Wong, Yiik Diew; Sun, Darren Delai; Lai, Dickson

    2007-01-01

    The feasibility of partial substitution of granite aggregate in hot-mix asphalt (HMA) with waste concrete aggregate was investigated. Three hybrid HMA mixes incorporating substitutions of granite fillers/fines with 6%, 45% untreated, and 45% heat-treated concrete were evaluated by the Marshall mix design method; the optimum binder contents were found to be 5.3%, 6.5% and 7.0% of grade Pen 60/70 bitumen, respectively. All three hybrid mixes satisfied the Marshall criteria of the Singapore Land Transport Authority (LTA) W3B wearing course specification. The hybrid mix with 6% concrete fillers gave comparable resilient modulus and creep resistance as the conventional W3B mix, while hybrid mixes with higher concrete substitutions achieved better performance. X-ray diffraction (XRD) showed the distinct presence of free lime in the heat-treated concrete, while the scanning electron microscope (SEM) provided an in-depth perspective of the concrete grains in the HMA matrix. The results suggest feasible use of waste concrete as partial aggregate substitution in HMA.

  3. Modeling of viscoplastic rate-dependent hardening-softening behavior of hot mix asphalt in compression

    NASA Astrophysics Data System (ADS)

    Yun, Taeyoung; Kim, Y. Richard

    2011-02-01

    The objective of this paper is to model viscoplastic rate-dependent hardening-softening behavior that is experimentally observed from hot mix asphalt (HMA) under repetitive creep and recovery loading in compression. A differential equation is utilized to incorporate the effects of the stress history into yield stress, and an internal variable representing rate dependence in the equation is set as a function of the viscoplastic strain rate to address the change in rate dependence of the material due to gradual hardening. Also, a separate rate-dependent function concept is adopted to describe the difference in rate dependence of the yield stress during unloading and loading. The developed viscoplastic model is applied using the time-temperature superposition principle and shows good agreement with the measured viscoplastic responses of HMA under repetitive creep and recovery loading with various load levels and rest periods.

  4. Predictors of dermal exposures to polycyclic aromatic compounds among hot-mix asphalt paving workers.

    PubMed

    Cavallari, Jennifer M; Osborn, Linda V; Snawder, John E; Kriech, Anthony J; Olsen, Larry D; Herrick, Robert F; McClean, Michael D

    2012-03-01

    The primary objective of this study was to identify the source and work practices that affect dermal exposure to polycyclic aromatic compounds (PACs) among hot-mix asphalt (HMA) paving workers. Four workers were recruited from each of three asphalt paving crews (12 workers) and were monitored for three consecutive days over 4 weeks for a total of 12 sampling days per worker (144 worker days). Two sampling weeks were conducted under standard conditions for dermal exposures. The third week included the substitution of biodiesel for diesel oil used to clean tools and equipment and the fourth week included dermal protection through the use of gloves, hat and neck cloth, clean pants, and long-sleeved shirts. Dermal exposure to PACs was quantified using two methods: a passive organic dermal (POD) sampler specifically developed for this study and a sunflower oil hand wash technique. Linear mixed-effects models were used to evaluate predictors of PAC exposures. Dermal exposures measured under all conditions via POD and hand wash were low with most samples for each analyte being below the limit of the detection with the exception of phenanthrene and pyrene. The geometric mean (GM) concentrations of phenanthrene were 0.69 ng cm(-2) on the polypropylene layer of the POD sampler and 1.37 ng cm(-2) in the hand wash sample. The GM concentrations of pyrene were 0.30 ng cm(-2) on the polypropylene layer of the POD sampler and 0.29 ng cm(-2) in the hand wash sample. Both the biodiesel substitution and dermal protection scenarios were effective in reducing dermal exposures. Based on the results of multivariate linear mixed-effects models, increasing frequency of glove use was associated with significant (P < 0.0001) reductions for hand wash and POD phenanthrene and pyrene concentrations; percent reductions ranged from 40 to 90%. Similar reductions in hand wash concentrations of phenanthrene (P = 0.01) and pyrene (P = 0.003) were observed when biodiesel was substituted for diesel oil

  5. Asphalt additives in thick hot mixed asphalt-concrete pavements. Research report (Interim), Sep 86-Oct 90

    SciTech Connect

    Button, J.W.; Prapnnachari, S.

    1991-01-01

    Asphalt concrete field test pavements were placed in District 19 north of Texarkana on US-59/71 in 1987 and 1988 to evaluate the ability of certain asphalt additives to enhance resistance to cracking and rutting. Two 10-inch thick and 0.9 mile (approx.) long test pavements and a similar untreated control section were constructed in the northbound and southbound lanes for a total of 6 field trials. Asphalt additives were incorporated in both the 8-inch base and the overlying 2-inch surface layers. The additives evaluated included Goodyear LPF 5812, Chemkrete-CTI 102, Exxon Polybilt 102, and Styrelf 13. Samples of paving materials including aggregates, asphalts, compacted mixes, and pavement cores were collected, conveyed to the laboratory, and tested to provide detailed documentation of their properties. Tests included rheological properties of the binders before and after artificial aging, characterization of aggregate, Hveem and Marshall stability, stiffness as a function of temperature, tensile properties before and after moisture conditioning and artificial aging, air void content, creep, and permanent deformation. Field tests and visual evaluations have been conducted to objectively evaluate field performance. Results of these tests are reported herein. Within 6 months after construction of the base layers and prior to placement of the surface course, the Chemkrete modified base became severely cracked. As a result, the surface mix placed on this base section was treated with Goodyear latex rather than Chemkrete. All other modified pavements and the control section have performed well and exhibited essentially equivalent performance after 2 1/2 years in service.

  6. Dielectric characterization of hot-mix asphalt at the smart road using GPR

    NASA Astrophysics Data System (ADS)

    Al-Qadi, Imad L.; Loulizi, A.; Lahouar, S.

    2000-04-01

    To better interpret collected ground penetrating radar (GPR) data, a project is currently underway at the Virginia Smart Road. Twelve different flexible pavement sections and a continuously reinforced concrete rigid pavement section are incorporated in the road design. Thirty-five copper plates were placed at different layer interfaces throughout the pavement sections. The copper plates serve as a reflecting material and thus allow the determination of layers' dielectric constant over the GPR frequency range. An initial development of a method to calculate the complex dielectric constant of hot-mix asphalt over the frequency range of 750 to 1750 MHz using an air-coupled GPR system is presented. Utilizing GPR data, this method will be used to predict changes of the dielectric properties of the different SuperPaveTM mixes used at the Smart Road over time. The method is based on equating the overall reflection coefficient as obtained from the radar measurements with the calculated reflection coefficient using electromagnetic theory. The measured overall reflection coefficient is obtained by dividing the reflected frequency spectrum over the incident one. The theoretical overall reflection coefficient is obtained using the multiple reflection model. A Gauss-Newton method is then used to solve for the complex dielectric constant.

  7. Emissions of polycyclic aromatic hydrocarbons from batch hot mix asphalt plants.

    PubMed

    Lee, Wen-Jhy; Chao, Wen-Hui; Shih, Minliang; Tsai, Cheng-Hsien; Chen, Thomas Jeng-Ho; Tsai, Perng-Jy

    2004-10-15

    This study was set out to assess the characteristics of polycyclic aromatic hydrocarbon (PAH) emissions from batch hot mix asphalt (HMA) plants and PAH removal efficiencies associated with their installed air pollution control devices. Field samplings were conducted on six randomly selected batch HMA plants. For each selected plant, stack flue gas samples were collected from both stacks of the batch mixer (n = 5) and the preheating boiler (n = 5), respectively. PAH samples were also collected from the field to assess PAHs that were directly emitted from the discharging chute (n = 3). To assess PAH removal efficiencies of the installed air pollution control devices, PAH contents in both cyclone fly ash (n=3) and bag filter fly ash (n = 3) were analyzed. Results show that the total PAH concentration (mean; RSD) in the stack flue gas of the batch mixer (354 microg/Nm3; 78.5%) was higher than that emitted from the discharging chute (107 microg/Nm3; 70.1%) and that in the stack flue gas of the preheating boiler (83.7 microg/Nm3; 77.6%). But the total BaPeq concentration of that emitted from the discharging chute (0.950 microg/Nm3; 84.4%) was higher than contained in the stack flue gas of the batch mixer (0.629 microg/Nm3; 86.8%) and the stack flue gas of the preheating boiler (= 0.112 microg/Nm3; 80.3%). The mean total PAH emission factor for all selected batch mix plants (= 139 mg/ton x product) was much higher than that reported by U.S. EPA for the drum mix asphalt plant (range = 11.8-79.0 mg/ton x product). We found the overall removal efficiency of the installed air pollution control devices (i.e., cyclone + bag filter) on total PAHs and total BaPeq were 22.1% and 93.7%, respectively. This implies that the installed air pollution control devices, although they have a very limited effect on the removal of total PAHs, do significantly reduce the carcinogenic potencies associated with PAH emissions from batch HMA plants.

  8. A methodology for use of digital image correlation for hot mix asphalt testing

    NASA Astrophysics Data System (ADS)

    Ramos, Estefany

    Digital Image Correlation (DIC) is a relatively new technology which aids in the measurement of material properties without the need for installation of sensors. DIC is a noncontact measuring technique that requires the specimen to be marked with a random speckled pattern and to be photographed during the test. The photographs are then post-processed based on the location of the pattern throughout the test. DIC can aid in calculating properties that would otherwise be too difficult even with other measuring instruments. The objective of this thesis is to discuss the methodology and validate the use of DIC in different hot mix asphalt (HMA) tests, such as, the Overlay Tester (OT) Test, Indirect Tensile (IDT) Test, and the Semicircular Bending (SCB) Test. The DIC system provides displacements and strains in any visible surface. The properly calibrated 2-D or 3-D DIC data can be used to understand the complex stress and strain distributions and the modes of the initiation and propagation of cracks. The use of this observational method will lead to further understanding of the complex boundary conditions of the different test, and therefore, allowing it to be implemented in the analysis of other materials. The use of digital image correlation will bring insight and knowledge onto what is happening during a test.

  9. Stripping in hot mix asphalt produced by aggregates from construction and demolition waste.

    PubMed

    Pérez, I; Pasandín, A R; Gallego, J

    2012-01-01

    This paper analyses the effect of water on the durability of hot asphalt mixtures made with recycled aggregates from construction and demolition debris. Indirect tensile stress tests were carried out to evaluate stripping behaviour. The mixtures tested were fabricated with 0, 20, 40 and 60% recycled aggregates. Two types of natural aggregates were used: schist and calcite dolomite. An increase in the percentage of recycled aggregates was found to produce a decrease in the tensile stress ratio of the hot asphalt mixtures. To study this phenomenon, two and three factor analyses of variance (ANOVA) were performed with indirect tensile stress being used as the dependent variable. The factors studied were the percentage of recycled aggregates (0, 20, 40 and 60%), the moisture state (dry, wet) and the type of natural aggregate (schist, calcite). On the basis of the ANOVA results, it was found that the most important factor affecting resistance was the moisture state (dry, wet) of the specimens. The percentage of recycled aggregate also affected indirect tensile stress, especially in the dry state. The type of natural aggregate did not have a significant effect on indirect tensile stress. The hot asphalt mixture specimens made with different percentages of recycled aggregates from construction and demolition debris and of natural quarry aggregates showed poor stripping behaviour. This stripping behaviour can be related to both the poor adhesion of the recycled aggregates and the high absorption of the mortar of cement adhered to them.

  10. Evaluation of low temperature properties of warm mix asphalt

    NASA Astrophysics Data System (ADS)

    Wen, Jin; Liu, Zhifei; Wu, Shaopeng

    2009-12-01

    Warm mix asphalt (WMA), which reduces the mixing and compaction temperature of conventional hot mix asphalt (HMA), is becoming an attractive paving material. It is critical to identify the low temperature properties of warm mix asphalt. In this study, the three-point bending, bending creep tests and indirect tensile tests were conducted to test the low-temperature properties of warm mix asphalt as well as the conventional hot mix asphalt, which was used as the control mixture. Sasobit and Aspha-min were used as additives for warm mix asphalt, which was mixed and compacted lower than the traditional hot mix asphalt about 25°C dosages accounted for 3% of asphalt, and 0.3% of mixture, respectively. The results of bending strength, bending modulus, and creep rate indicate that warm mix asphalt using Sasobit and Aspha-min slightly affects the resistance property to cracking compared with the conventional hot mix asphalt. The results suggest that the warm mix asphalt can maintain the low temperature properties of hot mix asphalt.

  11. Evaluation of low temperature properties of warm mix asphalt

    NASA Astrophysics Data System (ADS)

    Wen, Jin; Liu, Zhifei; Wu, Shaopeng

    2010-03-01

    Warm mix asphalt (WMA), which reduces the mixing and compaction temperature of conventional hot mix asphalt (HMA), is becoming an attractive paving material. It is critical to identify the low temperature properties of warm mix asphalt. In this study, the three-point bending, bending creep tests and indirect tensile tests were conducted to test the low-temperature properties of warm mix asphalt as well as the conventional hot mix asphalt, which was used as the control mixture. Sasobit and Aspha-min were used as additives for warm mix asphalt, which was mixed and compacted lower than the traditional hot mix asphalt about 25°C dosages accounted for 3% of asphalt, and 0.3% of mixture, respectively. The results of bending strength, bending modulus, and creep rate indicate that warm mix asphalt using Sasobit and Aspha-min slightly affects the resistance property to cracking compared with the conventional hot mix asphalt. The results suggest that the warm mix asphalt can maintain the low temperature properties of hot mix asphalt.

  12. Excess Foundry Sand Characterization and Experimental Investigation in Controlled Low-Strength Material and Hot-Mixing Asphalt

    SciTech Connect

    Pauul J. Tikalsky

    2004-10-31

    This report provides technical data regarding the reuse of excess foundry sand. The report addresses three topics: (1) a statistically sound evaluation of the characterization of foundry sand, (2) a laboratory investigation to qualify excess foundry sand as a major component in controlled low-strength material (CLSM), and (3) the identification of the best methods for using foundry sand as a replacement for natural aggregates for construction purposes, specifically in asphalt paving materials. The survival analysis statistical technique was used to characterize foundry sand over a full spectrum of general chemical parameters, metallic elements, and organic compounds regarding bulk analysis and leachate characterization. Not limited to characterization and environmental impact, foundry sand was evaluated by factor analyses, which contributes to proper selection of factor and maximization of the reuse marketplace for foundry sand. Regarding the integration of foundry sand into CLSM, excavatable CLSM and structural CLSM containing different types of excess foundry sands were investigated through laboratory experiments. Foundry sand was approved to constitute a major component in CLSM. Regarding the integration of foundry sand into asphalt paving materials, the optimum asphalt content was determined for each mixture, as well as the bulk density, maximum density, asphalt absorption, and air voids at N{sub ini}, N{sub des}, and N{sub max}. It was found that foundry sands can be used as an aggregate in hot-mix asphalt production, but each sand should be evaluated individually. Foundry sands tend to lower the strength of mixtures and also may make them more susceptible to moisture damage. Finally, traditional anti-stripping additives may decrease the moisture sensitivity of a mixture containing foundry sand, but not to the level allowed by most highway agencies.

  13. Excess Foundry Sand Characterization and Experimental Investigation in Controlled Low-Strength Material and Hot-Mixing Asphalt

    SciTech Connect

    Tikalsky, Paul J.; Bahia, Hussain U.; Deng, An; Snyder, Thomas

    2004-10-15

    This report provides technical data regarding the reuse of excess foundry sand. The report addresses three topics: a statistically sound evaluation of the characterization of foundry sand, a laboratory investigation to qualify excess foundry sand as a major component in controlled low-strength material (CLSM), and the identification of the best methods for using foundry sand as a replacement for natural aggregates for construction purposes, specifically in asphalt paving materials. The survival analysis statistical technique was used to characterize foundry sand over a full spectrum of general chemical parameters, metallic elements, and organic compounds regarding bulk analysis and leachate characterization. Not limited to characterization and environmental impact, foundry sand was evaluated by factor analyses, which contributes to proper selection of factor and maximization of the reuse marketplace for foundry sand. Regarding the integration of foundry sand into CLSM, excavatable CLSM and structural CLSM containing different types of excess foundry sands were investigated through laboratory experiments. Foundry sand was approved to constitute a major component in CLSM. Regarding the integration of foundry sand into asphalt paving materials, the optimum asphalt content was determined for each mixture, as well as the bulk density, maximum density, asphalt absorption, and air voids at Nini, Ndes, and Nmax. It was found that foundry sands can be used as an aggregate in hot-mix asphalt production, but each sand should be evaluated individually. Foundry sands tend to lower the strength of mixtures and also may make them more susceptible to moisture damage. Finally, traditional anti-stripping additives may decrease the moisture sensitivity of a mixture containing foundry sand, but not to the level allowed by most highway agencies.

  14. Assessment of the aging level of rejuvenated hot mixed asphalt concrete pavements

    NASA Astrophysics Data System (ADS)

    McGovern, Megan; Buttlar, William G.; Reis, Henrique

    2016-04-01

    The efficacy of asphalt rejuvenator on restoring the properties of oxidatively aged asphalt was tested via a non-collinear ultrasonic subsurface wave mixing technique modified for field use. Longitudinal transducers were mounted on angle wedges to generate subsurface dilatational waves to allow for pavement evaluation when there is only access to one side. Because in the field the asphalt concrete (AC) pavement properties (i.e., ultrasonic velocities and attenuations) are unknown, a pre-determined fixed incident angle (based on the AC mixture type) was used, which allows for practical implementation in the field. Oxidative aged AC specimens were coated with rejuvenator (10% by weight of the binder) and left to dwell for varying amounts of time. Once the dwell time reached the desired amount, the specimen was immediately ultrasonically tested. The frequency ratio, f2/f1, at which the interaction took place and the normalized nonlinear wave generation parameter, β/β0, were recorded and compared against a reference plot. It was observed that the rejuvenator had the effect of restoring the nonlinear properties to those corresponding to a virgin sample after a sufficient amount of dwell time. The ability of the rejuvenator to fully penetrate and act on the binder was observed to be dependent on the porosity and aggregate structure, and thus varied for each specimen. As a result, some portions of the binder were restored to a greater extent than others. This non-uniform nature was captured via the nonlinear ultrasonic technique.

  15. Non-destructive assessment of Hot Mix Asphalt density with a Step Frequency Radar - Case study

    NASA Astrophysics Data System (ADS)

    Fauchard, Cyrille; Beaucamp, Bruno

    2013-04-01

    The density of Hot Mix Asphalt (HMA) layers is a key parameter for assessing newly paved roads. It allows the quality control and ensures the time performance of the road layers. The standard methods for measuring the in-place HMA density are destructive and based on cores testing. Knowing the specific gravity of the HMA (data provided by builder), the bulk density can be determined in the laboratory either by weighting cores methods or by measuring the absorption ratio of gamma rays through road samples. Non destructive (ND) methods are highly needed in order to gain time and to avoid the strong constraints due to the nuclear gauges use. The Step Frequency Radar (SFR) is an electromagnetic method based on wave propagation in matter, similar in its principle to the Ground Penetrating Radar (GPR). It can use wide band and higher frequencies than GPR, allowing a thinner spatial resolution, but with a lower speed of acquisition. It is used in the present work as a tool providing the dielectric constant of HMA. Recent results in the laboratory have shown that the density can be relied on HMA dielectric constant with the use of a dielectric model (Complex Refractive Index model, or CRI model) taking into account the volume concentration and the dielectric constant of each HMA component. In this approach, the knowledge of the rock dielectric constant that composes the main part of HMA is required. If not, the in-place measurements can be calibrated according to one or more core drillings and the previous approach is still available. The main objective of this paper is to apply the methodology developed in the laboratory on a new HMA layer (case study located on A13 highway, nearby the city of Cagny, Normandie, France) for assessing the HMA density. The SFR system is composed of a vector network analyser sweeping a large frequency band [1.4 GHz - 20 GHz] and an ultra wide band antenna placed above the HMA surface. The whole system is pc-controlled and embedded in a

  16. Inferring strength and deformation properties of hot mix asphalt layers from the GPR signal: recent advances

    NASA Astrophysics Data System (ADS)

    Tosti, Fabio; Benedetto, Andrea; Bianchini Ciampoli, Luca; Adabi, Saba; Pajewski, Lara

    2015-04-01

    , of both the different strength provision of each layer composing the hot mix asphalt pavement structure, and of the attenuation occurring to electromagnetic waves during their in-depth propagation. Promising results are achieved by matching modelled and measured elastic modulus data. This continuous statistically-based model enables to consider the whole set of information related to each single depth, in order to provide a more comprehensive prediction of the strength and deformation behavior of such a complex multi-layered medium. Amongst some further developments to be tackled in the near future, a model improvement could be reached through laboratory activities under controlled conditions and by adopting several frequency bandwidths suited for purposes. In addition, the perspective to compare electromagnetic data with mechanical measurements retrieved continuously, i.e., by means of specifically equipped lorries, could pave the way to considerable enhancements in this field of research. Acknowledgements - This work has benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

  17. Effect of Warm Mix Asphalt on Aging of Asphalt Binders

    NASA Astrophysics Data System (ADS)

    Abbas, Ala R.; Nazzal, Munir; Kaya, Savas; Akinbowale, Sunday; Subedi, Bijay; Qtaish, Lana Abu

    This paper evaluated the rheological and chemical properties of asphalt binders recovered from short-term and long-term aged foamed warm mix asphalt (WMA) and traditional hot mix asphalt (HMA). AASHTO R 30 was utilized to simulate the short-term and long-term aging of the laboratory-prepared asphalt mixtures. The dynamic shear rheometer (DSR) was used to characterize the rheological properties of the unaged and aged asphalt binders. Fourier-transform infrared (FTIR) spectroscopy was used to identify and quantify the amount of functional groups present in these binders. Gel permeation chromatography (GPC) was utilized to determine the molecular size distribution within these binders. The asphalt binders recovered from short-term and long-term oven aged HMA mixtures exhibited slightly higher G*/sinδ and G*sinδ values than those recovered from foamed WMA mixtures. The FTIR and GPC test results agreed with those obtained in the DSR. This indicates that foamed WMA mixtures undergo less aging than traditional HMA mixtures.

  18. Study on infrared differential thermal non-destructive testing technology of the permeability of hot mix asphalt pavements

    NASA Astrophysics Data System (ADS)

    Wang, Duanyi; Shi, Jicun

    2017-06-01

    In order to non-destructive test (NDT) the permeability coefficient of hot mix asphalt (HMA) pavements fast, A methodology for assessing the permeability coefficient was proposed by infrared differential thermal testing of pavement after rain. The relationship between permeability coefficient and air voids of HMA specimen deter-mined. Finite element method (FEM) models were built to calculate the surface temperature difference with different exposure time after precipitation. Simulated solar radiation source and fully saturated plate specimens were set in laboratory, tests verify that the different exposure time the specimen surface temperature difference. Infrared differential thermal detection permeable pavement hardware and corresponding software developed. Based on many test results, the evaluation index and criteria of permeability coefficient of HMA pavements tested by infrared differential thermal were developed. The results showed that: There is correlation between air voids and permeability coefficient of HMA specimen. Permeability coefficient of HMA pavements can be determined by different surface temperature at different exposure time. 9:00 am - 14:00 pm is the best time to detect permeability coefficient by infrared differential thermal NDT. Permeable asphalt pavement permeability can be achieved by infrared detector quickly and continuously, a lane testing; Per the permeable assessment criteria, in-place pavements permeability coefficients can be accurately evaluated.

  19. Petroleum contaminated soil in Oman: evaluation of bioremediation treatment and potential for reuse in hot asphalt mix concrete.

    PubMed

    Jamrah, Ahmad; Al-Futaisi, Ahmed; Hassan, Hossam; Al-Oraimi, Salem

    2007-01-01

    This paper presents a study that aims at evaluating the leaching characteristics of petroleum contaminated soils as well as their application in hot mix asphalt concrete. Soil samples are environmentally characterized in terms of their total heavy metals and hydrocarbon compounds and leachability. The total petroleum hydrocarbon (TPH) present in the PCS before and after treatment was determined to be 6.8% and 5.3% by dry weight, indicating a reduction of 1% in the TPH of PCS due to the current treatment employed. Results of the total heavy metal analysis on soils indicate that the concentrations of heavy metals are lower when extraction of the soil samples is carried out using hexane in comparison to TCE. The results show that the clean soils present in the vicinity of contaminated sites contain heavy metals in the following decreasing order: nickel (Ni), followed by chromium (Cr), zinc (Zn), copper (Cu), lead (Pb), and vanadium (V). The current treatment practice employed for remediation of the contaminated soil reduces the concentrations of nickel and chromium, but increases the concentrations of all remaining heavy metals.

  20. Research on Surfactant Warm Mix Asphalt Construction Technology

    NASA Astrophysics Data System (ADS)

    Li, Guoliang; Sun, Jingxin; Guo, Xiufeng

    Discharging temperature of hot asphalt mixture is about 150°C-185°C, volatilization of asphalt fume harms people's health and fuel cost is high. Jinan Urban Construction Group applies PTL/01 asphalt warm mix agent to produce warm mix asphalt to construction of urban roads' asphalt bituminous pavement. After comparing it with performance of traditional hot asphalt mixture, mixing temperature may be reduced by 30°C-60°C, emission of poisonous gas is reduced, energy conservation and environmental protection are satisfied, construction quality reaches requirements of construction specifications and economic, social and environmental benefits are significant. Thus, it can be used for reference for green construction of urban roads.

  1. Modified Asphalt Binder with Natural Zeolite for Warm Mix Asphalt

    NASA Astrophysics Data System (ADS)

    Dubravský, Marián; Mandula, Ján

    2015-11-01

    In recent years, warm mix asphalt (WMA) is becoming more and more used in the asphalt industry. WMA provide a whole range of benefits, whether economic, environmental and ecological. Lower energy consumption and less pollution is the most advantages of this asphalt mixture. The paper deals with the addition of natural zeolite into the sub base asphalt layers, which is the essential constituent in the construction of the road. Measurement is focused on basic physic - mechanical properties declared according to the catalog data sheets. The aim of this article is to demonstrate the ability of addition the natural zeolite into the all asphalt layers of asphalt pavement. All asphalt mixtures were compared with reference asphalt mixture, which was prepared in reference temperature.

  2. Predictors of airborne exposures to polycyclic aromatic compounds and total organic matter among hot-mix asphalt paving workers and influence of work conditions and practices.

    PubMed

    Cavallari, Jennifer M; Osborn, Linda V; Snawder, John E; Kriech, Anthony J; Olsen, Larry D; Herrick, Robert F; McClean, Michael D

    2012-03-01

    We evaluated personal airborne exposures to polycyclic aromatic compounds (PACs) and total organic matter (TOM) among hot-mix asphalt (HMA) paving workers. The primary objectives of this study were to identify predictors of airborne PAC exposures, identify PAC exposure sources, and characterize how work practices may affect personal airborne exposure to PACs. Four workers were recruited from each of three asphalt paving crews (12 workers) and were monitored for three consecutive days over 4 weeks for a total of 12 sampling days per worker (144 worker-days). Three sampling weeks were conducted while maintaining standard working conditions with regard to airborne exposures. The fourth week included the substitution of biodiesel for diesel oil used to clean tools and equipment. Linear mixed-effects models were used to evaluate predictors of airborne exposures including weather parameters (air temperature, wind speed, and relative humidity), worksite conditions (HMA application temperature, work rate, asphalt grade, and biodiesel use), and personal factors (minutes sampled, minutes of downtime, and smoking status). Concentrations of the 33 individual PACs measured in personal air samples were generally below detection limits under all conditions with the exception of fluorene [geometric mean (GM) = 65 ng m(-3)], naphthalene (GM = 833 ng m(-3)), phenanthrene (GM = 385 ng m(-3)), and pyrene (GM = 57 ng m(-3)). The summary measures of TOM (GM = 864 μg m(-3)) and four- to six-ring PAC (GM = 0.13 μg m(-3)) were detected in the majority of air samples. Although task was not a predictor of airborne exposures, job site characteristics such as HMA application temperature were found to significantly (P ≤ 0.001) affect summary and individual PAC exposures. Based on the results of multivariate linear mixed-effects models, substituting biodiesel for diesel oil as a cleaning agent was associated with significant (P ≤ 0.01) reductions in TOM, four- to six-ring PACs, and

  3. Correlation between permanent deformation-related performance parameters of asphalt concrete mixes and binders

    NASA Astrophysics Data System (ADS)

    Adorjányi, Kálmán; Füleki, Péter

    2013-09-01

    This paper examines methods to predict the performance of hot asphalt concrete mixes based on performance parameters of binders. Specifically, relationships between binder parameters determined from multiple stress creep and recovery tests were correlated to the creep parameters of hot asphalt concrete mixes obtained from cyclic load compression testing. For the determination of creep parameters, a modified expression of the creep curve is proposed to cover the entire spectrum of permanent deformation; including the tertiary creep phase. Non-recoverable compliance, unrecovered strain, and recoverable strain of binders show good correlation to creep parameters of hot asphalt concrete mixes such as creep rate and high temperature performance ratio. Additionally, unrecovered strain and non-recoverable compliance of binders correlates well with mean rut depth of asphalt concrete mixes. However, no correlation has been detected between the difference in non-recoverable compliance of binders and permanent deformation parameters of asphalt concrete mixes.

  4. Personal breathing zone exposures among hot-mix asphalt paving workers; preliminary analysis for trends and analysis of work practices that resulted in the highest exposure concentrations.

    PubMed

    Osborn, Linda V; Snawder, John E; Kriech, Anthony J; Cavallari, Jennifer M; McClean, Michael D; Herrick, Robert F; Blackburn, Gary R; Olsen, Larry D

    2013-01-01

    An exposure assessment of hot-mix asphalt (HMA) paving workers was conducted to determine which of four exposure scenarios impacted worker exposure and dose. Goals of this report are to present the personal-breathing zone (PBZ) data, discuss the impact of substituting the releasing/cleaning agent, and discuss work practices that resulted in the highest exposure concentration for each analyte. One-hundred-seven PBZ samples were collected from HMA paving workers on days when diesel oil was used as a releasing/cleaning agent. An additional 36 PBZ samples were collected on days when B-100 (100% biodiesel, containing no petroleum-derived products) was used as a substitute releasing/cleaning agent. Twenty-four PBZ samples were collected from a reference group of concrete workers, who also worked in outdoor construction but had no exposure to asphalt emissions. Background and field blank samples were also collected daily. Total particulates and the benzene soluble fraction were determined gravimetrically. Total organic matter was determined using gas chromatography (GC) with flame ionization detection and provided qualitative information about other exposure sources contributing to worker exposure besides asphalt emissions. Thirty-three individual polycyclic aromatic compounds (PACs) were determined using GC with time-of-flight mass spectrometry; results were presented as either the concentration of an individual PAC or a summation of the individual PACs containing either 2- to 3-rings or 4- to 6-rings. Samples were also screened for PACs containing 4- to 6-rings using fluorescence spectroscopy. Arithmetic means, medians, and box plots of the PBZ data were used to evaluate trends in the data. Box plots illustrating the diesel oil results were more variable than the B-100. Also, the highest diesel oil results were much higher in concentration than the highest B-100 results. An analysis of the highest exposure results and field notes revealed a probable association between

  5. Personal Breathing Zone Exposures among Hot-Mix Asphalt Paving Workers; Preliminary Analysis for Trends and Analysis of Work Practices That Resulted in the Highest Exposure Concentrations

    PubMed Central

    Osborn, Linda V.; Snawder, John E.; Kriech, Anthony J.; Cavallari, Jennifer M.; McClean, Michael D.; Herrick, Robert F.; Blackburn, Gary R.; Olsen, Larry D.

    2015-01-01

    An exposure assessment of hot-mix asphalt (HMA) paving workers was conducted to determine which of four exposure scenarios impacted worker exposure and dose. Goals of this report are to present the personal-breathing zone (PBZ) data, discuss the impact of substituting the releasing/cleaning agent, and discuss work practices that resulted in the highest exposure concentration for each analyte. One-hundred-seven PBZ samples were collected from HMA paving workers on days when diesel oil was used as a releasing/cleaning agent. An additional 36 PBZ samples were collected on days when B-100 (100% biodiesel, containing no petroleum-derived products) was used as a substitute releasing/cleaning agent. Twenty-four PBZ samples were collected from a reference group of concrete workers, who also worked in outdoor construction but had no exposure to asphalt emissions. Background and field blank samples were also collected daily. Total particulates and the benzene soluble fraction were determined gravimetrically. Total organic matter was determined using gas chromatography (GC) with flame ionization detection and provided qualitative information about other exposure sources contributing to worker exposure besides asphalt emissions. Thirty-three individual polycyclic aromatic compounds (PACs) were determined using GC with time-offlight mass spectrometry; results were presented as either the concentration of an individual PAC or a summation of the individual PACs containing either 2- to 3-rings or 4- to 6-rings. Samples were also screened for PACs containing 4- to 6-rings using fluorescence spectroscopy. Arithmetic means, medians, and box plots of the PBZ data were used to evaluate trends in the data. Box plots illustrating the diesel oil results were more variable than the B-100. Also, the highest diesel oil results were much higher in concentration than the highest B-100 results. An analysis of the highest exposure results and field notes revealed a probable association between

  6. Viscoelastic behaviour of cold recycled asphalt mixes

    NASA Astrophysics Data System (ADS)

    Cizkova, Zuzana; Suda, Jan

    2017-09-01

    Behaviour of cold recycled mixes depends strongly on both the bituminous binder content (bituminous emulsion or foamed bitumen) and the hydraulic binder content (usually cement). In the case of cold recycled mixes rich in bitumen and with low hydraulic binder content, behaviour is close to the viscoelastic behaviour of traditional hot mix asphalt. With decreasing bituminous binder content together with increasing hydraulic binder content, mixes are characteristic with brittle behaviour, typical for concrete pavements or hydraulically bound layers. The behaviour of cold recycled mixes with low content of both types of binders is similar to behaviour of unbound materials. This paper is dedicated to analysing of the viscoelastic behaviour of the cold recycled mixes. Therefore, the tested mixes contained higher amount of the bituminous binder (both foamed bitumen and bituminous emulsion). The best way to characterize any viscoelastic material in a wide range of temperatures and frequencies is through the master curves. This paper includes interesting findings concerning the dependency of both parts of the complex modulus (elastic and viscous) on the testing frequency (which simulates the speed of heavy traffic passing) and on the testing temperature (which simulates the changing climate conditions a real pavement is subjected to).

  7. Evaluation of Warm Mix Asphalt Technologies and Recycled Asphalt Pavements in Truckee Meadows, Nevada

    NASA Astrophysics Data System (ADS)

    Diaz Montecino, Cristian

    This study evaluated the properties and laboratory-performance of Hot Mix Asphalt (HMA) and Warm Mix Asphalt (WMA) mixtures with different levels of Recycled Asphalt Pavements (RAP) content: none for control mixtures, around 15% by dry weight of aggregates, and more than 30% by dry weight of aggregates. The rheological properties were evaluated for virgin and recovered RAP asphalt binders. The target amount of RAP in the mixtures was determined by using Blending Charts and Mortar Experiments. The mixtures are design through the guidelines established in Marshall Mix Design Method considering additional modifications for RAP and WMA from Superpave Mix Design. The mixtures are evaluated for their resistance to moisture damage by means of measuring the Dynamic Modulus |E*| after three freeze/thaw cycles and the indirect tensile strength after one and three freeze/thaw cycles. The resistance of the mixtures to permanent deformation was also evaluated by using the Asphalt Mixture Performance Tester (AMPT) to measure the flow number (FN). For this study, it was determined that the resistance to moisture damage decreases as the number of freeze/thaw cycles increases for most of the evaluated mixtures. Mixtures exhibited an increase in dynamic modulus as the RAP percentage increased. A decrease in the resistance to moisture damage was detected with the increase in RAP content for most of the mixtures. HMA mixtures exhibited a better performance in rutting than the WMA mixtures. An increase in rutting resistance was observed with the increase in RAP percentage for HMA mixtures whereas an inconsistent trend was observed for WMA mixtures. Further study is needed to validate the use of the high percentage of RAP in Washoe County.

  8. Utilization of recycled asphalt concrete with warm mix asphalt and cost-benefit analysis.

    PubMed

    Oner, Julide; Sengoz, Burak

    2015-01-01

    The asphalt paving industries are faced with two major problems. These two important challenges are generated with an increase in demand for environmentally friendly paving mixtures and the problem of rapidly rising raw materials. Recycling of reclaimed asphalt pavement (RAP) is a critical necessity to save precious aggregates and reduce the use of costly bitumen. Warm Mix Asphalt (WMA) technology provides not only the option of recycling asphalt pavement at a lower temperature than the temperature maintained in hot mixtures but also encourages the utilization of RAP and therefore saves energy and money. This paper describes the feasibility of utilizing three different WMA additives (organic, chemical and water containing) at recommended contents with different percentages of RAP. The mechanical properties and cost-benefit analysis of WMA containing RAP have been performed and compared with WMA without RAP. The results indicated that, 30%, 10% and 20% can be accepted as an optimum RAP addition related to organic, chemical and water containing additives respectively and organic additive with 30% RAP content has an appreciable increase in tensile strength over the control mix. It was also concluded that the RAP with WMA technology is the ability to reduce final cost compared to HMA and WMA mixtures.

  9. Utilization of Recycled Asphalt Concrete with Warm Mix Asphalt and Cost-Benefit Analysis

    PubMed Central

    Oner, Julide; Sengoz, Burak

    2015-01-01

    The asphalt paving industries are faced with two major problems. These two important challenges are generated with an increase in demand for environmentally friendly paving mixtures and the problem of rapidly rising raw materials. Recycling of reclaimed asphalt pavement (RAP) is a critical necessity to save precious aggregates and reduce the use of costly bitumen. Warm Mix Asphalt (WMA) technology provides not only the option of recycling asphalt pavement at a lower temperature than the temperature maintained in hot mixtures but also encourages the utilization of RAP and therefore saves energy and money. This paper describes the feasibility of utilizing three different WMA additives (organic, chemical and water containing) at recommended contents with different percentages of RAP. The mechanical properties and cost-benefit analysis of WMA containing RAP have been performed and compared with WMA without RAP. The results indicated that, 30%, 10% and 20% can be accepted as an optimum RAP addition related to organic, chemical and water containing additives respectively and organic additive with 30% RAP content has an appreciable increase in tensile strength over the control mix. It was also concluded that the RAP with WMA technology is the ability to reduce final cost compared to HMA and WMA mixtures. PMID:25574851

  10. Hot in-place recycling of asphalt concrete. Final report

    SciTech Connect

    Button, J.W.; Little, D.N.; Estakhri, C.K.; Mason, L.S.

    1994-01-01

    ;Contents: Hot in place recycling processes and equipment; HIPR as a tool for asphalt pavement rehabilitation; Mixture design for HIPR processes; Relative performance of HIPR pavements; Guidelines for effective use of HIPR; and Conclusions and recommendations.

  11. Hot asphalt burns: a review of injuries and management options.

    PubMed

    Bosse, George M; Wadia, Shernaz A; Padmanabhan, Pradeep

    2014-07-01

    Hot asphalt burns to human tissue can increase the likelihood of infection and potential conversion of partial thickness to full-thickness injuries. Successful intervention for hot asphalt burns requires immediate and effective cooling of the asphalt on the tissue followed by subsequent gradual removal of the cooled asphalt. A review of the literature reveals that multiple substances have been used to remove asphalt, including topical antibiotics, petroleum jelly, a commercial product known as De-Solv-It (ORANGE-SOL, Chandler, AZ), sunflower oil, baby oil, liquid paraffin, butter, mayonnaise, and moist-exposed burn ointment (MEBO). Although many of these products may be effective in the removal of asphalt, they may not be readily available in an emergency department setting. Topical antibiotics are readily available, are more commonly described in the medical literature, and would be expected to be effective in the removal of asphalt. We developed guidelines for on scene (first-aid) management and the initial care of such patients upon presentation to a health care facility. These guidelines emphasize the principles of early cooling, gradual removal of adherent asphalt using topical antibiotics, and avoidance of the use of topical agents, which are likely to result in tissue toxicity.

  12. Asphalt and asphalt additives. Transportation research record

    SciTech Connect

    Not Available

    1992-01-01

    Contents: use of asphalt emulsions for in-place recycling: oregon experience; gap-graded cold asphalt concrete: benefits of polymer-modified asphalt cement and fibers; cold in-place recycling for rehabilitation and widening of low-volume flexible pavements in indiana; in situ cold recycling of bituminous pavements with polymer-modified high float emulsions; evaluation of new generation of antistripping additives; correlation between performance-related characteristics of asphalt cement and its physicochemical parameters using corbett's fractions and hpgc; reaction rates and hardening susceptibilities as determined from pressure oxygen vessel aging of asphalts; evaluation of aging characteristics of asphalts by using tfot and rtfot at different temperature levels; summary of asphalt additive performance at selected sites; relating asphalt absorption to properties of asphalt cement and aggregate; study of the effectiveness of styrene-butadiene rubber latex in hot mix asphalt mixes; stability of straight and polymer-modified asphalts.

  13. Analyzing the stripping potential of warm mix asphalt using imaging technique

    NASA Astrophysics Data System (ADS)

    Rafiq Kakar, Muhammad; Othman Hamzah, Meor; Valentin, Jan

    2017-09-01

    In asphalt mixtures, stripping occurs when the bond between the asphalt and the aggregate is broken due to the intrusion of water within the asphalt aggregate interface. Warm mix asphalt (WMA) is a technology that allows significant reduction in mixing and compaction temperatures of conventional hot mix asphalt. However, WMA is susceptible to moisture damage due to its lower production temperature. This can cause adhesive failure, hence stripping of asphalt binder from the aggregates. In this study, direct tensile strength (DTS) and indirect tensile strength (ITS) tests were applied to fracture the mixture specimen. Imaging technique was applied on the fractured faces of asphalt mixture to quantify the adhesive failure susceptibility due to the destructive effects of moisture. The results showed that adhesive failure increased with the number of freeze and thaw cycles and mixtures prepared with PG-76 binder exhibited lower adhesive failure compared to PG-64 binder. From fractured ITS samples, most of broken aggregates were found located in the vicinity where the indirect tensile load was applied. On the other hand, high adhesive failure was obtained at the center portion where maximum tensile stresses were developed. The image analysis method employed in this work has proven to be very effective to analyze the deterioration of asphalt mixtures subjected to moisture conditioning.

  14. Performance properties of asphalt mixes for rich bottom layers (RBL)

    NASA Astrophysics Data System (ADS)

    Bureš, Petr; Fiedler, Jiří; Kašpar, Jiří; Sýkora, Michal; Hýzl, Petr

    2017-09-01

    The binder content of asphalt mixes has an important influence on the performance properties. Higher binder content improves fatigue resistance. That is why the concept of RBL was developed in USA and applied for “perpetual pavements”. However excessive binder content could lead to the decrease of the mix stiffness and to permanent deformations of asphalt pavement during hot summer. The advantages and limitations of RBL concept have been studied in research project CESTI. Fatigue tests of mixes with road bitumen and polymer modified bitumen and RBL were realised. Deformation behaviour of these mixes was also evaluated. The experience from the test section with RBL laid in 2015 will be presented. The results corresponded to expectations. However, low void content was obtained on one subsection. In spite of it, there were no permanent deformations during summer 2016. The analysis of methods for the prediction of the permanent deformation was also undertaken in research project CESTI. Some information about the results of these analysis related to the use of RBL will be also briefly mentioned.

  15. Asphalt-Aggregate Interactions in Hot Recycling.

    DTIC Science & Technology

    1987-07-01

    showed that recycled systems resisted the action of water better than virgin systems. Bonding energy measurements indicated that asphalt-aggregate mixtures...Mexico Powders and Granular Materials Laboratory for surface area/porosity measurements and discussion of results John Husler and Les Mcfadden at the...FORMUJLA MIXTURE RESULTS.................. 70 22 F VALUES DERIVED FROM THE TWO-WAY ANOVA................. 79 23 BONDING ENERGY MEASUREMENTS FOR - #16 + #50

  16. Evaluation of mix ingredients on the performance of rubber-modified asphalt mixtures

    SciTech Connect

    Takallou, H.B.

    1987-01-01

    In rubber-modified asphalt pavements ground recycled tire particles are added to a gap-graded aggregate and then mixed with hot asphalt cement. In view of the significant reductions in wintertime stopping distances under icy or frosty road surface conditions, the use of coarse rubber in asphalt pavements should be seriously considered. This research project consisted of a laboratory study of mix properties as a function of variables such as rubber gradation and content, void content, aggregate graduation, mix process, temperature, and asphalt content. Twenty different mix combinations were evaluated for diametral modulus and fatigue at two different temperatures. Also, five different mix combinations were evaluated for static creep and permanent deformation. The findings of the laboratory study indicate that the rubber gradation and content, aggregate gradation, and use of surcharge during sample preparation have considerable effect on modulus and fatigue life of the mix. The results of static creep and permanent deformation tests indicate that the rubber asphalt mixes had low stability and high elasticity. Also, due to greater allowable tensile strain in rubber-modified mixtures, the thickness of the modified mixture can be reduced, using a layer equivalency of 1.4 to 1.0

  17. Investigation of PAH Biomarkers in the Urine of Workers Exposed to Hot Asphalt

    PubMed Central

    Sobus, Jon R.; Mcclean, Michael D.; Herrick, Robert F.; Waidyanatha, Suramya; Onyemauwa, Frank; Kupper, Lawrence L.; Rappaport, Stephen M.

    2009-01-01

    Airborne emissions from hot asphalt contain mixtures of polycyclic aromatic hydrocarbons (PAHs), including several carcinogens. We investigated urinary biomarkers of three PAHs, namely naphthalene (Nap), phenanthrene (Phe), and pyrene (Pyr) in 20 road-paving workers exposed to hot asphalt and in 6 road milling workers who were not using hot asphalt (reference group). Our analysis included baseline urine samples as well as postshift, bedtime, and morning samples collected over three consecutive days. We measured unmetabolized Nap (U-Nap) and Phe (U-Phe) as well as the monohydroxylated metabolites of Nap (OH-Nap), Phe (OH-Phe), and Pyr (OH-Pyr) in each urine sample. In baseline samples, no significant differences in biomarker levels were observed between pavers and millers, suggesting similar background exposures. In postshift, bedtime, and morning urine samples, the high pairwise correlations observed between levels of all biomarkers suggest common exposure sources. Among pavers, levels of all biomarkers were significantly elevated in postshift samples, indicating rapid uptake and elimination of PAHs following exposure to hot asphalt (biomarker levels were not elevated among millers). Results from linear mixed-effects models of levels of U-Nap, U-Phe, OH-Phe, and OH-Pyr across pavers showed significant effects of work assignments with roller operators having lower biomarker levels than the other workers. However, no work-related effect was observed for levels of OH-Nap, apparently due to the influence of cigarette smoking. Biological half-lives, estimated from regression coefficients for time among pavers, were 8 h for U-Phe, 10 h for U-Nap, 13 h for OH-Phe and OH-Pyr, and 26 h for OH-Nap. These results support the use of U-Nap, U-Phe, OH-Phe, and OH-Pyr, but probably not OH-Nap, as short-term biomarkers of exposure to PAHs emanating from hot asphalt. PMID:19602500

  18. Investigation of PAH biomarkers in the urine of workers exposed to hot asphalt.

    PubMed

    Sobus, Jon R; McClean, Michael D; Herrick, Robert F; Waidyanatha, Suramya; Onyemauwa, Frank; Kupper, Lawrence L; Rappaport, Stephen M

    2009-08-01

    Airborne emissions from hot asphalt contain mixtures of polycyclic aromatic hydrocarbons (PAHs), including several carcinogens. We investigated urinary biomarkers of three PAHs, namely naphthalene (Nap), phenanthrene (Phe), and pyrene (Pyr) in 20 road-paving workers exposed to hot asphalt and in 6 road milling workers who were not using hot asphalt (reference group). Our analysis included baseline urine samples as well as postshift, bedtime, and morning samples collected over three consecutive days. We measured unmetabolized Nap (U-Nap) and Phe (U-Phe) as well as the monohydroxylated metabolites of Nap (OH-Nap), Phe (OH-Phe), and Pyr (OH-Pyr) in each urine sample. In baseline samples, no significant differences in biomarker levels were observed between pavers and millers, suggesting similar background exposures. In postshift, bedtime, and morning urine samples, the high pairwise correlations observed between levels of all biomarkers suggest common exposure sources. Among pavers, levels of all biomarkers were significantly elevated in postshift samples, indicating rapid uptake and elimination of PAHs following exposure to hot asphalt (biomarker levels were not elevated among millers). Results from linear mixed-effects models of levels of U-Nap, U-Phe, OH-Phe, and OH-Pyr across pavers showed significant effects of work assignments with roller operators having lower biomarker levels than the other workers. However, no work-related effect was observed for levels of OH-Nap, apparently due to the influence of cigarette smoking. Biological half-lives, estimated from regression coefficients for time among pavers, were 8 h for U-Phe, 10 h for U-Nap, 13 h for OH-Phe and OH-Pyr, and 26 h for OH-Nap. These results support the use of U-Nap, U-Phe, OH-Phe, and OH-Pyr, but probably not OH-Nap, as short-term biomarkers of exposure to PAHs emanating from hot asphalt.

  19. Nonlinearly viscoelastic analysis of asphalt mixes subjected to shear loading

    NASA Astrophysics Data System (ADS)

    Huang, Chien-Wei; Masad, Eyad; Muliana, Anastasia H.; Bahia, Hussain

    2007-06-01

    This study presents the characterization of the nonlinearly viscoelastic behavior of hot mix asphalt (HMA) at different temperatures and strain levels using Schapery’s model. A recursive-iterative numerical algorithm is generated for the nonlinearly viscoelastic response and implemented in a displacement-based finite element (FE) code. Then, this model is employed to describe experimental frequency sweep measurements of two asphalt mixes with fine and coarse gradations under several combined temperatures and shear strain levels. The frequency sweep measurements are converted to creep responses in the time domain using a phenomenological model (Prony series). The master curve is created for each strain level using the time temperature superposition principle (TTSP) with a reference temperature of 40°C. The linear time-dependent parameters of the Prony series are first determined by fitting a master curve created at the lowest strain level, which in this case is 0.01%. The measurements at strain levels higher than 0.01% are analyzed and used to determine the nonlinear parameters. These parameters are shown to increase with increasing strain levels, while the time temperature shift function is found to be independent of strain levels. The FE model with the calibrated time-dependent and nonlinear material parameters is used to simulate the creep experimental tests, and reasonable predictions are shown.

  20. Evaluation of Warm Mix Asphalt Additives for Use in Modified Asphalt Mixtures

    NASA Astrophysics Data System (ADS)

    Chamoun, Zahi

    The objective of this research effort is to evaluate the use of warm-mix additives with polymer modified and terminal blend tire rubber asphalt mixtures from Nevada and California. The research completed over two stages: first stage evaluated two different WMA technologies; Sasobit and Advera, and second stage evaluated one additional WMA technology; Evotherm. The experimental program covered the evaluation of resistance of the mixtures to moisture damage, the performance characteristics of the mixtures, and mechanistic analysis of mixtures in simulated pavements. In the both stages, the mixture resistance to moisture damage was evaluated using the indirect tensile test and the dynamic modulus at multiple freeze-thaw cycles, and the resistance of the various asphalt mixtures to permanent deformation using the Asphalt Mixture Performance Tester (AMPT). Resistance of the untreated mixes to fatigue cracking using the flexural beam fatigue was only completed for the first stage. One source of aggregates was sampled in, two different batches, three warm mix asphalt technologies (Advera, Sasobit and Evotherm) and three asphalt binder types (neat, polymer-modified, and terminal blend tire rubber modified asphalt binders) typically used in Nevada and California were evaluated in this study. This thesis presents the resistance of the first stage mixtures to permanent deformation and fatigue cracking using two warm-mix additives; Advera and Sasobit, and the resistance to moisture damage and permanent deformation of the second stage mixtures with only one warm-mix additive; Evotherm.

  1. Evaluation of Asphalt Mixes Workability and Compactability Using Laboratory and Accelerated Field Testing

    NASA Astrophysics Data System (ADS)

    Dessouky, Samer; Diaz, Manuel

    Polymer-modified asphalt have been proven to improve mechanical characteristics of asphalt mixes, however there are concerns that mixes become drier and more difficult to compact. This study aims to develop compaction indices using routine laboratory compaction procedure to evaluate the workability and compactability of hot and warm mixes prior to laydown. Workability is reflected in the ease of blending while compactability is reflected in the mixes' stability and resistance to densification. To quantify thresholds for the indices, laboratory and accelerated field testing were implemented. The workability index was tentatively found to be a minimum of 4.5 while the compactability indices were tentatively found to be a maximum of 0.5 and a minimum of 20. The compactability indices were capable of predicting mix resistance to permanent deformation.

  2. Characteristics of asphalt mixes with FT additive

    NASA Astrophysics Data System (ADS)

    Štefunková, S.

    2012-03-01

    This article is focused on low-temperature asphalt mixture technologies using FT additive and RAP. The modern production and use of asphalt mixture technologies with reduced temperatures has many advantages. These advantages mainly help to save energy and the environment. Lower temperatures enable a reduction in energy consumption, a more acceptable working environment for workers, a reduction in negative environmental effects, such as greenhouse gas emissions, and an improvement in the workability of mixtures and a prolongation of their duration. This technology is currently becoming popular in many countries.

  3. Recycled rubber, aggregate, and filler in asphalt paving mixtures. Transportation research record

    SciTech Connect

    1996-12-31

    ;Contents(Partial): Evaluation Systems for Crumb Rubber Modified Binders and Mixtures; Hot Mix Asphalt Rubber Applications in Virginia; Evaluation of Pyrolized Carbon Black from Scrap Tires as Additive in Hot Mix Asphalt; Use of Scrap Tire Chips in Asphaltic Membrane; Effects of Mineral Fillers on Properties of Stone Matrix Asphalt Mixtures; and Quantitative Analysis of Aggregate Based on Hough Transform.

  4. User's guide: Cold-mix recycling of asphalt concrete pavements. Final report

    SciTech Connect

    Shoenberger, J.E.

    1992-09-01

    This guide provides the technical information required to implement the application of cold-mix recycling of asphalt concrete pavements. Included are details on areas on application, benefits/advantages, limitations/disadvantages, and costs associated with this technology. Information is provided on two demonstration sites at Fort Gillem, Georgia, and Fort Leavenworth, Kansas. Also provided is information concerning funding, procurement, maintenance, and performance monitoring. A fact sheet on recycling, contract specification example, and references are provided in the appendixes.... Asphalt pavement recycling, Emulsified asphalt cement, Cold milling, In-place cold-mix asphalt recycling, Cold-mix asphalt recycling, Recycling of asphalt.

  5. Effects of reclaimed asphalt pavement on indirect tensile strength test of foamed asphalt mix tested in dry condition

    NASA Astrophysics Data System (ADS)

    Yati Katman, Herda; Rasdan Ibrahim, Mohd; Yazip Matori, Mohd; Norhisham, Shuhairy; Ismail, Norlela

    2013-06-01

    Indirect tensile strength (ITS) test was conducted to analyse strength of the foamed asphalt mixes incorporating reclaimed asphalt pavement. Samples were tested for ITS after cured in the oven at 40°C for 72 hours. This testing condition known as dry condition or unconditioned. Laboratory results show that reclaimed asphalt pavement (RAP) contents insignificantly affect the ITS results. ITS results significantly affected by foamed bitumen contents.

  6. Asphalt mix reinforced with vegetable fibers

    NASA Astrophysics Data System (ADS)

    Gallo, Peter

    2017-09-01

    The use of a larger share of renewable materials in road construction is a trend that in the long term cannot be avoided. In some cases, due to this pressure, new innovative opportunities are generated. This article attempts to outline and bring one of such opportunity. The article describes selection and the use of special natural fibers from renewable natural resources adapted for use in various types of asphalt mixtures to improve the range of properties. Experimental results showed an improvement in stiffness modulus, indirect tensile strength (ITS) and good resistance to permanent deformation of blends containing vegetable fibers. This is a new topic in the road construction. But the results have so far proven that the used type of fibers can be a perspective way, as simple and in line with the policy of sustainable development, to improve the properties (reinforce) of the asphalt mixtures.

  7. Evaluation of permanent deformation and durability of epoxidized natural rubber modified asphalt mix

    NASA Astrophysics Data System (ADS)

    Al-Mansob, Ramez A.; Ismail, Amiruddin; Rahmat, Riza Atiq O. K.; Nazri Borhan, Muhamad; Alsharef, Jamal M. A.; Albrka, Shaban Ismael; Rehan Karim, Mohamed

    2017-09-01

    The road distresses have caused too much in maintenance cost. However, better understandings of the behaviours and properties of asphalt, couples with greater development in technology, have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, modifiers such as polymers are the most popular modifiers used to improve the performance of asphalt mix. This study was conducted to investigate the use of epoxidized natural rubber (ENR) to be mixed with asphalt mix. Tests were conducted to investigate the performance characteristics of ENR-asphalt mixes, where the mixes were prepared according to the wet process. Mechanical testing on the ENR-asphalt mixes have demonstrated that the asphalt mix permanent deformation performance at high temperature was found to be improved compared to the base mixes. However, the durability studies have indicated that ENR-asphalt mixes are slightly susceptible with the presence of moisture. The durability of the ENR-asphalt mixes were found to be enhanced in term of permanent deformation at high and intermediate temperatures compared to the base asphalt mixes. As conclusion, asphalt pavement performance can be enhanced by using ENR as modifier to face the major road distresses.

  8. Asphalt pavement surfaces and asphalt mixtures. Transportation research record

    SciTech Connect

    1996-12-31

    The papers in this volume, which deal with asphalt pavement surfaces and asphalt mixtures, should be of interest to state and local construction, design, materials, and research engineers as well as contractors and material producers. The papers in Part 1 include discussions of pavement smoothness specifications and skidding characteristics. The first four papers in Part 2 were submitted in response to a call for papers for a session at the 75th Annual Meeting of the Transportation Research Board on low-temperature properties of hot-mix asphalt. The next eight are on the influence of volumetric and strength properties on the performance of hot-mix asphalt. In the following three papers, the topics covered are the complex modulus of asphalt concrete, cold in-place asphalt recycling, and polymer modification of asphalt pavements in Ontario. The last two papers were presented in a session on relationship of materials characterization to accelerated pavement performance testing.

  9. Specifications and Construction Methods for Asphalt Concrete and Other Plant-Mix Types, 3rd Edition.

    ERIC Educational Resources Information Center

    Asphalt Inst., College Park, MD.

    The purpose of this publication is to assist engineers in the analysis, design and control of paving projects that use asphalt concrete and other asphalt plant-mixes. The scope of this new third edition has been enlarged, and changes necessitated by advances in asphalt technology have been incorporated. Chapters I and II and Appendices A and B…

  10. Inherent Control - Hot-Mix Asphalt Industry

    EPA Pesticide Factsheets

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  11. Performance of skid resistance of warm-mix asphalt with buton natural asphalt-rubber (BNA-R) and zeolite additives as a result of road surface temperature changes

    NASA Astrophysics Data System (ADS)

    Anagi, Natasha; Hadiwardoyo, Sigit Pranowo; Sumabrata, R. Jachrizal; Wahjuningsih, Nurul

    2017-06-01

    Roughness of the road surface acts as an obstacle for the vehicle wheel slip on the road surface especially in wet conditions. Road surface roughness can be generated from the properties of the aggregate or bitumen as a characteristic of asphalt mixture. Various types of added material have been used to improve the performance of hot mix asphalt mixture as well as the warm mix asphalt. The addition of BNA-R and zeolite on the warm asphalt mixtures has been investigated, particularly related with its effect on the value of the skid surface due to the wheels track of the vehicle. The study was conducted in an asphalt mixture before and after the traversed wheel condition. In this study, 7.560 trajectory path using the Wheel Tracking Machine and skid resistance test using a modified British Pendulum Tester, were conducted. Skid resistance test involved various temperatures on the surface of the specimen. The results showed that the addition of BNA-R can increase the value of the skid at the beginning of the track, but at the last track, skid resistance performance was stagnant. Zeolite additive material in warm mix asphalt has improved skid resistance, especially the resistance of asphalt concrete mixture to temperature changes.

  12. Effects of two warm-mix additives on aging, rheological and failure properties of asphalt cements

    NASA Astrophysics Data System (ADS)

    Omari, Isaac Obeng

    Sustainable road construction and maintenance could be supported when excellent warm-mix additives are employed in the modification of asphalt. These warm-mix additives provide remedies for today's requirements such as fatigue cracking resistance, durability, thermal cracking resistance, rutting resistance and resistance to moisture damage. Warm-mix additives are based on waxes and surfactants which reduce energy consumption and carbon dioxide emissions significantly during the construction phase of the pavement. In this study, the effects of two warm mix additives, siloxane and oxidised polyethylene wax, on roofing asphalt flux (RAF) and asphalt modified with waste engine oil (655-7) were investigated to evaluate the rheological, aging and failure properties of the asphalt binders. In terms of the properties of these two different asphalts, RAF has proved to be superior quality asphalt whereas 655-7 is poor quality asphalt. The properties of the modified asphalt samples were measured by Superpave(TM) tests such as Dynamic Shear Rheometer (DSR) test and Bending Beam Rheometer (BBR) test as well as modified protocols such as the extended BBR (eBBR) test (LS-308) and the Double- Edge-Notched Tension (DENT) test (LS-299) after laboratory aging. In addition, the Avrami theory was used to gain an insight on the crystallization of asphalt or the waxes within the asphalt binder. This study has however shown that the eBBR and DENT tests are better tools for providing accurate specification tests to curb thermal and fatigue cracking in contemporary asphalt pavements.

  13. Rheology of crumb-rubber modified asphalt binders and mixes

    NASA Astrophysics Data System (ADS)

    Sheth, Vikas Rameshchandra

    Laboratory test procedures are presented to determine the rheological properties of crumb rubber modified asphalt (CRMA) binders and mixes. These tests provide simple, fast, and cost-effective alternatives to evaluate the performance (rutting and cracking potential) of binders and mixes used for pavement construction. Viscoelastic properties of CRMA binders are measured using dynamic shear analysis. Master curves were generated using the principle of time-temperature superposition to evaluate the effects of aging, rubber concentration, and curing conditions on the rheology of the modified binder. Results indicate that the rheology of CRMA binders can be divided into three regions of viscoelasticity: glassy region at high frequencies, transition/viscoelastic region at intermediate frequencies, and viscous region at low frequencies. Modification of the asphalt by addition of rubber leads to an improvement in both the high and low temperature properties, as reflected by changes in Gsp' and Gsp{''}, which causes the binder to have a greater resistance to specific pavement failure mechanisms. Both transient and dynamic properties of CRMA mixes were measured in the laboratory using the creep and recovery, direct tension, and frequency sweep tests. Rheological properties of the mix generated from the test data were compared to those of the binder to evaluate the effect of aging, rubber concentration, and curing conditions on mix performance. Several rheological parameters have been identified to characterize the rutting and cracking potential of mixes. A power law equation was found to give good correlations between several mix rheological parameters. Analysis of binder and mix failure energies show that work of cohesion of the binder is negligible compared to the failure energies. A unique relationship between Paris law material parameters has been confirmed. It is also shown that mix failure properties bear a one-to-one correlation with binder failure properties. Based

  14. Demonstration project number 39, hot mix recycling, Gray County, Kansas

    NASA Astrophysics Data System (ADS)

    Maag, R. G.; Parcells, W. H., Jr.

    1983-01-01

    The objective of this demonstration project was to evaluate the hot mix recycling process as a method of renovating a badly cracked and otherwise deteriorated section of road mixed bituminous paving in southwestern Kansas. The equipment used on the project included a cold milling machine to reclaim the upper portion of existing pavement; a drum dryer hot mix plant modified to process the material; and other standard hot mix laydown and compaction machines. Energy consumption comparisons in equivalent gallons of fuel indicate a savings of 17.8% when the recycled method is compared to using all new aggregate. The energy savings is primarily due to less asphaltic cement required and less fuel needed to mill and reuse the existing pavement than to quarry and haul in an equivalent quantity of new aggregate.

  15. Influence of roofing shingles on asphalt concrete mixture properties. Final report, 1992-1993

    SciTech Connect

    Newcomb, D.; Stroup-Gardiner, M.; Weikle, B.; Drescher, A.

    1993-06-01

    The objective of the study was to evaluate the use of waste shingles from manufacturing and roof reconstruction projects in hot mix asphalt concrete mixtures. In dense-graded asphalt mixtures, it was hypothesized that the waste material might serve as an extender for the new asphalt in the mix as well as a fiber reinforcement. In the stone mastic asphalt (SMA), it could serve as the binder stiffener typically used to prevent the asphalt from draining out of these types of mixtures.

  16. Recycling asphalt proves economical for paving contractors

    SciTech Connect

    Not Available

    1982-09-01

    Methods of recyclig asphalt to repair roads are described and evaluated. Need for recycling is caused by the escalating price of asphalt (an oil product). The economics and efficiency of the various processes used are evaluated. Methods described are: (1) cold-mix recycling in which the road is crushed, mixed with a new asphalt emulsion and reapplied; (2) hot mix, which involves ripping up pavement, trucking it to an asphalt plant, and mixing the old pavement material with virgin paving materials; and (3) cold planing (when only the top few inches of the road are deteriorated). Mining of asphalt roads, by removing top layers from old roads which are thick from many repair jobs, is described as well as mining of old airstrips. Value of asphalt available has been estimated as high as $50 billion. Recycling processes for asphalt are described briefly. (MJJ)

  17. Hot in-place recycling of asphalt pavements. Final report, 1988-1989

    SciTech Connect

    Shoenberger, J.E.; Vollor, T.W.

    1990-09-01

    This report contains the results of a literature search concerning hot in-place asphalt pavement recycling. Current methods and procedures for hot in-place recycling were reviewed and the advantages and disadvantages of each presented. Four construction sites were visited. Each site used a different procedure to recycle the pavement. These procedures along with the equipment used are discussed in regard to selecting a recycling method, material controls, and available cost data.

  18. Effects of reclaimed asphalt pavement on indirect tensile strength test of conditioned foamed asphalt mix

    NASA Astrophysics Data System (ADS)

    Yati Katman, Herda; Rasdan Ibrahim, Mohd; Yazip Matori, Mohd; Norhisham, Shuhairy; Ismail, Norlela

    2013-06-01

    This paper presents the results of Indirect Tensile Strength (ITS) Test for samples prepared with reclaimed asphalt pavement (RAP). Samples were conditioned in water at 25°C for 24 hours prior to testing. Results show that recycled aggregate from reclaimed asphalt pavement performs as well as virgin aggregate.

  19. The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis.

    PubMed

    Wang, Fusong; Wang, Zipeng; Li, Chao; Xiao, Yue; Wu, Shaopeng; Pan, Pan

    2017-05-24

    Using a rejuvenator to improve the performance of asphalt pavement is an effective and economic way of hot asphalt recycling. This research analyzes the rejuvenating effect on aged asphalt by means of a Mortar Transfer Ratio (MTR) test, which concerns the ratio of asphalt mortar that moves from recycled aggregates (RAP aggregates) to fresh added aggregates when aged asphalt is treated with a regenerating agent and comes into contact with fresh aggregates. The proposed MTR test analyzes the regeneration in terms of the softening degree on aged asphalt when the rejuvenator is applied. The covered area ratio is studied with an image analyzing tool to understand the possibility of mortar transferring from RAP aggregates to fresh aggregates. Additionally, a micro-crack closure test is conducted and observed through a microscope. The repairing ability and diffusion characteristics of micro-cracks can therefore be analyzed. The test results demonstrate that the proposed mortar transfer ratio is a feasible way to evaluate rejuvenator diffusion during hot recycling. The mortar transfer ratio and uncovered area ratio on fresh aggregates are compatible, and can be used to quantify the contribution of the rejuvenator. Within a certain temperature range, the diffusing effect of the rejuvenator is better when the diffusing temperature is higher. The diffusion time of the rejuvenator is optimum when diffusion occurs for 4-8 h. When the rejuvenator is properly applied, the rough and cracking surface can be repaired, resulting in better covered aggregates. The micro-closure analysis visually indicates that rejuvenators can be used to repair the RAP aggregates during hot recycling.

  20. The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis

    PubMed Central

    Wang, Fusong; Wang, Zipeng; Li, Chao; Xiao, Yue; Wu, Shaopeng; Pan, Pan

    2017-01-01

    Using a rejuvenator to improve the performance of asphalt pavement is an effective and economic way of hot asphalt recycling. This research analyzes the rejuvenating effect on aged asphalt by means of a Mortar Transfer Ratio (MTR) test, which concerns the ratio of asphalt mortar that moves from recycled aggregates (RAP aggregates) to fresh added aggregates when aged asphalt is treated with a regenerating agent and comes into contact with fresh aggregates. The proposed MTR test analyzes the regeneration in terms of the softening degree on aged asphalt when the rejuvenator is applied. The covered area ratio is studied with an image analyzing tool to understand the possibility of mortar transferring from RAP aggregates to fresh aggregates. Additionally, a micro-crack closure test is conducted and observed through a microscope. The repairing ability and diffusion characteristics of micro-cracks can therefore be analyzed. The test results demonstrate that the proposed mortar transfer ratio is a feasible way to evaluate rejuvenator diffusion during hot recycling. The mortar transfer ratio and uncovered area ratio on fresh aggregates are compatible, and can be used to quantify the contribution of the rejuvenator. Within a certain temperature range, the diffusing effect of the rejuvenator is better when the diffusing temperature is higher. The diffusion time of the rejuvenator is optimum when diffusion occurs for 4–8 h. When the rejuvenator is properly applied, the rough and cracking surface can be repaired, resulting in better covered aggregates. The micro-closure analysis visually indicates that rejuvenators can be used to repair the RAP aggregates during hot recycling. PMID:28772935

  1. Performance testing of asphalt concrete containing crumb rubber modifier and warm mix additives

    NASA Astrophysics Data System (ADS)

    Ikpugha, Omo John

    Utilisation of scrap tire has been achieved through the production of crumb rubber modified binders and rubberised asphalt concrete. Terminal and field blended asphalt rubbers have been developed through the wet process to incorporate crumb rubber into the asphalt binder. Warm mix asphalt technologies have been developed to curb the problem associated with the processing and production of such crumb rubber modified binders. Also the lowered production and compaction temperatures associated with warm mix additives suggests the possibility of moisture retention in the mix, which can lead to moisture damage. Conventional moisture sensitivity tests have not effectively discriminated good and poor mixes, due to the difficulty of simulating field moisture damage mechanisms. This study was carried out to investigate performance properties of crumb rubber modified asphalt concrete, using commercial warm mix asphalt technology. Commonly utilised asphalt mixtures in North America such as dense graded and stone mastic asphalt were used in this study. Uniaxial Cyclic Compression Testing (UCCT) was used to measure permanent deformation at high temperatures. Indirect Tensile Testing (IDT) was used to investigate low temperature performance. Moisture Induced Sensitivity Testing (MiST) was proposed to be an effective method for detecting the susceptibility of asphalt mixtures to moisture damage, as it incorporates major field stripping mechanisms. Sonnewarm(TM), Sasobit(TM) and Evotherm(TM) additives improved the resistance to permanent deformation of dense graded mixes at a loading rate of 0.5 percent by weight of the binder. Polymer modified mixtures showed superior resistance to permanent deformation compared to asphalt rubber in all mix types. Rediset(TM) WMX improves low temperature properties of dense graded mixes at 0.5 percent loading on the asphalt cement. Rediset LQ and Rediset WMX showed good anti stripping properties at 0.5 percent loading on the asphalt cement. The

  2. Asphalt cement poisoning

    MedlinePlus

    ... petroleum material that hardens when it cools. Asphalt cement poisoning occurs when someone swallows asphalt. If hot ... found in: Road paving materials Roofing materials Tile cements Asphalt may also be used for other purposes.

  3. Chemical aspects of incorporating contaminated soil into cold-mix asphalt

    SciTech Connect

    Testa, S.M.

    1994-12-31

    The chemical aspects associated with the incorporation of petroleum hydrocarbons- and metals-affected soil has been extensively studied in regards to pavement properties, leaching behavior, sensitivities to moisture-damage and function group analysis. These studies provide information that can be used to evaluate the stability of these constituents in soil that have been incorporated as an ingredient in asphalt. These studies also indicate that cold-mix asphalt incorporating contaminated soil will be highly stable and perform adequately as an end product. Maximum chemical performance is achieved when the asphalt is comprised of high contents of pyridinic, phenolic and ketone groups, which can be achieved by selectively choosing the source material. If the situation requires special stability or redundancy, small amounts of shale oil and lime can be used as additives. Situations and conditions which favor the presence of inorganic sulfur, monovalent salts and high strength solutions in the asphalt should be avoided since these conditions decrease the chemical stability of the asphalt cement by disruption of the functional group-aggregate bonds and by increasing the overall permeability. However, these conditions are not typically expected in the anticipated uses of asphalt cement to stabilize contaminants in soil using Environmentally Processed Asphalt{trademark} (EPA{trademark}) or Asphaltic Metals Stabilization{trademark} (AMS{trademark}) remedial technologies.

  4. Environmental impacts of asphalt mixes with electric arc furnace steel slag.

    PubMed

    Milačič, Radmila; Zuliani, Tea; Oblak, Tina; Mladenovič, Ana; Ančar, Janez Šč

    2011-01-01

    Electric arc furnace (EAF) steel slag can be used as an alternative high-quality material in road construction. Although asphalts with slag aggregates have been recognized as environmentally acceptable, there is a lack of data concerning the potential leaching of toxic Cr(VI) due to the highly alkaline media of EAF slag. Leaching of selected water extractable metals from slag indicated elevated concentrations of total chromium and Cr(VI). To estimate the environmental impacts of asphalt mixes with slag, leachability tests based on diffusion were performed using pure water and salt water as leaching agents. Compact and ground asphalt composites with natural aggregates, and asphalt composites in which the natural aggregates were completely replaced by slag were prepared. The concentrations of total chromium and Cr(VI) were determined in leachates over a time period of 6 mo. After 1 and 6 mo, the concentrations of some other metals were also determined in the leachates. The results indicated that chromium in leachates from asphalt composites with the addition of slag was present almost solely in its hexavalent form. However, the concentrations were very low (below 25 μg L) and did not represent an environmental burden. The leaching of other metals from asphalt composites with the addition of slag was negligible. Therefore, the investigated EAF slag can be considered as environmentally safe substitute for natural aggregates in asphalt mixes. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  5. Exposing the nonlinear viscoelastic behavior of asphalt-aggregate mixes

    NASA Astrophysics Data System (ADS)

    Levenberg, Eyal; Uzan, Jacob

    2012-05-01

    In this study asphalt-aggregate mixes are treated as both viscoelastic and viscoplastic. Following a damage mechanics approach, a nonlinear viscoelastic constitutive formulation is generated from a linear formulation by replacing `applied stresses' with `effective viscoelastic stresses'. A non-dimensional scalar entity called `relative viscoelastic stiffness' is introduced; it is defined as the ratio of applied to effective viscoelastic stress and encapsulates different types of nonlinearities. The paper proposes a computational scheme for exposing these nonlinearities by uncovering, through direct analysis of any test data, changes experienced by the `relative viscoelastic stiffness'. In general terms, the method is based on simultaneous application of creep and relaxation formulations while preserving the interrelationship between the corresponding time functions. The proposed scheme is demonstrated by analyzing a uniaxial tension test and a uniaxial compression test (separately). Results are presented and discussed, unveiling and contrasting the character of viscoelastic nonlinearities in both cases. A conceptual viewpoint is offered to explain the observations, illustrating the requirements from any candidate constitutive theory.

  6. Black curves and creep behaviour of crumb rubber modified binders containing warm mix asphalt additives

    NASA Astrophysics Data System (ADS)

    Gallego, Juan; Rodríguez-Alloza, Ana María; Giuliani, Felice

    2016-08-01

    Warm mix asphalt (WMA) is a new research topic in the field of road pavement materials. This technology allows lower energy consumption and greenhouse gas (GHG) emissions by reducing compaction and placement temperatures of the asphalt mixtures. However, this technology is still under study, and the influence of the WMA additives has yet to be investigated thoroughly and clearly identified, especially in the case of crumb rubber modified (CRM) binders.

  7. Hot in-Place Recycling of Asphalt Pavements.

    DTIC Science & Technology

    1987-08-04

    64 4. Road Sampling ................................... 65 5. Records ......................................... 66 6. Field Testing ...67 C. Mix Design 1. General ......................................... 67 2. Laboratory Testing ...81 E. Mix i ng .......................................... 82 F. Relaying and Compacting.84 G. Testing

  8. Asphalt-aggregate interactions in hot recycling. Final report, April 1985-March 1987

    SciTech Connect

    Kiggundu, B.M.; Newman, J.K.

    1987-07-01

    This report summarizes results of an investigation of asphalt-aggregate interactions in hot recycled systems. Materials used in the research included a severe stripping aggregate and a nonstripping aggregate. Both were evaluated using the Lottman 70% retained tensile-strength criteria. Additional materials included a 40/60 RAP new aggregate system, one virgin asphalt, two RAP recovered binders, one modifier or recycling agent, and two blends. The modifier was selected using a recently developed specification involving physical, composition, and solubility properties. Aggregates were evaluated for surface area, bulk composition, water-soluble ions, cation exchange capacity, gradation, and specific gravities. Binders were tested for physical properties and composition properties using a modified Clay-Gel procedure, and compatibility properties using a modified Heithaus procedure.

  9. The use of natural sand from lampusatu beach, kabupatenmerauke, papua for mixed asphalt concrete

    NASA Astrophysics Data System (ADS)

    Huwae, D. D. M.; Parera, L. R.; Alpius; Tanijaya, J.

    2017-05-01

    The natural sand from LampuSatu Beach, KabupatenMerauke, Papua, is often used as building material by local people. This research aims to test the use of this natural sand for mixed asphalt concrete. Asphalt Concrete Wearing Course (AC-WC) with bitumen penetration 60/70 and variations of asphalt content 5%, 6%, 7%, 8% and 9% are used in this research. Testing result shows the stability 1372.17 kg, VIM 3.95%, VMA 16.81%, Flow 4.14 mm, and MQ 332.89 kg/mm. It has fulfilled the standard requirements set by Indonesian Director General for Highways. The percentage of Optimum Asphalt Content (OAC) is 7% and the Index of Retained Strength (IRS) is 107.84% (≥ 75%). These indicate that the mixture can fulfill the Stability and Marshall Immersion Test.

  10. Performance evaluation of high modulus asphalt concrete mixes

    NASA Astrophysics Data System (ADS)

    Haritonovs, V.; Tihonovs, J.; Zaumanis, M.

    2016-04-01

    Dolomite is one of the most available sedimentary rocks in the territory of Latvia. Dolomite quarries contain about 1000 million tons of this material. However, according to Latvian Road Specifications, this dolomite cannot be used for average and high intensity roads because of its low quality (mainly, LA index). Therefore, mostly imported magmatic rocks (granite, diabase, gabbro, basalt) or imported dolomite are used which makes asphalt expensive. However, practical experience shows that even with these high quality materials roads exhibit rutting, fatigue and thermal cracks. The aim of the research is to develop a high performance asphalt concrete for base and binder courses using only locally available aggregates. In order to achieve resistance against deformations at a high ambient temperature, a hard grade binder was used. Workability, fatigue and thermal cracking resistance, as well as sufficient water resistance is achieved by low porosity (3-5%) and higher binder content compared to traditional asphalt mixtures. The design of the asphalt includes a combination of empirical and performance based tests, which in laboratory circumstances allow simulating traffic and environmental loads. High performance AC 16 base asphalt concrete was created using local dolomite aggregate with polymer modified (PMB 10/40-65) and hard grade (B20/30) bitumen. The mixtures were specified based on fundamental properties in accordance to EN 13108-1 standard.

  11. Assessment of low temperature cracking in asphalt pavement mixes and rheological performance of asphalt binders

    NASA Astrophysics Data System (ADS)

    Sowah-Kuma, David

    Government spends a lot of money on the reconstruction and rehabilitation of road pavements in any given year due to various distresses and eventual failure. Low temperature (thermal) cracking, one of the main types of pavement distress, contributes partly to this economic loss, and comes about as a result of accumulated tensile strains exceeding the threshold tensile strain capacity of the pavement. This pavement distress leads to a drastic reduction of the pavement's service life and performance. In this study, the severity of low temperature (thermal) cracking on road pavements selected across the Province of Ontario and its predicted time to failure was assessed using the AASTHO Mechanistic-Empirical Pavement Design Guide (MEPDG) and AASHTOWARE(TM) software, with inputs such as creep compliance and tensile strength from laboratory test. Highway 400, K1, K2, Y1, Sasobit, Rediset LQ, and Rediset WMX were predicted to have a pavement in-service life above 15 years. Additionally, the rheological performance of the recovered asphalt binders was assessed using Superpave(TM) tests such as the dynamic shear rheometer (DSR) and bending beam rheometer (BBR). Further tests using modified standard protocols such as the extended bending beam rheometer (eBBR) (LS-308) test method and double-edge notched tension (DENT) test (LS-299) were employed to evaluate the failure properties associated with in service performance. The various rheological tests showed K1 to be the least susceptible to low temperature cracking compared to the remaining samples whiles Highway 24 will be highly susceptible to low temperature cracking. X-ray fluorescence (XRF) analysis was performed on the recovered asphalt binders to determine the presence of metals such as zinc (Zn) and molybdenum (Mo) believed to originate from waste engine oil, which is often added to asphalt binders. Finally, the severity of oxidative aging (hardening) of the recovered asphalt binders was also evaluated using the

  12. Effect of Crumb Rubber and Warm Mix Additives on Asphalt Aging, Rheological, and Failure Properties

    NASA Astrophysics Data System (ADS)

    Agrawal, Prashant

    Asphalt-rubber mixtures have been shown to have useful properties with respect to distresses observed in asphalt concrete pavements. The most notable change in properties is a large increase in viscosity and improved low-temperature cracking resistance. Warm mix additives can lower production and compaction temperatures. Lower temperatures reduce harmful emissions and lower energy consumption, and thus provide environmental benefits and cut costs. In this study, the effects of crumb rubber modification on various asphalts such as California Valley, Boscan, Alaska North Slope, Laguna and Cold Lake were also studied. The materials used for warm mix modification were obtained from various commercial sources. The RAF binder was produced by Imperial Oil in their Nanticoke, Ontario, refinery on Lake Erie. A second commercial PG 52-34 (hereafter denoted as NER) was obtained/sampled during the construction of a northern Ontario MTO contract. Some regular tests such as Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR), Multiple Stress Creep Recovery (MSCR) and some modified new protocols such as the extended BBR test (LS-308) and the Double-Edge Notched Tension (DENT) test (LS-299) are used to study, the effect of warm mix and a host of other additives on rheological, aging and failure properties. A comparison in the properties of RAF and NER asphalts has also been made as RAF is good quality asphalt and NER is bad quality asphalt. From the studies the effect of additives on chemical and physical hardening tendencies was found to be significant. The asphalt samples tested in this study showed a range of tendencies for chemical and physical hardening.

  13. Sustainable asphalt pavement: Application of slaughterhouse waste oil and fly ash in asphalt binder

    NASA Astrophysics Data System (ADS)

    Sanchez Ramos, Jorge Luis

    Increasing energy costs, lack of sufficient natural resources and the overwhelming demand for petroleum has stimulated the development of alternative binders to modify or replace petroleum-based asphalt binders. In the United States, the petroleum-based asphalt binder is mainly used to produce the Hot Mix Asphalt (HMA). There are approximately 4000 asphalt plants that make 500 million tons of asphalt binder valued at roughly 3 billion/year. The instability of the world's oil market has pushed oil prices to more than 80 per barrel in 2012, which increased the cost of asphalt binder up to $570 per ton. Therefore, there is a timely need to find alternative sustainable resources to the asphalt binder. This paper investigates the possibility of the partial replacement of the asphalt binder with slaughterhouse waste and/or fly ash. In order to achieve this objective, the asphalt binder is mixed with different percentages of waste oil and/or fly ash. In order to investigate the effect of these additives to the performance of the asphalt binder, a complete performance grade test performed on multiple samples. The results of the performance grade tests are compared with a control sample to observe how the addition of the waste oil and/or fly ash affects the sample. Considering the increasing cost and demand of asphalt, the use of slaughterhouse waste oil and/or fly ash as a partial replacement may result in environmental and monetary improvements in the transportation sector.

  14. Development of a simplified asphalt mix stability procedure for use in Superpave volumetric mix design

    NASA Astrophysics Data System (ADS)

    Hafez, Ihab Hussein Fahmy

    Over the last five decades, two common test methods (Marshall and Hveem) have evolved for the design of asphaltic mixes. These design methods have been historically found to be generally reliable and reasonable for most application in design. However, premature distress in many flexible pavements suggests that these empirical methods of design do not guarantee a stable mix. Recently, many studies have been carried out in order to develop a rational mix design procedure that accounts for both the mix volumetric properties as well as fundamental engineering properties. Among those is the Superpave design procedure, which was originally divided into three, hierarchical levels termed the volumetric mix design (level I), the abbreviated mix design (level II), and the full mix design (level III). In the volumetric design, the entire mix design process is based upon the volumetric properties and does not include a test method to evaluate the stability/strength of the mix. Although both the abbreviated level and the full level of design included test methods that considered the engineering properties in a complete and a comprehensive manner; they required the purchase of very expensive equipment and a large number of samples to be tested. The objective of this research was to develop a new rational "fundamental" mix strength (stability) test for the design of dense graded mixes to overcome the limitations of the Hveem and Marshall empirical methods and to fill the gaps and major deficiencies in the current Superpave volumetric mix design. The new procedure is based upon the Superpave volumetric design (level I) but is augmented by the simple, but fundamental mix strength (stability) test. Such a test is now currently absent in the existing Superpave approach. The new procedure introduces the flow time as a fundamental engineering design criterion in the mix design. This parameter is defined as the time (in seconds) at which plastic flow in a mix occurs under creep loading

  15. Recycling of contaminated soils by the AMREC cold-mix, asphalt-emulsion process

    SciTech Connect

    Camougis, G.

    1993-12-31

    This paper describes the management of contaminated soils by recycling with a cold-mix, asphalt-emulsion process developed by the American Reclamation Corporation (AmRec). This is a soil recycling/reuse process in which soils contaminated with petroleum products and other contaminants can be processed into asphalt products with beneficial uses. Most of the discussion will center on soils contaminated with petroleum products. However, the recycling of soils with other contaminants (e.g., heavy metals) will also be discussed. AmRec has produced approximately 500,000 tons of asphalt products with recycled materials. These products have been used beneficially in roadways, access roads, parking areas and landfills throughout the northwest.

  16. Short-term markers of DNA damage among roofers who work with hot asphalt.

    PubMed

    Serdar, Berrin; Brindley, Stephen; Dooley, Greg; Volckens, John; Juarez-Colunga, Elizabeth; Gan, Ryan

    2016-10-20

    Roofers are at increased risk for various malignancies and their occupational exposures to polycyclic aromatic hydrocarbons (PAHs) have been considered as important risk factors. The overall goal of this project was to investigate the usefulness of phosphorylated histone H2AX (γH2AX) as a short-term biomarker of DNA damage among roofers. Blood, urine, and dermal wipe samples were collected from 20 roofers who work with hot asphalt before and after 6 h of work on Monday and Thursday of the same week (4 sampling periods). Particle-bound and gas-phase PAHs were collected using personal monitors during work hours. γH2AX was quantified in peripheral lymphocytes using flow cytometry and 8-hydroxy-2-deoxyguanosine (8-OHdG) was assessed in urine using ELISA. General linear mixed models were used to evaluate associations between DNA damage and possible predictors (such as sampling period, exposure levels, work- and life-style factors). Differences in mean biomarker and DNA damage levels were tested via ANOVA contrasts. Exposure measurements did not show an association with any of the urinary biomarkers or the measures of DNA damage. Naphthalene was the most abundant PAH in gas-phase, while benzo(e)pyrene was the most abundant particle-bound PAH. Post-shift levels of γH2AX and 8-OHdG were higher on both study days, when compared to pre-shift levels. Cigarette smoking was a predictor of γH2AX and urinary creatinine was a predictor of urinary 8-OHdG. Between-subject variance to total variance ratio was 35.3 % for γH2ax and 4.8 % for 8-OHdG. γH2AX is a promising biomarker of DNA damage in occupational epidemiology studies. It has a lower within-subject variation than urinary 8-OHdG and can easily be detected in large scale groups. Future studies that explore the kinetics of H2AX phosphorylation in relation to chemical exposures may reveal the transient and persistent nature of this sensitive biomarker of early DNA damage.

  17. Reclaimed manufacturer asphalt roofing shingles in asphalt mixtures. Final research report

    SciTech Connect

    Reed, A.B.

    1999-04-23

    The purpose of this project was to pave a test section using hot mix asphalt with roofing shingle pieces in the wearing and binder courses and to evaluate. The test project near Allentown, PA plus two other test projects in 1998 provide evidence of very good pavement performance. The bituminous concrete mix was modified with shredded shingles with a maximum size of 1/2 inch which added 1% of the asphalt content. The Department issued a statewide Provisional Specification titled Reclaimed Manufacturer Asphalt Roofing Shingles in Plant-Mixed Bituminous Concrete Courses'' on March 15, 1999. New manufacturer asphalt roofing shingle scrap including tab punch-outs can be successfully incorporated in bituminous concrete pavements if the shingles are shredded to 100% passing the 3/4 inch sieve. To take full advantage of the potential to replace a portion of the asphalt and therefore, reduce mix costs, shingles should be shredded to 100% passing minus 1/2 inch sieve.

  18. Influence of fundamental material properties and air void structure on moisture damage of asphalt mixes

    NASA Astrophysics Data System (ADS)

    Arambula Mercado, Edith

    2007-12-01

    Moisture damage in asphalt mixes refers to the loss of serviceability due to the presence of moisture. The extent of moisture damage, also called moisture susceptibility, depends on internal and external factors. The internal factors relate to the properties of the materials and the microstructure distribution, while the external factors include the environmental conditions, production and construction practices, pavement design, and traffic level. The majority of the research on moisture damage is based on the hypothesis that infiltration of surface water is the main source of moisture. Of the two other principal mechanisms of water transport, permeation of water vapor and capillary rise of subsurface water, the latter has been least explored. A laboratory test and analysis methods based on X-ray computed tomography (CT) were established to assess the capillary rise of water. The amount and size of air voids filled with water were used in the capillary rise equation to estimate the distribution of the contact angles between the water and the mastic. The results were able to show the influence of air void size on capillary rise and contact angles. The relationship between air void structure and moisture susceptibility was evaluated using a fundamental fracture model based on dissipated energy of viscoelastic materials. Detailed description is provided in this dissertation on the deduction of the model equation, the selection of the model parameters, and the required testing protocols. The model parameters were obtained using mechanical tests and surface energy measurements. The microstructure of asphalt mixes prepared in the laboratory having different air void structures was captured using X-ray CT, and image analysis techniques were used to quantify the air void structure and air void connectivity. The air void structure was found to influence the mix resistance to moisture damage. To validate the fracture model, asphalt mixes with known field performance were

  19. Demonstration project number 39, hot mix recycling, Gray County, Kansas. Final report Jun 78-Nov 82

    SciTech Connect

    Maag, R.G.; Parcells, W.H. Jr.

    1983-01-01

    The objective of this demonstration project was to evaluate the hot-mix recycling process as a method of renovating a badly cracked and otherwise deteriorated section of road-mixed bituminous paving in southwestern Kansas. The equipment used on the project included a cold milling machine to reclaim the upper portion of existing pavement; a drum dryer hot-mix plant modified to process the material; and other standard hot-mix laydown and compaction machines. Energy consumption comparisons in equivalent gallons of fuel indicate a savings of 17.8% when the recycled method is compared to using all new aggregate. The energy saving is primarily due to less asphaltic cement required and less fuel needed to mill and reuse the existing pavement than to quarry and haul in an equivalent quantity of new aggregate.

  20. Current Practices on Nighttime Pavement Construction Asphaltic Concrete.

    DTIC Science & Technology

    1982-07-01

    foot width. This production amounted to approximately 1520 tons per night. 9. Equipment: a. Asphalt Spreader. The Contractor utilized one Blaw Knox ...Diego, CA. to monitor the testing of the Port Authority requirements. 11. Grade Control Requirements. a. Ski. The Blaw Knox paving machine was specified...q 16. Crack Reflection Membrane: None. 17. Hot Mix Asphaltic Concrete Overlay Placing: a. Asphalt Spreaders Operating in Echelon. Only one Blaw - Knox

  1. Quantification of the inherent uncertainty in the relaxation modulus and creep compliance of asphalt mixes

    NASA Astrophysics Data System (ADS)

    Kassem, Hussein A.; Chehab, Ghassan R.; Najjar, Shadi S.

    2017-08-01

    Advanced material characterization of asphalt concrete is essential for realistic and accurate performance prediction of flexible pavements. However, such characterization requires rigorous testing regimes that involve mechanical testing of a large number of laboratory samples at various conditions and set-ups. Advanced measurement instrumentation in addition to meticulous and accurate data analysis and analytical representation are also of high importance. Such steps as well as the heterogeneous nature of asphalt concrete (AC) constitute major factors of inherent variability. Thus, it is imperative to model and quantify the variability of the needed asphalt material's properties, mainly the linear viscoelastic response functions such as: relaxation modulus, E(t), and creep compliance, D(t). The objective of this paper is to characterize the inherent uncertainty of both E(t) and D(t) over the time domain of their master curves. This is achieved through a probabilistic framework using Monte Carlo simulations and First Order approximations, utilizing E^{*} data for six AC mixes with at least eight replicates per mix. The study shows that the inherent variability, presented by the coefficient of variation (COV), in E(t) and D(t) is low at small reduced times, and increases with the increase in reduced time. At small reduced times, the COV in E(t) and D(t) are similar in magnitude; however, differences become significant at large reduced times. Additionally, the probability distributions and COVs of E(t) and D(t) are mix dependent. Finally, a case study is considered in which the inherent uncertainty in D(t) is forward propagated to assess the effect of variability on the predicted number of cycles to fatigue failure of an asphalt mix.

  2. Multiscale imaging and characterization of the effect of mixing temperature on asphalt concrete containing recycled components.

    PubMed

    Cavalli, M C; Griffa, M; Bressi, S; Partl, M N; Tebaldi, G; Poulikakos, L D

    2016-10-01

    When producing asphalt concrete mixture with high amounts of reclaimed asphalt pavement (RAP), the mixing temperature plays a significant role in the resulting spatial distribution of the components as well as on the quality of the resulting mixture, in terms of workability during mixing and compaction as well as in service mechanical properties. Asphalt concrete containing 50% RAP was investigated at mixing temperatures of 140, 160 and 180°C, using a multiscale approach. At the microscale, using energy dispersive X-ray spectroscopy the RAP binder film thickness was visualized and measured. It was shown that at higher mixing temperatures this film thickness was reduced. The reduction in film thickness can be attributed to the loss of volatiles as well as the mixing of RAP binder with virgin binder at higher temperatures. X-ray computer tomography was used to characterize statistically the distribution of the RAP and virgin aggregates geometric features: volume, width and shape anisotropy. In addition using X-ray computer tomography, the packing and spatial distribution of the RAP and virgin aggregates was characterized using the nearest neighbour metric. It was shown that mixing temperature may have a positive effect on the spatial distribution of the aggregates but did not affect the packing. The study shows a tendency for the RAP aggregates to be more likely distributed in clusters at lower mixing temperatures. At higher temperatures, they were more homogeneously distributed. This indicates a higher degree of blending both at microscale (binder film) and macroscale (spatial distribution) between RAP and virgin aggregates as a result of increasing mixing temperatures and the ability to quantify this using various imaging techniques. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  3. Applicability Determination for PSD- Hot Mix Asphalt Operations

    EPA Pesticide Factsheets

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  4. Use of recycled chunk rubber asphalt concrete (CRAC) on low volume roads and use of recycled crumb rubber modifier in asphalt pavements. Final report, June 1993-June 1995

    SciTech Connect

    Hossain, M.; Funk, L.P.; Sadeq, M.A.; Marucci, G.

    1995-06-01

    The major objective of this project was to formulate a Chunk Rubber Asphalt Concrete (CRAC) mix for use on low volume roads. CRAC is a rubber modified asphalt concrete product produced by the `dry process` where rubber chunks of 1/2 inch size are used as aggregate in a cold mix with a type C fly ash. The second objective of this project was to develop guidelines concerning the use of rubber modified asphalt concrete hot mix to include: (1) Design methods for use of asphalt-rubber mix for new construction and overlay, (2) Mix design method for asphalt-rubber, and (3) Test method for determining the amount of rubber in an asphalt-rubber concrete for quality control purposes.

  5. Characterization of asphalt and asphalt recyclability

    SciTech Connect

    Painter, P.C.

    1993-10-01

    The goal of the research program was to construct a simple model and computer programs that will allow at least a qualitative understand of the phase behavior of asphalt (i.e., how asphalt components mix with one another), mixtures of different types of asphalt (i.e., in recycling) and mixtures of asphalt with other materials, such as synthetic polymers. The authors have constructed such a model and computer programs (for Macintosh computers) that allow such calculations to be performed easily.

  6. Characteristics of permanent deformation rate of warm mix asphalt with additives variation (BNA-R and zeolite)

    NASA Astrophysics Data System (ADS)

    Wahjuningsih, Nurul; Hadiwardoyo, Sigit Pranowo; Sumabrata, R. Jachrizal

    2017-06-01

    Permanent deformation is one of the criteria of failure on asphalt concrete mixture. The nature of the bitumen melt at high temperatures, this condition causes the asphalt concrete mixture tends to soften due to an increase in temperature of the road surface. The increase in surface temperature and the load wheel that has repeated itself on the same trajectory causes deformation groove has formed. Conditions rutting due to permanent deformation has resulted in inconvenience to the passengers and can lead to high costs of road maintenance. On the road planning process required a prediction of the rate of the permanent deformation of asphalt concrete mixtures. It is important to know early on the road surface damage due to vehicle load and surface temperature during service life. Asphalt has been mixed with the additive BNA-R and Zeolite intended to make variations in the characteristics of bitumen in this study. This variation is further combined with variations in the composition of aggregate in order to obtain a combination of asphalt-aggregate mixture. This mixture using warm mix, and to determine the permanent deformation of asphalt mix with material combinations was performed through the wheel tracking test machine with 3,780 cycles or 7,560 tracks for 3 hours. Another analysis to determine the characteristics of asphalt concrete mixtures have also been carried out changes in the surface temperature at the time of the test track. From the results of the test track to nearly 8 thousand passes has seen permanent deformation characteristics of asphalt concrete mixture with a variation of the characteristics of bitumen and aggregate variation. Groove of deformation due to a wheel load from the initial until the last passes shows that there are influence of compaction temperature on the variation of bitumen and aggregate composition to the relationship of permanent deformation of the wheel groove, especially on the road surface temperature changes.

  7. Diagnosis of moisture damage in asphalt pavements

    NASA Astrophysics Data System (ADS)

    Canning, Jacqueline S.; Niezrecki, Christopher; Birgisson, Bjorn

    2004-07-01

    One of the most common modes of premature failure of asphalt pavements is water damage. Moisture damage in hot-mix asphalt (HMA) pavements occurs when water infiltrates the pavement system, causing premature failure of hot-mix asphalt pavements, primarily through loss of adhesion between the asphalt binder and the aggregates. Loss of adhesion can lead to stripping of the asphalt film from the aggregate and raveling, where aggregates are dislodged from the pavement. The laboratory testing procedures currently available for testing HMA moisture susceptibility were primarily developed to determine the degree of resistance to moisture damage by a particular combination of asphalt and aggregate as well as compare mixes composed of different types and quantities of aggregate. These methods are all based on destructive testing. There is currently a need for innovative nondestructive testing technologies that can be used to identify and isolate the effects of water damage in mixtures. As a first step in the development of a non-destructive method to test HMA pavements, modal hammer tests were conducted on several test specimens of fine and coarse grained granite-based mixes commonly used by the Florida Department of Transportation (FDOT). The results of the testing indicate that there is a large frequency shift in the transfer function measurements for the damaged samples compared to the undamaged samples. The results imply that modal hammer testing may be used as a method to characterize the health of HMA pavements.

  8. Prediction of frequency for simulation of asphalt mix fatigue tests using MARS and ANN.

    PubMed

    Ghanizadeh, Ali Reza; Fakhri, Mansour

    2014-01-01

    Fatigue life of asphalt mixes in laboratory tests is commonly determined by applying a sinusoidal or haversine waveform with specific frequency. The pavement structure and loading conditions affect the shape and the frequency of tensile response pulses at the bottom of asphalt layer. This paper introduces two methods for predicting the loading frequency in laboratory asphalt fatigue tests for better simulation of field conditions. Five thousand (5000) four-layered pavement sections were analyzed and stress and strain response pulses in both longitudinal and transverse directions was determined. After fitting the haversine function to the response pulses by the concept of equal-energy pulse, the effective length of the response pulses were determined. Two methods including Multivariate Adaptive Regression Splines (MARS) and Artificial Neural Network (ANN) methods were then employed to predict the effective length (i.e., frequency) of tensile stress and strain pulses in longitudinal and transverse directions based on haversine waveform. It is indicated that, under controlled stress and strain modes, both methods (MARS and ANN) are capable of predicting the frequency of loading in HMA fatigue tests with very good accuracy. The accuracy of ANN method is, however, more than MARS method. It is furthermore shown that the results of the present study can be generalized to sinusoidal waveform by a simple equation.

  9. Prediction of Frequency for Simulation of Asphalt Mix Fatigue Tests Using MARS and ANN

    PubMed Central

    Fakhri, Mansour

    2014-01-01

    Fatigue life of asphalt mixes in laboratory tests is commonly determined by applying a sinusoidal or haversine waveform with specific frequency. The pavement structure and loading conditions affect the shape and the frequency of tensile response pulses at the bottom of asphalt layer. This paper introduces two methods for predicting the loading frequency in laboratory asphalt fatigue tests for better simulation of field conditions. Five thousand (5000) four-layered pavement sections were analyzed and stress and strain response pulses in both longitudinal and transverse directions was determined. After fitting the haversine function to the response pulses by the concept of equal-energy pulse, the effective length of the response pulses were determined. Two methods including Multivariate Adaptive Regression Splines (MARS) and Artificial Neural Network (ANN) methods were then employed to predict the effective length (i.e., frequency) of tensile stress and strain pulses in longitudinal and transverse directions based on haversine waveform. It is indicated that, under controlled stress and strain modes, both methods (MARS and ANN) are capable of predicting the frequency of loading in HMA fatigue tests with very good accuracy. The accuracy of ANN method is, however, more than MARS method. It is furthermore shown that the results of the present study can be generalized to sinusoidal waveform by a simple equation. PMID:24688400

  10. Development of a crumb rubber modified (CRM) asphalt concrete mix design. Final report, June 1993-May 1995

    SciTech Connect

    Hossain, M.; Swartz, S.E.; Hoque, M.E.; Funk, L.P.

    1995-05-01

    The objective of this project was to develop an asphalt mix design method incorporating crumb rubber and using the `Wet` or `Dry` method of producing Crumb Rubber Modified Asphalt (CRM). Several resurfacing projects have been constructed using both the `Wet` and `Dry` methods. Based on this study, KDOT could use CRM mixes with a binder content between 7.5% and 9.0% depending on the percent air voids, with 19% to 22% rubber content. In this study, it was observed that using 24% rubber produced mixed were too sticky to manage. With a rubber content of less than 18% combined with AC-5 it was difficult to satisfy the minimum requirements. Fracture tests can be used as a basis to determine the optimum binder content for any asphalt-rubber mix.

  11. City finds new efficiencies in hot in-place asphalt recycling

    SciTech Connect

    Not Available

    1993-07-01

    This article reviews the experience of Boulder, Colorado, in recycling asphalt pavement in place during repair of a major city artery. The method used was able to recover, level and compact one inch of the existing roadway while filling potholes, cracks and other surface defects with asphaltic patching material. There was considerable savings in materials, cost and down-time for the roadway section.

  12. Asphalt coking method

    SciTech Connect

    Bonilla, J.A.; Elliott, J.D.

    1987-08-11

    A process is described for treating a heavy hydrocarbon fluid containing asphaltenes comprising: contacting the heavy hydrocarbon fluid with a solvent, wherein the solvent is light naphtha, C/sub 4/ hydrocarbons, C/sub 5/ hydrocarbons, C/sub 6/ hydrocarbons, or a mixture of any of light naphtha and C/sub 4/, C/sub 5/ and C/sub 6/ hydrocarbons, to obtain an asphalt mix, containing asphalt and the solvent, and deasphalted oil mix, containing deasphalted oil and the solvent; feeding the asphalt mix to a delayed coking process to form coke, wherein the asphalt mix is heated by passing the asphalt mix through conduit means in a heater in the delayed coking process. The flow of the asphalt mix through the conduit means is assisted by vaporization in the heater of the solvent in the asphalt mix, and the asphalt mix includes sufficient solvent to provide a residence time of the asphalt mix in the heater adequate for heating the asphalt mix for coking while reducing the formation of coke in the heater; separating the solvent in the deasphalted oil mix from the deasphalted oil mix to yield deasphalted oil; and recovering the deasphalted oil, bypassing the delayed coking process.

  13. Assessment of the potential suitability of southwest Brooklyn incinerator residue in asphaltic-concrete mixes. Final report

    SciTech Connect

    Chesner, W.H.; Collins, R.J.; Fung, T.

    1988-02-01

    The results of a one-year incinerator residue sampling program at the Southwest Brooklyn Incinerator in New York City are reported. The program was designed to characterize the physical properties of incinerator residue. Asphalt mixes were prepared using blends of sampled incinerator residue with conventional aggregate, to determine the suitability of using incinerator residue in asphaltic concrete for road paving applications. The results of the investigation are compared with those of previous studies. Engineering and processing requirements are presented for converting residue into a usable aggregate material. Capital costs, operating costs, potential revenues and net annual costs are provided for a full-scale residue processing facility at the Southwest Brooklyn Incinerator. Environmental issues associated with residue recycling are identified and discussed. Recommendations are provided for additional laboratory work and field applications needed to demonstrate the use of residue in asphalt mixes.

  14. Hot rolled asphalt: Effect of binder properties on resistance to deformation

    NASA Astrophysics Data System (ADS)

    Jacobs, F. A.

    Those properties of binders that most affect the resistance to deformation of rolled asphalt are discussed. Thirteen binders were studied and mixtures containing them were subjected to design tests and the wheel tracking test. These laboratory mechanical tests show that, within the range of binders tested, significant improvements in resistance to deformation can be achieved over a range of high road temperatures by increasing the softening point of the binder, irrespective of its penetration at 25 C.

  15. Analysis of Adhesive Characteristics of Asphalt Based on Atomic Force Microscopy and Molecular Dynamics Simulation.

    PubMed

    Xu, Meng; Yi, Junyan; Feng, Decheng; Huang, Yudong; Wang, Dongsheng

    2016-05-18

    Asphalt binder is a very important building material in infrastructure construction; it is commonly mixed with mineral aggregate and used to produce asphalt concrete. Owing to the large differences in physical and chemical properties between asphalt and aggregate, adhesive bonds play an important role in determining the performance of asphalt concrete. Although many types of adhesive bonding mechanisms have been proposed to explain the interaction forces between asphalt binder and mineral aggregate, few have been confirmed and characterized. In comparison with chemical interactions, physical adsorption has been considered to play a more important role in adhesive bonding between asphalt and mineral aggregate. In this study, the silicon tip of an atomic force microscope was used to represent silicate minerals in aggregate, and a nanoscale analysis of the characteristics of adhesive bonding between asphalt binder and the silicon tip was conducted via an atomic force microscopy (AFM) test and molecular dynamics (MD) simulations. The results of the measurements and simulations could help in better understanding of the bonding and debonding procedures in asphalt-aggregate mixtures during hot mixing and under traffic loading. MD simulations on a single molecule of a component of asphalt and monocrystalline silicon demonstrate that molecules with a higher atomic density and planar structure, such as three types of asphaltene molecules, can provide greater adhesive strength. However, regarding the real components of asphalt binder, both the MD simulations and AFM test indicate that the colloidal structural behavior of asphalt also has a large influence on the adhesion behavior between asphalt and silicon. A schematic model of the interaction between asphalt and silicon is presented, which can explain the effect of aging on the adhesion behavior of asphalt.

  16. Comparing Production and Placement of Warm-Mix Asphalt to Traditional Hot-Mix Asphalt for Constructing Airfield Pavements

    DTIC Science & Technology

    2013-08-01

    Sasobit® STA 0+35 cross-section layer thicknesses as constructed............................... 36  Figure 50. Evotherm ™ center-line layer thicknesses...as constructed. ................................................ 37  Figure 51. Evotherm ™ STA 0+15 cross-section layer thicknesses as constructed...37  Figure 52. Evotherm ™ STA 0+25 cross-section layer thicknesses as constructed. .......................... 38  Figure 53

  17. Oxidation and photooxidation of asphalts

    SciTech Connect

    Mill, T.; Tse, D. )

    1990-07-01

    Oxidation of asphalt is a major cause of pavement failure owing to hardening of the asphalt binder with accompanying changes in viscosity, separation of components, embrittlement and loss of cohesion and adhesion of the asphalt in the mix. However oxidation of asphalt-aggregate mixes at high temperature is deliberately done to partly harden the mix prior to laydown; hardening then continues during cooling. Excessive hardening at this point is undesirable because of embrittlement and cracking. Slow oxidation of asphalt continues during the service life of the roadbed at a rate that appears to be partly determined by the void volume of the roadbed, as well as the properties of the asphalt and (possibly) the properties of the aggregate. The authors focused their efforts on understanding the mechanistic basis for slow oxidation of asphalt under service conditions in order to predict how rapidly an asphalt will oxidize, based on its composition, and to find better ways to inhibit the process under service conditions.

  18. Analysis of the binder yield energy test as an indicator of fatigue behaviour of asphalt mixes

    NASA Astrophysics Data System (ADS)

    O’Connell, Johan; Mturi, Georges A. J.; Komba, Julius; Du Plessis, Louw

    2017-09-01

    Empirical binder testing has increasingly failed to predict pavement performance in South Africa, with fatigue cracking being one of the major forms of premature pavement distress. In response, it has become a national aspiration to incorporate a performance related fatigue test into the binder specifications for South Africa. The Binder Yield Energy Test (BYET) was the first in a series of tests analysed for its potential to predict the fatigue performance of the binder. The test is performed with the dynamic shear rheometer, giving two key parameters, namely, yield energy and shear strain at maximum shear stress (γτmax). The objective of the investigation was to perform a rudimentary evaluation of the BYET; followed by a more in-depth investigation should the initial BYET results prove promising. The paper discusses the results generated from the BYET under eight different conditions, using six different binders. The results are then correlated with four point bending beam fatigue test results obtained from asphalt mix samples that were manufactured from the same binders. Final results indicate that the BYET is not ideal as an indicator of fatigue performance.

  19. Laboratory Performance Testing of Warm-Mix Asphalt Technologies for Airfield Pavements

    DTIC Science & Technology

    2013-12-01

    2.4.3  Hamburg Loaded Wheel Tracker (HLWT) ................................................................ 11  2.4.4  Asphalt Pavement Analyzer ( APA ...21  3.5  APA wheel tracking...34  4.5  APA wheel tracking

  20. Coal-based synthetic asphalts

    SciTech Connect

    Kang, J.H.

    1986-01-01

    The study investigated the technical and economic feasibility of producing a specification-grade, local-based asphalt from a raw coal available in the United States. Bench-scale hydrogenation experiments were performed in a one-gallon autoclave to produce asphalts from Illinois No. 6 bituminous coal and Clovis Point subbituminous coal. Samples from the process streams of a continuous coal liquefaction pilot plant at Wilsonville, AL were also evaluated to determine the potential for making a paving asphalt. The results showed that coal-based asphalts have a higher age-hardening rate than petroleum asphalts; also, they have a higher viscosity-temperature susceptibility (VTS) number. The high age-hardening rate of coal-based asphalts could be offset satisfactorily via catalytic hydrogenation. The VTS of these asphalts could be markedly reduced by adding a certain amount of styrene/butadiene copolymer. As a result, a specification grade, coal-based asphalt was successfully made via catalytic hydrogenation of coal combined with the incorporation of ca. 3 wt% styrene/butadiene copolymer into the coal-based asphalt. Marshall stability testing showed that coal based asphalt/aggregate compacted mixes had excellent resistance to plastic flow. Immersion compression testing revealed that the compacted mixes had a high initial compression strength and retained strength. A two-stage coal-based asphalt process was designed for producing 1000 tons/day. Economic analyses showed that the coal-based asphalt would be more expensive than currently used petroleum asphalt.

  1. Recycled materials in asphalt pavements. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-05-01

    The bibliography contains citations concerning the recycling of asphalt pavement materials, and the use of other recycled materials to manufacture asphalt pavement. Articles discuss methods used for recycling bituminous pavement including hot-mix and cold-mix. Materials used to improve recycled pavement, and recycled materials used in asphalt pavement include latexes, rubber scrap such as tires, glass shards, concretes, dusts, waste oils, roofing wastes, sulfur, and metal refining sludges. Testing and evaluation of recycled pavements both in laboratories and in test cases are considered. (Contains a minimum of 160 citations and includes a subject term index and title list.)

  2. Bone Glue Modified Asphalt: A Step towards Energy Conservation and Environment Friendly Modified Asphalts.

    PubMed

    Rizvi, Hashim Raza; Khattak, Mohammad Jamal; Gallo, August A

    2014-01-01

    Asphalt has been modified for the past several decades using various additives, including synthetic polymers. Polymer modification improves structural and engineering characteristics of the binder, which is a result of improvement in rheological characteristics of binder as well as its adhesion capability with the aggregate. Such enhancement inevitably enhances the performance characteristics of hot mix asphalts (HMA) such as fatigue life, resistance to rutting, and thermal cracking. Even though polymer-modified HMA is popular in North America and European countries, its use is still limited in developing countries of Southeast Asia due to high costs associated with its manufacturing, processing, and energy consumption. In this study, a new kind of asphalt modifier derived from animal wastes, such as bones, hides, and flesh commonly known as Bone Glue, is studied. This biomaterial which is a by-product of food and cattle industries is cheap, conveniently available, and produced locally in developing countries. The results of the research study showed that the bone glue can easily be mixed with asphalt without significantly altering the asphalt binder's viscosity and mixing and compaction temperatures of HMA. Additionally, improvements in complex shear modulus for a range of temperatures were also determined and it was found that complex shear modulus was improved by bone glue modification.

  3. Bone Glue Modified Asphalt: A Step towards Energy Conservation and Environment Friendly Modified Asphalts

    PubMed Central

    Rizvi, Hashim Raza; Gallo, August A.

    2014-01-01

    Asphalt has been modified for the past several decades using various additives, including synthetic polymers. Polymer modification improves structural and engineering characteristics of the binder, which is a result of improvement in rheological characteristics of binder as well as its adhesion capability with the aggregate. Such enhancement inevitably enhances the performance characteristics of hot mix asphalts (HMA) such as fatigue life, resistance to rutting, and thermal cracking. Even though polymer-modified HMA is popular in North America and European countries, its use is still limited in developing countries of Southeast Asia due to high costs associated with its manufacturing, processing, and energy consumption. In this study, a new kind of asphalt modifier derived from animal wastes, such as bones, hides, and flesh commonly known as Bone Glue, is studied. This biomaterial which is a by-product of food and cattle industries is cheap, conveniently available, and produced locally in developing countries. The results of the research study showed that the bone glue can easily be mixed with asphalt without significantly altering the asphalt binder's viscosity and mixing and compaction temperatures of HMA. Additionally, improvements in complex shear modulus for a range of temperatures were also determined and it was found that complex shear modulus was improved by bone glue modification. PMID:27437456

  4. State of the practice: Design and construction of asphalt paving materials with crumb-rubber modifier. Final report

    SciTech Connect

    Heitzman, M.A.

    1992-05-01

    The document is a comprehensive overview of the terminology, processes, products, and applications of crumb rubber modifier (CRM) technology. The technology includes any use of scrap tire rubber in asphalt paving materials. In general, CRM technology can be divided into two categories--the wet process and the dry process. When CRM is incorporated into an asphalt paving material, it will modify the properties of the binder (asphalt rubber) and/or act as a rubber aggregate (rubber modified hot mix asphalt). The five concepts for using CRM discussed in the report are McDonald, PlusRide, generic dry, chunk rubber asphalt concrete, and continuous blending asphalt rubber. There are two principal unresolved engineering issues related to the use of CRM in asphalt paving materials. On the national level, the ability to recycle asphalt paving mixes containing CRM has not been demonstrated. At the State and local levels, these modified asphalt mixes must be field evaluated to establish expected levels of performance. The appendices provide guidelines for material specifications, mix design, and construction specifications. An experimental work plan for monitoring performance and a stack emission testing program are also included.

  5. 9. Tower building. Hot water tap floor shown. Mixing vat ...

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

    9. Tower building. Hot water tap floor shown. Mixing vat at center level. Juices mix and flow and left lower level. Copper kettles are down below view level. Looking toward front of building. - Tivoli-Union Brewery, 1320-1348 Tenth Street, Denver, Denver County, CO

  6. Feasibility of crumb rubber use for asphalt pavement construction in Rhode Island. Final research report

    SciTech Connect

    Lee, K.W.; Kovacs, W.D.; Marcus, A.S.; Madapati, R.R.

    1995-12-15

    This is the final report of the research project, entitled `Viable Use of Crumb Rubber for Highway Construction in Rhode Island.` This study dealt with the investigation of the means by which the State of Rhode Island can effectively comply with the mandate of the Section 1038 of the 1991 Intermodal Surface Transportation Efficiency Act (ISTEA) to use recycled rubber in asphalt pavements. More specifically, this laboratory investigation characterized Hot Mix Asphalt (HMA) with Crumb Rubber Modifiers (CRM).

  7. Feasibility of the use of ultrasound measurements for grade verification of the performance grade asphalt binders

    NASA Astrophysics Data System (ADS)

    Khalili, Mehdi

    This research investigates the feasibility of application of high frequency immersion ultrasonic measurement (UM) to discriminate different performance grade (PG) asphalt binders. PG asphalt binder is one of the main components of hot mix asphalt used for roadway construction. UT may provide an inexpensive alternative to sophisticated tests currently used for quality control of PG asphalt binders. Nine different PG asphalt binders used were selected for this investigation. Velocity (V) and integrated response (IR) of the ultrasonic wave were measured. The IR is a measure of the ratio of ultrasonic energy transmitted into the material to the ultrasonic energy reflected from the surface of material, in decibels. The physical properties of PG asphalt binders are temperature sensitive. Accordingly, the UM was performed at five temperatures. The results indicate that velocity decrease with increase in temperature of the asphalt binder. UT could distinguish between modified and non-modified asphalt binders. Discriminant Function Analysis was used to predict the grade of the performance grade asphalt binders using the UM.

  8. Crumb rubber modified asphalt concrete in Oregon. Summary report. Report for 1985-94

    SciTech Connect

    Hunt, E.; Peters, W.

    1995-07-01

    Over the last nine years, the Oregon Department of Transportation (ODOT) has constructed 13 projects using crumb rubber modifiers (CRM) in asphalt concrete pavements using both the wet and dry process. State and federal legislation may require the use of recycled rubber in asphalt concrete, therefore, the Oregon Department of Transportation is interested in determining the most cost -effective crumb rubber modified asphalt concrete. The report includes a literature review on the use of crumb rubber modifiers in asphalt concrete pavement; a review on non-ODOT CRM paving projects constructed by Oregon counties and cities; and the Washington Department of Transportation. In additon, the report summarizes the data collected on all CRM hot mix asphalt concrete pavement projects constructed by ODOT. The ODOT information includes background constitution, cost, and performance data for each of the test and control sections. Finally, the future activities of the project are reviewed.

  9. Bacteria and asphalt stripping. Final report, December 1983-August 1987

    SciTech Connect

    Ramamurti, K.; Jayaprakash, G.P.

    1987-08-01

    Major types of bituminous pavement distress were rutting, cracking (longitudinal, transverse, and alligator) and stripping. The rubble and loosely bound material contained bacteria. The deterioration lessened upward from the pavement-soil interface. The soil appears to be the prime source of the bacteria. Most of the bacterial cells were sausage shaped with polar flagellation. They appeared to belong to the genus Pseudomonas, which is a known user of asphaltic hydrocarbons. Cocci-type bacteria and a virus were also noted. Increasing the density of some asphaltic concrete and strengthening the bond between aggregate and asphalt are considered as the preferred alternatives to using chemical biocides. Anything to reduce pavement cracking would help. Adding lime to asphalt mixes may be one effective means of improving aggregate-asphalt bond and controlling biodeterioration. Lime stabilization of soils under asphalt pavements may provide an added protection against bacterial attack by rendering the soil more hostile to bacterial habitat. Full-depth hot-mix recycling would be more effective than partial-depth recycling in retarding bacterial decay at cracks.

  10. The Potential of Heat Collection from Solar Radiation in Asphalt Solar Collectors in Malaysia

    NASA Astrophysics Data System (ADS)

    Beddu, Salmia; Talib, Siti Hidayah Abdul; Itam, Zarina

    2016-03-01

    The implementation of asphalt solar collectors as a means of an energy source is being widely studied in recent years. Asphalt pavements are exposed to daily solar radiation, and are capable of reaching up to 70°C in temperature. The potential of harvesting energy from solar pavements as an alternative energy source in replace of non-renewable energy sources prone to depletion such as fuel is promising. In Malaysia, the sun intensity is quite high and for this reason, absorbing the heat from sun radiation, and then utilizing it in many other applications such as generating electricity could definitely be impressive. Previous researches on the different methods of studying the effect of heat absorption caused by solar radiation prove to be quite old and inaffective. More recent findings, on the otherhand, prove to be more informative. This paper focuses on determining the potential of heat collection from solar radiation in asphalt solar collectors using steel piping. The asphalt solar collector model constructed for this research was prepared in the civil engineering laboratory. The hot mixed asphalt (HMA) contains 10% bitumen mixed with 90% aggregates of the total size of asphalt. Three stainless steel pipes were embedded into the interior region of the model according to the design criteria, and then put to test. Results show that harvesting energy from asphalt solar collectors proves highly potential in Malaysia due its the hot climate.

  11. Recycled materials in asphalt pavements, January 1980-June 1991 (citations from the NTIS database). Rept. for Jan 80-Jun 91

    SciTech Connect

    Not Available

    1991-06-01

    The bibliography contains citations concerning the recycling of asphalt pavement materials, and the use of other recycled materials to manufacture asphalt pavement. Articles discuss methods used for recycling bituminous pavement including hot-mix and cold-mix. Materials used to improve recycled pavement, and recycled materials used in asphalt pavement include latexes, rubber scrap such as tires, glass shards, concretes, dusts, waste oils, roofing wastes, sulfur, and metal refining sludges. Testing and evaluation of recycled pavements both in laboratories and in test cases are considered. (The bibliography contains 75 citations.) (Also includes title list and subject index.)

  12. Investigation of factors affecting asphalt pavement recycling and asphalt compatibility

    SciTech Connect

    Venable, R.L.; Petersen, J.C.; Robertson, R.E.; Plancher, H.

    1983-03-01

    Both economic and environmental factors dictate that asphalt pavement be recycled. Many recycling projects have been completed using a variety of recycling additives, but little work has been done on the physiochemical aspects of pavement recycling. The present exploratory study was undertaken to better define the physiochemical variables of recycling. Objectives of the present study include: (1) to determine if molecular structuring in the asphalt binder could be observed in oxidized (air-aged) asphalt-aggregate briquets, and if so, how was structuring affected during briquits, and if so, how was structuring affected during briquet recycling and (2) to determine if recycling agents penetrate the strongly adsorbed asphalt layer on the aggregate surface. Differences were seen in asphalt component compatibility as judged by the state of peptization parameters. In extreme cases the values of the parameters correlated with properties of asphalts of known compatibility; however, a relationship between the parameters determined on a series of asphalts in pavements was not established. The parameters might be useful in evaluating additives for pavement recycling; however, more systems need to be studied to fully assess their potential usefulness. Finally, the parameters need to be correlated with performance-related measurements such as asphalt rheological and mix properties. Examination of the parameters and their changes on asphalt oxidative aging may also be informative with regard to asphalt durability inasmuch as oxidation-induced changes are a major cause of asphalt pavement failure.

  13. Asphalt Roofing Shingles Into Energy Project Summary Report

    SciTech Connect

    Jameson, Rex, PE

    2008-04-28

    Based on a widely cited September, 1999 report by the Vermont Agency of Natural Resources, nearly 11 million tons of asphalt roofing shingle wastes are produced in the United States each year. Recent data suggests that the total is made up of about 9.4 million tons from roofing tear-offs and about 1.6 million tons from manufacturing scrap. Developing beneficial uses for these materials would conserve natural resources, promote protection of the environment and strengthen the economy. This project explored the feasibility of using chipped asphalt shingle materials in cement manufacturing kilns and circulating fluidized bed (CFB) boilers. A method of enhancing the value of chipped shingle materials for use as fuel by removing certain fractions for use as substitute raw materials for the manufacture of new shingles was also explored. Procedures were developed to prevent asbestos containing materials from being processed at the chipping facilities, and the frequency of the occurrence of asbestos in residential roofing tear-off materials was evaluated. The economic feasibility of each potential use was evaluated based on experience gained during the project and on a review of the well established use of shingle materials in hot mix asphalt. This project demonstrated that chipped asphalt shingle materials can be suitable for use as fuel in circulating fluidized boilers and cement kilns. More experience would be necessary to determine the full benefits that could be derived and to discover long term effects, but no technical barriers to full scale commercial use of chipped asphalt shingle materials in these applications were discovered. While the technical feasibility of various options was demonstrated, only the use of asphalt shingle materials in hot mix asphalt applications is currently viable economically.

  14. Full-Scale Accelerated Pavement Testing of Warm-Mix Asphalt (WMA) for Airfield Pavements

    DTIC Science & Technology

    2014-01-01

    software and Pavement Engineering Utility (PSEVEN) were used 50 ft 65 ft 130 ft 24 ft Item 3 Sasobit ® Item 4 Evotherm 3G Item 1 HMA... Evotherm 3G Air Top Mid-depth Bottom Target temperature = 109 ºF ERDC/GSL TR-14-3 25 The target pavement temperature for this study was 109 ºF, and it is...the locations of the I-buttons and their layout in relation to the vents. 90 95 100 105 110 115 120 HMA Foamed Asphalt Sasobit Evotherm 3G Av er ag e

  15. Construction of an experimental sulfur-extended-asphalt pavement

    NASA Astrophysics Data System (ADS)

    Dodge, K. S.

    1982-07-01

    The design, placement and collection of initial data from a sulfur extended asphalt (SEA) pavement and a conventional pavement used as a control is documented. The SEA pavement used 30 percent sulfur by total weight of the binder. Mix temperatures, hot bin gradations, and toxic emissions were monitored at the plant and the site throughout placement. Aggregates were collected from the hot bin during production of the control and SEA mixes for use in a Marshall mix design. Cores were extracted from both SEA and control pavements 1 month after placement for laboratory testing. Pavement surface properties were also examined after 1 month of service.

  16. Hot spot mix in ICF implosions on the NIF

    NASA Astrophysics Data System (ADS)

    Ma, Tammy

    2016-10-01

    In the quest to achieve ignition through the inertial confinement fusion scheme, one of the critical challenges is to drive a symmetric implosion at high velocity without hydrodynamic instabilities becoming detrimental. These instabilities, primarily at the ablation front and the fuel-ablator interface, can cause mix of the higher-Z shell into the hot spot, resulting in increased radiation loss and thus reduced temperature and neutron yield. To quantify the level of mix, we developed a model that infers the level of hot spot contamination using the ratio of the enhanced x-ray production relative to the neutron yield. Applying this methodology to the full ensemble of indirect-drive National Ignition Facility (NIF) cryogenically layered DT implosions provides insight on the sensitivity of performance to the level of ablator-hot spot mix. In particular, the improvement seen with the High Foot design can be primarily attributed to a reduction in ablation-front instability mix that enabled the implosions to be pushed to higher velocity and performance. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, Lawrence Livermore National Security, LLC.

  17. Recycling asphalt pavements. January 1975-January 1990 (a Bibliography from the COMPENDEX data base). Report for January 1975-January 1990

    SciTech Connect

    Not Available

    1990-03-01

    This bibliography contains citations concerning the recycling of asphalt-containing pavement materials. Articles include examples of recycling asphalt pavements; performance testing of recycled paving; methods including cold in-place, cold off-site, and hot-mix recycling; additives in recycled pavement for better performance; use of scrap roofing asphalt in conjunction with recycled paving; economics of recycling; process design; and process variables. Recycling of other materials is considered in related bibliographies. (Contains 130 citations fully indexed and including a title list.)

  18. Airborne Exposures to Polycyclic Aromatic Compounds Among Workers in Asphalt Roofing Manufacturing Facilities.

    PubMed

    Trumbore, David C; Osborn, Linda V; Johnson, Kathleen A; Fayerweather, William E

    2015-01-01

    We studied exposure of 151 workers to polycyclic aromatic compounds and asphalt emissions during the manufacturing of asphalt roofing products-including 64 workers from 10 asphalt plants producing oxidized, straight-run, cutback, and wax- or polymer-modified asphalts, and 87 workers from 11 roofing plants producing asphalt shingles and granulated roll roofing. The facilities were located throughout the United States and used asphalt from many refiners and crude oils. This article helps fill a gap in exposure data for asphalt roofing manufacturing workers by using a fluorescence technique that targets biologically active 4-6 ring polycyclic aromatic compounds and is strongly correlated with carcinogenic activity in animal studies. Worker exposures to polycyclic aromatic compounds were compared between manufacturing plants, at different temperatures and using different raw materials, and to important external benchmarks. High levels of fine limestone particulate in the plant air during roofing manufacturing increased polycyclic aromatic compound exposure, resulting in the hypothesis that the particulate brought adsorbed polycyclic aromatic compounds to the worker breathing zone. Elevated asphalt temperatures increased exposures during the pouring of asphalt. Co-exposures in these workplaces which act as confounders for both the measurement of total organic matter and fluorescence were detected and their influence discussed. Exposures to polycyclic aromatic compounds in asphalt roofing manufacturing facilities were lower than or similar to those reported in hot-mix paving application studies, and much below those reported in studies of hot application of built-up roofing asphalt. These relatively low exposures in manufacturing are primarily attributed to air emission controls in the facilities, and the relatively moderate temperatures, compared to built-up roofing, used in these facilities for oxidized asphalt. The exposure to polycyclic aromatic compounds was a very

  19. Recycled materials in asphalt pavements. October 1973-November 1989 (Citations from the NTIS data base). Report for October 1973-November 1989

    SciTech Connect

    Not Available

    1989-12-01

    This bibliography contains citations concerning the recycling of asphalt-pavement materials, and the use of other recycled materials to manufacture asphalt pavement. Articles discuss methods used for recycling bituminous pavement including hot-mix and cold-mix. Materials used to improve recycled pavement, and recycled materials used in asphalt pavement include latexes, rubber scrap such as tires, glass shards, concretes, dusts, waste oils, roofing wastes, sulfur, and metal refining sludges. Testing and evaluation of recycled pavements both in laboratories and in test cases are considered. (Contains 110 citations fully indexed and including a title list.)

  20. Asphalt emulsion sealing of uranium mill tailings. 1980 annual report

    SciTech Connect

    Hartley, J.N.; Koehmstedt, P.L; Esterl, D.J.; Freeman, H.D.; Buelt, J.L.; Nelson, D.A.; Elmore, M.R.

    1981-05-01

    Studies of asphalt emulsion sealants conducted by the Pacific Northwest Laboratory have demonstrated that the sealants are effective in containing radon and other potentially hazardous material within uranium tailings. The laboratory and field studies have further demonstrated that radon exhalation from uranium tailings piles can be reduced by greater than 99% to near background levels. Field tests at the tailings pile in Grand Junction, Colorado, confirmed that an 8-cm admix seal containing 22 wt% asphalt could be effectively applied with a cold-mix paver. Other techniques were successfully tested, including a soil stabilizer and a hot, rubberized asphalt seal that was applied with a distributor truck. After the seals were applied and compacted, overburden was applied over the seal to protect the seal from ultraviolet degradation.

  1. Application of asphalt emulsion seals to uranium mill tailings

    SciTech Connect

    Hartley, J.N.; Koehmstedt, P.L.; Esterl, D.J.; Freeman, H.D.; Clark, R.L.

    1980-11-01

    Studies of asphalt emulsion sealants have demonstrated that the sealants are effective in containing radon and other potentially hazardous material within uranium tailings. The laboratory and field studies have further demonstrated that radon exhalation from uranium tailings piles can be reduced by greater than 99% to less than background levels. Field tests at the tailings pile in Grand Junction, Colorado confirmed that an 8-cm admix seal containing 22 wt % asphalt could be effectively applied with a cold-mix paver. Other techniques were successfully tested, including a soil stabilizer and a hot, rubberized asphalt seal that was applied with a distributor truck. After the seals were applied and conpacted, overburden was applied over the seal to protect the seal from ultraviolet degradation. 14 figures.

  2. Incorporation de particules de bardeaux d'asphalte de postconsommation dans les enrobes bitumineux

    NASA Astrophysics Data System (ADS)

    Malo, Jean-Michel

    Every year, more than 200 000 tons of used residential roofing asphalt shingles are sent to landfills in Quebec. In order to reduce this amount, a research project funded by the 3RMCDQ and RECYC-QUÉBEC is ongoing at the LCMB at École de technologie supérieure (ÉTS) in Montreal. This project studies the feasibility of incorporating tear-off shingles particles in hot mix asphalt which could be used on Quebec roads. Currently, in Quebec, the ministry of Transportation (MTQ), allows the use of 5% of new asphalt shingles (factory reject) in the base course and 3% in the surface course, and tear-off shingles are not allowed. Incorporating new shingles particles is valued notably by the MTQ standardization for a reduction of binder in these mixes. As of now, the MTQ does not have a standard on the use of tear-off shingles, but the subject of experimental boards. The research done at ETS aim to characterize a standard base mix, GB20, and a standard surface mix, ESG-10, that contains tear-off shingles. Mixes containing different percentage of virgin binder were fabricated then tested on compaction capacity, on rutting resistance, on thermal cracking resistance (TSRST) and on complex modulus (E*). The amount of Virgin binder is calculated according to different percentage of effective binder from the shingles. This study has permitted to identify an optimal formula for both types of hot mix asphalt that were tested. Results show that for the standard ESG-10 surface mix, the possible contribution of tear-off asphalt shingles would be about 20%. For the standard GB-20 base mix, no reduction in the virgin binder may be considered for now when 5% of tear-off asphalt shingles are incorporated in the formula mix. In this case, further testing on complex modulus are recommended to obtain meaningful results that will determine if a reduction of the virgin binder would not be favorable.

  3. Nature of the chemical reaction for furfural modified asphalt

    SciTech Connect

    Memon, G.M.; Chollar, B.H.

    1994-12-31

    Three of the most serious problems of asphalt pavements today are rutting, cracking, and susceptibility to moisture damage (stripping). Asphalt manufacturers have been mixing asphalts with polymers to produce polymer-modified asphalts with improved rheological properties. However, the costs for these improved polymer-modified asphalts are almost double that of regular asphalts. FHWA researchers have found that asphalt modified by the chemical, furfural (which is prepared by simple elimination reaction of aldopentoses obtained from oat hulls), exhibited better stripping properties and was less temperature susceptible than the virgin asphalt while costing less than polymer-modified asphalts. This paper discusses the possible structure of the furfural-modified asphalt, data for the virgin and furfural-modified asphalts and their Corbett fractions, data from a model reaction between phenol and furfural, and a possible explanation of this structure based on these data.

  4. A review on using crumb rubber in reinforcement of asphalt pavement.

    PubMed

    Mashaan, Nuha Salim; Ali, Asim Hassan; Karim, Mohamed Rehan; Abdelaziz, Mahrez

    2014-01-01

    An immense problem affecting environmental pollution is the increase of waste tyre vehicles. In an attempt to decrease the magnitude of this issue, crumb rubber modifier (CRM) obtained from waste tyre rubber has gained interest in asphalt reinforcement. The use of crumb rubber in the reinforcement of asphalt is considered as a smart solution for sustainable development by reusing waste materials, and it is believed that crumb rubber modifier (CRM) could be an alternative polymer material in improving hot mix asphalt performance properties. In this paper, a critical review on the use of crumb rubber in reinforcement of asphalt pavement will be presented and discussed. It will also include a review on the effects of CRM on the stiffness, rutting, and fatigue resistance of road pavement construction.

  5. A Review on Using Crumb Rubber in Reinforcement of Asphalt Pavement

    PubMed Central

    Mashaan, Nuha Salim; Ali, Asim Hassan; Karim, Mohamed Rehan; Abdelaziz, Mahrez

    2014-01-01

    An immense problem affecting environmental pollution is the increase of waste tyre vehicles. In an attempt to decrease the magnitude of this issue, crumb rubber modifier (CRM) obtained from waste tyre rubber has gained interest in asphalt reinforcement. The use of crumb rubber in the reinforcement of asphalt is considered as a smart solution for sustainable development by reusing waste materials, and it is believed that crumb rubber modifier (CRM) could be an alternative polymer material in improving hot mix asphalt performance properties. In this paper, a critical review on the use of crumb rubber in reinforcement of asphalt pavement will be presented and discussed. It will also include a review on the effects of CRM on the stiffness, rutting, and fatigue resistance of road pavement construction. PMID:24688369

  6. Development of superior asphalt recycling agency: Phase 1, Technical feasibility. Technical progress report

    SciTech Connect

    Bullin, J.A.; Glover, C.J.; Davison, R.R.; Lin, Moon-Sun; Chaffin, J.; Liu, Meng; Eckhardt, C.

    1996-04-01

    About every 12 years, asphalt roads must be reworked, and this is usually done by placing thick layers (hot-mix overlays) of new material on top of failed material, resulting in considerable waste of material and use of new asphalt binder. A good recycling agent is needed, not only to reduce the viscosity of the aged material but also to restore compatibility. Objective is to establish the technical feasibility (Phase I) of determining the specifications and operating parameters for producing high quality recycling agents which will allow most/all the old asphalt-based road material to be recycled. It is expected that supercritical fractionation can be used. The advanced road aging simulation procedure will be used to study aging of blends of old asphalt and recycling agents.

  7. Recycling of plastic and rubber tire waste in asphalt pavements

    SciTech Connect

    Morrison, G.R.; Lee, N.K.; Hesp, S.A.M.

    1994-12-31

    This paper discusses some important issues related to the use of recycled thermoplastics and rubber tire waste in asphalt binders for hot-mix pavements. Both high temperature rheological and low temperature fracture studies are presented on recycled polyethylene, devulcanized and crumb rubber-modified asphalt binders. The results are compared to unmodified and commercially available modified binders. This research is especially timely in light of the US Intermodal Surface Transportation Efficiency Act of 1991, Section 1038 which, starting in 1995, will force state and local governments to use significant amounts of recycled rubber tire or plastic waste in federally funded highway projects. High temperature rheological measurements of the loss modulus, loss tangent and complex modulus show a significant improvement when only small quantities of crumb rubber, devulcanized crumb rubber or waste polyethylene are added to the asphalt binders. The low temperature fracture performance of the modified asphalts is greatly influenced by the interfacial strength between the dispersed and continuous phase. The fracture toughness increases dramatically, only when low molecular weight polymers are grafted in-situ onto the rubber and polymer dispersed phases in order to strength the interface. This points to a crack-pinning mechanism as being responsible for the dramatic increase in fracture toughness that is observed in this work. Single phase, devulcanized crumb rubber-asphalt systems perform quite poorly at low temperatures.

  8. A feasibility study to use coal tar contaminated soil in asphalt cement mixture production

    SciTech Connect

    Dulam, C.S.; Hoag, G.E.; Dahmani, A.; Nadim, F.

    1996-11-01

    Coal tars are the residues produced during the gasification of coal. Traditionally, coal tars were buried onsite at the power plants or left as residuals in the bottom of gas holders. Currently, there are more than 1,500 such historic sites which will undergo site assessment in the near future. The use of coal tar residuals in asphalt-based products could result in greatly reduced disposal costs, in comparison to current methods of disposal. Present disposal practice of coal tar contaminated residuals includes disposal in hazardous waste landfills or incineration. Treatment and disposal costs are reported to be as much as $1,000/ton for current coal tar contaminated residuals disposal options. This feasibility study was performed to determine the use of coal tar contaminated soil (CTCS) in bituminous materials to produce hot asphalt mix. Mixtures of varying composition of CTCS and bituminous material were produced to perform TCLP. The air emissions during the mixing process were captured and analyzed. In this study, a bench scale investigation was performed to identify and quantify the emissions from heating the CTCS at the mixer temperature. The pilot scale investigations were performed by replacing reclaimable asphalt pavement (RAP) with CTCS during the hot asphalt mix production. The investigations were performed on two types of mixtures; using CTCS as the direct additive in the first type, and using SS-1 (slow setting asphalt emulsion) stabilized CTCS as an additive in the second type.

  9. Field and laboratory study of cold-asphalt-mix recycling in Ohio. Final report

    SciTech Connect

    Majidzadeh, K.; Ilves, G.J.; Abdulshafi, A.; Kaloush, K.

    1987-09-01

    The report presents a study initiated in 1984 to develop specification guidelines and mix-design recommendations and to obtain performance data on cold-mix recycling projects in Ohio. Two mainline, low-volume roads and one shoulder pavement were selected for the study. Documentation and evaluation of the projects are discussed generally in two parts. The first part includes the site-selection criteria, pre-construction evaluation, mix designs, construction specifications and construction monitoring. The second part discusses performance evaluation through field inspection, data collection, and laboratory evaluation of material properties.

  10. Moisture Content Numerical Simulation on Structural Damage of Hot Mix Asphaltic Pavement

    NASA Astrophysics Data System (ADS)

    Abejide, O. S.; Mostafa, M. M. H.

    2017-06-01

    Considering the merits of road transportation in the economy and communication activities of the modern societies, it is imperative to design a safe, stable, efficient and cost effective road that will lead to increased economic development and growth of the South African nation. Although, the overarching effect of failed roads has in many ways led to increased travel time, loss of life and property; leading to reduced driver control on failed road sections (riding quality). Thus, time rate delamination of flexible pavement is a major focus of this study. Since structural collapse in a flexible pavement structure is caused by the evolution of different types of damage mechanisms; fatigue cracking, advanced crushing, temperature variation, and delamination. The effect of moisture content on HMA was analysed. The analysis from the multi-layered elastic model indicates that increase in moisture content in the underlying layer of HMA pavement results to increase in the strain of the individual layers and culminates to a decrease in the structural carrying capacity of the pavement with respect to number of load cycles that can be carried on the HMA pavement. This study shows a clear relationship between the moisture/saturation coefficient and the Elastic Modulus of the underlying geometric material layer properties of the pavement during the service life of the pavement.

  11. Evaluating the Accuracy of Common Runoff Estimation Methods for New Impervious Hot-Mix Asphalt

    EPA Science Inventory

    Accurately predicting runoff volume from impervious surfaces for water quality design events (e.g., 25.4 mm) is important for sizing green infrastructure stormwater control measures to meet water quality and infiltration design targets. The objective of this research was to quan...

  12. Evaluating the Accuracy of Common Runoff Estimation Methods for New Impervious Hot-Mix Asphalt

    EPA Science Inventory

    Accurately predicting runoff volume from impervious surfaces for water quality design events (e.g., 25.4 mm) is important for sizing green infrastructure stormwater control measures to meet water quality and infiltration design targets. The objective of this research was to quan...

  13. Evaluation and improvement of micro-surfacing mix design method and modelling of asphalt emulsion mastic in terms of filler-emulsion interaction

    NASA Astrophysics Data System (ADS)

    Robati, Masoud

    This Doctorate program focuses on the evaluation and improving the rutting resistance of micro-surfacing mixtures. There are many research problems related to the rutting resistance of micro-surfacing mixtures that still require further research to be solved. The main objective of this Ph.D. program is to experimentally and analytically study and improve rutting resistance of micro-surfacing mixtures. During this Ph.D. program major aspects related to the rutting resistance of micro-surfacing mixtures are investigated and presented as follow: 1) evaluation of a modification of current micro-surfacing mix design procedures: On the basis of this effort, a new mix design procedure is proposed for type III micro-surfacing mixtures as rut-fill materials on the road surface. Unlike the current mix design guidelines and specification, the new mix design is capable of selecting the optimum mix proportions for micro-surfacing mixtures; 2) evaluation of test methods and selection of aggregate grading for type III application of micro-surfacing: Within the term of this study, a new specification for selection of aggregate grading for type III application of micro-surfacing is proposed; 3) evaluation of repeatability and reproducibility of micro-surfacing mixture design tests: In this study, limits for repeatability and reproducibility of micro-surfacing mix design tests are presented; 4) a new conceptual model for filler stiffening effect on asphalt mastic of micro-surfacing: A new model is proposed, which is able to establish limits for minimum and maximum filler concentrations in the micro-surfacing mixture base on only the filler important physical and chemical properties; 5) incorporation of reclaimed asphalt pavement and post-fabrication asphalt shingles in micro-surfacing mixture: The effectiveness of newly developed mix design procedure for micro-surfacing mixtures is further validated using recycled materials. The results present the limits for the use of RAP and RAS

  14. Mixing and compaction temperatures for Superpave mixes

    NASA Astrophysics Data System (ADS)

    Yildirim, Yetkin

    included during viscosity measurements. The use of practical shear rates results in reasonable mixing and compaction temperatures for hot mix asphalt design and construction with modified asphalt binders. It was found that application of the shear rate concept, rather than the traditional approach used for unmodified binders, can reduce the mixing and compaction temperatures from between roughly 10 and 30°C, depending on the type and the amount of modifier.

  15. Effect of asphalt rejuvenating agent on aged reclaimed asphalt pavement and binder properties

    NASA Astrophysics Data System (ADS)

    Sabahfar, Nassim

    Hot in-place recycling (HIR) preserves distressed asphalt pavements while minimizing use of virgin binder and aggregates. The final quality of an HIR mixture depends on characteristics of the original binder, aging of the pavement surface during service, and whether or not new binder or rejuvenator was added to the mixture. An HIR mixture should maintain desired properties for additional service periods, making asphalt binder modification inevitable. Asphalt binder modifications in HIR are commonly done by adding an asphalt rejuvenating agent (ARA). However, ARA may adversely affect the qualities of new HIR and potentially fail to improve the quality of the final surface. The objective of this research was to investigate the effects of rejuvenation on HIR performance characteristics by assessing critical performance indicators such as stiffness, permanent deformation, moisture susceptibility, and cracking resistance. A two-step experimental program was designed that included mechanical property measurements of the HIR mixture and rheological properties of the extracted binder. The level of mixing occurring between new and aged binder with ARA was also investigated. HIR Samples were obtained from three Kansas Department of Transportation projects, and Hamburg wheel-tracking device, dynamic modulus, flow number, Texas overlay, thermal stress restrained specimen, and moisture susceptibility tests were conducted on mixtures with and without ARA. Rheological studies on the extracted binder included dynamic shear rheometer and bending beam rheometer tests. The miscibility of new and aged binder was investigated using scanning electron microscope (SEM) images, energy dispersive X-ray spectroscopy (EDXS), and the exudation droplet test (EDT). Study results showed significant variability in the mechanical performance of HIR mixtures, which was attributed to the variability of binders as observed in EDT, SEM and EDXS studies. Life cycle cost analysis (LCCA) showed that HIR

  16. An assessment of SBS modified asphalt concrete pavements performance features performing numerical analysis

    NASA Astrophysics Data System (ADS)

    Karakas, Ahmet Sertac; Bozkurt, Tarik Serhat; Sayin, Baris; Ortes, Faruk

    2017-07-01

    In passenger and freight traffic on the roads, which has the largest share of the hot mix asphalt (HMA) prepared asphalt concrete pavement is one of the most preferred type of flexible superstructure. During the service life of the road, they must provide the performance which is expected to show. HMA must be high performance mix design, comfortable, safe and resistance to degradation. In addition, it becomes a critical need to use various additives materials for roads to be able to serve long-term against environmental conditions such as traffic and climate due to the fact that the way of raw materials is limited. Styrene Butadiene Styrene (SBS) polymers are widely used among additives. In this study, the numerical analysis of SBS modified HMA designed asphalt concrete coatings prepared with different thicknesses with SBS modified HMA is performed. After that, stress and deformation values of the three pavement models are compared and evaluated.

  17. Numerical Simulation of Mixing Enhancement in a Hot Supersonic Jet

    NASA Technical Reports Server (NTRS)

    Grosch, C. E.; Seiner, J. M.; Hussaini, M. Y.; Jackson, T. L.

    1996-01-01

    Experimental observations show that the presence of small tabs on the edge of a hot, compressible jet exiting into a slower moving, colder ambient flow can increase the rate of spreading of the jet. This suggests that the rate of mixing of the jet and the ambient fluid is also increased. In order to elucidate the physical mechanism responsible for the increased spreading rate a set of calculations were carried out within the framework of the compressible three dimensional Navier-Stokes equations. A series of grid refinements were made to assess the accuracy of the results. The first simulated the flow without the tabs, obtaining reasonable agreement with experimental measurements of the velocity. We then simulated the flow, without tabs, over a range of values of the convective Mach number in order to determine the dependence of the mixing on this parameter. Simulations with modeled tabs were also carried out. In these calculations the effect of the tabs on the flow was modeled by pairs of counter rotating vortices. The results of these calculations indeed show that the presence of the tabs increase the spreading rate of the jet. The basic physical mechanism responsible for the enhanced spreading rate is discussed and qualitative comparisons with flow visualizations are made.

  18. Using pyrolized carbon black from waste tires in asphalt pavement. Part 1. Limestone aggregate. Final report, September 1993-May 1995

    SciTech Connect

    Park, T.; Lovell, C.W.

    1996-02-20

    The study presents the viability of using pyrolyzed carbon black (PCB) as an additive in hot mix asphalt concrete. Different ratios of PCB (5%, 10%, 15%, 20% by weight of asphalt) were blended with two grades of asphalt (AC-10 and AC-20). The complete behaviors of the PCB modified asphalt concrete were investigated by comprehensive laboratory testing and evaluation. The Marshall method was used to determine the optimum binder content, and the mechanical properties and void relationships were investigated by this method. The Gyratory Testing Machine was used to define the stress-strain relationships of the PCB mixtures. The rutting potential of PCB mixtures was investigated using the Dynamic Creep Testing. The performance of the PCB mixtures at low temperature (5 degrees C) was determined by the Indirect Tensile Testing. The strength performance of the PCB mixtures at intermediate temperatures (5 degrees C and 25 degrees C) was examined by the Resilient Modulus Test. The Hamburg Wheel Tracking Device was employed to ascertain the stripping potential of the PCB mixtures. The findings of the study show beneficial effects of added PCB for asphalt mixture. Specifically, test results show that PCB contents of 10% to 15% by weigh of asphalt produce a number of significant 0mprovements. The rutting potential, the temperature susceptibility and the stripping potential can be reduced by the inclusion of PCB in the asphalt mixture. Added material costs of about 6% may well be justified by expected improvements in performance.

  19. The Asphalt Handbook.

    ERIC Educational Resources Information Center

    Asphalt Inst., College Park, MD.

    The new and completely revised edition of the Asphalt Handbook, a standard reference work in the field of asphalt technology and construction, summarizes with reference the information contained in other Asphalt Institute technical manuals. Major areas discussed include the following--(1) uses of asphalt, (2) terms relating to asphalt and its…

  20. The Asphalt Handbook.

    ERIC Educational Resources Information Center

    Asphalt Inst., College Park, MD.

    The new and completely revised edition of the Asphalt Handbook, a standard reference work in the field of asphalt technology and construction, summarizes with reference the information contained in other Asphalt Institute technical manuals. Major areas discussed include the following--(1) uses of asphalt, (2) terms relating to asphalt and its…

  1. Application of pyrolized carbon black from scrap tires in asphalt pavement design and construction

    SciTech Connect

    Park, T.; Coree, B.J.; Lovell, C.W.

    1995-12-31

    According to EPA reports (1991) of the over 242 million waste generated each year in the United State, 5% are exported, 6% recycled, 11% incinerated, and 78% are landfilled, stockpiled, or illegally dumped. A variety of uses for these tires are being studied. Among these is pyrolysis which produces 5 5% of oil, 25% of carbon black, 9% of steel, 5% of fiber and 6% of gas. Pyrolized carbon black contains 9 % of ash, 4% of sulfur, 12% of butadine copolymer and 75% of carbon black. The objective of this research is to investigate the viability of using PCB as an additive in hot mix asphalt. The use of PCB in asphalt pavement is expected not only to improve the performance of conventional asphalt, but also to provide a means for the mass disposal of waste fires.

  2. Recycled tire rubber and other waste materials in asphalt mixtures. Transportation research record

    SciTech Connect

    1995-12-31

    The papers in this volume, dealing with various facets of recycled tire rubber and other waste materials in asphalt mixtures, should be of interest to state and local construction, design, materials, and research engineers as well as contractors and material producers. In the first papers, Rebala and Estakhri, Malpass and Khosla, and Baker and Connolly describe research related to crumb rubber modified mixtures that was done for the Texas, North Carolina, and New Jersey State Departments of Transportation. Ali et al. report on their research in Canada to determine the feasibility of sing reclaimed roofing materials in hot mix asphalt pavement. Emery discusses the evaluation of 11 Ontario rubber modified demonstration projects in terms of pavement performance, environmental impacts, and recyclability. In the last paper, Fwa and Aziz report on their work in Singapore related to the use of incinerator residue in asphalt mixtures.

  3. Use of asphalt emulsion sealants in disposal of uranium mill tailings

    SciTech Connect

    Hartley, J.N.; Freeman, H.D.; Elmore, M.R.

    1981-07-01

    Studies of asphalt emulsion sealants conducted by the Pacific Northwest Laboratory have demonstrated that the sealants are effective in containing radon within uranium tailings. The laboratory and field studies have further demonstrated that radon exhalation from uranium tailings piles can be reduced by greater than 99% to near background levels. Field tests at the tailings pile in Grand Junction, Colorado confirmed that an 8-cm admix seal containing 22 wt % asphalt could be effectively applied with a cold-mix paver. Other techniques were successfully tested, including a soil stabilizer and a hot, rubberized asphalt seal that was applied with a distributor truck. After the seals were applied and compacted, overburden was applied over the seal to protect the seal from ultraviolet degradation.

  4. Use of waste toner in asphaltic concrete. Research report (Final)

    SciTech Connect

    Solaimanian, M.; Kennedy, T.W.; McGennis, R.B.

    1997-02-01

    Every year, a tremendous amount of toner is produced for copiers and printers by toner manufacturing companies throughout the United States. Some of this toner does not meet quality specifications and consequently becomes a waste product of the manufacturing process. This manufacturing waste, along with the spent toner (residue) from copiers and printer cartridges, is dumped into landfills for lack of a better way utilizing the material. A cooperative research project undertaken by the Texas Department of Transportation and The University of Texas at Austin investigated the feasibility and potential benefits of utilizing waste toner in hot-mix asphalt concrete. The research program included procuring a number of different waste and spent toners, blending them with asphalt cement at different ratios, and evaluating the binder and mixtures properties resulting from the waste toner addition.

  5. Biodegradation of Asphalt Cement-20 by Aerobic Bacteria

    PubMed Central

    Pendrys, John P.

    1989-01-01

    Seven gram-negative, aerobic bacteria were isolated from a mixed culture enriched for asphalt-degrading bacteria. The predominant genera of these isolates were Pseudomonas, Acinetobacter, Alcaligenes, Flavimonas, and Flavobacterium. The mixed culture preferentially degraded the saturate and naphthene aromatic fractions of asphalt cement-20. A residue remained on the surface which was resistant to biodegradation and protected the underlying asphalt from biodegradation. The most potent asphalt-degrading bacterium, Acinetobacter calcoaceticus NAV2, excretes an emulsifier which is capable of emulsifying the saturate and naphthene aromatic fractions of asphalt cement-20. This emulsifier is not denatured by phenol. PMID:16347928

  6. Hot-spot mix in ignition-scale implosions on the NIF [Hot-spot mix in ignition-scale implosions on the National Ignition Facility (NIF)

    DOE PAGES

    Regan, S. P.; Epstein, R.; Hammel, B. A.; ...

    2012-03-30

    Ignition of an inertial confinement fusion (ICF) target depends on the formation of a central hot spot with sufficient temperature and areal density. Radiative and conductive losses from the hot spot can be enhanced by hydrodynamic instabilities. The concentric spherical layers of current National Ignition Facility (NIF) ignition targets consist of a plastic ablator surrounding 2 a thin shell of cryogenic thermonuclear fuel (i.e., hydrogen isotopes), with fuel vapor filling the interior volume. The Rev. 5 ablator is doped with Ge to minimize preheat of the ablator closest to the DT ice caused by Au M-band emission from the hohlraummore » x-ray drive. Richtmyer–Meshkov and Rayleigh–Taylor hydrodynamic instabilities seeded by high-mode (50 < t < 200) ablator-surface perturbations can cause Ge-doped ablator to mix into the interior of the shell at the end of the acceleration phase. As the shell decelerates, it compresses the fuel vapor, forming a hot spot. K-shell line emission from the ionized Ge that has penetrated into the hot spot provides an experimental signature of hot-spot mix. The Ge emission from tritium–hydrogen–deuterium (THD) and DT cryogenic targets and gas-filled plastic shell capsules, which replace the THD layer with a massequivalent CH layer, was examined. The inferred amount of hot-spot mix mass, estimated from the Ge K-shell line brightness using a detailed atomic physics code, is typically below the 75 ng allowance for hot-spot mix. Furthermore, predictions of a simple mix model, based on linear growth of the measured surface-mass modulations, are consistent with the experimental results.« less

  7. Hot-spot mix in ignition-scale implosions on the NIF [Hot-spot mix in ignition-scale implosions on the National Ignition Facility (NIF)

    SciTech Connect

    Regan, S. P.; Epstein, R.; Hammel, B. A.; Suter, L. J.; Ralph, J.; Scott, H.; Barrios, M. A.; Bradley, D. K.; Callahan, D. A.; Cerjan, C.; Collins, G. W.; Dixit, S. N.; Doeppner, T.; Edwards, M. J.; Farley, D. R.; Glenn, S.; Glenzer, S. H.; Golovkin, I. E.; Haan, S. W.; Hamza, A.; Hicks, D. G.; Izumi, N.; Kilkenny, J. D.; Kline, J. L.; Kyrala, G. A.; Landen, O. L.; Ma, T.; MacFarlane, J. J.; Mancini, R. C.; McCrory, R. L.; Meezan, N. B.; Meyerhofer, D. D.; Nikroo, A.; Peterson, K. J.; Sangster, T. C.; Springer, P.; Town, R. P. J.

    2012-03-30

    Ignition of an inertial confinement fusion (ICF) target depends on the formation of a central hot spot with sufficient temperature and areal density. Radiative and conductive losses from the hot spot can be enhanced by hydrodynamic instabilities. The concentric spherical layers of current National Ignition Facility (NIF) ignition targets consist of a plastic ablator surrounding 2 a thin shell of cryogenic thermonuclear fuel (i.e., hydrogen isotopes), with fuel vapor filling the interior volume. The Rev. 5 ablator is doped with Ge to minimize preheat of the ablator closest to the DT ice caused by Au M-band emission from the hohlraum x-ray drive. Richtmyer–Meshkov and Rayleigh–Taylor hydrodynamic instabilities seeded by high-mode (50 < t < 200) ablator-surface perturbations can cause Ge-doped ablator to mix into the interior of the shell at the end of the acceleration phase. As the shell decelerates, it compresses the fuel vapor, forming a hot spot. K-shell line emission from the ionized Ge that has penetrated into the hot spot provides an experimental signature of hot-spot mix. The Ge emission from tritium–hydrogen–deuterium (THD) and DT cryogenic targets and gas-filled plastic shell capsules, which replace the THD layer with a massequivalent CH layer, was examined. The inferred amount of hot-spot mix mass, estimated from the Ge K-shell line brightness using a detailed atomic physics code, is typically below the 75 ng allowance for hot-spot mix. Furthermore, predictions of a simple mix model, based on linear growth of the measured surface-mass modulations, are consistent with the experimental results.

  8. Investigation of modified asphalt concrete

    NASA Astrophysics Data System (ADS)

    Zimich, Vita

    2016-01-01

    Currently the problem of improving the asphalt quality is very urgent. It is used primarily as topcoats exposed to the greatest relative to the other layers of the road, dynamic load - impact and shear. The number of cars on the road, the speed of their movement, as well as the traffic intensity increase day by day. We have to upgrade motor roads, which entails a huge cost. World experience shows that the issue is urgent not only in Russia, but also in many countries in Europe, USA and Asia. Thus, the subject of research is the resistance of asphalt concrete to water and its influence on the strength of the material at different temperatures, and resistance of pavement to deformation. It is appropriate to search for new modifiers for asphaltic binder and mineral additives for asphalt mix to form in complex the skeleton of the future asphalt concrete, resistant to atmospheric condensation, soil characteristics of the road construction area, as well as the growing road transport load. The important task of the work is searching special modifying additives for bitumen binder and asphalt mixture as a whole, which will improve the quality of highways, increasing the period between repairs. The methods described in the normative-technical documentation were used for the research. The conducted research allowed reducing the frequency of road maintenance for 7 years, increasing it from 17 to 25 years.

  9. Effect of Cement on Emulsified Asphalt Mixtures

    NASA Astrophysics Data System (ADS)

    Oruc, Seref; Celik, Fazil; Akpinar, M. Vefa

    2007-10-01

    Emulsified asphalt mixtures have environmental, economical, and logistical advantages over hot mixtures. However, they have attracted little attention as structural layers due to their inadequate performance and susceptibility to early life damage by rainfall. The objective of this article is to provide an improved insight into how the mechanical properties of emulsion mixtures may be improved and to determine the influence of cement on emulsified asphalt mixtures. Laboratory tests on strength, temperature susceptibility, water damage, creep and permanent deformation were implemented to evaluate the mechanical properties of emulsified asphalt mixtures. The test results showed that mechanical properties of emulsified asphalt mixtures have significantly improved with Portland cement addition. This experimental study suggested that cement modified asphalt emulsion mixtures might be an alternate way of a structural layer material in pavement.

  10. Minimum Thickness Requirements for Asphalt Surface Course and Base Layer in Airfield Pavements

    DTIC Science & Technology

    2011-08-01

    shear stress, and therefore, to rutting, some minimum thickness of hot- mix asphalt (HMA) is needed to protect this strong base course from the...pavements with different thicknesses of bituminous materials, and base and subbase quality materials. The analysis indicated that at elevated...temperatures, the bituminous bound pavement layers were not superior in load distributing capability to excellent quality (100 CBR) base materials. A 100-CBR

  11. Hot-spot mix in ignition-scale inertial confinement fusion targets

    DOE PAGES

    Regan, S. P.; Epstein, R.; Hammel, B. A.; ...

    2013-07-22

    Mixing of plastic ablator material, doped with Cu and Ge dopants, deep into the hot spot of ignition-scale inertial confinement fusion implosions by hydrodynamic instabilities is diagnosed with x-ray spectroscopy on the National Ignition Facility. The amount of hot-spot mix mass is determined from the absolute brightness of the emergent Cu and Ge K-shell emission. The Cu and Ge dopants placed at different radial locations in the plastic ablator show the ablation-front hydrodynamic instability is primarily responsible for hot-spot mix. As a result, low neutron yields and hot-spot mix mass between 34(–13,+50) ng and 4000(–2970,+17 160) ng are observed.

  12. A historical review of additives and modifiers used in paving asphalt refining processes in the United States.

    PubMed

    Mundt, Diane J; Adams, Robert C; Marano, Kristin M

    2009-11-01

    The U.S. asphalt paving industry has evolved over time to meet various performance specifications for liquid petroleum asphalt binder (known as bitumen outside the United States). Additives to liquid petroleum asphalt produced in the refinery may affect exposures to workers in the hot mix paving industry. This investigation documented the changes in the composition and distribution of the liquid petroleum asphalt products produced from petroleum refining in the United States since World War II. This assessment was accomplished by reviewing documents and interviewing individual experts in the industry to identify current and historical practices. Individuals from 18 facilities were surveyed; the number of facilities reporting use of any material within a particular class ranged from none to more than half the respondents. Materials such as products of the process stream, polymers, elastomers, and anti-strip compounds have been added to liquid petroleum asphalt in the United States over the past 50 years, but modification has not been generally consistent by geography or time. Modifications made to liquid petroleum asphalt were made generally to improve performance and were dictated by state specifications.

  13. A review of air quality issues and compliance for the asphalt paving industry in Maryland

    SciTech Connect

    Courtright, B.F.; Caughlin, M.J.

    1999-07-01

    The Maryland Air and Radiation Management Administration (ARMA) conducted a Sector Initiative in order to achieve a compliance audit of the asphalt paving industry sector in Maryland. This sector is commonly referred to as the hot-mix asphalt (HMA) industry. There are 59 HMA production plants in Maryland. Each asphalt production facility was reviewed to determine their compliance status with federal NSPS requirements (stack particulate and visible emission requirements), as well as with Maryland's more comprehensive and generally more restrictive requirements including visible emission, particulate matter, air toxics, dust, nuisance, odor, and other criteria pollutant requirements. The study included reviewing past data (stack test reports, inspections, VE observations, complaint histories) and conducting new inspections and observations at all 59 of the plants. The study also included conducting new particulate stack tests (Summer of 1998) at nine HMA plants. The historic data demonstrated general compliance with stack-tested particulate emission rates. The new stack tests all demonstrated compliance with applicable particulate limits. Visible emissions observations revealed a lesser degree of compliance. Asphalt plants, if not carefully controlled, can be a major source of nuisance complaints. Complaint histories were also reviewed. This paper presents detailed results of ARMA's compliance review of the asphalt industry in Maryland. This includes test results, compliance determinations, and compliance rates. Other issues including impacts on surrounding communities, changing Department of Transportation requirements, and air toxics requirements are also reviewed.

  14. Mixing Hot and Cold Water Streams at a T-Junction

    ERIC Educational Resources Information Center

    Sharp, David; Zhang, Mingqian; Xu, Zhenghe; Ryan, Jim; Wanke, Sieghard; Afacan, Artin

    2008-01-01

    A simple mixing of a hot- and cold-water stream at a T-junction was investigated. The main objective was to use mass and energy balance equations to predict mass low rates and the temperature of the mixed stream after the T-junction, and then compare these with the measured values. Furthermore, the thermocouple location after the T-junction and…

  15. Mixing Hot and Cold Water Streams at a T-Junction

    ERIC Educational Resources Information Center

    Sharp, David; Zhang, Mingqian; Xu, Zhenghe; Ryan, Jim; Wanke, Sieghard; Afacan, Artin

    2008-01-01

    A simple mixing of a hot- and cold-water stream at a T-junction was investigated. The main objective was to use mass and energy balance equations to predict mass low rates and the temperature of the mixed stream after the T-junction, and then compare these with the measured values. Furthermore, the thermocouple location after the T-junction and…

  16. Use of scrap rubber in asphalt pavement surfaces. Special report

    SciTech Connect

    Eaton, R.A.; Roberts, R.J.; Blackburn, R.R.

    1991-12-01

    Scrap tire rubber was mixed into an asphalt concrete wearing course to study the effect of ice disbonding from the pavement surface under traffic. Rubber contents of 0, 3, 6, and 12% by weight were studied. Initial laboratory ice disbonding test results led to the development of a new paving material, Chunk Rubber Asphalt Concrete (CRAC), that uses larger pieces of rubber in a much denser asphalt concrete mix. Strength values doubled and ice disbonding performance was enhanced.

  17. An investigation of the effectiveness of asphalt durability tests

    NASA Astrophysics Data System (ADS)

    Predoehl, N. H.; Kemp, G. R.

    1980-05-01

    Included are analyses which show that the effects of voids and aggregate porosity are less severe than the thermal oxidation effect in hot desert climates. A comparison of the results of laboratory tests for predicting asphalt hardening with the results for the field weathered briquettes show that none of the procedures is capable of adequately predicting asphalt weathering in a hot weathering site. A procedure was developed to approximate the effect produced at Indio in two years. Some correlation to briquette results was obtained. A climatic specification to control asphalt hardening in the hot climatic areas is proposed.

  18. Revealing the Location of the Mixing Layer in a Hot Bubble

    NASA Astrophysics Data System (ADS)

    Guerrero, M. A.; Fang, X.; Chu, Y. H.; Toalá, J. A.; Gruendl, R. A.

    2017-03-01

    The fast stellar winds can blow bubbles in the circumstellar material ejected from previous phases of stellar evolution. These are found at different scales, from planetary nebulae (PNe) around stars evolving to the white dwarf stage, to Wolf-Rayet (WR) bubbles and up to large-scale bubbles around massive star clusters. In all cases, the fast stellar wind is shock-heated and a hot bubble is produced. At the mixing layer between the hot bubble and optical nebula, processes of mass evaporation and mixing of nebular material and heat conduction are key to determine the thermal structure of these bubbles and their evolution. In this contribution we review our current understanding of the X-ray observations of hot bubbles in PNe and present the first spatially-resolved study of a mixing layer in a PN.

  19. Performance of recycled asphalt concrete airport pavement surfaces

    NASA Astrophysics Data System (ADS)

    Cline, G. D.; Hironaka, M. C.

    1986-10-01

    The objective of this research was to make an assessment of the relative performance of recycled versus new asphalt concrete pavement surfaces constructed for airport facilities. To make this assessment, pavement condition index (PCI) surveys and tests on core samples from the hot-mix recycled pavements located on the airports at Needles, California, and Valley City, North Dakota were conducted. Both pavements have a condition rating of very good. The survey and test data were compared with those for recycled highway and virgin material Navy airfield pavements. The recycle pavement at Needles is performing as good as those Navy pavements constructed with virgin material. The recycled pavement at Valley City has a higher deterioration rate than the Navy pavements but this could be attributed to the harsh climate found in North Dakota. The results of this study show that hot-mix recycling was successful at these airports but additional studies are required to determine the applicability of Asphalt Concrete (AC) recycling for reconstruction at all airports.

  20. Rubberized asphalt emulsion

    SciTech Connect

    Wilkes, E.

    1986-09-02

    A method is described of making a rubberized asphalt composition which comprises the steps of: (a) combining asphalt with a hydrocarbon oil having a flash point of 300/sup 0/F. or more to provide a homogenous asphalt-oil mixture or solution, (b) then combining the asphalt-oil mixture with a particulate rubber at a temperature sufficient to provide a homogenous asphalt-rubber-oil gel, and (c) emulsifying the asphalt-rubber-oil gel by passing the gel, water, and an emulsifying agent through a colloid mill to provide an emulsion.

  1. Mixing temperature design and properties evaluation for SMA-13 mixture

    NASA Astrophysics Data System (ADS)

    Huang, X. Y.; Li, B. Y.

    2017-01-01

    The mixing temperature of hot asphalt mixture could be reduced by adding WMA additive Sasobit, as well as reducing smoke emissions and energy construction during the mixing construction and paving. The reasonable mixing temperature were investigated in this paper. In addition, high temperature stability, water stability and low-temperature performance of warm asphalt mixture were evaluaterd. The test results indicate that the mixing temperature of SMA-13 with WMA additive Sasobit may reduce 15-20°C at the same energy (compaction times). the dynamic stability were improved after adding WMA additive Sasobit, and the Water stability and low-temperature performance of mixture decreased, while all kinds of asphalt mixture properties can meet the requirements.

  2. A Multiscale Virtual Fabrication and Lattice Modeling Approach for the Fatigue Performance Prediction of Asphalt Concrete

    NASA Astrophysics Data System (ADS)

    Dehghan Banadaki, Arash

    Predicting the ultimate performance of asphalt concrete under realistic loading conditions is the main key to developing better-performing materials, designing long-lasting pavements, and performing reliable lifecycle analysis for pavements. The fatigue performance of asphalt concrete depends on the mechanical properties of the constituent materials, namely asphalt binder and aggregate. This dependent link between performance and mechanical properties is extremely complex, and experimental techniques often are used to try to characterize the performance of hot mix asphalt. However, given the seemingly uncountable number of mixture designs and loading conditions, it is simply not economical to try to understand and characterize the material behavior solely by experimentation. It is well known that analytical and computational modeling methods can be combined with experimental techniques to reduce the costs associated with understanding and characterizing the mechanical behavior of the constituent materials. This study aims to develop a multiscale micromechanical lattice-based model to predict cracking in asphalt concrete using component material properties. The proposed algorithm, while capturing different phenomena for different scales, also minimizes the need for laboratory experiments. The developed methodology builds on a previously developed lattice model and the viscoelastic continuum damage model to link the component material properties to the mixture fatigue performance. The resulting lattice model is applied to predict the dynamic modulus mastercurves for different scales. A framework for capturing the so-called structuralization effects is introduced that significantly improves the accuracy of the modulus prediction. Furthermore, air voids are added to the model to help capture this important micromechanical feature that affects the fatigue performance of asphalt concrete as well as the modulus value. The effects of rate dependency are captured by

  3. Development of superior asphalt recycling agents. Phase 1, Technical feasibility. Technical progress report

    SciTech Connect

    Bullin, J.A.; Glover, C.J.; Davison, R.R.; Chaffin, J.; Lin, Moon-Sun

    1995-07-01

    About 27 million tons of asphalt and nearly twenty times this much aggregate are consumed each year to build and maintain over two million miles of roads in this country. Over a cycle of about 12 years on the average, these roads must be reworked and much of these millions of tons of rock and asphalt cannot be reused with present recycling technology. Instead, much of the maintenance is accomplished by placing thick layers (hot-mix overlays) of new material on top of the failed material. This results in considerable waste of material, both in terms of quality aggregate and in terms of asphalt binder. In addition, the new asphalt binder represents a significant source of potential energy. The main impediment to recycling asphalt binder is the poorly developed science of recycling agent composition and, as a result, optimum recycling agents are not available. An excellent recycling agent should not only be able to reduce the viscosity of the aged material, but it must also be able to restore compatibility. The properties of the old material and recycling agent must be compatible to give both good initial properties and aging characteristics, and this must be understood. The agent must also be inexpensive and easily manufactured. A large quantity of potential feedstock for the production of recycling agents is available and much of it is now fed to cokers. This material could be recovered by supercritical extraction which is an existing refinery technology. A supercritical pilot plant is available at Texas A&M and has been used to produce fractions for study. The objective of this research is to establish the technical feasibility of determining the specifications and operating parameters necessary to produce high quality recycling agents which will allow most old asphalt-based road material to be recycled.

  4. Polypropylene - asphalt mixtures for waterproofing membranes

    SciTech Connect

    Italia, P.; Brandolese, E.

    1996-12-31

    In any field of polymer-asphalt mixtures application is extremely important to achieve a very good compatibility between the components in order to improve as much as possible the performances due to the polymer content. In the case of waterproofing membranes application this compatibility reduce, moreover, the amount of polymer required to obtain the best performances. Using the Colloidal Instability Index Ic, as measured by the Iatroscan device, we propose a correlation between asphalt`s chemical characteristics and the polymer minimum amount sufficient to disperse in a stable way the asphalt itself in the polymeric matrix. As a result, through the proposed correlation, with a simple asphalt composition analysis it is possible to predict its performance when mixed with polypropilene. In the paper, beside the description of the Iatroscan analytical technique, we also present a method for determining phase inversion based on optical fluorescence microscopy performed on about 30 different samples of asphalt. We also present the experimental correlation laws between the polymer amount at phase inversion and the asphalt single components content.

  5. Application of ultraviolet spectrophotometry to estimate occupational exposure to airborne polyaromatic compounds in asphalt pavers.

    PubMed

    Buratti, Marina; Campo, Laura; Fustinoni, Silvia; Valla, Carla; Martinotti, Irene; Cirla, Piero E; Cavallo, Domenico; Foà, Vito

    2007-06-01

    An ultraviolet (UV) spectrophotometric procedure was devised for the determination of polycyclic aromatic compound-oriented organic soluble matter in vapors and particulate collected from emissions of hot asphalt mix. Ultrasonic extraction was carried out with acetonitrile, followed by UV measurements at 254 nm. Polycyclic aromatic compounds (PACs) in volatile and particulate fraction were quantified as phenanthrene or benzo[k]fluoranthene equivalents. A comparison between UV and high-pressure liquid chromatography with fluorescence detection showed that PACs were one to three orders of magnitude higher than the sum of 15 priority polycyclic aromatic hydrocarbons (PAHs); still, significant correlations were found between volatile or particulate PACs and, respectively, total volatile or particulate PAHs. Moreover, in the particulate phase, PACs correlated with total particulate matter quantified by gravimetry. The proposed procedure was employed in a field study for monitoring personal exposure to asphalt emissions of workers engaged in road construction. Observed levels of acetonitrile-soluble PACs in air samples were very low (2-20 microg/m3); however, asphalt pavers were exposed to significantly higher concentrations of volatile PACs than construction workers (geometric mean, 5.9 microg/m3 vs. 4.1 microg/m3). This method for estimating the global content of volatile or particulate PACs in air samples satisfies our requirements of simplicity and is suitable for conducting an initial screening to assess exposure to airborne polyaromatic organics in asphalt pavers.

  6. Technical, financial, and geographic challenges in recycling asphalt composition roof shingles

    SciTech Connect

    Reith, C.C.; Carpenter, M.; Robertson, D.T.

    1999-07-01

    Eleven million tons of asphalt composition shingles are disposed of annually in US landfills. The wastes from roof removal or repair operations are a promising, but under-harvested feedstock for recycling. This waste stream generally arrives by truck at local landfills, where it is relatively unmixed and ready for recycling. However, in most cases the shingles are landfilled at the local tipping fee. The authors analyzed impediments and opportunities in recycling asphalt shingles and elected to commence operations in the east San Francisco Bay area, where tipping fees as high as $50 per ton provide an economic incentive to intercept and recycle this waste stream. Their approach has been to use a 60 inch x 38 inch rotating-head grinder propelled by a 400 horsepower diesel engine. Roofing waste is introduced to the grinder, which processes up to 50 tons per hour. The product is half-inch minus granular asphalt with co-mingled sand that may be used as a feedstock (approximately 5%) in the production of hot-mix asphalt, as used for road construction. A potentially more profitable reuse of recycled product is in the production of a cold patch for road repair which, when fully commercialized, will further improve the economics of shingles recycling. Other reuse scenarios are being explored. The authors are carefully chronicling and optimizing the Bay Area recycling campaign with the intent of promoting similar activities nationwide as soon as the economics become favorable.

  7. Rehabilitating asphalt highways

    SciTech Connect

    Butalia, T.S.

    2007-07-01

    Coal fly ash has been used on two Ohio full-depth reclamation projects in Delaware and Warren. The object of the project carried out with the Department of Civil and Environmental Engineering and Geodetic Science at Ohio State University is to demonstrate the effective use of Class fly ash in combination with lime or lime kiln dust in the full depth reclamation of asphalt pavements. The article describes the mixes used for the highway reconstruction of part of Section Line Road Delaware County and of a road in Warren County. During construction the pavement sections were instrumented with several structural and environmental monitoring devices and data is being collected on a quarterly basis. Falling Weight Deflectometer (FWD) tests to measure load defection behaviour, resilient of pavement layers and soil and base structural layer coefficient are being carried out twice a year. It was shown that use of fly ash increased the elastic modulus of base layers. This article first appeared in the Feb/May 2007 issue of Asphalt Contractor. 4 photos.

  8. Formulation and Characterization of Solid Dispersion Prepared by Hot Melt Mixing: A Fast Screening Approach for Polymer Selection

    PubMed Central

    Enose, Arno A.; Dasan, Priya K.; Sivaramakrishnan, H.; Shah, Sanket M.

    2014-01-01

    Solid dispersion is molecular dispersion of drug in a polymer matrix which leads to improved solubility and hence better bioavailability. Solvent evaporation technique was employed to prepare films of different combinations of polymers, plasticizer, and a modal drug sulindac to narrow down on a few polymer-plasticizer-sulindac combinations. The sulindac-polymer-plasticizer combination that was stable with good film forming properties was processed by hot melt mixing, a technique close to hot melt extrusion, to predict its behavior in a hot melt extrusion process. Hot melt mixing is not a substitute to hot melt extrusion but is an aid in predicting the formation of molecularly dispersed form of a given set of drug-polymer-plasticizer combination in a hot melt extrusion process. The formulations were characterized by advanced techniques like optical microscopy, differential scanning calorimetry, hot stage microscopy, dynamic vapor sorption, and X-ray diffraction. Subsequently, the best drug-polymer-plasticizer combination obtained by hot melt mixing was subjected to hot melt extrusion process to validate the usefulness of hot melt mixing as a predictive tool in hot melt extrusion process. PMID:26556187

  9. Evaluating the Superpave Option in Unified Facilities Guide Specification 32-12-15.13, Hot Mix Asphalt Airfield Paving

    DTIC Science & Technology

    2014-06-01

    than with the manual Marshall compaction. Four of the six SGC specimens were tested in the APA . The test temperature was set to 64°C, the high PG...mixture quality. Six paving mixtures were sampled to compact specimens using 75 blows of the manual Marshall hammer and 75 gyrations of the SGC. Three...compacted using the manual Marshall hammer. Using the SGC to prepare specimens for quality control and quality assurance is not expected to change

  10. 77 FR 50651 - Approval and Promulgation of Air Quality Implementation Plans; New Hampshire; Hot Mix Asphalt Plants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-22

    ... holidays. Please see the direct final rule which is located in the Rules Section of this Federal Register... INFORMATION: In the Final Rules Section of this Federal Register, EPA is approving the State's SIP submittal... submittal and anticipates no adverse comments. A detailed rationale for the approval is set forth in the...

  11. 77 FR 50608 - Approval and Promulgation of Air Quality Implementation Plans; New Hampshire; Hot Mix Asphalt Plants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-22

    ... submit an electronic comment, EPA recommends that you include your name and other contact information in... your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. Docket: All documents in the electronic docket are listed in the...

  12. The Study of the Improvement of Mechanical Performance of Asphalt Modified by the Optimization of Mixing Time of EVA Bitumen

    NASA Astrophysics Data System (ADS)

    Saoula, Samia; Haddadi, Smail; Mokhtar, Khedidja Ait

    2011-12-01

    To improve the performances of a bitumen, the mixing time of bitumen-EVA is studied using two contents of EVA (3 and 5%). For the study analytical and chemical tests are carried out such as penetrability, softening point, ductility, FTIR, DSC, MEB and the storage stability. The aim of this work is to change and optimize the formula of the sample of EVA, which are not conform with the Algerian standards. This work showed that the mixing time is function of the content polymer. The mixing time has a strong effect on the properties; in fact it has improved the mechanical characteristics of the bituminous. Also, the mechanical tests showed that the permanent deformations and the indirect tensile strength at the temperatures of service resistances are improved.

  13. Assessments of low emission asphalt mixtures produced using combinations of foaming agents

    NASA Astrophysics Data System (ADS)

    Mohd Hasan, Mohd Rosli

    workability, and having a higher expulsion rate from the foamed binder compared to water as a foaming agent. The addition of foaming agents to the asphalt binder has also lowered the activation energy of the asphalt binder, which has high potential in lowering the energy demand during production processes. The foamed WMA mixture prepared at 100°C was found to have behavior comparable with the control Hot Mix Asphalt (HMA) prepared at 155°C in terms of coatability, workability and compactability. Based on the mixture performance tests, the foamed WMA has a comparable or better performance than the HMA in terms of resistance to moisture damage, permanent deformation, fracture cracking and thermal cracking. The application of nano-hydrated lime is efficient in enhancing the aggregate coatability and improving the bearing capacity of asphalt pavement to lower the rutting potential and moisture susceptibility of foamed WMA mixtures. Limitations for each of the related parameters are also reported in this dissertation for the lab production of foamed WMA mixtures using ethanol and NaHCO 3 as foaming agents. The specified values were made based on the binder test, service characteristics and performance of foamed WMA mixtures in order to yield a comparable or better performance than the control HMA. Field validations should be carried out to understand the overall performance and durability of the proposed foaming WMA.

  14. Hot-spot mix in ignition-scale implosions on the NIF

    SciTech Connect

    Regan, S. P.; Epstein, R.; McCrory, R. L.; Meyerhofer, D. D.; Sangster, T. C.; Hammel, B. A.; Suter, L. J.; Ralph, J.; Scott, H.; Barrios, M. A.; Bradley, D. K.; Callahan, D. A.; Cerjan, C.; Collins, G. W.; Dixit, S. N.; Doeppner, T.; Edwards, M. J.; Farley, D. R.; Glenn, S.; Glenzer, S. H.; and others

    2012-05-15

    Ignition of an inertial confinement fusion (ICF) target depends on the formation of a central hot spot with sufficient temperature and areal density. Radiative and conductive losses from the hot spot can be enhanced by hydrodynamic instabilities. The concentric spherical layers of current National Ignition Facility (NIF) ignition targets consist of a plastic ablator surrounding a thin shell of cryogenic thermonuclear fuel (i.e., hydrogen isotopes), with fuel vapor filling the interior volume [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)]. The Rev. 5 ablator is doped with Ge to minimize preheat of the ablator closest to the DT ice caused by Au M-band emission from the hohlraum x-ray drive [D. S. Clark et al., Phys. Plasmas 17, 052703 (2010)]. Richtmyer-Meshkov and Rayleigh-Taylor hydrodynamic instabilities seeded by high-mode () ablator-surface perturbations can cause Ge-doped ablator to mix into the interior of the shell at the end of the acceleration phase [B. A. Hammel et al., Phys. Plasmas 18, 056310 (2011)]. As the shell decelerates, it compresses the fuel vapor, forming a hot spot. K-shell line emission from the ionized Ge that has penetrated into the hot spot provides an experimental signature of hot-spot mix. The Ge emission from tritium-hydrogen-deuterium (THD) and deuterium-tritium (DT) cryogenic targets and gas-filled plastic-shell capsules, which replace the THD layer with a mass-equivalent CH layer, was examined. The inferred amount of hot-spot-mix mass, estimated from the Ge K-shell line brightness using a detailed atomic physics code [J. J. MacFarlane et al., High Energy Density Phys. 3, 181 (2006)], is typically below the 75-ng allowance for hot-spot mix [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)]. Predictions of a simple mix model, based on linear growth of the measured surface-mass modulations, are consistent with the experimental results.

  15. Evaluation of Cement, Lime, and Asphalt Amended Municipal Solid Waste Incinerator Residues

    DTIC Science & Technology

    1989-09-01

    waste does not contain sufficient pozzolans for lime solidification, or if organics in the cement residue mixes are excessive, a low 3 strength material...occur due to insufficient coverage of the residue by the asphalt binder . This defeats the asphalt’s primary metal immobilization mechanism...stabilized waste form direct contact with an cidic environment (Cote, 1986). Asphalt Amended Wastes. As with most thermoplastic agent, asphalt binder

  16. Disturbance, A Mechanism for Increased Microbial Diversity in a Yellowstone National Park Hot Spring Mixing Zone

    NASA Astrophysics Data System (ADS)

    Howells, A. E.; Oiler, J.; Fecteau, K.; Boyd, E. S.; Shock, E.

    2014-12-01

    The parameters influencing species diversity in natural ecosystems are difficult to assess due to the long and experimentally prohibitive timescales needed to develop causative relationships among measurements. Ecological diversity-disturbance models suggest that disturbance is a mechanism for increased species diversity, allowing for coexistence of species at an intermediate level of disturbance. Observing this mechanism often requires long timescales, such as the succession of a forest after a fire. In this study we evaluated the effect of mixing of two end member hydrothermal fluids on the diversity and structure of a microbial community where disturbance occurs on small temporal and spatial scales. Outflow channels from two hot springs of differing geochemical composition in Yellowstone National Park, one pH 3.3 and 36 °C and the other pH 7.6 and 61 °C flow together to create a mixing zone on the order of a few meters. Geochemical measurements were made at both in-coming streams and at a site of complete mixing downstream of the mixing zone, at pH 6.5 and 46 °C. Compositions were estimated across the mixing zone at 1 cm intervals using microsensor temperature and conductivity measurements and a mixing model. Qualitatively, there are four distinct ecotones existing over ranges in temperature and pH across the mixing zone. Community analysis of the 16S rRNA genes of these ecotones show a peak in diversity at maximal mixing. Principle component analysis of community 16S rRNA genes reflects coexistence of species with communities at maximal mixing plotting intermediate to communities at distal ends of the mixing zone. These spatial biological and geochemical observations suggest that the mixing zone is a dynamic ecosystem where geochemistry and biological diversity are governed by changes in the flow rate and geochemical composition of the two hot spring sources. In ecology, understanding how environmental disruption increases species diversity is a foundation

  17. Direct verification of mixing rules in the hot and dense regime

    SciTech Connect

    Lambert, F.; Clerouin, J.; Danel, J.-F.; Kazandjian, L.; Zerah, G.

    2008-02-15

    We perform orbital-free molecular dynamics simulations in the hot and dense regime for two mixtures: equimolar helium-iron and asymmetric deuterium-copper plasmas. For thermodynamic properties, we test two isobaric-isothermal mixing rules whose definitions involve either the equality of total pressures or the equality of the so-defined excess pressures of the components; the pressure and internal energy obtained by direct simulations are in very good agreement with those given by the mixing rule involving the equality of excess pressures. The viscosity of the deuterium-copper mixture is also extracted from a direct simulation and compared to the result given by a mixing rule applied to the viscosities of the pure elements. Finally, for structural properties, the effective charges given by the isobaric-isothermal mixing rule for the average atom model, used in the binary ionic mixture model, yield partial pair distribution functions in good agreement with those obtained by a direct simulation.

  18. Elimination chemistry in asphalt

    SciTech Connect

    Boucher, J.L.; Ihsiung Wang; Martinez, D.F. )

    1990-07-01

    Elimination chemistry provides important information, not only about the chemical properties of asphalt, but also the chemical modification method of asphalt. The chemical reactions which use the natural abundance of radicals are important for free-radical halogenation reaction. Spectral data demonstrates the formation of halogenated asphalt. The utility of dehydrohalogenation modified asphalt is limited. However, the resulting dehydrohalogenation modified asphalt does produce a significant unsaturated intermediate, which can incorporate elastomeric polymers (and monomers) via condensation or addition process. The second chemical modification method is the Hofmann elimination reaction, which was performed by reaction of methyl iodide with asphalt, followed by treatment of base. Spectroscopic data shows that a methyl group attached to nitrogen or sulfur in asphalt after Hofmann elimination reaction. Physical data shows that the Hofmann elimination modification improved the quality of asphalt, such as low temperature susceptibility measured by PVN. The modified asphalt also studied by HP-GPC in order to correlate their physical properties. The result shows that the molecular size distribution has changed and reduced the amount of LMS. The amount of decreasing LMS is also dependent on the content of nitrogen and sulfur in asphalts.

  19. Characterization of cold recycled asphalt mixtures

    SciTech Connect

    Tia, M.

    1982-01-01

    In this study, the long-term behavior of the cold-recycled asphalt mixtures was investigated through nine experimental designs. The scope of the study covered two types of pavement material, three levels of oxydized condition of the old binder and one type of virgin aggregate. The added softening agents included a high-float asphalt emulsion AE-150, a foamed asphalt, and the rejuvenating agents, Reclamite, Mobilsol and DUTREX 739. The Water Sensitivity Test was used to evaluate the resistance of the recycled mixes to water. The results of the study indicated that most of the rejuvenating action of the added binder on the old binder took place during the compaction process. The binders of the recycled mixes which underwent the initial softening during the compaction process generally increased in stiffness with increasing curing time. The results indicated that the gyratory stability index and the gyratory elasto-plastic index could be used to determine the optimum binder content of a recycled mix. However, they could not be used to estimate the resilient modulus or the Marshall stability of the mix.A higher compactive effort generally produced a higher resilient modulus and Marshall stability of the recycled mix. When the binder content is too high, a higher compactive effort generally produces a lower Hveem R-value.The structural performance of these recycled mixes was compared to that of an asphalt concrete using a linear elastic multilayer analysis.

  20. HPLC and NMR spectroscopy to characterize asphaltic materials

    SciTech Connect

    Jennings, P.W.; Pribanic, J.A.S.; Dawson, K.R.; Bricca, C.E.

    1981-09-01

    High performance liquid chromatography (HPLC) using gel permeation columns seems to offer a practical alternative for asphalt characterization because analyses can be performed quickly. The technique shows a unique molecular size distribution for each asphalt and this profile have been correlated with results of performance of pavement from which asphalt was extracted. Conclusions have shown that a larger quantity of larger molecular size materials are present in asphalts from roadways which exhibit cracking than in those from old, uncracked pavements. The effects on asphalt of a variety of treatments have been initiated. One method includes heating asphalt for 1 h at 163/sup 0/C in the presence of oxygen or nitrogen. The asphalt is mixed with lime and various aggregates and/or fly ash, as well. The mixture is then cooled and extracted with benzene. Once the solvent has been removed, the sample is redissolved in tetrahydrofuran and analyzed by HPLC. Results show that heating this particular asphalt with an aggregate with or without lime results in a 20% increase of large-sized molecules. Use of both fly ash and aggregate increases the total effect to 34%. The HPLC method can be used to substantiate new asphalt blends. 5 figures, 1 table.

  1. Stabilization/solidification of munition destruction waste by asphalt emulsion.

    PubMed

    Cervinkova, Marketa; Vondruska, Milan; Bednarik, Vratislav; Pazdera, Antonin

    2007-04-02

    Destruction of discarded military munitions in an explosion chamber produces two fractions of hazardous solid waste. The first one is scrap waste that remains in the chamber after explosion; the second one is fine dust waste, which is trapped on filters of gas products that are exhausted from the chamber after explosion. The technique of stabilization/solidification of the scrap waste by asphalt emulsion is described in this paper. The technique consists of simple mixing of the waste with anionic asphalt emulsion, or two-step mixing of the waste with cationic asphalt emulsion. These techniques are easy to use and the stabilized scrap waste proves low leachability of contained heavy metals assessed by TCLP test. Hence, it is possible to landfill the scrap waste stabilized by asphalt emulsion. If the dust waste, which has large specific surface, is stabilized by asphalt emulsion, it is not fully encapsulated; the results of the leaching tests do not meet the regulatory levels. However, the dust waste solidified by asphalt emulsion can be deposited into an asphalted disposal site of the landfill. The asphalt walls of the disposal site represent an efficient secondary barrier against pollutant release.

  2. International State-of-the-Art Colloquium on Low-Temperature Asphalt Pavement Cracking Held in Hanover, New Hampshire on 6-8 May 1987

    DTIC Science & Technology

    1991-02-01

    tem- perature susceptibility of the asphalt cement appear to General discussion be worse than it actually is. Further, air- blown asphalt The first...the fracture temperature was calculc’, ,where point for waxy and air- blown asphalt cements, and the the stress in the mix exceeded the strength of...of sured using a two-point bending apparatus and trapezoi- air- blown asphalts to reduce thermal cracking of asphalt dal-shaped spc.,inens. Twelve

  3. Characterization of asphalt materials containing bio oil from michigan wood

    NASA Astrophysics Data System (ADS)

    Mills-Beale, Julian

    The objective of this research is to develop sustainable wood-blend bioasphalt and characterize the atomic, molecular and bulk-scale behavior necessary to produce advanced asphalt paving mixtures. Bioasphalt was manufactured from Aspen, Basswood, Red Maple, Balsam, Maple, Pine, Beech and Magnolia wood via a 25 KWt fast-pyrolysis plant at 500 °C and refined into two distinct end forms - non-treated (5.54% moisture) and treated bioasphalt (1% moisture). Michigan petroleum-based asphalt, Performance Grade (PG) 58-28 was modified with 2, 5 and 10% of the bioasphalt by weight of base asphalt and characterized with the gas chromatography-mass spectroscopy (GC-MS), Fourier Transform Infra-red (FTIR) spectroscopy and the automated flocculation titrimetry techniques. The GC-MS method was used to characterize the Carbon-Hydrogen-Nitrogen (CHN) elemental ratio whiles the FTIR and the AFT were used to characterize the oxidative aging performance and the solubility parameters, respectively. For rheological characterization, the rotational viscosity, dynamic shear modulus and flexural bending methods are used in evaluating the low, intermediate and high temperature performance of the bio-modified asphalt materials. 54 5E3 (maximum of 3 million expected equivalent standard axle traffic loads) asphalt paving mixes were then prepared and characterized to investigate their laboratory permanent deformation, dynamic mix stiffness, moisture susceptibility, workability and constructability performance. From the research investigations, it was concluded that: 1) levo, 2, 6 dimethoxyphenol, 2 methoxy 4 vinylphenol, 2 methyl 1-2 cyclopentandione and 4-allyl-2, 6 dimetoxyphenol are the dominant chemical functional groups; 2) bioasphalt increases the viscosity and dynamic shear modulus of traditional asphalt binders; 3) Bio-modified petroleum asphalt can provide low-temperature cracking resistance benefits at -18 °C but is susceptible to cracking at -24 °C; 3) Carbonyl and sulphoxide

  4. Convective Mixing in Distal Pipes Exacerbates Legionella pneumophila Growth in Hot Water Plumbing

    PubMed Central

    Rhoads, William J.; Pruden, Amy; Edwards, Marc A.

    2016-01-01

    Legionella pneumophila is known to proliferate in hot water plumbing systems, but little is known about the specific physicochemical factors that contribute to its regrowth. Here, L. pneumophila trends were examined in controlled, replicated pilot-scale hot water systems with continuous recirculation lines subject to two water heater settings (40 °C and 58 °C) and three distal tap water use frequencies (high, medium, and low) with two pipe configurations (oriented upward to promote convective mixing with the recirculating line and downward to prevent it). Water heater temperature setting determined where L. pneumophila regrowth occurred in each system, with an increase of up to 4.4 log gene copies/mL in the 40 °C system tank and recirculating line relative to influent water compared to only 2.5 log gene copies/mL regrowth in the 58 °C system. Distal pipes without convective mixing cooled to room temperature (23–24 °C) during periods of no water use, but pipes with convective mixing equilibrated to 30.5 °C in the 40 °C system and 38.8 °C in the 58 °C system. Corresponding with known temperature effects on L. pneumophila growth and enhanced delivery of nutrients, distal pipes with convective mixing had on average 0.2 log more gene copies/mL in the 40 °C system and 0.8 log more gene copies/mL in the 58 °C system. Importantly, this work demonstrated the potential for thermal control strategies to be undermined by distal taps in general, and convective mixing in particular. PMID:26985908

  5. Convective Mixing in Distal Pipes Exacerbates Legionella pneumophila Growth in Hot Water Plumbing.

    PubMed

    Rhoads, William J; Pruden, Amy; Edwards, Marc A

    2016-03-12

    Legionella pneumophila is known to proliferate in hot water plumbing systems, but little is known about the specific physicochemical factors that contribute to its regrowth. Here, L. pneumophila trends were examined in controlled, replicated pilot-scale hot water systems with continuous recirculation lines subject to two water heater settings (40 °C and 58 °C) and three distal tap water use frequencies (high, medium, and low) with two pipe configurations (oriented upward to promote convective mixing with the recirculating line and downward to prevent it). Water heater temperature setting determined where L. pneumophila regrowth occurred in each system, with an increase of up to 4.4 log gene copies/mL in the 40 °C system tank and recirculating line relative to influent water compared to only 2.5 log gene copies/mL regrowth in the 58 °C system. Distal pipes without convective mixing cooled to room temperature (23-24 °C) during periods of no water use, but pipes with convective mixing equilibrated to 30.5 °C in the 40 °C system and 38.8 °C in the 58 °C system. Corresponding with known temperature effects on L. pneumophila growth and enhanced delivery of nutrients, distal pipes with convective mixing had on average 0.2 log more gene copies/mL in the 40 °C system and 0.8 log more gene copies/mL in the 58 °C system. Importantly, this work demonstrated the potential for thermal control strategies to be undermined by distal taps in general, and convective mixing in particular.

  6. Ice melting properties of steel fiber modified asphalt mixtures with induction heating

    NASA Astrophysics Data System (ADS)

    Fang, Hao; Sun, Yihan; Liu, Quantao; Li, Bin; Wu, Shaopeng; Tang, Jin

    2017-03-01

    In this paper, the ice melting performance of asphalt concrete with steel fibers was studied. Steel fiber modified asphalt mixtures were prepared, five different fiber amount of steel fiber modified asphalt mixtures were mixed to study their induction heating rate. The samples covered with different thickness of ice were heated with induction heating to study their ice melting efficency. It was proved that the induction heating of steel fiber modified asphalt mixtures could significantly improve their ice melting efficency compared with the natural condition. And it was found that the thickness of the ice had little influence on the induction heating rate of the asphalt concrete.

  7. Asphalt in Pavement Maintenance.

    ERIC Educational Resources Information Center

    Asphalt Inst., College Park, MD.

    Maintenance methods that can be used equally well in all regions of the country have been developed for the use of asphalt in pavement maintenance. Specific information covering methods, equipment and terminology that applies to the use of asphalt in the maintenance of all types of pavement structures, including shoulders, is provided. In many…

  8. 3d Mixing In Hot-jupiter Atmospheres: Application To Tio Clouds On Hd209458b

    NASA Astrophysics Data System (ADS)

    Parmentier, Vivien; Showman, A. P.; Lian, Y.

    2012-10-01

    Like brown dwarfs, hot Jupiters exhibit atmospheric temperatures ranging from hundreds to thousands of Kelvins. But unlike them, they are highly 3D objects with strongly asymmetric heating and a huge day/night temperature contrast. Thus, many chemical species that can exist in gas phase on the dayside can condense and gravitationally settle on the nightside. The abundance of such species in the atmosphere therefore depends whether or not the atmospheric circulation can loft them vertically despite their tendency to gravitationally settle on the nightside. To understand the three-dimensional distribution of such species, we present global circulation models of HD209458b including passive tracers that advect with the three-dimensional flow, including a source/sink on the nightside to represent condensation and gravitational settling. We show that global advection patterns produce very strong vertical mixing that can keep particles lofted as long as the particles sizes are a few microns or less. A key point is that the region being vigorously mixed is stably stratified; the vertical mixing results not from small-scale convection but from the large-scale circulation driven by the day-night heating contrast. Although this vertical mixing is not diffusive in any rigorous sense, a comparison of our results with idealized diffusion models allows a rough estimate of the effective vertical eddy diffusivities in these atmospheres; we will present these diffusivities, which can be used in 1D models of the atmosphere. Moreover, we show that the models produce strong spatial and temporal variability in the tracer concentration that could result in observable variations in the secondary eclipse depth of hot Jupiters. Finally, we focus on TiO in HD209458b and show that the day-night cold trap would deplete TiO if it condenses into particles bigger than a few microns on the planet's night side, making it unable to create the observed stratosphere of the planet.

  9. Coal-based synthetic asphalt. Final report

    SciTech Connect

    Guin, J.A.; Curtis, C.W.; Tarrer, A.R.

    1986-02-01

    The objective of the work was to investigate in the laboratory the technical and economic aspects of the production of a synthetic asphalt from U.S. bituminous and subbituminous coals. Bench-scale autoclave hydrogenation experiments were used to produce coal-based asphalt cements from Illinois No. 6 bituminous coal and a Wyoming subbituminous coal. A factorially designed experiment showed that VTS of coal-based asphalts was insensitive to process conditions. Hydrated lime treatment lowered VTS slightly, but the polymer additive was required to achieve specification VTS values. Age hardening was primarily due to oxidation with a minor contribution from volatiles loss. Marshall stability testing shhowed the coal-based compacted mixes to have excellent resistance to plastic flow. Immersion compression testing showed high stability and retained strengths.

  10. Characterization and design of asphalt mixtures with asphaltites from Boyacá for use in low traffic volume roads

    NASA Astrophysics Data System (ADS)

    Manrique-Espindola, R.

    2013-11-01

    The high availability of asphaltites in Boyacá and their low cost make this material a viable alternative for low traffic road paving; nevertheless, the traditional way in which this material is used generates, in cases, pavements with deficient behavior. This investigation, presents the results of the mixture design using asphaltites from the municipality of Pesca-Boyacá as well as coarse and fine aggregates produced in the region, 70-80 asphalt cement and slow-break asphalt emulsion. Working formulas for dense mixing in hot and cold and particularly MDF-2 and MDC-2 are presented from the characterization information; as benchmarks to define technical viability for use in low- traffic volume roads, according to NT1 regulation from INVIAS. The mixture design was performed according to the procedures defined in the RAMCODES and MARSHALL methodologies.

  11. Voids characteristics of asphaltic concrete containing coconut shell

    NASA Astrophysics Data System (ADS)

    Ezree Abdullah, Mohd; Hannani Madzaili, Amirah; Putra Jaya, Ramadhansyah; Yaacob, Haryati; Hassan, Norhidayah Abdul; Nazri, Fadzli Mohamed

    2017-07-01

    Asphalt durability is often linked to the thickness of the asphalt coating on the aggregate particles. In order to have adequate film thickness in asphaltic concrete, there must be sufficient space between the aggregate particles in the compacted pavement. This void space is referred to as voids in total mix (VTM), voids with filled bitumen (VFB), and voids in mineral aggregate (VMA). Hence, this study investigates the performance of coconut shell (CS) as coarse aggregate replacement on voids characteristics of asphaltic concrete. Four CS were used as coarse aggregates replacement in asphalt mixture namely 0%, 10%, 20%, 30%, and 40% (by weight volume). The voids properties of asphalt mixture were determined based on Marshall Mix design test. Test results show that VTM and VMA values were decrease with the increasing bitumen content where VFB was increase with increasing bitumen content. Furthermore, increasing the percentage of coconut shell in asphalt mixture was found to increases the voids value up to a peak level and then decreases with further additions of CS.

  12. Thickness and air voids measurement on asphalt concrete pavements using ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Dhakal, Sharad Raj

    Layer thickness and air voids are important parameters in quality assurance of newly paved hot mix asphalt (HMA) pavements. A non-destructive testing (NDT) technique was used to collect layer thickness information. The thicknesses estimated by the technique were compared with core thicknesses. Ground penetrating radar (GPR) system with air coupled antennas was used for on-site pavement data collection. Two application softwares - RADAN and ROAD DOCTOR - were used to process the field data for estimating layer thicknesses and air voids along the scanned pavements. 150 mm diameter cores taken from random locations on the pavements were tested in the laboratory to determine layer thickness and air voids. Statistical analyses were conducted to compare thicknesses and generate a regression equation relating air voids and dielectric constant of the pavement material. No significant differences were found between thickness estimates from RADAN and ROAD DOCTOR softwares when compared to the core measurements. However, RADAN and ROAD DOCTOR results are marginally significantly different from each other. ROAD DOCTOR software was used to generate air voids for the pavements scanned. Laboratory results from cores were utilized to determine calibration factors for the air voids -- dielectric equation. A relationship between air voids and dielectric constant is presented. It is concluded that GPR system with air coupled antennas used alongside a reduced core testing has a potential for quality control of newly paved hot mixed asphalt pavements.

  13. The role of hot spot mix in the low-foot and high-foot implosions on the NIF

    NASA Astrophysics Data System (ADS)

    Ma, T.; Patel, P. K.; Izumi, N.; Springer, P. T.; Key, M. H.; Atherton, L. J.; Barrios, M. A.; Benedetti, L. R.; Bionta, R.; Bond, E.; Bradley, D. K.; Caggiano, J.; Callahan, D. A.; Casey, D. T.; Celliers, P. M.; Cerjan, C. J.; Church, J. A.; Clark, D. S.; Dewald, E. L.; Dittrich, T. R.; Dixit, S. N.; Döppner, T.; Dylla-Spears, R.; Edgell, D. H.; Epstein, R.; Field, J.; Fittinghoff, D. N.; Frenje, J. A.; Gatu Johnson, M.; Glenn, S.; Glenzer, S. H.; Grim, G.; Guler, N.; Haan, S. W.; Hammel, B. A.; Hatarik, R.; Herrmann, H. W.; Hicks, D.; Hinkel, D. E.; Berzak Hopkins, L. F.; Hsing, W. W.; Hurricane, O. A.; Jones, O. S.; Kauffman, R.; Khan, S. F.; Kilkenny, J. D.; Kline, J. L.; Kozioziemski, B.; Kritcher, A.; Kyrala, G. A.; Landen, O. L.; Lindl, J. D.; Le Pape, S.; MacGowan, B. J.; Mackinnon, A. J.; MacPhee, A. G.; Meezan, N. B.; Merrill, F. E.; Moody, J. D.; Moses, E. I.; Nagel, S. R.; Nikroo, A.; Pak, A.; Parham, T.; Park, H.-S.; Ralph, J. E.; Regan, S. P.; Remington, B. A.; Robey, H. F.; Rosen, M. D.; Rygg, J. R.; Ross, J. S.; Salmonson, J. D.; Sater, J.; Sayre, D.; Schneider, M. B.; Shaughnessy, D.; Sio, H.; Spears, B. K.; Smalyuk, V.; Suter, L. J.; Tommasini, R.; Town, R. P. J.; Volegov, P. L.; Wan, A.; Weber, S. V.; Widmann, K.; Wilde, C. H.; Yeamans, C.; Edwards, M. J.

    2017-05-01

    Hydrodynamic mix of the ablator into the DT fuel layer and hot spot can be a critical performance limitation in inertial confinement fusion implosions. This mix results in increased radiation loss, cooling of the hot spot, and reduced neutron yield. To quantify the level of mix, we have developed a simple model that infers the level of contamination using the ratio of the measured x-ray emission to the neutron yield. The principal source for the performance limitation of the "low-foot" class of implosions appears to have been mix. Lower convergence "high-foot" implosions are found to be less susceptible to mix, allowing velocities of >380 km/s to be achieved.

  14. The role of hot spot mix in the low-foot and high-foot implosions on the NIF

    DOE PAGES

    Ma, T.; Patel, P. K.; Izumi, N.; ...

    2017-05-18

    Hydrodynamic mix of the ablator into the DT fuel layer and hot spot can be a critical performance limitation in inertial confinement fusion implosions. This mix results in increased radiation loss, cooling of the hot spot, and reduced neutron yield. To quantify the level of mix, we have developed a simple model that infers the level of contamination using the ratio of the measured x-ray emission to the neutron yield. The principal source for the performance limitation of the “low-foot” class of implosions appears to have been mix. As a result, lower convergence “high-foot” implosions are found to be lessmore » susceptible to mix, allowing velocities of >380 km/s to be achieved.« less

  15. Performance of Granite Asphalt Mixture Modified by Silane Coupling Agent

    NASA Astrophysics Data System (ADS)

    Liu, Zhihang; Li, Xia; Wang, Li; Kang, Rongling

    2017-06-01

    In order to improve pavement performance of granite asphalt mixture, the surface of granite mineral powder was organic modified by silane coupling agent. The water stability and high temperature stability of the asphalt mixture were analyzed by Marshall tests, immersion Marshall test, freeze-thaw splitting test and rutting test. The results show that the mixing amount of silane coupling agent in the range from 0.5% to 2.5% can significantly improve the high temperature stability and water stability of the asphalt mixture. Taking into account the performance and economic factors, 2.0% silane coupling agent on the surface of granite filler was recommended.

  16. Control of the morphology and optical properties of ZnO nanostructures via hot mixing of reverse micelles.

    PubMed

    Mao, Jing; Li, Xiao-Lei; Qin, Wen-Jing; Niu, Kai-Yang; Yang, Jing; Ling, Tao; Du, Xi-Wen

    2010-09-07

    ZnO nanostructures with controllable morphology were obtained by hot mixing reverse micelles containing Zn(NO(3))(2) or monoethanol amine aqueous solution. The ratio of water to surfactant concentration (omega(0)) was found to play a decisive role in determining the final morphology, namely, nanotetrahedrons formed at a lower omega(0) value and nanorods formed at a higher value. However, the hot mixing technique is propitious for obtaining nanostructures with uniform size. The ZnO nanotetrahedrons obtained gave a strong blue emission arising from interface state, and the ZnO nanorods emitted green light related to donor defects. Our results indicate that the hot mixing of reverse micelles is a unique way to tune the morphology and properties of nanostructures.

  17. Multiscale Constitutive Modeling of Asphalt Concrete

    NASA Astrophysics Data System (ADS)

    Underwood, Benjamin Shane

    Multiscale modeling of asphalt concrete has become a popular technique for gaining improved insight into the physical mechanisms that affect the material's behavior and ultimately its performance. This type of modeling considers asphalt concrete, not as a homogeneous mass, but rather as an assemblage of materials at different characteristic length scales. For proper modeling these characteristic scales should be functionally definable and should have known properties. Thus far, research in this area has not focused significant attention on functionally defining what the characteristic scales within asphalt concrete should be. Instead, many have made assumptions on the characteristic scales and even the characteristic behaviors of these scales with little to no support. This research addresses these shortcomings by directly evaluating the microstructure of the material and uses these results to create materials of different characteristic length scales as they exist within the asphalt concrete mixture. The objectives of this work are to; 1) develop mechanistic models for the linear viscoelastic (LVE) and damage behaviors in asphalt concrete at different length scales and 2) develop a mechanistic, mechanistic/empirical, or phenomenological formulation to link the different length scales into a model capable of predicting the effects of microstructural changes on the linear viscoelastic behaviors of asphalt concrete mixture, e.g., a microstructure association model for asphalt concrete mixture. Through the microstructural study it is found that asphalt concrete mixture can be considered as a build-up of three different phases; asphalt mastic, fine aggregate matrix (FAM), and finally the coarse aggregate particles. The asphalt mastic is found to exist as a homogenous material throughout the mixture and FAM, and the filler content within this material is consistent with the volumetric averaged concentration, which can be calculated from the job mix formula. It is also

  18. Physical Parameters of Hot Horizontal-Branch Stars in NGC 6752: Deep Mixing and Radiative Levitation

    NASA Technical Reports Server (NTRS)

    Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Heber, U.; Catelan, M.

    1999-01-01

    Atmospheric parameters (T(sub eff), log g and log n(sub He)/n(sub H-dot)) are derived for 42 hot horizontal branch (HB) stars in the globular cluster NGC 6752. For 19 stars Mg II and Fe II lines are detected indicating an iron enrichment by a factor 50 on average with respect to the cluster abundance whereas the magnesium abundances are consistent with the cluster metallicity. This finding adds to the growing evidence that radiative levitation plays a significant role in determining the physical parameters of blue HB stars. Indeed, we find that iron enrichment can explain part, but not all, of the problem of anomalously low gravities along the blue HB. Thus the physical parameters of horizontal branch stars hotter than about 11,500 K in NGC 6752, as derived in this paper, are best explained by a combination of helium mixing and radiative levitation effects.

  19. Large eddy simulation of mixing between hot and cold sodium flows - comparison with experiments

    SciTech Connect

    Simoneau, J.P.; Noe, H.; Menant, B.

    1995-09-01

    The large eddy simulation is becoming a potential powerful tool for the calculation of turbulent flows. In nuclear liquid metal cooled fast reactors, the knowledge of the turbulence characteristics is of great interest for the prediction and the analysis of thermal stripping phenomena. The objective of this paper is to give a contribution in the evaluation of the large eddy simulation technique is an individual case. The problem chosen is the case of the mixing between hot and cold sodium flows. The computations are compared with available sodium tests. This study shows acceptable qualitative results but the simple model used is not able to predict the turbulence characteristics. More complex models including larger domains around the fluctuating zone and fluctuating boundary conditions could be necessary. Validation works are continuing.

  20. Supercritical refining of asphalt to produce asphalt recycling agents

    SciTech Connect

    Chaffin, J.M.; Davison, R.R.; Glover, C.J.; Bullin, J.A.

    1995-12-31

    Several asphalts were fractionated using supercritical pentane. These fractions were analyzed and Gel Permeation Chromatography and High Performance Liquid Chromatography and their viscosities were measured. The properties of these fractions vary not only among the fractions of a given asphalt, but also for the same fraction produced from different asphalts. These widely varied fractions previously have been shown to have potential for reblending to produce superior asphalts. This study investigates the potential for using some of the fractions as asphalt recycling agents. A modified SHRP PAV test was conducted on nine recycled asphalts. The aging indices of eight of the recycled asphalts are superior to the aging index of the original asphalt. In addition, two of the blends using industrial supercritical fractions and the three blends using laboratory supercritical fractions have lower aging indices than blends using commercial recycling agents.

  1. Application of mixed models to assess exposures monitored by construction workers during hot processes.

    PubMed

    Rappaport, S M; Weaver, M; Taylor, D; Kupper, L; Susi, P

    1999-10-01

    Particulate exposures were assessed among construction workers engaged in hot processes in four jobs (boilermakers, ironworkers, pipefitters and welder-fitters) at nine sites in the U.S. After being trained by occupational hygienists, the workers obtained shift-long personal samples at each site for total particulates (TP). Selected samples were also assayed for manganese (Mn), nickel (Ni), and chromium (Cr). Workers provided information about process- and task-related covariates that were present on the days of monitoring. Data were investigated with mixed-model regression analyses that designated the jobs and covariates as fixed effects and the worker and error terms as random effects. Results indicated that the within-worker variance components, but not the between-worker variance components, could be pooled among jobs. Mean air levels for a given agent varied by roughly six to 100 fold among the jobs, with boilermakers and ironworkers experiencing much higher levels of TP and Mn than pipefitters and welder-fitters. Limited data also suggested that welder-fitters were exposed to greater levels of Ni and Cr than pipefitters. Sufficient sample sizes were available to evaluate the effects of covariates upon exposures to TP and Mn. As expected, processes involving more than 50% hot work led to substantially higher levels of TP and Mn than those involving shorter durations of hot work. Local-exhaust or mechanical ventilation reduced exposure to TP (but not Mn) by as much as 44%, and shielded or manual arc welding increased exposure to Mn (but not TP) by about 80%. Parameters estimated with these mixed models were used to calculate probabilities that workers were exposed at levels above U.S. occupational exposure limits (OELs). Regarding TP and Mn, these calculations suggested that 26-95% of exposures to boilermakers and pipefitters and 2-13% of exposures to pipefitters and welder-fitters exceeded the current Threshold Limit Values. Among welder-fitters, limited data

  2. Crumb rubber modifier (CRM) in asphalt pavement: Summary of practices in Arizona, California, and Florida. Interim report, 1 February-30 June 1995

    SciTech Connect

    Hicks, R.G.; Lundy, J.R.; Leahy, R.B.; Hanson, D.; Epps, J.

    1995-09-01

    Highway agencies have been evaluating crumb rubber modifier (CRM) in hot mix asphalt (HMA) since the 1970`s. Three agencies, Arizona, California, and Florida, currently use CRM in HMA at levels that would approach or exceed the mandate in Section 1038 of the Intermodal Surface Transportation Efficiency Act of 1991. This report documents the use of CRM in HMA in these three States. In particular, it addresses issues including thickness design, materials and mix design, construction procedure, including control, and pavement performance. The report also addresses the following questions: (1) What processes are used, (2) Why are they used, (3) How are they performing.

  3. Feasibility of using 100% Recycled Asphalt Pavement mixtures for road construction

    NASA Astrophysics Data System (ADS)

    Carlson, Russell Edgar, IV

    Recycled Asphalt Pavement (RAP) is the largest recycled good in the United States and 80 million tons are recycled yearly, saving taxpayers about $1.5 billion dollars. This paper explores the possibility of utilizing 100% RAP materials in asphalt pavement. Asphalt mixtures are produced at 135°C in a typical asphalt plant. However, at 135°C, not all binder from RAP materials may not become effective for coating aggregates. The main objective of the study is to determine the amount of effective binder available from RAP in the asphalt plant. The 100% RAP mixes have aged binder that can alter mix designs and interaction with virgin binder. In this study, to determine low temperature cracking resistance and fatigue performance, samples were prepared using a 100% RAP mix with no virgin binder and a 100% RAP mix with virgin asphalt binder to achieve the optimum binder content of the mix. Second, to determine the effectiveness of binder from RAP materials, compaction tests were performed by heating RAP materials at various temperatures. It was found that 100% RAP mixes cannot be feasible for field use if additional virgin binder is added to reach the optimum asphalt content. Based on limited test results, the low temperature grade was not within proper limits but the beam fatigue testing results were acceptable. Based on compaction test results, additional heating is needed to increase the effectiveness of asphalt binder from RAP materials.

  4. Rutting Performance of Cold-Applied Asphalt Repair Materials for Airfield Pavements

    DTIC Science & Technology

    2017-06-23

    ER D C/ G SL T R- 17 -1 0 Rutting Performance of Cold-Applied Asphalt Repair Materials for Airfield Pavements G eo te ch ni ca l a nd S...of Cold-Applied Asphalt Repair Materials for Airfield Pavements Ben C. Cox, John F. Rushing, and Web Floyd Geotechnical and Structures Laboratory...at ambient tempera- tures. This study primarily evaluated the rutting performance of nine commercial cold mix asphalt repair materials . Both

  5. The reinforcement and healing of asphalt mastic mixtures by rejuvenator encapsulation in alginate compartmented fibres

    NASA Astrophysics Data System (ADS)

    Tabaković, A.; Post, W.; Cantero, D.; Copuroglu, O.; Garcia, S. J.; Schlangen, E.

    2016-08-01

    This paper explores the potential use of compartmented alginate fibres as a new method of incorporating rejuvenators into asphalt pavement mixtures. The compartmented fibres are employed to locally distribute the rejuvenator and to overcome the problems associated with spherical capsules and hollow fibres. The work presents proof of concept of the encapsulation process which involved embedding the fibres into the asphalt mastic mixture and the survival rate of fibres in the asphalt mixture. To prove the effectiveness of the alginate as a rejuvenator encapsulating material and to demonstrate its ability survive asphalt production process, the fibres containing the rejuvenator were prepared and subjected to thermogravimetric analysis and uniaxial tensile test. The test results demonstrated that fibres have suitable thermal and mechanical strength to survive the asphalt mixing and compaction process. The CT scan of an asphalt mortar mix containing fibres demonstrated that fibres are present in the mix in their full length, undamaged, providing confirmation that the fibres survived the asphalt production process. In order to investigate the fibres physiological properties and ability to release the rejuvenator into cracks in the asphalt mastic, the environmental scanning electron microscope and optical microscope analysis were employed. To prove its success as an asphalt healing system, compartmented alginate fibres containing rejuvenator were embedded in asphalt mastic mix. The three point bend tests were performed on the asphalt mastic test samples and the degree to which the samples began to self-heal in response was measured and quantified. The research findings indicate that alginate fibres present a promising new approach for the development of self-healing asphalt pavement systems.

  6. Microbial Degradation of Asphalt1

    PubMed Central

    Phillips, U. A.; Traxler, R. W.

    1963-01-01

    Organisms of the genera Pseudomonas, Chromobacterium, and Bacillus capable of degrading asphalt were isolated by enrichment cultures. The asphalt degradation by these organisms varied from 3 to 25% after incubation for 1 week. The effects of temperature, pH, and atmosphere of incubation on asphalt degradation were investigated and were shown to vary with different organisms on the same substrate. PMID:16349633

  7. HP-GPC characterization of asphalt and modified asphalts from gulf countries and their relation to performance based properties

    SciTech Connect

    Wahhab, H.I.A.; Ali, M.F.; Asi, I.M.; Dubabe, I.A.

    1996-12-31

    Asphalt producing refineries in the Gulf countries include Ras Tanura and Riyadh (Saudi Arabia), Al-Ahmadi (Kuwait), and BAPCO (Bahrain). Riyadh and Ras Tanura refineries are located in the central and eastern Saudi Arabia respectively. Arabian light crude oil is used to produce 2000 to 3000 tons of asphalt per day using vacuum distillation, air blowing and grade blending techniques to produce 60/70 penetration grade asphalts in each of these two Saudi refineries. All of the asphalt cement used in Saudi Arabia, Qatar and parts of the United Arab Emirates is supplied by Riyadh and Ras Tanura refineries. Al-Ahmadi refinery supplies all of the asphalt cement needed for construction in the state of Kuwait. Ratwi-Burgan crude off mix is used to produce 750 to 1000 tons of asphalt per day using vacuum distillation and air blowing processes. This study was initiated to evaluate different locally available polymers in order to identify potential polymers to modify asphalts to satisfy the performance requirements in the Gulf countries environmental conditions.

  8. Microbial life in a liquid asphalt desert.

    PubMed

    Schulze-Makuch, Dirk; Haque, Shirin; de Sousa Antonio, Marina Resendes; Ali, Denzil; Hosein, Riad; Song, Young C; Yang, Jinshu; Zaikova, Elena; Beckles, Denise M; Guinan, Edward; Lehto, Harry J; Hallam, Steven J

    2011-04-01

    Pitch Lake in Trinidad and Tobago is a natural asphalt reservoir nourished by pitch seepage, a form of petroleum that consists of mostly asphaltines, from the surrounding oil-rich region. During upward seepage, pitch mixes with mud and gases under high pressure, and the lighter portion evaporates or is volatilized, which produces a liquid asphalt residue characterized by low water activity, recalcitrant carbon substrates, and noxious chemical compounds. An active microbial community of archaea and bacteria, many of them novel strains (particularly from the new Tar ARC groups), totaling a biomass of up to 10(7) cells per gram, was found to inhabit the liquid hydrocarbon matrix of Pitch Lake. Geochemical and molecular taxonomic approaches revealed diverse, novel, and deeply branching microbial lineages with the potential to mediate anaerobic hydrocarbon degradation processes in different parts of the asphalt column. In addition, we found markers for archaeal methane metabolism and specific gene sequences affiliated with facultative and obligate anaerobic sulfur- and nitrite-oxidizing bacteria. The microbial diversity at Pitch Lake was found to be unique when compared to microbial communities analyzed at other hydrocarbon-rich environments, which included Rancho Le Brea, a natural asphalt environment in California, USA, and an oil well and a mud volcano in Trinidad and Tobago, among other sites. These results open a window into the microbial ecology and biogeochemistry of recalcitrant hydrocarbon matrices and establish the site as a terrestrial analogue for modeling the biotic potential of hydrocarbon lakes such as those found on Saturn's largest moon Titan.

  9. Microbial Life in a Liquid Asphalt Desert

    NASA Astrophysics Data System (ADS)

    Schulze-Makuch, Dirk; Haque, Shirin; de Sousa Antonio, Marina Resendes; Ali, Denzil; Hosein, Riad; Song, Young C.; Yang, Jinshu; Zaikova, Elena; Beckles, Denise M.; Guinan, Edward; Lehto, Harry J.; Hallam, Steven J.

    2011-04-01

    Pitch Lake in Trinidad and Tobago is a natural asphalt reservoir nourished by pitch seepage, a form of petroleum that consists of mostly asphaltines, from the surrounding oil-rich region. During upward seepage, pitch mixes with mud and gases under high pressure, and the lighter portion evaporates or is volatilized, which produces a liquid asphalt residue characterized by low water activity, recalcitrant carbon substrates, and noxious chemical compounds. An active microbial community of archaea and bacteria, many of them novel strains (particularly from the new Tar ARC groups), totaling a biomass of up to 107 cells per gram, was found to inhabit the liquid hydrocarbon matrix of Pitch Lake. Geochemical and molecular taxonomic approaches revealed diverse, novel, and deeply branching microbial lineages with the potential to mediate anaerobic hydrocarbon degradation processes in different parts of the asphalt column. In addition, we found markers for archaeal methane metabolism and specific gene sequences affiliated with facultative and obligate anaerobic sulfur- and nitrite-oxidizing bacteria. The microbial diversity at Pitch Lake was found to be unique when compared to microbial communities analyzed at other hydrocarbon-rich environments, which included Rancho Le Brea, a natural asphalt environment in California, USA, and an oil well and a mud volcano in Trinidad and Tobago, among other sites. These results open a window into the microbial ecology and biogeochemistry of recalcitrant hydrocarbon matrices and establish the site as a terrestrial analogue for modeling the biotic potential of hydrocarbon lakes such as those found on Saturn's largest moon Titan.

  10. Development of indirect ring tension test for fracture characterization of asphalt mixtures

    NASA Astrophysics Data System (ADS)

    Zeinali Siavashani, Alireza

    Low temperature cracking is a major distress in asphalt pavements. Several test configurations have been introduced to characterize the fracture properties of hot mix (HMA); however, most are considered to be research tools due to the complexity of the test methods or equipment. This dissertation describes the development of the indirect ring tension (IRT) fracture test for HMA, which was designed to be an effective and user-friendly test that could be deployed at the Department of Transportation level. The primary advantages of this innovative and yet practical test include: relatively large fracture surface test zone, simplicity of the specimen geometry, widespread availability of the required test equipment, and ability to test laboratory compacted specimens as well as field cores. Numerical modeling was utilized to calibrate the stress intensity factor formula of the IRT fracture test for various specimen dimensions. The results of this extensive analysis were encapsulated in a single equation. To develop the test procedure, a laboratory study was conducted to determine the optimal test parameters for HMA material. An experimental plan was then developed to evaluate the capability of the test in capturing the variations in the mix properties, asphalt pavement density, asphalt material aging, and test temperature. Five plant-produced HMA mixtures were used in this extensive study, and the results revealed that the IRT fracture test is highly repeatable, and capable of capturing the variations in the fracture properties of HMA. Furthermore, an analytical model was developed based on the viscoelastic properties of HMA to estimate the maximum allowable crack size for the pavements in the experimental study. This analysis indicated that the low-temperature cracking potential of the asphalt mixtures is highly sensitive to the fracture toughness and brittleness of the HMA material. Additionally, the IRT fracture test data seemed to correlate well with the data from

  11. Predicting rheological parameters of reclaimed asphalt cement with wave propagation techniques. Research report, 1 September 1993-31 August 1995

    SciTech Connect

    Nazarian, S.; Pezo, R.; Nori, S.R.G.; Picornell, M.

    1996-07-01

    A methodology to predict the rheological of asphalt cement from elastic modulus or from the indirect tensile (IDT) strength of the mix is presented. Wave propagation techniques were used to determine the modulus of the mix. Numerous specimens, prepared from four different mixtures with different asphalt contents and voids in the total mixes (VTM`s), were-oven aged for different periods. The elastic modulus and IDT strength of each specimen were determined, and its asphalt cement was recovered to evalutate its rheological properties. The effects of different parameters, such as asphalt content and VTM, on relationships between elastic modulus or IDT strength with rheological properties were determined.

  12. Studies of mixing and combustion in hypervelocity flows with hot hydrogen injection

    NASA Astrophysics Data System (ADS)

    Belanger, Jacques Jean

    1993-01-01

    The ability to build an air-breathing single-stage-to-orbit propulsion system requires the examination of key elements such as turbulent mixing rates, especially at the 'zero shear' fuel-air mixing condition, and combustion efficiency. The required data can only be obtained in experiments which simultaneously match the flight total pressure and total enthalpy as well as the fuel conditions. GALCIT, with its new free piston shock tunnel T5, has the capability to do some of these combustion experiments. But prior to these tests, it was felt that there was a need to simulate the gas dynamical processes in the free piston shock tunnel and also in a new combustion driven shock tunnel built for these experiments so that both systems could be used as efficiently as possible. The numerical code helped explain the piston motion in the free piston shock tunnel. The code was also very useful for the design of the combustion driven shock tunnel. Because hydrogen has to be injected into the combustion chamber of the propulsion system after being used as a cooling fluid, a combustion driven shock tunnel was built to reproduce this 'hot' hydrogen at up to 1500 K for the experiments. To reduce the complexity of the problem, a very basic configuration for the hydrogen injection system was tested. This was first done with an injection system mounted flush with the surface of a flat plate in the test section of T5. Different test conditions as well as Mach 2 and 5 nozzle injectors at angles of 15 or 30 degrees were tested to determine criteria for significant combustion. Lower limits in pressure and enthalpy were found where hydrogen combustion becomes very limited using this 'hot' hydrogen fuel. The second set of experiments still used an injection system mounted slush with the surface but involved a small combustor model previously tested in the hypervelocity HYPULSE facility. Low pressure experiments were performed to reproduce some of the HYPULSE tests and excellent agreement was

  13. Performance modeling of Arabian asphalt using HP-GPC

    NASA Astrophysics Data System (ADS)

    Asi, I. M.; Wahhab, H. I. Al-Abdul; Al-Dubabi, I. A.; Ali, M. F.

    1997-08-01

    In this study, Arabian neat asphalt samples were collected from different asphalt producing refineries in the Gulf countries. Another set of polymer modified samples was also included in this study. In the polymer modification process, 5,10, and 15% crumb rubber (CRT) and 3,6, and 9% styrene-butadiene-styrene (SBS) were used. All asphalt samples were subjected to two aging processes to simulate heating, mixing, compaction, and in-service aging. The asphalt samples at the different aging stages were subjected to performance-based tests that were adapted and/or modified by the Strategic Highway Research Program (SHRP) team. High pressure gel permeation chromatography (HP-GPC) was used to chemically analyze the test samples by generating profiles of their molecular size distribution. Models were built to predict the performance-based properties from the produced HP-GPC profiles.

  14. An Innovative Concept for Testing Rutting Susceptibility of Asphalt Mixture

    NASA Astrophysics Data System (ADS)

    Mohseni, Alaeddin; Azari, Haleh

    Currently, flow number (FN) is being used for measuring permanent deformation resistance of asphalt mixtures. The provisional AASHTO TP 79-10 test method specifies the requirements of the FN test; however, there are undefined levels of test variables, such as temperature, axial stress, and confinement. Therefore, agreeable FN criteria that can reliably discriminate between various mixtures have not been established yet. As the asphalt industry continues to develop more sophisticated mixtures (Warm Mix, RAP and RAS), the FN value has failed to capture the true complexity of the asphalt mixtures. These shortcomings and the unpredictable testing time of the FN test have affected its usefulness for evaluating high temperature performance of asphalt mixtures. A new test procedure for evaluation of rutting susceptibility of asphalt mixtures is being proposed. The new procedure is conducted at one temperature and multiple stresses on the same replicate in three increments of 500 cycles, which only takes 33 minutes to complete. The property of the test is the permanent strain due to the last cycle of each test increment (Minimum Strain Rate, or MSR). A master curve is developed by plotting the MSR values versus parameter TP, which is a product of Temperature and Pressure. The MSR master curve represents the unit rutting damage (rut per axle) of asphalt mixtures at any stress and temperature and can be used in laboratory for material characterization, mix design verification, ranking of the mixtures, or for pavement design applications to predict rut depth for project climate and design traffic.

  15. Prevention of hot tap water burns--a comparative study of three types of automatic mixing valve.

    PubMed

    Stephen, F R; Murray, J P

    1993-02-01

    To prevent fatal outbreaks of Legionnaires' disease, particularly in hospitals and other health-care premises, building services engineers are recommended to store and operate hot water systems at a temperature of 60 degrees C. However, water at this temperature can cause serious scalding. It is therefore advised that mixing valves be installed in the hot water supply pipework to provide hot water at safe temperatures for washing and bathing. Electricity Association Technology Ltd (EATL) investigated the performance of three makes of automatic mixing valve. Tests showed that with constant supply conditions there was little difference in performance between the three valves when blending hot and cold water. However, the ability of the valves to respond to the loss of the cold water supply was quite valve was able, consistently, to shut the hot water off in the event of cold water failure. These results suggest that where it is necessary to safeguard people or patients against any risk of scalding, e.g. young children and handicapped patients, a quality thermostatic valve should be installed rather than a cheaper tempering valve.

  16. Slow mechanical relaxation in asphalt

    SciTech Connect

    Stastna, J.; Zanzotto, L.

    1996-12-31

    Asphalt (or bitumen) is one of the earliest construction materials used by mankind. However, despite the long history of its use and the important role it plays at the present time, in the construction of pavements, the composition and especially the structure of asphalt is still not fully understood. It is generally believed that asphalt is a multiphase system in which the large and polar molecules called asphaltenes, or their agglomerates are dispersed in the medium consisting of the smaller molecules with low or no polarity. Opinions on how the asphalt structure is arranged vary. The study of asphalt structure is made extremely difficult by the nature of this material. Non-invasive methods such as dynamic mechanical or electric testing, which investigate the asphalt in its original state may greatly contribute to our knowledge of the asphalt internal structure.

  17. APPLICATION OF LOW TEMPERATU RE PROPERTIES IMPROVEMENT ASPHALT TO REPAIRE WORK OF RO CK FILL DAM WITH ASPHALT FACING

    NASA Astrophysics Data System (ADS)

    Shimazaki, Masaru; Tsunoo, Takashi; Kasahara, Atsushi

    The low temperature properties improvement asphalt that is no decreasing the transformation follow and the stress relaxation properties at the low temperature was developed. It aimed at properties of PG64-28 (lowest temperature 28 degree C and maximum temperature 64 degree C that was able to be used) from PG (Performance Grade) of mix design method SUPERPAVE (Superior Performance Pavement) of new road-building plan SHRP (Strategic Highway Research Program) in the United States when developing. When the repair work of the rock fill dam with asphalt facing located in Kyogoku-cho Abuta-gun Hokkaido was planned, the applicability of the developed asphalt was verified. As for the verification outcome and the developed asphalt, it was proven that it was applied to the repair construction, and there was no problem in manufacturing and construction.

  18. Quantum optical devices based on four-wave mixing in hot rubidium vapor

    NASA Astrophysics Data System (ADS)

    Fang, YaMi; Qin, ZhongZhong; Wang, HaiLong; Cao, LeiMing; Xin, Jun; Feng, JingLiang; Zhang, WeiPing; Jing, JieTai

    2015-06-01

    In this paper, we briefly review the recent experimental progresses in quantum optics based on four-wave mixing (FWM) processes in hot rubidium vapor, particularly our two recent experiments in quantum information. We have experimentally produced strong quantum correlations between three bright beams generated by two cascaded FWM processes. The intensity difference squeezing with the cascaded system is enhanced to (-7.0±0.1)dB from the (-5.5±0.1)dB/(-4.5±0.1)dB with only one FWM process. Also, this system can be easily extended to multiple modes using multiple FWM processes. Besides, we have also successfully realized a cascade all-optical transistor (AOT), which is driven by a very weak light beam about 800 photons in total. The required probe power for achieving a switching efficiency of 50% can be as low as 180 pW, and it can manipulate a light beam with power of 5.0×106 times more, which proves the cascade of the AOT. Both experiments may find wide applications in quantum information and optical communication.

  19. Evaluation of western and eastern shale oil residua as asphalt pavement recycling agents

    SciTech Connect

    Harnsberger, P.M.; Robertson, R.E.

    1990-03-01

    The objective of this investigation was to perform a preliminary evaluation of the utility of residual materials prepared from Green River Formation (western) and New Albany Shale (eastern) shale oils as recycling agents for aged asphalt pavement. Four petroleum asphalts were first aged by a thin-film accelerated-aging test, which simulates long service life of asphalt in pavement. The aged asphalts were mixed (recycled) with Green River Formation shale oil distillation residua to restore the original viscosities. Separately, for comparison, a commercial recycling agent was used to recycle the aged asphalts under the same circumstances. The recycled asphalts were reaged and the properties of both binder and asphalt-aggregate mixtures studied. Originally, the same study was intended for an eastern shale residua. However, the eastern shale oil distillation residua with the required flash point specification also had the properties of a viscosity builder; therefore, it was studied as such with asphalts that do not achieve sufficient viscosity during processing to serve as usable binders. Results show that Green River Formation shale oil residuum can be used to restore the original asphalt properties with favorable rheological properties, the shale oil residuum has a beneficial effect on resistance to moisture damage, the low-temperature properties of the shale oil residuum recycled asphalts are not adversely affected, and the low-temperature properties of the shale oil residuum recycled asphalts are dependent upon the chemistry of the mixture. The eastern shale oil residua was blended with soft petroleum asphalts. Results show the products have higher viscosities than the starting materials, the rheological properties of the soft asphalt-eastern shale oil residue blends are acceptable, and the eastern shale oil residue has dispersant properties despite its high viscosity. 11 refs., 3 figs., 9 tabs.

  20. Water, ammonia, and H 2S mixing ratios in Jupiter's five-micron hot spots: A dynamical model

    NASA Astrophysics Data System (ADS)

    Friedson, A. James

    2005-09-01

    The Galileo probe entered the jovian atmosphere at the southern edge of a 5-micron hot spot, one of typically 8-10 quasi-evenly-spaced longitudinal areas of anomalously high 5-micron IR emission that reside in a narrow latitude band centered on +7.5 degrees. These hot spots are characterized primarily by a low abundance of the cloud particles that dominate the 5-micron opacity at other locations on the planet, and by significant desiccation of ammonia, water and hydrogen sulfide in the upper layers of the troposphere. Ortiz et al. [1998. Evolution and persistence of 5-micron hot spots at the Galileo probe entry latitude. J. Geophys. Res. 103, 23,051-23,069] found that the latitude and drift rate of the hot spots could be explained if they are formed by an equatorially trapped Rossby wave of meridional degree 1 moving with a phase speed between 99 and 103 m s -1 relative to System III. Here we model additional properties of the hot spots in terms of the amplitude saturation of such a wave propagating in the weakly stratified deep troposphere. We identify the hot spots with locations where the wave plus mean thermal stratification becomes marginally stable. In these locations, potential temperature isotherms stretch downward to very deep levels in the troposphere. Since fluid parcels follow these isotherms under adiabatic flow conditions, the parcels dive downward when they enter the portion of the wave associated with the hot spot and soar upward upon leaving the spot. We show that this model can account for the anomalous vertical profiles of NH 3, H 2O, and H 2S mixing ratio measured by the Galileo probe. Pressures vary by as much as 20 bar over potential temperature isotherms in solutions that produce sufficient desiccation of water and H 2S in hot spots. Approximately 6×10 of Jupiter's internal heat flux must be tapped to maintain the wave over the mean hot spot lifetime of 10 7 s. The results suggest that the phenomenon that causes hot spots may occur widely

  1. A review of the fundamentals of polymer-modified asphalts: Asphalt/polymer interactions and principles of compatibility.

    PubMed

    Polacco, Giovanni; Filippi, Sara; Merusi, Filippo; Stastna, George

    2015-10-01

    During the last decades, the number of vehicles per citizen as well as the traffic speed and load has dramatically increased. This sudden and somehow unplanned overloading has strongly shortened the life of pavements and increased its cost of maintenance and risks to users. In order to limit the deterioration of road networks, it is necessary to improve the quality and performance of pavements, which was achieved through the addition of a polymer to the bituminous binder. Since their introduction, polymer-modified asphalts have gained in importance during the second half of the twentieth century, and they now play a fundamental role in the field of road paving. With high-temperature and high-shear mixing with asphalt, the polymer incorporates asphalt molecules, thereby forming a swallowed network that involves the entire binder and results in a significant improvement of the viscoelastic properties in comparison with those of the unmodified binder. Such a process encounters the well-known difficulties related to the poor solubility of polymers, which limits the number of macromolecules able to not only form such a structure but also maintain it during high-temperature storage in static conditions, which may be necessary before laying the binder. Therefore, polymer-modified asphalts have been the subject of numerous studies aimed to understand and optimize their structure and storage stability, which gradually attracted polymer scientists into this field that was initially explored by civil engineers. The analytical techniques of polymer science have been applied to polymer-modified asphalts, which resulted in a good understanding of their internal structure. Nevertheless, the complexity and variability of asphalt composition rendered it nearly impossible to generalize the results and univocally predict the properties of a given polymer/asphalt pair. The aim of this paper is to review these aspects of polymer-modified asphalts. Together with a brief description of

  2. Flash Mixing on the White-Dwarf Cooling Curve: Understanding Hot Horizontal Branch Anomalies in NGC 2808

    NASA Technical Reports Server (NTRS)

    Brown, Thomas M.; Sweigart, Allen V.; Lanz, Thierry; Landsman, Wayne B.; Hubeny, Ivan; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We present an ultraviolet color-magnitude diagram (CMD) spanning the hot horizontal branch (HB), blue straggler, and white dwarf populations of the globular cluster NGC 2808. These data, obtained with the Space Telescope Imaging Spectrograph (STIS), demonstrate that NGC 2808 harbors a significant population of hot subluminous HB stars, an anomaly only previously reported for the globular cluster omega Cen. Our theoretical modeling indicates that the location of these subluminous stars in the CMD, as well as the high temperature gap along the HB of NGC 2808, can be explained if these stars underwent a late helium-core flash while descending the white dwarf cooling curve. We show that the convective zone produced by such a late helium flash will penetrate into the hydrogen envelope, thereby mixing hydrogen into the hot helium-burning interior, where it is rapidly consumed. This phenomenon is analogous to the "born again" scenario for producing hydrogen-deficient stars following a late helium-shell flash. The flash mixing of the envelope greatly enhances the envelope helium and carbon abundances that, in turn, leads to a discontinuous increase in the HB effective temperatures. We argue that the hot HB gap is associated with this theoretically predicted dichotomy in the HB properties. Moreover, the changes in the emergent spectral energy distribution caused by these abundance changes are primarily responsible for explaining the hot subluminous HB stars. Although further evidence is needed to confirm that a late helium-core flash can account for the subluminous HB stars and the hot HB gap, we demonstrate that an understanding of these stars requires the use of appropriate theoretical models for their evolution, atmospheres, and spectra.

  3. Flash Mixing on the White-Dwarf Cooling Curve: Understanding Hot Horizontal Branch Anomalies in NGC 2808

    NASA Technical Reports Server (NTRS)

    Brown, Thomas M.; Sweigart, Allen V.; Lanz, Thierry; Landsman, Wayne B.; Hubeny, Ivan; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We present an ultraviolet color-magnitude diagram (CMD) spanning the hot horizontal branch (HB), blue straggler, and white dwarf populations of the globular cluster NGC 2808. These data, obtained with the Space Telescope Imaging Spectrograph (STIS), demonstrate that NGC 2808 harbors a significant population of hot subluminous HB stars, an anomaly only previously reported for the globular cluster omega Cen. Our theoretical modeling indicates that the location of these subluminous stars in the CMD, as well as the high temperature gap along the HB of NGC 2808, can be explained if these stars underwent a late helium-core flash while descending the white dwarf cooling curve. We show that the convective zone produced by such a late helium flash will penetrate into the hydrogen envelope, thereby mixing hydrogen into the hot helium-burning interior, where it is rapidly consumed. This phenomenon is analogous to the "born again" scenario for producing hydrogen-deficient stars following a late helium-shell flash. The flash mixing of the envelope greatly enhances the envelope helium and carbon abundances that, in turn, leads to a discontinuous increase in the HB effective temperatures. We argue that the hot HB gap is associated with this theoretically predicted dichotomy in the HB properties. Moreover, the changes in the emergent spectral energy distribution caused by these abundance changes are primarily responsible for explaining the hot subluminous HB stars. Although further evidence is needed to confirm that a late helium-core flash can account for the subluminous HB stars and the hot HB gap, we demonstrate that an understanding of these stars requires the use of appropriate theoretical models for their evolution, atmospheres, and spectra.

  4. Identifying binding hot spots on protein surfaces by mixed-solvent molecular dynamics: HIV-1 protease as a test case.

    PubMed

    Ung, Peter M U; Ghanakota, Phani; Graham, Sarah E; Lexa, Katrina W; Carlson, Heather A

    2016-01-01

    Mixed-solvent molecular dynamics (MixMD) simulations use full protein flexibility and competition between water and small organic probes to achieve accurate hot-spot mapping on protein surfaces. In this study, we improved MixMD using human immunodeficiency virus type-1 protease (HIVp) as the test case. We used three probe-water solutions (acetonitrile-water, isopropanol-water, and pyrimidine-water), first at 50% w/w concentration and later at 5% v/v. Paradoxically, better mapping was achieved by using fewer probes; 5% simulations gave a superior signal-to-noise ratio and far fewer spurious hot spots than 50% MixMD. Furthermore, very intense and well-defined probe occupancies were observed in the catalytic site and potential allosteric sites that have been confirmed experimentally. The Eye site, an allosteric site underneath the flap of HIVp, has been confirmed by the presence of a 5-nitroindole fragment in a crystal structure. MixMD also mapped two additional hot spots: the Exo site (between the Gly16-Gly17 and Cys67-Gly68 loops) and the Face site (between Glu21-Ala22 and Val84-Ile85 loops). The Exo site was observed to overlap with crystallographic additives such as acetate and dimethyl sulfoxide that are present in different crystal forms of the protein. Analysis of crystal structures of HIVp in different symmetry groups has shown that some surface sites are common interfaces for crystal contacts, which means that they are surfaces that are relatively easy to desolvate and complement with organic molecules. MixMD should identify these sites; in fact, their occupancy values help establish a solid cut-off where "druggable" sites are required to have higher occupancies than the crystal-packing faces.

  5. Laboratory evaluation of selected tar sand asphalts

    SciTech Connect

    Button, J.W.; Epps, J.A.; Gallaway, B.M.

    1980-12-01

    Three tar sand asphalts of similar grades prepared from one syncrude by three different refining methods were characterized by tests commonly used to specify paving asphalts together with certain special tests. Asphalt-aggregate mixtures were prepared using these asphalts and tested in the laboratory to determine strength stiffness stability, tensile properties, temperature effects and water susceptibility. Comparison of the tar sand asphalt properties to conventional petroleum asphalt properties reveal no striking differences.

  6. Acoustic Properties of Absorbent Asphalts

    NASA Astrophysics Data System (ADS)

    Trematerra, Amelia; Lombardi, Ilaria

    2017-08-01

    Road traffic is one of the greater cause of noise pollution in urban centers; a prolonged exposure to this source of noise disturbs populations subjected to it. In this paper is reported a study on the absorbent coefficients of asphalt. The acoustic measurements are carried out with a impedance tube (tube of Kundt). The sample are measured in three conditions: with dry material (traditional), “wet” asphalt and “dirty” asphalt.

  7. Chapopote Asphalt Volcano may have been generated by supercritical water

    NASA Astrophysics Data System (ADS)

    Hovland, M.; MacDonald, I. R.; Rueslåtten, H.; Johnsen, H. K.; Naehr, T.; Bohrmann, G.

    Asphalt volcanoes and lava-like flows of solidified asphalt on the seafloor (Figure 1) were first discovered and described by MacDonald et al. [2004]. The flows covered more than one square kilometer of a dissected salt dome at abyssal depths (˜3000 m) in the southern Gulf of Mexico. “Chapopote” (93°26‧W, 21°54‧N) was one of two asphalt volcanoes they discovered. MacDonald et al. determined that the apparently fresh asphalt must initially have flowed in a hot state, and subsequently chilled, contracted, and solidified, much in the same way as normal lava does on the surface of the Earth.The two asphalt-volcanoes discovered occur at the apex of salt domes that pierce through the seafloor. These “piercement salt domes,” known as the Campeche Knolls, are pertinent features of the deep Campeche Sedimentary Basin, which has a sediment thickness of about 10 km. According to conventional theory [Vendeville and Jackson, 1992], piercement salt domes represent “salt diapirs” that have risen up, due partly to density contrasts between salt and clay/sand from the “mother salt” located between 7 and 10 km below seafloor. A salt diapir is a vertical body of sub-surface salt, which is most often circular in cross section, is one to several kilometers in diameter, and can be 8-10 km high.

  8. Building America Residential System Research Results. Achieving 30% Whole House Energy Savings Level in Hot-Dry and Mixed-Dry Climates

    SciTech Connect

    Anderson, R.; Hendron, R.; Eastment, M.; Jalalzadeh-Azar, A.

    2006-01-01

    This report summarizes Building America research results for the 30% energy savings level and demonstrates that lead builders can successfully provide 30% homes in the Hot-Dry/Mixed-Dry Climate Region on a cost-neutral basis.

  9. Development of guidelines and performance for asphalt concrete containing recycled rubber. Final report

    SciTech Connect

    Mahboub, K.C.; Hancher, D.E.

    1994-12-01

    The primary objective of this study was to investigate the feasibility of implementation of the crumb rubber technology in Kentucky. The impetus for this study was provided by the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). In July 1993, a field trial project was constructed on a portion of the US 421, Franklin County, Kentucky. The project involved milling of approximately 2.54 cm (one-inch) of the wearing surface followed up by a nominally 2.54 cm (one-inch) overlay. The four-lane trial project (two lanes in each direction) was divided into two approximately 0.8 km (half-mile) sections. This allowed for a comparison of performance between the CRM hot mix asphalt (HMA) and the conventional HMA.

  10. Hot DQ white dwarfs: a pulsational test of the mixing scenario for their formation

    NASA Astrophysics Data System (ADS)

    Romero, A.; Córsico, A. H.; Althaus, L. G.; García-Berro, E.

    2010-11-01

    Hot DQ white dwarfs constitute a new class of white dwarf stars, uncovered recently within the framework of SDSS project. There exist nine of them, out of a total of several thousands white dwarfs spectroscopically identified. Recently, three hot DQ white dwarfs have been reported to exhibit photometric variability with periods compatible with pulsation g-modes. In this contribution, we presented the results of a non-adiabatic pulsation analysis of the recently discovered carbon-rich hot DQ white dwarf stars. Our study relies on the full evolutionary models of hot DQ white dwarfs recently developed by Althaus et al. (2009), that consistently cover the whole evolution from the born-again stage to the white dwarf cooling track. Specifically, we performed a stability analysis on white dwarf models from stages before the blue edge of the DBV instability strip (Teff ≈ 30000 K) until the domain of the hot DQ white dwarfs (18000-24000 K), including the transition DB→hot DQ white dwarf. We explore evolutionary models with M*= 0.585M⊙ and M* = 0.87M⊙, and two values of thickness of the He-rich envelope (MHe = 2 × 10-7M* and MHe = 10-8M*).

  11. The Cobb hot spot: HIMU-DMM mixing and melting controlled by a progressively thinning lithospheric lid

    NASA Astrophysics Data System (ADS)

    Chadwick, John; Keller, Randall; Kamenov, George; Yogodzinski, Gene; Lupton, John

    2014-08-01

    Cobb Seamount Chain in the northeast Pacific basin records the composition of the Cobb hot spot for the past 33 Myr, as the migrating Juan de Fuca Ridge approached and ultimately overran it ca. 0.5 Myr ago. In this first comprehensive geochemical study of the Cobb chain, major and trace element compositions and Sr, Nd, Pb, and Hf isotopic ratios were measured for whole-rock samples from throughout the chain, and He isotopes were acquired for olivine phenocrysts from one seamount. Trace element modeling indicates increased melting along the chain over time, with progressively more depleted lavas as the ridge approached the hot spot. The isotopic data reveal the first evidence of the high µ (µ = 238U/204Pb) (HIMU) mantle component in the north Pacific basin and are consistent with a progressively decreasing mixing proportion of HIMU melts relative to those from depleted mid-ocean ridge basalt mantle (DMM) in the chain over time. Decreasing lithospheric thickness over the Cobb hot spot due to the approach of the migrating Juan de Fuca ridge allowed adiabatic melting to continue to shallower depths, leading to increased melt fractions of the refractory DMM component in the hot spot and more depleted and MORB-like lavas in the younger Cobb seamounts.

  12. Computational microstructure modeling of asphalt mixtures subjected to rate-dependent fracture

    NASA Astrophysics Data System (ADS)

    Aragao, Francisco Thiago Sacramento

    2011-12-01

    incorporated into the mainframe of ABAQUS in the form of a customized user element (UEL) subroutine. The applicability of the rate-dependent microstructure fracture model is demonstrated and a parametric analysis is performed to evaluate the effects of different mixture parameters on the mechanical behavior of virtually generated hot-mix asphalt (HMA) microstructures. The results presented in this research demonstrate that computational microstructure models, such as the one developed in this study, have a great potential to become efficient design tools for asphalt mixtures and pavement structures.

  13. Polyurethane synthesis reactions in asphalts

    SciTech Connect

    Bukowski, A.; Gretkiewicz, J.

    1982-04-01

    A series of asphalt-polyurethane composites was prepared by means of polyurethane synthesis in asphalt and carried out in melt. The applied materials were asphalts of differentiated group components content, polyester polyols of chain structure from linear to strongly branched, 2,4-tolylene diisocyanate, 4,4-methylenebis(phenyl isocyanate), and tinorganic catalyst. The asphalt components react with isocyanates to a minimal degree. The influence of the applied substrates, temperature, and polyurethane content in the system on the basic kinetic relations characterizing the process is presented. Polyurethane synthesis in asphalts does not differ in a fundamental way from the obtaining of polyurethanes, especially when their content in the composition is significant, 20 wt% and more.

  14. Hydrodynamic Mixing of Ablator Material into the Compressed Fuel and Hot Spot of Direct-Drive DT Cryogenic Implosions

    NASA Astrophysics Data System (ADS)

    Regan, S. P.; Goncharov, V. N.; Epstein, R.; Betti, R.; Bonino, M. J.; Cao, D.; Collins, T. J. B.; Campbell, E. M.; Forrest, C. J.; Glebov, V. Yu.; Harding, D. R.; Marozas, J. A.; Marshall, F. J.; McKenty, P. W.; Sangster, T. C.; Stoeckl, C.; Luo, R. W.; Schoff, M. E.; Farrell, M.

    2016-10-01

    Hydrodynamic mixing of ablator material into the compressed fuel and hot spot of direct-drive DT cryogenic implosions is diagnosed using time-integrated, spatially resolved xray spectroscopy. The laser drive ablates most of the 8- μm-thick CH ablator, which is doped with trace amounts of Ge ( 0.5 at.) and surrounds the cryogenic DT layer. A small fraction of the ablator material is mixed into the compressed shell and the hot spot by the ablation-front Rayleigh-Taylor hydrodynamic instability seeded by laser imprint, the target mounting stalk, and surface debris. The amount of mix mass inferred from spectroscopic analysis of the Ge K-shell emission will be presented. This material is based upon work supported by the Department Of Energy National Nuclear Security Administration under Award Number DE-NA0001944. Part of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  15. Improving Asphalt Mixtures Performance by Mitigating Oxidation Using Anti-Oxidants Additives

    NASA Astrophysics Data System (ADS)

    Dessouky, Samer; Diaz, Manuel

    Polymer modified additives are typically used to improve rheological properties of asphalt binder as well as mechanical properties of asphalt concrete mix. In this study, polymer-modified binder PG70-22 is mixing with two co-polymers enhanced with anti-oxidant agents namely; Solution Styrene-Butadiene Rubber (SSBR) and Solution Ethylene-Butylene/Styrene (SEBS). The objective of this study is to characterize the effect of those additives into the rheological properties of the asphalt binder using temperature sweep test and mechanical properties of asphalt mixes. The aging index is determined to evaluate the role of additives to reduce brittleness after aging of the binder. The performance of asphalt mixes were characterized by Hamburg Wheel Tracking Test for moisture damage, Beam Fatigue Test for fatigue properties and Flow Number Test for rutting performance. It is found that the asphalt mixes with enhanced binders are improving its rutting and moisture resistance but decreased its fatigue life compared to the control mix.

  16. Beneficial uses of recycled asphalt-stabilized products as landfill cover and capping systems

    SciTech Connect

    Camougis, G.

    1996-12-31

    The American Reclamation Corporation (AMREC{reg_sign}) has played a major role in the development of new programs for the recycling of discarded materials from construction, demolition, remediation and manufacturing operations. Excavated petroleum-contaminated soils (oily soils), asphalt paving, concrete rubble, and discarded asphalt roofing shingles have been processed and recycled into beneficially useful construction products. AMREC uses a cold-mix, asphalt-emulsion technology to process many of the recyclables received at its recycling facility in Charlton, MA. Recyclable materials are processed and blended to produce recycled, asphalt-stabilized products. In addition, recycled, asphalt-stabilized products are being investigated and tested for other beneficial uses. This includes their uses as capping materials and as containment materials.

  17. Automated titration method for use on blended asphalts

    DOEpatents

    Pauli, Adam T [Cheyenne, WY; Robertson, Raymond E [Laramie, WY; Branthaver, Jan F [Chatham, IL; Schabron, John F [Laramie, WY

    2012-08-07

    A system for determining parameters and compatibility of a substance such as an asphalt or other petroleum substance uses titration to highly accurately determine one or more flocculation occurrences and is especially applicable to the determination or use of Heithaus parameters and optimal mixing of various asphalt stocks. In a preferred embodiment, automated titration in an oxygen gas exclusive system and further using spectrophotometric analysis (2-8) of solution turbidity is presented. A reversible titration technique enabling in-situ titration measurement of various solution concentrations is also presented.

  18. Characteristics of dynamic triaxial testing of asphalt mixtures

    NASA Astrophysics Data System (ADS)

    Ulloa Calderon, Alvaro

    Due to the increasing traffic loads and tire pressures, a serious detrimental impact has occurred on flexible pavements in the form of excessive permanent deformation once the critical combination of loading and environmental conditions are reached. This distress, also known as rutting, leads to an increase in road roughness and ultimately jeopardizes the road users' safety. The flow number (FN) simple performance test for asphalt mixtures was one of the final three tests selected for further evaluation from the twenty-four test/material properties initially examined under the NCHRP 9-19 project. Currently, no standard triaxial testing conditions in terms of the magnitude of the deviator and confining stresses have been specified. In addition, a repeated haversine axial compressive load pulse of 0.1 second and a rest period of 0.9 second are commonly used as part of the triaxial testing conditions. The overall objective of this research was to define the loading conditions that created by a moving truck load in the hot mixed asphalt (HMA) layer. The loading conditions were defined in terms of the triaxial stress levels and the corresponding loading time. Dynamic mechanistic analysis with circular stress distribution was used to closely simulate field loading conditions. Extensive mechanistic analyses of three different asphalt pavement structures subjected to moving traffic loads at various speeds and under braking and non-braking conditions were conducted using the 3D-Move model. Prediction equations for estimating the anticipated deviator and confining stresses along with the equivalent deviator stress pulse duration as a function of pavement temperature, vehicle speed, and asphalt mixture's stiffness have been developed. The magnitude of deviator stress, sigmad and confining stress, sigmac, were determined by converting the stress tensor computed in the HMA layer at 2" below pavement surface under a moving 18-wheel truck using the octahedral normal and shear

  19. Performance-based asphalt mixture design methodology

    NASA Astrophysics Data System (ADS)

    Ali, Al-Hosain Mansour

    Today, several State D.O.T.s are being investigating the use of tire rubber with local conventional materials. Several of the ongoing investigations identified potential benefits from the use of these materials, including improvements in material properties and performance. One of the major problems is being associated with the transferability of asphalt rubber technology without appropriately considering the effects of the variety of conventional materials on mixture behavior and performance. Typically, the design of these mixtures is being adapted to the physical properties of the conventional materials by using the empirical Marshall mixture design and without considering fundamental mixture behavior and performance. Use of design criteria related to the most common modes of failure for asphalt mixtures, such as rutting, fatigue cracking, and low temperature thermal cracking have to be developed and used for identifying the "best mixture," in term of performance, for the specific local materials and loading conditions. The main objective of this study was the development of a mixture design methodology that considers mixture behavior and performance. In order to achieve this objective a laboratory investigation able to evaluate mixture properties that can be related to mixture performance, (in terms of rutting, low temperature cracking, moisture damage and fatigue), and simulating the actual field loading conditions that the material is being exposed to, was conducted. The results proved that the inclusion of rubber into asphalt mixtures improved physical characteristics such as elasticity, flexibility, rebound, aging properties, increased fatigue resistance, and reduced rutting potential. The possibility of coupling the traditional Marshall mix design method with parameters related to mixture behavior and performance was investigated. Also, the SHRP SUPERPAVE mix design methodology was reviewed and considered in this study for the development of an integrated

  20. Asphalt emulsion sealing of uranium mill tailings. 1979 annual report

    SciTech Connect

    Hartley, J.N.; Koehmstedt, P.L.; Esterl, D.J.; Freeman, H.D.

    1980-06-01

    Uranium mill tailings are a source of low-level radiation and radioactive materials that may be released into the environment. Stabilization or disposal of these tailings in a safe and environmentally sound way is necessary to minimize radon exhalation and other radioactive releases. One of the most promising concepts for stabilizing uranium tailings is being investigated at the Pacific Northwest Laboratory: the use of asphalt emulsion to contain radon and other potentially hazardous materials in uranium tailings. Results of these studies indicate that radon flux from uranium tailings can be reduced by greater than 99% by covering the tailings with an asphalt emulsion that is poured on or sprayed on (3.0 to 7.0 mm thick), or mixed with some of the tailings and compacted to form an admixture seal (2.5 to 15.2 cm) containing 18 wt % residual asphalt.

  1. Evaluation of asphalt-rubber interlayers. (Revised). Final research report, September 1986-September 1992

    SciTech Connect

    Estakhri, C.K.; Pendleton, O.; Lytton, R.L.

    1994-02-01

    The report presents the field performance results of three asphalt-rubber interlayer test roads in terms of the effectiveness of the interlayer at reducing the rate of reflection cracking. Several variables were included in the field experiments: concentration of rubber, binder application rate, type or source of rubber, and digestion (or mixing) time of asphalt and rubber. Control sections were made up of no interlayer and interlayer binders of polymer-modified asphalt and conventional asphalt cement. Results of the statistical analyses of the data indicated that, in general, asphalt-rubber interlayers are more effective at reducing reflection cracking than no interlayer at all. Asphalt-rubber also peerformed better than control sections composed of asphalt cement interlayers and polymer-modified interlayers except in one case where the interlyaer was composed of a double application of asphalt cement/aggregate. The data also indicated that higher binder application rates lead to imnproved cracking resistance; however, on many test sections, excessively high binder application rates caused flushing at the pavement surface.

  2. The Utilization of Graphene Oxide in Traditional Construction Materials: Asphalt.

    PubMed

    Zeng, Wenbo; Wu, Shaopeng; Pang, Ling; Sun, Yihan; Chen, Zongwu

    2017-01-07

    In the advanced research fields of solar cell and energy storing materials, graphene and graphene oxide (GO) are two of the most promising materials due to their high specific surface area, and excellent electrical and physical properties. However, they was seldom studied in the traditional materials because of their high cost. Nowadays, graphene and GO are much cheaper than before with the development of production technologies, which provides the possibility of using these extraordinary materials in the traditional construction industry. In this paper, GO was selected as a nano-material to modify two different asphalts. Then a thin film oven test and a pressure aging vessel test were applied to simulate the aging of GO-modified asphalts. After thermal aging, basic physical properties (softening point and penetration) were tested for the samples which were introduced at different mass ratios of GO (1% and 3%) to asphalt. In addition, rheological properties were tested to investigate how GO could influence the asphalts by dynamic shearing rheometer tests. Finally, some interesting findings and potential utilization (warm mixing and flame retardants) of GO in asphalt pavement construction were explained.

  3. Spallation as a dominant source of pusher-fuel and hot-spot mix in inertial confinement fusion capsules

    DOE PAGES

    Orth, Charles D.

    2016-02-23

    We suggest that a potentially dominant but previously neglected source of pusher-fuel and hot-spot “mix” may have been the main degradation mechanism for fusion energy yields of modern inertial confinement fusion (ICF) capsules designed and fielded to achieve high yields — not hydrodynamic instabilities. This potentially dominant mix source is the spallation of small chunks or “grains” of pusher material into the fuel regions whenever (1) the solid material adjacent to the fuel changes its phase by nucleation, and (2) this solid material spalls under shock loading and sudden decompression. Finally, we describe this mix mechanism, support it with simulationsmore » and experimental evidence, and explain how to eliminate it and thereby allow higher yields for ICF capsules and possibly ignition at the National Ignition Facility.« less

  4. Spallation as a dominant source of pusher-fuel and hot-spot mix in inertial confinement fusion capsules

    SciTech Connect

    Orth, Charles D.

    2016-02-23

    We suggest that a potentially dominant but previously neglected source of pusher-fuel and hot-spot “mix” may have been the main degradation mechanism for fusion energy yields of modern inertial confinement fusion (ICF) capsules designed and fielded to achieve high yields — not hydrodynamic instabilities. This potentially dominant mix source is the spallation of small chunks or “grains” of pusher material into the fuel regions whenever (1) the solid material adjacent to the fuel changes its phase by nucleation, and (2) this solid material spalls under shock loading and sudden decompression. Finally, we describe this mix mechanism, support it with simulations and experimental evidence, and explain how to eliminate it and thereby allow higher yields for ICF capsules and possibly ignition at the National Ignition Facility.

  5. Synthesis and thermal properties of paramylon mixed esters and optical, mechanical, and crystal properties of their hot-pressed films.

    PubMed

    Shibakami, Motonari; Sohma, Mitsugu

    2017-01-02

    Acylation of paramylon, a storage polysaccharide of Euglena gracilis, using multiple acid anhydrides yielded thermoplastic paramylon mixed esters without significant depolymerization. DSC examination showed that the shorter the acyl chain, the higher both the melting and glass transition temperature of the ester. TG analyses revealed their higher thermostability with the 5% weight loss temperature of ∼330°C. Melt volume flow rate examination revealed that the longer the acyl chain, the higher the thermoplasticity of the ester and that the esters exhibited higher thermoplasticity than structurally analogous esters made from cellulose and curdlan. A notable feature of the thermoplastic paramylon mixed esters is the availability of hot-pressing as a means of molding them into a film. Light transmittance and XRD measurements revealed that these films were transparent and in the amorphous state. Tensile tests indicated that the films had adequate mechanical strength comparable to those of the cellulose and curdlan analogues. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. 3D mixing in hot Jupiters atmospheres. I. Application to the day/night cold trap in HD 209458b

    NASA Astrophysics Data System (ADS)

    Parmentier, Vivien; Showman, Adam P.; Lian, Yuan

    2013-10-01

    Context. Hot Jupiters exhibit atmospheric temperatures ranging from hundreds to thousands of Kelvin. Because of their large day-night temperature differences, condensable species that are stable in the gas phase on the dayside - such as TiO and silicates - may condense and gravitationally settle on the nightside. Atmospheric circulation may counterbalance this tendency to gravitationally settle. This three-dimensional (3D) mixing of condensable species has not previously been studied for hot Jupiters, yet it is crucial to assess the existence and distribution of TiO and silicates in the atmospheres of these planets. Aims: We investigate the strength of the nightside cold trap in hot Jupiters atmospheres by investigating the mechanisms and strength of the vertical mixing in these stably stratified atmospheres. We apply our model to the particular case of TiO to address the question of whether TiO can exist at low pressure in sufficient abundances to produce stratospheric thermal inversions despite the nightside cold trap. Methods: We modeled the 3D circulation of HD 209458b including passive (i.e. radiatively inactive) tracers that advect with the 3D flow, with a source and sink term on the nightside to represent their condensation into haze particles and their gravitational settling. Results: We show that global advection patterns produce strong vertical mixing that can keep condensable species aloft as long as they are trapped in particles of sizes of a few microns or less on the nightside. We show that vertical mixing results not from small-scale convection but from the large-scale circulation driven by the day-night heating contrast. Although this vertical mixing is not diffusive in any rigorous sense, a comparison of our results with idealized diffusion models allows a rough estimate of the effective vertical eddy diffusivities in these atmospheres. The parametrization Kzz=5 × 104/ Pbar m2s-1, valid from ~1 bar to a few μbar, can be used in 1D models of HD

  7. Interaction nonlinearity in asphalt binders

    NASA Astrophysics Data System (ADS)

    Motamed, Arash; Bhasin, Amit; Liechti, Kenneth M.

    2012-05-01

    Asphalt mixtures are complex composites that comprise aggregate, asphalt binder, and air. Several research studies have shown that the mechanical behavior of the asphalt mixture is strongly influenced by the matrix, i.e. the asphalt binder. Characterization and a thorough understanding of the binder behavior is the first and crucial step towards developing an accurate constitutive model for the composite. Accurate constitutive models for the constituent materials are critical to ensure accurate performance predictions at a material and structural level using micromechanics. This paper presents the findings from a systematic investigation into the nature of the linear and nonlinear response of asphalt binders subjected to different types of loading using the Dynamic Shear Rheometer (DSR). Laboratory test data show that a compressive normal force is generated in an axially constrained specimen subjected to torsional shear. This paper investigates the source of this normal force and demonstrates that the asphalt binder can dilate when subjected to shear loads. This paper also presents the findings from a study conducted to investigate the source of the nonlinearity in the asphalt binder. Test results demonstrate that the application of cyclic shear loads results in the development of a normal force and a concomitant reduction in the dynamic shear modulus. This form of nonlinear response is referred to as an "interaction nonlinearity". A combination of experimental and analytical tools is used to demonstrate and verify the presence of this interaction nonlinearity in asphalt binders. The findings from this study highlight the importance of modeling the mechanical behavior of asphalt binders based on the overall stress state of the material.

  8. Estimates of air emissions from asphalt storage tanks and truck loading

    SciTech Connect

    Trumbore, D.C.

    1999-12-31

    Title V of the 1990 Clean Air Act requires the accurate estimation of emissions from all US manufacturing processes, and places the burden of proof for that estimate on the process owner. This paper is published as a tool to assist in the estimation of air emission from hot asphalt storage tanks and asphalt truck loading operations. Data are presented on asphalt vapor pressure, vapor molecular weight, and the emission split between volatile organic compounds and particulate emissions that can be used with AP-42 calculation techniques to estimate air emissions from asphalt storage tanks and truck loading operations. Since current AP-42 techniques are not valid in asphalt tanks with active fume removal, a different technique for estimation of air emissions in those tanks, based on direct measurement of vapor space combustible gas content, is proposed. Likewise, since AP-42 does not address carbon monoxide or hydrogen sulfide emissions that are known to be present in asphalt operations, this paper proposes techniques for estimation of those emissions. Finally, data are presented on the effectiveness of fiber bed filters in reducing air emissions in asphalt operations.

  9. 75 FR 12988 - National Emission Standards for Hazardous Air Pollutants for Area Sources: Asphalt Processing and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-18

    ... Sources: Asphalt Processing and Asphalt Roofing Manufacturing; Technical Correction AGENCY: Environmental... the asphalt processing and asphalt roofing manufacturing area source category (74 FR 63236). Following... the asphalt processing and asphalt roofing manufacturing area source category on December 2, 2009 (40...

  10. Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China

    PubMed Central

    Ma, Feng; Sha, Aimin; Lin, Ruiyu; Huang, Yue; Wang, Chao

    2016-01-01

    In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase. PMID:27011196

  11. Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China.

    PubMed

    Ma, Feng; Sha, Aimin; Lin, Ruiyu; Huang, Yue; Wang, Chao

    2016-03-22

    In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase.

  12. Imaging and spatio-temporal analysis of turbulent mixing of hydrothermal water discharging into a river (Breitenbush Hot Springs, Oregon)

    NASA Astrophysics Data System (ADS)

    Andrews, B. J.; Cardenas, M. B.; Bennett, P.

    2009-12-01

    High-frequency (16 Hz), high-resolution (1-2 mm pixels) thermal infrared images show the effects of jet entry conditions on spatial and temporal scales of mixing between a discharging plume of hot spring water (~60 °C) and a small stream (~10 °C) at Breitenbush Hot Springs, Oregon. Images of thermal plumes showing eddy cascades through space and time are analyzed with correlation analyses to obtain timescales and length-scales of mixing. Optical flow velocimetry of the images provides insight to the transient two-dimensional flow fields of the plumes. The 3-inch diameter discharge pipe was positioned such that the jet is at the surface, partially submerged, or at the bottom of the 15-cm deep stream. The three jet entry conditions are hereafter referred to as “shallow”, “middle”, and “deep”. In the shallow and middle positions, the jet is apparent on the stream surface as a hot region extending downstream from the pipe. Turbulent mixing between the jet and the stream occurs along the jet margins, such that the discharge plume broadens and cools downstream. In the deep position, the jet reaches the surface as a broad plume ~7.5 cm downstream from the pipe; the highest measured temperatures are not directly above the pipe mouth, but displaced downstream. Streamwise spatial autocorrelation analysis of the temperature field under shallow and middle entry conditions show correlation length scales of ~30 cm for a transect along the center ~7.5 cm of the jet; the correlation length scale abruptly reduces to <10 cm on either side of the jet. Under deep conditions, the streamwise correlation length scale is ~20 cm along the middle ~10 cm of the plume and ~10 cm on either side of the plume. Temporal autocorrelation analysis of the temperature fields shows quasi-periodicity for all three pipe positions and decrease in frequency with distance from the pipe (shallow and middle) or center of the upwelling plume (deep). Correlation analyses of the velocity fields

  13. The Spontaneous Combustion of Railway Ties and Asphalt Shingles

    NASA Astrophysics Data System (ADS)

    Leslie, Geoffrey

    Many Low Carbon Fuels (LCFs) present unknown spontaneous combustion risks, which must be quantified before their use as fossil fuel replacements. Wood and coal spontaneous combustion is well understood; however, LCFs weather, and subsequent chemical changes could affect their spontaneous combustion properties. LCF spontaneous combustion could lead to accidental fires with possible loss of life, limb and property. The spontaneous combustion risks of two LCFs, discarded creosote-treated wooden railway ties and roofing asphalt shingles, were investigated with calorimetry and heat transfer experiments. Chemical changes due to weathering were studied with pyrolysis-Gas Chromatography/Mass Spectrometry (py-GC/MS). Creosote-treated wooden railway tie dust, roofing asphalt shingle particles, poplar wood pellets, and petroleum coke self-heating were studied with isothermal calorimetry. Railway tie dust and asphalt shingle heat transfer were characterized with a guarded hot plate. Petroleum coke self-heating was consistent with coal, while both poplar pellets and railway tie dust were found to be more reactive compared to oven test results of similar materials. The observed increase in reactivity was probably a result of significant moisture contenint in the pellet and railway tie dust. Critical conditions for spontaneous combustion were evaluated with the Frank-Kamenetskii parameter, assuming an ambient temperature of 40°C and constant moisture content. Kamenetskii calculations indicate that a 1.6 m cube of railway tie dust, or a 58 m cube of asphalt particles, would be unstable and combust. LCF chemistry may have been affected by weathering, which would cause chemical changes that affect their spontaneous combustion properties. Therefore, railway tie wood and roofing asphalt shingle chemistry were investigated by identifying products of 250° and 550°C pyrolysis with py-GC/MS. Railway tie wood pyrolyzates did not show signs of weathering; in contrast, asphalt pyrolysis

  14. Bettis Asphalt and Construction, Inc.

    EPA Pesticide Factsheets

    The EPA is providing notice of a proposed Administrative Penalty Assessment against Bettis Asphalt and Construction, Inc. for alleged violations at its facility located at 2350 Northwest Water Works Drive, Topeka, Kansas 66606.

  15. Effect of new type of synthetic waxes on reduced production and compaction temperature of asphalt mixture with reclaimed asphalt

    NASA Astrophysics Data System (ADS)

    Valentová, Tereza; Benešová, Lucie; Mastný, Jan; Valentin, Jan

    2017-09-01

    Lower mixing and paving temperatures of asphalt mixtures, which are an important issue in recent years, with respect to increased energy demand of civil engineering structures during their processing, allow reduction of this demand and result in minimized greenhouse gas production. In present time, there are many possibilities how to achieve reduction of production temperature during the mixing and paving of an asphalt mixture. The existing solutions distinguish in target operating temperature behaviour which has to be achieved in terms of good workability. This paper is focused on technical solutions based on use of new types of selected synthetic and bio-based waxes. In case of bio-based additive sugar cane wax was used, which is free of paraffins and is reclaimed as waste product during processing of sugar cane. The used waxes are added to bituminous binder in form of free-flowing granules or fine-grained powder. Synthetic waxes are represented by new series of Fischer-Tropsch wax in form of fine granules as well as by polyethylene waxes in form of fine-grained powder or granules. Those waxes were used to modify a standard paving grade bitumen dosed into asphalt mixture of ACsurf type containing up to 30 % of reclaimed asphalt (RA).

  16. Viscosity function in polymer-modified asphalts.

    PubMed

    Stastna, J; Zanzotto, L; Vacin, O J

    2003-03-01

    Asphalt is a multidisperse micellar system with rheological behavior resembling that of a low-molecular-weight polymer. Nowadays, asphalt is frequently modified by blending it with various polymers. Such modified asphalt has rheological properties that differ from the properties of the base asphalt. It is quite common to study asphalt in dynamic experiments. Such studies, however useful, cannot reveal all characteristic features of polymer-modified asphalts. Asphalt modification by polymers is strongly manifested in the region of transitions from a viscoelastic fluid to the Newtonian fluid. The viscosity study in this region can reveal behavior characteristic of the used polymer modifier, thus complementing the dynamic studies of these materials. The viscosity of base asphalt modified by styrene-butadiene-styrene and by ethylene-vinyl acetate polymers (in several concentrations) is studied and discussed in this note.

  17. 7 CFR 3201.77 - Asphalt restorers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Asphalt restorers. 3201.77 Section 3201.77... Designated Items § 3201.77 Asphalt restorers. (a) Definition. Products designed to seal, protect, or restore poured asphalt and concrete surfaces. (b) Minimum biobased content. The Federal preferred procurement...

  18. 7 CFR 3201.77 - Asphalt restorers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Asphalt restorers. 3201.77 Section 3201.77... Designated Items § 3201.77 Asphalt restorers. (a) Definition. Products designed to seal, protect, or restore poured asphalt and concrete surfaces. (b) Minimum biobased content. The Federal preferred procurement...

  19. Advances in chemical and physical properties of electric arc furnace carbon steel slag by hot stage processing and mineral mixing.

    PubMed

    Liapis, Ioannis; Papayianni, Ioanna

    2015-01-01

    Slags are recognised as a highly efficient, cost effective tool in the metal processing industry, by minimising heat losses, reducing metal oxidation through contact with air, removing metal impurities and protecting refractories and graphite electrodes. When compared to natural aggregates for use in the construction industry, slags have higher specific weight that acts as an economic deterrent. A method of altering the specific weight of EAFC slag by hot stage processing and mineral mixing, during steel production is presented in this article. The method has minimal interference with the production process of steel, even by limited additions of appropriate minerals at high temperatures. Five minerals are examined, namely perlite, ladle furnace slag, bauxite, diatomite and olivine. Measurements of specific weight are accompanied by X-ray diffraction (XRD) and fluorescence (XRF) analysis and scanning electron microscopy spectral images. It is also shown how altering the chemical composition is expected to affect the furnace refractory lining. Additionally, the process has been repeated for the most suitable mix in gas furnace and physical properties (FI, SI, LA, PSV, AAV, volume stability) examined. Alteration of the specific weight can result in tailoring slag properties for specific applications in the construction sector.

  20. Assessing Mixing Quality of a Copovidone-TPGS Hot Melt Extrusion Process with Atomic Force Microscopy and Differential Scanning Calorimetry.

    PubMed

    Lamm, Matthew S; DiNunzio, James; Khawaja, Nazia N; Crocker, Louis S; Pecora, Anthony

    2016-02-01

    Atomic force microscopy (AFM) and modulated differential scanning calorimetry (mDSC) were used to evaluate the extent of mixing of a hot melt extrusion process for producing solid dispersions of copovidone and D-α-tocopherol polyethylene glycol 1000 succinate (TPGS 1000). In addition to composition, extrusion process parameters of screw speed and thermal quench rate were varied. The data indicated that for 10% TPGS and 300 rpm screw speed, the mixing was insufficient to yield a single-phase amorphous material. AFM images of the extrudate cross section for air-cooled material indicate round domains 200 to 700 nm in diameter without any observed alignment resulting from the extrusion whereas domains in extrudate subjected to chilled rolls were elliptical in shape with uniform orientation. Thermal analysis indicated that the domains were predominantly semi-crystalline TPGS. For 10% TPGS and 600 rpm screw speed, AFM and mDSC data were consistent with that of a single-phase amorphous material for both thermal quench rates examined. When the TPGS concentration was reduced to 5%, a single-phase amorphous material was achieved for all conditions even the slowest screw speed studied (150 rpm).

  1. [PAH exposure in asphalt workers].

    PubMed

    Garattini, Siria; Sarnico, Michela; Benvenuti, Alessandra; Barbieri, P G

    2010-01-01

    There has been interest in evaluating the potential carcinogenicity of bitumen fumes in asphalt workers since the 1960's. The IARC classified air-refined bitumens as possible human carcinogens, while coal-tar fumes were classified as known carcinogens. Occupational/environmental PAH exposure can be measured by several urinary markers. Urinary 1-OHP has become the most commonly used biological marker of PAH exposure in asphalt workers. The aim of this study was to assess asphalt workers' exposure levels by monitoring 1-OHP urinary excretion and compare this data with those of non-occupationally exposed subjects. We investigated three groups of asphalt workers: 100 in summer 2007, 29 in winter 2007, and 148 during summer 2008 and compared 1-OHP urinary concentrations using Kruskall-Wallis test. Median 1-OHP urinary concentrations during the three biomonitoring sampling periods were 0.65, 0.17 and 0.53 microg/g creatinine respectively. There was a significant difference in 1-OHP values between the three groups (p < 0.001). our study showed that PAH exposure of asphalt workers' is higher than that observed in the general population and in workers in urban areas. Our results suggest that PAH exposure in the three groups studied is not sufficiently kept under control by the use of personal protective equipment and that biomonitoring is useful in evaluating PAH exposure and for risk assessment. Regulations need to be enforced for workers exposed to cancer risk, such as the register of workers exposed to carcinogens.

  2. Foaming of amorphous drug delivery systems prepared by hot melt mixing and extrusion

    NASA Astrophysics Data System (ADS)

    Terife, Graciela

    Currently there is considerable interest from both academe and pharmaceutical industry in exploring foaming processes and their products in drug delivery applications. However, there is still little knowledge of the impact of the morphology of the foamed structures on the performance of drug products in spite of some publications in this area. Therefore, the main objective of this dissertation is to gain a fundamental understanding of the correlation between foam morphology and performance of amorphous drug delivery systems, which are comprised of an Active Pharmaceutical Ingredient (API) and Polymer excipient. The Hot Melt Extrusion (HME) process is used to compound the following API / polymer binary systems: Indomethacin (INM) with SoluplusRTM (PVCap-PVAc-PEG); Carbamazepine (CBZ) with PVCap-PVAc-PEG; and INM with EudragitRTM EPO. Comprehensive characterization of these binary systems carried out by combining Differential Scanning Calorimetry, Fourier Transform Infrared spectroscopy, X-Ray Diffraction, and Scanning Electron Microscopy, shows that in all HME-prepared and foamed samples the APIs are amorphous and dissolved in the polymer excipients. The most important contributions of this dissertation can be grouped into three areas: (a) an understanding of the mechanisms by which foamed dosage forms can lead to faster API release, as well as the key morphological aspects of the cellular structures to achieve this, (b) an understanding of the correlation between the mechanism controlling the release of an API from an amorphous dosage and the enhancement in its release rate upon foaming, and (c) an understanding of the impact of the morphology of the cellular structures in the milling efficiency of HME products and the dissolution performance of the particles produced. In the first area, foamed amorphous solid solutions with three different morphologies are produced through the batch foaming process. A strong correlation between foam morphology and the enhancement

  3. Study on mixed convective flow penetration into subassembly from reactor hot plenum in FBRs

    SciTech Connect

    Kobayashi, J.; Ohshima, H.; Kamide, H.; Ieda, Y.

    1995-09-01

    Fundamental experiments using water were carried out in order to reveal the phenomenon of mixed convective flow penetration into subassemblies from a reactor`s upper plenum of fast breeder reactors. This phenomenon appears under a certain natural circulation conditions during the operation of the direct reactor auxiliary cooling system for decay heat removal and might influence the natural circulation head which determines the core flow rate and therefore affects the core coolability. In the experiment, a simplified model which simulates an upper plenum and a subassembly was used and the ultrasonic velocity profile monitor as well as thermocouples were applied for the simultaneous measurement of velocity and temperature distributions in the subassembly. From the measured data, empirical equations related to the penetration flow onset condition and the penetration depth were obtained using relevant parameters which were derived from dimensional analysis.

  4. Molybdenum-based additives to mixed-metal oxides for use in hot gas cleanup sorbents for the catalytic decomposition of ammonia in coal gases

    DOEpatents

    Ayala, Raul E.

    1993-01-01

    This invention relates to additives to mixed-metal oxides that act simultaneously as sorbents and catalysts in cleanup systems for hot coal gases. Such additives of this type, generally, act as a sorbent to remove sulfur from the coal gases while substantially simultaneously, catalytically decomposing appreciable amounts of ammonia from the coal gases.

  5. Field Performance of Asphalt Pavements with New Technologies in Northern Nevada

    NASA Astrophysics Data System (ADS)

    Faeth, Benjamin Michael

    The Regional Transportation Commission (RTC) of the Washoe Valley Area has been tasked to determine if three advanced asphalt pavement technologies and one modified aggregate gradation are suitable for implementation within Reno, Stead, and Sparks Nevada. This was accomplished through research and test roads and Intersections to determine if Recycled Asphalt Pavement (RAP), Warm Mix Asphalt (WMA), Polymer-Modified Asphalt Binder, and the Type 2-R aggregate gradation were succeeding in their design plans. Over the course of several years the streets being used by RTC to test the technologies are succeeding within their design lifespans, and the Intersections being used to test the Type 2-R aggregate gradation are showing significant resistance to rutting. Due to the roads and Intersections not being more than 10 years old, these conclusions are subject to change over time.

  6. Contributions of performance-graded asphalt to low temperature cracking resistance of pavements. Final report

    SciTech Connect

    Loh, S.W.; Olek, J.

    1999-05-01

    The purpose of this research was to study and evaluate the role that asphalt cracking. As part of the Strategic Highway Research Program (SHRP) new specifications for asphalt binders were developed that are based on the performance of the material. The asphalt binder graded and specified according to these new performance-based specifications is called PG binder. These new specifications are commonly referred to as Superpave (Superior Performing Asphalt Pavement) binder specifications. A section of Interstate 64 in southern Indiana was experiencing severe low temperature cracking before it was reconstructed over the summers of 1995 and 1996. The binder used in the new pavement mixes was PG material. Dynamic Shear Rheometer (DSR) tests, Bending Beam Rheometer (BBR) tests, and viscosity tests were performed on this binder. Comparisons were made between test results obtained from the binders in the old pavement and the new pavement. All tests and comparisons were based on the Superpave binder specifications.

  7. Review of crumb-rubber modified asphalt concrete technology. Final research report

    SciTech Connect

    Papagiannakis, A.T.; Lougheed, T.J.

    1995-11-01

    This study presents an analysis of the characteristics of crumb-rubber modified (CRM) asphalt pavements. It is comprised of a state-of-the-art literature review and laboratory testing conducted with a Brookfield viscometer. The reaction that occurs between the rubber and asphalt is not a chemical reaction, but rather a diffusion process that includes the physical absorption of aromatic oils from the asphalt into the polymer chain of the rubber. The presence of CRM in asphalt produces a thicker binder, which increases aging and oxidation resistance. The presence of carbon black in CRM improves binder durability. The temperature susceptibility of the mix is reduced, causing more uniform fatigue characteristics. CRM applications have been met with various degrees of success because existing quality control and quality assurance methods have not been developed enough to ensure desired binder properties in the field.

  8. Physical and environmental properties of asphalt mixtures containing incinerator bottom ash.

    PubMed

    Huang, Chin-Ming; Chiu, Chui-Te; Li, Kung-Cheh; Yang, Wan-Fa

    2006-10-11

    This paper presents parts of the results from a research project sponsored by Taiwan Environmental Protection Administration (TEPA), investigating both the physical and environmental properties of asphalt mixtures using different amount of incinerator bottom ash (IBA) as fine aggregate substitution. The Marshall mix design method was used to determine the design asphalt content and evaluate the potential performance of these IBA-asphalt mixtures. Water sensitivity and wheel track rutting were also performed on these mixtures. Leachates, from both laboratory and outdoor leaching tests, were performed to measure the concentration of selected heavy metals and the level of daphnia toxicity. While with adequate Marshall stability, the IBA-asphalt mixtures were shown to have excessively high Marshall flow and excessively low VMA (voids in the mineral aggregate). The results of the wheel tracking tests also indicated that the IBA-asphalt mixtures had low rutting resistance. The results of the water sensitivity test according to procedure of AASHTO T283 method showed that the IBA-asphalt mixtures had a higher tensile strength ratio (TSR) as compared with the conventional asphalt mixtures. Considering the environmental aspects, outdoor leaching tests showed that IBA had a high level of daphnia toxicity. From an ecological perspective, IBA could be identified as hazardous waste in Taiwan. However, after being mixed with asphalt binder, the concentration of heavy metals and the levels of daphnia toxicity were significantly reduced. The leachates of 10-day flat plate leaching tests on Marshall specimens containing IBA indicated that the heavy metal were undetectable and the daphnia toxicity was ineffective.

  9. Characteristics and applications of high-performance fiber reinforced asphalt concrete

    NASA Astrophysics Data System (ADS)

    Park, Philip

    Steel fiber reinforced asphalt concrete (SFRAC) is suggested in this research as a multifunctional high performance material that can potentially lead to a breakthrough in developing a sustainable transportation system. The innovative use of steel fibers in asphalt concrete is expected to improve mechanical performance and electrical conductivity of asphalt concrete that is used for paving 94% of U. S. roadways. In an effort to understand the fiber reinforcing mechanisms in SFRAC, the interaction between a single straight steel fiber and the surrounding asphalt matrix is investigated through single fiber pull-out tests and detailed numerical simulations. It is shown that pull-out failure modes can be classified into three types: matrix, interface, and mixed failure modes and that there is a critical shear stress, independent of temperature and loading rate, beyond which interfacial debonding will occur. The reinforcing effects of SFRAC with various fiber sizes and shapes are investigated through indirect tension tests at low temperature. Compared to unreinforced specimens, fiber reinforced specimens exhibit up to 62.5% increase in indirect tensile strength and 895% improvements in toughness. The documented improvements are the highest attributed to fiber reinforcement in asphalt concrete to date. The use of steel fibers and other conductive additives provides an opportunity to make asphalt pavement electrically conductive, which opens up the possibility for multifunctional applications. Various asphalt mixtures and mastics are tested and the results indicate that the electrical resistivity of asphaltic materials can be manipulated over a wide range by replacing a part of traditional fillers with a specific type of graphite powder. Another important achievement of this study is development and validation of a three dimensional nonlinear viscoelastic constitutive model that is capable of simulating both linear and nonlinear viscoelasticity of asphaltic materials. The

  10. Development of criteria for the use of asphalt-rubber as a Stress-Absorbing Membrane Interlayer (SAMI)

    NASA Astrophysics Data System (ADS)

    Newcomb, D. E.; McKeen, R. G.

    1983-12-01

    This report documents over 2 years of research efforts to characterize asphalt-rubber mixtures to be used in Stress-Absorbing Membrane Interlayers (SAMI). The purpose of these SAMIs is to retard or prevent reflection cracking in asphalt-concrete overlays. Several laboratory experiments and one field trial were conducted to define significant test methods and parameters for incorporation into construction design and specification documents. Test methods used in this study included a modified softening point test, force-ductility, and Schweyer viscosity. Variables investigated included (1) Laboratory-mixing temperature; (2) Rubber type; (3) Laboratory storage time; (4) Laboratory storage condition; (5) Laboratory batch replication; (6) Laboratory mixing time; (7) Field mixing time; (8) Laboratory test temperature; (9) Force-Ductility elongation rates; and (10) Asphalt grade. It was found that mixing temperature, mixing time, rubber type, and asphalt grade all have significant effects upon the behavior of asphalt-rubber mixtures. Significant variability was also noticed in different laboratory batch replications. Varying laboratory test temperature and force-ductility elongation rate revealed further differences in asphalt-rubber mixtures.

  11. Hot HB Stars in Globular Clusters: Physical Parameters and Consequences for Theory. 5; Radiative Levitation Versus Helium Mixing

    NASA Technical Reports Server (NTRS)

    Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Heber, U.

    2000-01-01

    Atmospheric parameters (T(sub eff), log g), masses and helium abundances are derived for 42 hot horizontal branch (HB) stars in the globular cluster NGC6752. For 19 stars we derive magnesium and iron abundances as well and find that iron is enriched by a factor of 50 on average with respect to the cluster abundance whereas the magnesium abundances are consistent with the cluster abundance. Radiation pressure may levitate heavy elements like iron to the surface of the star in a diffusive process. Taking into account the enrichment of heavy elements in our spectroscopic analyses we find that high iron abundances can explain part, but not all, of the problem of anomalously low gravities along the blue HB. The blue HB stars cooler than about 15,100 K and the sdB stars (T(sub eff) greater than or = 20,000 K) agree well with canonical theory when analysed with metal-rich ([M/H] = +0.5) model atmospheres, but the stars in between these two groups remain offset towards lower gravities and masses. Deep Mixing in the red giant progenitor phase is discussed as another mechanism that may influence the position of the blue HB stars in the (T(sub eff), log g)-plane but not their masses.

  12. Hot HB Stars in Globular Clusters: Physical Parameters and Consequences for Theory. 5; Radiative Levitation Versus Helium Mixing

    NASA Technical Reports Server (NTRS)

    Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Heber, U.

    2000-01-01

    Atmospheric parameters (T(sub eff), log g), masses and helium abundances are derived for 42 hot horizontal branch (HB) stars in the globular cluster NGC6752. For 19 stars we derive magnesium and iron abundances as well and find that iron is enriched by a factor of 50 on average with respect to the cluster abundance whereas the magnesium abundances are consistent with the cluster abundance. Radiation pressure may levitate heavy elements like iron to the surface of the star in a diffusive process. Taking into account the enrichment of heavy elements in our spectroscopic analyses we find that high iron abundances can explain part, but not all, of the problem of anomalously low gravities along the blue HB. The blue HB stars cooler than about 15,100 K and the sdB stars (T(sub eff) greater than or = 20,000 K) agree well with canonical theory when analysed with metal-rich ([M/H] = +0.5) model atmospheres, but the stars in between these two groups remain offset towards lower gravities and masses. Deep Mixing in the red giant progenitor phase is discussed as another mechanism that may influence the position of the blue HB stars in the (T(sub eff), log g)-plane but not their masses.

  13. Flame retarded asphalt blend composition

    SciTech Connect

    Walters, R.B.

    1987-04-21

    This patent describes a flame retarded asphalt composition consisting essentially of a blend of: (a) thermoplastic elastomer modified bitumen; (b) 20-30 wt % inert filler; (c) 1-20 wt % of at least one halogenated flame retardant; and (d) 1-5 wt % of at least one inorganic phosphorus containing compound selected from the group consisting of ammonium phosphate compounds and red phosphorus.

  14. Determination of Specific Heat Capacity on Composite Shape-Stabilized Phase Change Materials and Asphalt Mixtures by Heat Exchange System.

    PubMed

    Ma, Biao; Zhou, Xue-Yan; Liu, Jiang; You, Zhanping; Wei, Kun; Huang, Xiao-Feng

    2016-05-19

    Previous research has shown that composite shape-stabilized phase change material (CPCM) has a remarkable capacity for thermal storage and stabilization, and it can be directly applied to highway construction without leakage. However, recent studies on temperature changing behaviors of CPCM and asphalt mixture cannot intuitively reflect the thermoregulation mechanism and efficiency of CPCM on asphalt mixture. The objective of this paper is to determine the specific heat capacity of CPCM and asphalt mixtures mixed with CPCM using the heat exchange system and the data acquisition system. Studies have shown that the temperature-rise curve of 5 °C CPCM has an obvious temperature plateau, while an asphalt mixture mixed with 5 °C CPCM does not; with increasing temperature, the specific heat capacities of both 5 °C CPCM and asphalt mixture first increase and then decrease, while the variation rate of 5 °C CPCM is larger than that of the asphalt mixture, and the maximum specific heat capacity of 5 °C CPCM appears around the initial phase change temperature. It is concluded that the temperature intervals of 5 °C CPCM are -18 °C-7 °C, 7 °C-25 °C and 25 °C-44 °C, respectively, and that of the asphalt mixture are -18 °C~10 °C, -10 °C~5 °C and 5 °C~28 °C. A low dosage of 5 °C CPCM has little influence on the specific heat capacity of asphalt mixture. Finally, the functions of specific heat capacities and temperature for CPCM and asphalt mixture mixed with CPCM were recommended by the sectional regression method.

  15. Determination of Specific Heat Capacity on Composite Shape-Stabilized Phase Change Materials and Asphalt Mixtures by Heat Exchange System

    PubMed Central

    Ma, Biao; Zhou, Xue-yan; Liu, Jiang; You, Zhanping; Wei, Kun; Huang, Xiao-feng

    2016-01-01

    Previous research has shown that composite shape-stabilized phase change material (CPCM) has a remarkable capacity for thermal storage and stabilization, and it can be directly applied to highway construction without leakage. However, recent studies on temperature changing behaviors of CPCM and asphalt mixture cannot intuitively reflect the thermoregulation mechanism and efficiency of CPCM on asphalt mixture. The objective of this paper is to determine the specific heat capacity of CPCM and asphalt mixtures mixed with CPCM using the heat exchange system and the data acquisition system. Studies have shown that the temperature-rise curve of 5 °C CPCM has an obvious temperature plateau, while an asphalt mixture mixed with 5 °C CPCM does not; with increasing temperature, the specific heat capacities of both 5 °C CPCM and asphalt mixture first increase and then decrease, while the variation rate of 5 °C CPCM is larger than that of the asphalt mixture, and the maximum specific heat capacity of 5 °C CPCM appears around the initial phase change temperature. It is concluded that the temperature intervals of 5 °C CPCM are −18 °C–7 °C, 7 °C–25 °C and 25 °C–44 °C, respectively, and that of the asphalt mixture are −18 °C~10 °C, −10 °C~5 °C and 5 °C~28 °C. A low dosage of 5 °C CPCM has little influence on the specific heat capacity of asphalt mixture. Finally, the functions of specific heat capacities and temperature for CPCM and asphalt mixture mixed with CPCM were recommended by the sectional regression method. PMID:28773510

  16. A study on engineering characteristics of asphalt concrete using filler with recycled waste lime.

    PubMed

    Sung Do, Hwang; Hee Mun, Park; Suk keun, Rhee

    2008-01-01

    This study focuses on determining the engineering characteristics of asphalt concrete using mineral fillers with recycled waste lime, which is a by-product of the production of soda ash (Na(2)CO(3)). The materials tested in this study were made using a 25%, 50%, 75%, and 100% mixing ratio based on the conventional mineral filler ratio to analyze the possibility of using recycled waste lime. The asphalt concretes, made of recycled waste lime, hydrated lime, and conventional asphalt concrete, were evaluated through their fundamental engineering properties such as Marshall stability, indirect tensile strength, resilient modulus, permanent deformation characteristics, moisture susceptibility, and fatigue resistance. The results indicate that the application of recycled waste lime as mineral filler improves the permanent deformation characteristics, stiffness and fatigue endurance of asphalt concrete at the wide range of temperatures. It was also determined that the mixtures with recycled waste lime showed higher resistance against stripping than conventional asphalt concrete. It was concluded from various test results that a waste lime can be used as mineral filler and, especially, can greatly improve the resistance of asphalt concrete to permanent deformation at high temperatures.

  17. A laboratory investigation on the use of framed asphalt for recycled bituminous pavements

    NASA Astrophysics Data System (ADS)

    Brennan, M.

    1981-03-01

    The foaming characteristics of a selection of asphalts commonly used in construction in Indiana were recorded in terms of expansion ratio and half life. The performance of three of these asphalts as binders for a recycled bituminous paving mixture was evaluated using: (1) the Gyratory and the Marshall Compactive methods; (2) the Marshall stability testing procedure; and (3) the Hveem stability testing procedure. The effect of curing time and moisture on the stability of a recycled mix was also determined. A foaming temperature of 160 C (325 F) and an added water content of 2% were selected as the best conditions for optimum foam volume and half life. Excellent Marshall stability values were obtained with 0.5% and 1.0% foamed asphalt added to the recycled mixtures. Curing time had a marked effect on the lower additions of foamed asphalt. The effect of water decreases with increased amounts of foamed asphalt. Comparison of the Marshall Stability values and the Hveem Stability values indicates that the same optimum percent of foamed asphalt was obtained.

  18. Investigation of Low Heat Accumulation Asphalt Mixture and Its Impact on Urban Heat Environment.

    PubMed

    Xie, Jianguang; Yang, Zhaoxu; Liang, Leilei

    2015-01-01

    This study is focused on investigating the effectiveness of low heat accumulation asphalt mixture and its impact on the urban heat environment. Infrared radiation experiments showed that the temperature of the asphalt mixture decreased with the increase in far-infrared radiant material. The results also revealed that, compared to asphalt with 0% far-infrared radiant content, the asphalt material with a certain ratio of far-infrared radiation material had higher stability at high and low temperatures as well as good water absorption capacity. The Marshall stability of the specimen mixed with 6% far-infrared radiant was higher by 12.2% and had a residual stability of up to 98.9%. Moreover, the low-temperature splitting tensile strength of the asphalt mixture with 6% far-infrared radiation material increased by 21.3%. The friction coefficient of the asphalt mixtures with 6% and 12% far-infrared radiation material increased by 17.7% and 26.9%, respectively.

  19. Investigation of Low Heat Accumulation Asphalt Mixture and Its Impact on Urban Heat Environment

    PubMed Central

    Xie, Jianguang; Yang, Zhaoxu; Liang, Leilei

    2015-01-01

    This study is focused on investigating the effectiveness of low heat accumulation asphalt mixture and its impact on the urban heat environment. Infrared radiation experiments showed that the temperature of the asphalt mixture decreased with the increase in far-infrared radiant material. The results also revealed that, compared to asphalt with 0% far-infrared radiant content, the asphalt material with a certain ratio of far-infrared radiation material had higher stability at high and low temperatures as well as good water absorption capacity. The Marshall stability of the specimen mixed with 6% far-infrared radiant was higher by 12.2% and had a residual stability of up to 98.9%. Moreover, the low-temperature splitting tensile strength of the asphalt mixture with 6% far-infrared radiation material increased by 21.3%. The friction coefficient of the asphalt mixtures with 6% and 12% far-infrared radiation material increased by 17.7% and 26.9%, respectively. PMID:26222762

  20. Microstructural and rheological analysis of fillers and asphalt mastics

    NASA Astrophysics Data System (ADS)

    Geber, R.; Simon, A.; Kocserha, I.; Buzimov, A.

    2017-01-01

    Pavements are made of different grades of mineral aggregates and organic binder. The aggregates are sorted in different sizes and different amount which are mixed together with bitumen. The finest mineral fraction (d<0.063 mm) is called filler. This component has an important role in asphalt mixture - it fills the gaps between the aggregates and if mixed with bitumen (which is called asphalt mastics) it sticks the larger particles together. Particle size, microstructure and surface properties of fillers highly affect the cohesion with bitumen, therefore the aim of our research was to investigate the microstructure of mineral fillers (limestone, dolomite) which are used in Hungarian road constructions with the use of different techniques (particle size distribution, scanning electronmicroscopy tests, mercury intrusion porosimetry, BET specific surface tests, determination of hydrophobicity). After the tests of fillers, asphalt mastics were prepared and rheological examinations were obtained. These examinations served to observe the interaction and the effect of fillers. The stiffening effect of fillers and the causes of rutting were also investigated. Based on our results, it can be stated that particle size, hydrophobic properties and the amount of fillers highly affect the rheological properties of mastics.

  1. Investigation of thermal properties of raw materials of asphalt mixtures

    NASA Astrophysics Data System (ADS)

    Géber, R.; Simon, A.; Kocserha, I.

    2017-02-01

    Asphalt mixtures are composite materials, which are made of different grades of mineral aggregates and bitumen. During the mixing process mineral materials were blended with bitumen at relatively high temperature (∼200 °C). As the binding process come off in these higher temperature range, thermal properties of asphaltic materials are important. The aim of this project is to reveal the thermal properties of raw materials. During our research two types of mineral aggregates were tested (limestone and dolomite) by different methods. Differential thermal analysis, thermal expansion and thermal conductivity were investigated at technologically important temperatures. The results showed that the structure of mineral materials did not change at elevated temperatures, expansion of samples was neglible, while thermal conductivity changed by temperature.

  2. Effects of mixed-method cooling on recovery of medium-fast bowling performance in hot conditions on consecutive days.

    PubMed

    Minett, Geoffrey M; Duffield, Rob; Kellett, Aaron; Portus, Marc

    2012-01-01

    This investigation examined physiological and performance effects of cooling on recovery of medium-fast bowlers in the heat. Eight, medium-fast bowlers completed two randomised trials, involving two sessions completed on consecutive days (Session 1: 10-overs and Session 2: 4-overs) in 31 ± 3°C and 55 ± 17% relative humidity. Recovery interventions were administered for 20 min (mixed-method cooling vs. control) after Session 1. Measures included bowling performance (ball speed, accuracy, run-up speeds), physical demands (global positioning system, counter-movement jump), physiological (heart rate, core temperature, skin temperature, sweat loss), biochemical (creatine kinase, C-reactive protein) and perceptual variables (perceived exertion, thermal sensation, muscle soreness). Mean ball speed was higher after cooling in Session 2 (118.9 ± 8.1 vs. 115.5 ± 8.6 km · h⁻¹; P = 0.001; d = 0.67), reducing declines in ball speed between sessions (0.24 vs. -3.18 km · h⁻¹; P = 0.03; d = 1.80). Large effects indicated higher accuracy in Session 2 after cooling (46.0 ± 11.2 vs. 39.4 ± 8.6 arbitrary units [AU]; P = 0.13; d = 0.93) without affecting total run-up speed (19.0 ± 3.1 vs. 19.0 ± 2.5 km · h⁻¹; P = 0.97; d = 0.01). Cooling reduced core temperature, skin temperature and thermal sensation throughout the intervention (P = 0.001-0.05; d = 1.31-5.78) and attenuated creatine kinase (P = 0.04; d = 0.56) and muscle soreness at 24-h (P = 0.03; d = 2.05). Accordingly, mixed-method cooling can reduce thermal strain after a 10-over spell and improve markers of muscular damage and discomfort alongside maintained medium-fast bowling performance on consecutive days in hot conditions.

  3. Final Rule to Reduce Toxic Air Emissions from Asphalt Processing and Asphalt Roofing Manufacturing Facilities Fact Sheet

    EPA Pesticide Factsheets

    This page contains a February 2003 fact sheet with information regarding the National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Asphalt Processing and Asphalt Roofing Manufacturing.

  4. Method and apparatus for fragmenting asphalt

    SciTech Connect

    Eftefield, L. G.; Simmons, G. P.; Stone, G. L.

    1985-12-24

    A method and apparatus for laterally severing an asphalt layer to form a ribbon, separating the asphalt ribbon from an underlying base, elevating the separated asphalt ribbon, and fracturing the elevated asphalt ribbon by bending same. A cutting member having a leading edge which is insertable between the asphalt ribbon and base provides separation thereof along a lateral line. A ramp and elevating structure elevatingly guide the separated asphalt ribbon into a pair of breaker drums which are rotatable in opposite circumferential directions. Each breaker drum has protruding teeth which are arranged in laterally separated circumferential rows with the teeth in adjacent circumferential rows being preferably arcuately offset. Corresponding circumferential rows on the opposed breaker drums are laterally aligned and the teeth in those rows engage opposite surfaces of the asphalt ribbon during rotation of the breaker drums. The teeth in corresponding rows on the respective breaker drums alternately engage opposite surfaces of the asphalt ribbon at longitudinally spaced locations to bend and fracture the asphalt ribbon by displacing it in generally opposite transverse directions at the engaged locations.

  5. Optimizing the durability of the coarse fraction of porous asphalt RAP for effective recycling

    NASA Astrophysics Data System (ADS)

    Holleran, Irina; Wilson, Douglas J.; Black, Philippa; Holleran, Glynn; Walubita, Lubinda F.

    2017-09-01

    Porous asphalt (PA) durability depends not only on the binder used to manufacture the mix, but also on the aggregates chosen, particularly the coarse fraction component. Aggregates for PA should be of the highest quality and highly durable to withstand the effects of weather and traffic. To recycle PA into a new PA mix, without compromising the long-term performance, the durability of the recovered aggregates from PA-derived reclaimed asphalt pavement (RAP) should be assessed alongside the aged binder properties. In this study, the Micro-Deval (MD) Abrasion test, combined with water absorption, was found to be a good predictor of asphalt mix performance for PA. Minerology of the aggregates is an important factor when setting limits for MD loss. New Zealand (NZ) aggregates are significantly younger in geological terms, and chemically and physically less stable compared to the aggregates used in many other countries. This is especially true for greywacke, the most used aggregate in NZ for road construction. If the MD limits reported in some literature are applied to NZ PA-derived RAP aggregates, poor performing material can be erroneously incorporated in asphalt mixes. Findings from this study contributes in understanding how PA-derived RAP can be recycled into new value PA mixes.

  6. Evaluation of Asphalt Binder Modifiers

    DTIC Science & Technology

    1990-01-01

    or SBS rubber described as an oil-extended polymer produced in pellet form. This type of rubber is available in other solid forms such as crumb or...is done to improve the performance characteristics of future pavements. Many research programs have been conducted on asphalt modifiers. Most of...tests were conducted during the second year of the study and resultant data were used to choose five materials to meet the test objectives of this

  7. Supercritical fractions as asphalt recycling agents and preliminary aging studies on recycled asphalts

    SciTech Connect

    Chaffin, J.M.; Liu, M.; Davison, R.R.; Glover, C.J.; Bullin, J.A.

    1997-03-01

    Several asphalts were fractionated using supercritical pentane. These fractions were analyzed by gel permeation chromatography and high-performance liquid chromatography, and their viscosities were measured. The properties of these fractions vary not only among the fractions of a given asphalt but also for the same fraction produced from different asphalts. These widely varied fractions previously have been shown to have potential for reblending to produce superior asphalts. This study investigates the potential for using some of the fractions as asphalt recycling agents. A modified strategic highway research program (SHRP) pressure aging vessel (PAV) test and kinetics studies were conducted on nine recycled asphalts and the original asphalt. The aging indexes of eight of the recycled asphalts are superior to the aging index of the original asphalt. Two of the blends using industrial supercritical fractions and the three blends using laboratory supercritical fractions have lower aging indexes than blends using commercial recycling agents. The kinetics investigation also indicates that at road conditions the recycled asphalts will harden more slowly than the original asphalt. The degree of hardening for a given amount of oxidation in the recycled binders was found to be a strong function of the total saturate content in the recycled binder.

  8. 40 CFR 60.91 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Hot Mix Asphalt Facilities § 60.91... Act and in subpart A of this part. (a) Hot mix asphalt facility means any facility, as described in § 60.90, used to manufacture hot mix asphalt by heating and drying aggregate and mixing with asphalt...

  9. 40 CFR 60.91 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Hot Mix Asphalt Facilities § 60.91... Act and in subpart A of this part. (a) Hot mix asphalt facility means any facility, as described in § 60.90, used to manufacture hot mix asphalt by heating and drying aggregate and mixing with asphalt...

  10. 40 CFR 60.91 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Hot Mix Asphalt Facilities § 60.91... Act and in subpart A of this part. (a) Hot mix asphalt facility means any facility, as described in § 60.90, used to manufacture hot mix asphalt by heating and drying aggregate and mixing with asphalt...

  11. 40 CFR 60.91 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Hot Mix Asphalt Facilities § 60.91... Act and in subpart A of this part. (a) Hot mix asphalt facility means any facility, as described in § 60.90, used to manufacture hot mix asphalt by heating and drying aggregate and mixing with asphalt...

  12. 40 CFR 60.91 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Hot Mix Asphalt Facilities § 60.91... Act and in subpart A of this part. (a) Hot mix asphalt facility means any facility, as described in § 60.90, used to manufacture hot mix asphalt by heating and drying aggregate and mixing with asphalt...

  13. EVALUATION OF EMISSIONS FROM PAVING ASPHALTS

    EPA Science Inventory

    The report provides data from pilot-scale measurements of the emissions of specific air pollutants from paving asphalt both with and without recycled crumb rubber additives. The methods used in this work measured emissions from a static layer of asphalt maintained for several hou...

  14. Asphalt Raking. Instructor Manual. Trainee Manual.

    ERIC Educational Resources Information Center

    Laborers-AGC Education and Training Fund, Pomfret Center, CT.

    This packet consists of the instructor and trainee manuals for an asphalt raking course. The instructor manual contains a course schedule for 4 days of instruction, content outline, and instructor outline. The trainee manual is divided into five sections: safety, asphalt basics, placing methods, repair and patching, and clean-up and maintenance.…

  15. EVALUATION OF EMISSIONS FROM PAVING ASPHALTS

    EPA Science Inventory

    The report provides data from pilot-scale measurements of the emissions of specific air pollutants from paving asphalt both with and without recycled crumb rubber additives. The methods used in this work measured emissions from a static layer of asphalt maintained for several hou...

  16. Asphalt Raking. Instructor Manual. Trainee Manual.

    ERIC Educational Resources Information Center

    Laborers-AGC Education and Training Fund, Pomfret Center, CT.

    This packet consists of the instructor and trainee manuals for an asphalt raking course. The instructor manual contains a course schedule for 4 days of instruction, content outline, and instructor outline. The trainee manual is divided into five sections: safety, asphalt basics, placing methods, repair and patching, and clean-up and maintenance.…

  17. MATCON MODIFIED ASPHALT COVER CONTAINMENT SYSTEM DEMONSTRATION

    EPA Science Inventory

    In order to make improvements to conventional paving asphalt to make it more suitable for containment applications, Wilder Construction Co. of Everett, WA offers MatCon, a polymer modified asphalt system comprised of proprietary binder, when coupled with a selected aggregate type...

  18. Heating Techniques for Asphalt/Aggregate Mixtures.

    DTIC Science & Technology

    1979-12-01

    aggregate mixtures. Rec- ommendations are made for techniques to be developed which will meet the rapid repair time that is specified. Microwave ...Plants . . . . . . . . . . . . . . . . . . . . IV LITERATURE SEARCH . . . . . . . . . . . . . . . . . . . . . Microwave -Powered Units...33 iii 4 I - ’ .. .. LIST OF FIGURES Figure Title Page I Solar- Microwave Asphalt Storage Tank. .. ... ........ 22 2 Asphalt-Mobile

  19. Soil temperatures under urban trees and asphalt

    Treesearch

    Howard G. Halverson; Gordon M. Heisler

    1981-01-01

    Summer temperatures under trees planted in holes cut through an asphalt cover in a parking lot and in soil beneath the surrounding asphalt were higher than soil temperatures under trees at a control site. Winter minimums were not different, but maximum summer temperature exceeded the control by 3ºC beneath the parking lot trees and up to 10ºC beneath...

  20. MATCON MODIFIED ASPHALT COVER CONTAINMENT SYSTEM DEMONSTRATION

    EPA Science Inventory

    In order to make improvements to conventional paving asphalt to make it more suitable for containment applications, Wilder Construction Co. of Everett, WA offers MatCon, a polymer modified asphalt system comprised of proprietary binder, when coupled with a selected aggregate type...

  1. Recommendations and strategies for using reclaimed asphalt pavement in the Flemish Region based on a first life cycle assessment research

    NASA Astrophysics Data System (ADS)

    Van den bergh, Wim; Kara, Patricia; Anthonissen, Joke; Margaritis, Alexandros; Jacobs, Geert; Couscheir, Karolien

    2017-09-01

    In Flanders, using Reclaimed Asphalt Pavement (RAP) is allowed in asphalt mixes for base layers. Primary economic and secondary laboratory-measured mechanical properties are given as justification for higher amounts in specific mixes. However, one should evaluate the performance of these mixes on long-term by environmental impact of the production until end-of-life. In this paper recommendations and strategies for using RA, based on current research, are discussed in a broader perspective such as using a carbon-footprint tool and warm-mix asphalt production in the Flemish Region. The paper aims to a wide discussion by reporting several outcomes of laboratory research, statistics and practical application in order to set a general strategy for the road engineering sector in the Flemish Region.

  2. Building America Best Practices Series: Volume 2; Builders and Buyers Handbook for Improving New Home Efficiency, Comfort, and Durability in the Hot-Dry and Mixed-Dry Climates

    SciTech Connect

    2005-09-01

    This guidebook is a resource to help builders large and small build high-quality, energy-efficient homes that achieve 30% energy savings in space conditioning and water heating in the hot-dry and mixed-dry climates.

  3. Mixture design and performance prediction of rubber-modified asphalt in Ohio. Final report

    SciTech Connect

    Liang, R.Y.

    1997-08-01

    Appropriate disposal of scrap tires has been a major environmental concern over the years, mainly due to potential fire and health hazards associated with uncontrolled stockpiling. Primarily driven by this environmental concern, the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 has required each State to begin incorporating scrap tire rubber into its asphalt paving materials. Although in the revision of the original ISTEA, the mandate has been eliminated, there remains a language of encouraging the use of crumb rubbers in asphalt paving materials. Ohio Department of Transportation (ODOT) desires to develop the mix design procedure, construction practice, and performance specifications for crumb rubber modified asphalt paving materials. This research was conducted to develop the needed design and construction guidance for meeting the ODOT anticipated needs. Specifically, the objectives of this research encompass the following scope: (1) investigation of the rheological properties of asphalt-rubber binder to determine optimum content of crumb rubber, (2) development of optimum mix design for various applications, including both wet and dry mix processes, (3) characterization of mechanical properties of recommended paving mixtures, including resilient modulus, fatigue cracking behavior, low-temperature thermal cracking resistance, water sensitivity test, incremental creep test and loaded wheel track test, and (4) comparison of performance of selected paving mixes.

  4. Latex improvement of recycled asphalt pavement

    NASA Astrophysics Data System (ADS)

    Drennon, C.

    1982-08-01

    The performance of a single unmodified milled recycled asphalt concrete was compared to milled asphalt concrete modified by addition of three types of rubber latex. Latex was added at 2, 3, 5, and 8 percent latex by weight of asphalt in the asphalt concrete. Lattices used were a styrene butadiene (SBR), a natural rubber (NR), an acrylonitrile butadiene (NBR), and four varieties of out of specification SBR lattices. Marshall tests, while indecisive, showed a modest improvement in properties of SBR and NR added material at 3 and 5 percent latex. Addition of NBR latex caused deterioration in Marshall stability and flow over that of control. Repeated load tests were run using the indirect tensile test, analyzed by the VESYS program, which computes life of pavements. Repeated load tests showed improvement in asphalt concrete life when 3 and 5 percent SBR was added. Improvement was also shown by the out of specification SBR.

  5. Softening agents for recycling asphalt pavement

    SciTech Connect

    Sawatzky, H.; Clelland, F.I.; Farnand, B.A.; Houde, J. Jr.

    1993-08-10

    An asphaltic composition is described consisting essentially of: comminuted aged asphaltic pavement material; an effective amount, from about 2% to about 15 % by weight of a blend of an agent selected from the group consisting of a soft asphalt cement, a conventional asphalt cement, and a cutback asphalt, with a nitrogen-containing, adhesion-improving, anti-stripping agent comprising a sewage sludge-derived oil, or a fraction thereof, said sewage sludge-derived oil comprising a mixture of saturated aliphatic hydrocarbons, monoaromatic hydrocarbons, diaromatic hydrocarbons, polyaromatic hydrocarbons, polar compounds and basic, pyridene-soluble compounds, having the following elemental chemical composition: nitrogen, about 3.4% to about 5% by weight; oxygen, about 5.8% to about 6.9% by weight; sulfur, about 0.3% to about 0.8% by weight; hydrogen, about 9.7% to about 10.4%, and carbon, about 76.9% to about 79.8%.

  6. Compatibilizer for crumb rubber modified asphalt

    SciTech Connect

    Labib, M.E.; Memon, G.M.; Chollar, B.H.

    1996-12-31

    The United States of America discards more than 300 million tires each year, and out of that a large fraction of the tires is dumped into stock piles. This large quantity of tires creates an environmental problem. The use of scrap tires is limited. There is a usage potential in such fields as fuel for combustion and Crumb Rubber-Modified Asphalt binder (CRMA). The use of crumb rubber in modifying asphalt is not a new technique; it is been used since early 1960 by pavement engineers. Crumb rubber is a composite of different blends of natural and synthetic rubber (natural rubber, processing oils, polybutadiene, polystyrene butadiene, and filler). Prior research had concluded that the performance of crumb rubber modified asphalt is asphalt dependent. In some cases it improves the Theological properties and in some cases it degrades the properties of modified asphalt.

  7. Assessing the durability of North Buton Asphalt seal with Polymer Modified and Rejuvenation in warm mixture design

    NASA Astrophysics Data System (ADS)

    Zalman; Yulianto, B.; Setyawan, A.

    2017-02-01

    Utilization of Buton Asphalt has been expanded with various optimizations through modification of the base material so that it can be used either as an additive in granular form or as modified asphalt. While in North Buton using Asphalt Buton that uses a special material specification Buton Asphalt cold mixture of Butur Seal, a thin layer of Buton Asphalt B 50/30 above the base course or existing asphalt pavement layer, which has been prepared in accordance with the General Specifications. Technically utilization of Butur Seal is still very sensitive to human resource capacity in understanding the physical condition of Asbuton, and severely affects construction to failure. Buton asphalt cold mix in the field also showed some kind of damage caused by difficulties or not fitting rejuvenation materials used. Making the challenge to do research on the characteristic properties of Asphalt Buton B50 / 30 with modifications, to get Asbuton that has higher durability in use in the field. Quality performance of the Asbuton cold mixtures is observed through a series of tests in the laboratory. This test includes testing the stability and the compressive test. Tests conducted in the laboratory are expected to be directly applicable as it is done in the field. This research aimed to investigate the characteristics of Butur Seal in warm mixture that can be used in the construction and maintenance of roads in North Burton and to investigate the characteristics of Butur Seal with the addition of elastomeric polymers and rejuvenation materials in warm mixing temperature of 30, 40, 60 and 80° C.

  8. Mechanical Performance of Asphalt Mortar Containing Hydrated Lime and EAFSS at Low and High Temperatures

    PubMed Central

    Moon, Ki Hoon; Wang, Di; Riccardi, Chiara; Wistuba, Michael P.

    2017-01-01

    In this paper, the possibility of improving the global response of asphalt materials for pavement applications through the use of hydrated lime and Electric Arc-Furnace Steel Slag (EAFSS) was investigated. For this purpose, a set of asphalt mortars was prepared by mixing two different asphalt binders with fine granite aggregate together with hydrated lime or EAFSS at three different percentages. Bending Beam Rheometer (BBR) creep tests and Dynamic Shear Rheometer (DSR) complex modulus tests were performed to evaluate the material response both at low and high temperature. Then, the rheological Huet model was fitted to the BBR creep results for estimating the impact of filler content on the model parameters. It was found that an addition of hydrated lime and EAFSS up to 10% and 5%, respectively, results in satisfactory low-temperature performance with a substantial improvement of the high-temperature behavior. PMID:28773100

  9. Mechanical Performance of Asphalt Mortar Containing Hydrated Lime and EAFSS at Low and High Temperatures.

    PubMed

    Moon, Ki Hoon; Falchetto, Augusto Cannone; Wang, Di; Riccardi, Chiara; Wistuba, Michael P

    2017-07-03

    In this paper, the possibility of improving the global response of asphalt materials for pavement applications through the use of hydrated lime and Electric Arc-Furnace Steel Slag (EAFSS) was investigated. For this purpose, a set of asphalt mortars was prepared by mixing two different asphalt binders with fine granite aggregate together with hydrated lime or EAFSS at three different percentages. Bending Beam Rheometer (BBR) creep tests and Dynamic Shear Rheometer (DSR) complex modulus tests were performed to evaluate the material response both at low and high temperature. Then, the rheological Huet model was fitted to the BBR creep results for estimating the impact of filler content on the model parameters. It was found that an addition of hydrated lime and EAFSS up to 10% and 5%, respectively, results in satisfactory low-temperature performance with a substantial improvement of the high-temperature behavior.

  10. High temperature performance of scrap tire rubber modified asphalt concrete

    SciTech Connect

    Coomarasamy, A.; Manolis, S.; Hesp, S.

    1996-12-31

    Wheel track rutting tests on mixes modified with 30 mesh, 80 mesh, and very fine colloidal crumb rubber particles show that a very significant improvement in performance occurs with a reduction in the rubber particle size. The SHRP binder test for rutting, which was originally developed for homogeneous systems only, does not predict the performance improvement for smaller rubber particles. If these new scrap rubber binder systems are to be used in pavements then rutting tests on the asphalt-aggregate mixture should be conducted in order to accurately predict high temperature performance.

  11. Evaluation of the treatment of chromite ore processing residue by ferrous sulfate and asphalt.

    PubMed

    Moon, Deok Hyun; Wazne, Mahmoud; Koutsospyros, Agamemnon; Christodoulatos, Christos; Gevgilili, Halil; Malik, Moinuddin; Kalyon, Dilhan M

    2009-07-15

    The effectiveness of the treatment of chromite ore processing residue (COPR) with ferrous sulfate and encapsulation into asphalt were explored separately and in combination. The asphalt treatment was conducted by mixing COPR or ferrous sulfate pretreated COPR with varying amounts of asphalt. To assess the efficacy of the treatment, the leachability of toxicity characteristic leaching procedure (TCLP) total chromium (Cr) from all treated samples was determined for curing periods up to 16 months. X-ray absorption near edge structure (XANES) analyses were also performed to evaluate the Cr(6+) concentration in the selected samples. The combination treatment of ferrous sulfate and the encapsulation of the treated COPR into asphalt reduced the TCLP total Cr concentration to lower than the regulatory limit of 5mg/L for Cr contaminated soils, after 16 months. However, the Cr concentrations were still higher than the universal treatment standards (UTS) of 0.6 mg/L for hazardous waste. On the other hand, treatment with ferrous sulfate alone or the encapsulation of the COPR in asphalt failed to meet the TCLP total Cr concentration of 5mg/L, after 16 months. XANES analyses results showed that more than 75% Cr(6+) reduction was achieved upon pretreatment with ferrous sulfate.

  12. Effects of carboxylic acids on the rheological properties of crumb rubber modified asphalt

    SciTech Connect

    Tauer, J.E.; Robertson, R.E.

    1996-12-31

    The Federal mandate of 1991-1995 on the use of scrap tires in Federal roadway construction sparked a major interest in gaining a fundamental understanding of the behavior of rubber in asphalt. This study is a systematic elucidation of what chemistry controls the final crumb rubber modified asphalt (CRMA) product quality. We discovered that the type and total acid content in the asphalt are the most influential chemical factors that determine the changes in the important roadway properties of shear modulus (G*) and loss angle ({delta}) of CRMA. Low acid (<0.005 m/L) asphalts were modified with three types of carboxylic acid and each made into CRMA using typical field mixing conditions of 1 hour at 175{degrees}C. Rheological measurements were then made at various storage times up to 192 hours following storage at both 156 and 200{degrees}C. We found the changes in CRMA theological properties correspond to the acid type spiked into the asphalt.

  13. The use of a non-nuclear density gauge for monitoring the compaction process of asphalt pavement

    NASA Astrophysics Data System (ADS)

    Van den bergh, Wim; Vuye, Cedric; Kara, Patricia; Couscheir, Karolien; Blom, Johan; Van Bouwel, Philippe

    2017-09-01

    The mechanical performance of an asphalt pavement affects its durability – thus carbon footprint. Many parameters contribute to the success of a durable asphalt mix, e.g. material selection, an accurate mix and even the road design in which the asphalt mix quality is quantified. The quality of the asphalt mix, by its mechanical properties, is also related to the compaction degree. However, and specifically for high volume rates, the laying process at the construction site needs an effective method to monitor and adjust immediately the compaction quality before cooling and without damaging the layer, which is now absent. In this paper the use of a non-nuclear density gauge (PQI – Pavement Quality Indicator) is evaluated, based on a site at Brussels Airport. Considering the outcome of the present research, this PQI is advised as a unique tool for continuous density measurements and allow immediate adjustments during compaction, and decreases the number of core drilling for quality control, and as a posteriori asphalt pavement density test where cores are prohibited. The use of PQI could be recommended to be a part of the standard quality control process in the Flemish region.

  14. Temperatures and CH4 mixing ratios near the homopause of the 8 μm north polar hot spot of Jupiter

    NASA Astrophysics Data System (ADS)

    Kim, Sang Joon; Geballe, Thomas R.; Greathouse, Thomas K.; Yung, Yuk L.; Miller, Steve; Orton, G. S.; Minh, Y. C.

    2017-01-01

    We have derived homopause temperatures of 180-250 K for the 8-μm north-polar hot spot (8NPHS) of Jupiter by fitting CH4 emission models to 3 and 8 μm spectra of the 8NPHS obtained 24 days apart in 2013. From the fits, we find that CH4 mixing ratios at the 8NPHS are consistent with those reported by Kim et al. (2014) in equatorial regions. We propose possible mechanisms to account for the temperature of the 8NPHS homopause, which is relatively cool compared with the temperatures of other auroral regions, including locally-fixed and transient but energetic auroral particle precipitation.

  15. Characteristics of Ceramic Fiber Modified Asphalt Mortar.

    PubMed

    Wan, Jiuming; Wu, Shaopeng; Xiao, Yue; Liu, Quantao; Schlangen, Erik

    2016-09-21

    Ceramic fiber, with a major composition of Al₂O₃ and SiO₂, has advantages of stability at relatively high temperature, big specific surface area and resistance to external mechanical vibration. It has the potential contribution of improving the rutting resistance and temperature sensitivity of modified asphalt binder by proper modification design. In this research, ceramic fiber was introduced into both pen 60/80 and pen 80/100 asphalt binder by different weight ratios. An asphalt penetration test, softening point test, ductility test and dynamic viscoelastic behavior were conducted to characterize and predict the ceramic fiber modified asphalt mortar (CFAM). Research results indicated that the ceramic fiber has a great effect on reinforcement of asphalt, which makes the asphalt stiffer so that the asphalt can only undertake less strain under the same stress. The heat insulation effect of the ceramic fiber will improve the temperature stability. Complex modulus and phase angle results indicate that the ceramic fiber can significantly enhance the high temperature resistance of soft binder.

  16. Characteristics of Ceramic Fiber Modified Asphalt Mortar

    PubMed Central

    Wan, Jiuming; Wu, Shaopeng; Xiao, Yue; Liu, Quantao; Schlangen, Erik

    2016-01-01

    Ceramic fiber, with a major composition of Al2O3 and SiO2, has advantages of stability at relatively high temperature, big specific surface area and resistance to external mechanical vibration. It has the potential contribution of improving the rutting resistance and temperature sensitivity of modified asphalt binder by proper modification design. In this research, ceramic fiber was introduced into both pen 60/80 and pen 80/100 asphalt binder by different weight ratios. An asphalt penetration test, softening point test, ductility test and dynamic viscoelastic behavior were conducted to characterize and predict the ceramic fiber modified asphalt mortar (CFAM). Research results indicated that the ceramic fiber has a great effect on reinforcement of asphalt, which makes the asphalt stiffer so that the asphalt can only undertake less strain under the same stress. The heat insulation effect of the ceramic fiber will improve the temperature stability. Complex modulus and phase angle results indicate that the ceramic fiber can significantly enhance the high temperature resistance of soft binder. PMID:28773908

  17. Thermal behavior of crumb-rubber modified asphalt concrete mixtures

    NASA Astrophysics Data System (ADS)

    Epps, Amy Louise

    Thermal cracking is one of the primary forms of distress in asphalt concrete pavements, resulting from either a single drop in temperature to an extreme low or from multiple temperature cycles above the fracture temperature of the asphalt-aggregate mixture. The first mode described is low temperature cracking; the second is thermal fatigue. The addition of crumb-rubber, manufactured from scrap tires, to the binder in asphalt concrete pavements has been suggested to minimize both types of thermal cracking. Four experiments were designed and completed to evaluate the thermal behavior of crumb-rubber modified (CRM) asphalt-aggregate mixtures. Modified and unmodified mixture response to thermal stresses was measured in four laboratory tests. The Thermal Stress Restrained Specimen Test (TSRST) and the Indirect Tensile Test (IDT) were used to compare mixture resistance to low temperature cracking. Modified mixtures showed improved performance, and cooling rate did not affect mixture resistance according to the statistical analysis. Therefore results from tests with faster rates can predict performance under slower field rates. In comparison, predicted fracture temperatures and stresses (IDT) were generally higher than measured values (TSRST). In addition, predicted fracture temperatures from binder test results demonstrated that binder testing alone is not sufficient to evaluate CRM mixtures. Thermal fatigue was explored in the third experiment using conventional load-induced fatigue tests with conditions selected to simulate daily temperature fluctuations. Test results indicated that thermal fatigue may contribute to transverse cracking in asphalt pavements. Both unmodified and modified mixtures had a finite capacity to withstand daily temperature fluctuations coupled with cold temperatures. Modified mixtures again exhibited improved performance. The fourth experiment examined fracture properties of modified and unmodified mixtures using a common fracture toughness test

  18. Building America Best Practices Series, Volume 9: Builders Challenge Guide to 40% Whole-House Energy Savings in the Hot-Dry and Mixed-Dry Climates

    SciTech Connect

    Baechler, Michael C.; Gilbride, Theresa L.; Hefty, Marye G.; Williamson, Jennifer L.; Ruiz, Kathleen A.; Bartlett, Rosemarie; Love, Pat M.

    2009-10-23

    This best practices guide is the ninth in a series of guides for builders produced by the U.S. Department of Energy’s Building America Program. This guide book is a resource to help builders design and construct homes that are among the most energy-efficient available, while addressing issues such as building durability, indoor air quality, and occupant health, safety, and comfort. With the measures described in this guide, builders in the hot-dry and mixed-dry climates can achieve homes that have whole house energy savings of 40% over the Building America benchmark (a home built to mid-1990s building practices roughly equivalent to the 1993 Model Energy Code) with no added overall costs for consumers. These best practices are based on the results of research and demonstration projects conducted by Building America’s research teams. The guide includes information for managers, designers, marketers, site supervisors, and subcontractors, as well as case studies of builders who are successfully building homes that cut energy use by 40% in the hot-dry and mixed-dry climates.

  19. Average atom transport properties for pure and mixed species in the hot and warm dense matter regimes

    SciTech Connect

    Starrett, C. E.; Kress, J. D.; Collins, L. A.; Hanson, D. E.; Clerouin, J.; Recoules, V.

    2012-10-15

    The Kubo-Greenwood formulation for calculation of optical conductivities with an average atom model is extended to calculate thermal conductivities. The method is applied to species and conditions of interest for inertial confinement fusion. For the mixed species studied, the partial pressure mixing rule is used. Results including pressures, dc, and thermal conductivities are compared to ab initio calculations. Agreement for pressures is good, for both the pure and mixed species. For conductivities, it is found that the ad hoc renormalization method with line broadening, described in the text, gives best agreement with the ab initio results. However, some disagreement is found and the possible reasons for this are discussed.

  20. Linking asphalt binder fatigue to asphalt mixture fatigue performance using viscoelastic continuum damage modeling

    NASA Astrophysics Data System (ADS)

    Safaei, Farinaz; Castorena, Cassie; Kim, Y. Richard

    2016-08-01

    Fatigue cracking is a major form of distress in asphalt pavements. Asphalt binder is the weakest asphalt concrete constituent and, thus, plays a critical role in determining the fatigue resistance of pavements. Therefore, the ability to characterize and model the inherent fatigue performance of an asphalt binder is a necessary first step to design mixtures and pavements that are not susceptible to premature fatigue failure. The simplified viscoelastic continuum damage (S-VECD) model has been used successfully by researchers to predict the damage evolution in asphalt mixtures for various traffic and climatic conditions using limited uniaxial test data. In this study, the S-VECD model, developed for asphalt mixtures, is adapted for asphalt binders tested under cyclic torsion in a dynamic shear rheometer. Derivation of the model framework is presented. The model is verified by producing damage characteristic curves that are both temperature- and loading history-independent based on time sweep tests, given that the effects of plasticity and adhesion loss on the material behavior are minimal. The applicability of the S-VECD model to the accelerated loading that is inherent of the linear amplitude sweep test is demonstrated, which reveals reasonable performance predictions, but with some loss in accuracy compared to time sweep tests due to the confounding effects of nonlinearity imposed by the high strain amplitudes included in the test. The asphalt binder S-VECD model is validated through comparisons to asphalt mixture S-VECD model results derived from cyclic direct tension tests and Accelerated Loading Facility performance tests. The results demonstrate good agreement between the asphalt binder and mixture test results and pavement performance, indicating that the developed model framework is able to capture the asphalt binder's contribution to mixture fatigue and pavement fatigue cracking performance.

  1. Road pavers' occupational exposure to asphalt containing waste plastic and tall oil pitch.

    PubMed

    Väänänen, Virpi; Elovaara, Eivor; Nykyri, Erkki; Santonen, Tiina; Heikkilä, Pirjo

    2006-01-01

    Waste plastic (WP) and tall oil pitch (T), which are organic recycled industrial by-products, have been used as a binder with bitumen in stone mastic asphalt (SMA) and asphalt concrete (AC). We compared the exposure over one workday in 16 road pavers participating in a survey at four paving sites, using mixes of conventional asphalt (SMA, AC) or mixes containing waste material (SMA-WPT, AC-WPT). The concentrations of 11 aldehydes in air were 515 and 902 microg m(-3) at the SMA-WPT and AC-WPT worksites, being 3 and 13 times greater than at the corresponding worksites laying conventional asphalt. Resin acids (2-42 microg m(-3)), which are known sensitizers, were detected only during laying of AC-WPT. The emission levels (microg m(-3)) of total particulates (300-500), bitumen fumes (60-160), bitumen vapour (80-1120), naphthalene (0.59-1.2), phenanthrene (0.21-0.32), pyrene (<0.015-0.20), benzo(a)pyrene (<0.01) and the sum of 16 PAHs (polycyclic aromatic hydrocarbons, 1.28-2.00) were similar for conventional and WPT asphalts. The dermal deposition of 16 PAHs on exposure pads (on workers' wrist) was low in all pavers (0.7-3.5 ng cm(-2)). Eight OH-PAH biomarkers of naphthalene, phenanthrene and pyrene exposures were quantified in pre- and post-shift urine specimens. The post-shift concentrations (mean +/- SD, micromol mol(-1) creatinine) of 1- plus 2-naphthol; 1-,2-,3-,4- plus 9-phenanthrol; and 1-hydroxypyrene were, respectively, for asphalt workers: 18.1+/- 8.0, 2.41 +/- 0.71 and 0.66+/- 0.58 (smokers); 6.0+/- 2.3, 1.70+/- 0.72 and 0.27+/- 0.15 (non-smokers); WPT asphalt workers: 22.0+/- 9.2, 2.82+/- 1.11 and 0.76+/- 0.18 (smokers); 6.8+/- 2.6, 2.35+/- 0.69 and 0.46+/- 0.13 (non-smokers). The work-related uptake of PAHs was low in all pavers, although it was significantly greater in smokers than in non-smokers. The WPT asphalt workers complained of eye irritation and sore throat more than the pavers who had a much lower exposure to aldehydes and resin acids.

  2. Characterization of asphalt additive produced from hydroretorted Alabama shale

    SciTech Connect

    Rue, D.M.; Roberts, M.J.

    1992-12-31

    Shale oil, produced from beneficiated Alabama shale by pressurized fluidized-bed hydroretorting, was fractionated to produce shale oil asphalt additives (SOA). Three shale oil fractions boiling above 305{degrees}C were added to standard AC-20 asphalt to improve pavement properties. The physical properties and aging characteristics of AC-20 asphalt binder (cement) containing SOA are similar to those of unmodified AC-20 asphalt binder. Asphalt pavement briquettes made with AC-20 asphalt binder containing 5 to 10 percent SOA have superior resistance to freeze-thaw cracking and a greater retention of tensile strength when wet compared to pavement briquettes containing AC-20 binder alone.

  3. Glass transition and physical hardening of asphalts

    NASA Astrophysics Data System (ADS)

    Kriz, Pavel

    Glass transition and physical hardening was studied in straight-run paving asphalt binders. Two methods, modulated differential scanning calorimetry and dynamic mechanical analysis, were utilized in this study. Kinetic nature of the glass transition was observed in studied asphalts. The glass transition temperature, which represents the transition, was found to be a quantity dependent on observation time and thus meaningless without observation time being specified. The glass transition of asphalts was found to be very broad on the temperature scale due to complexity of the chemical composition. Asphalts were found to be multiphase systems, with glassy amorphous, non-glassy amorphous and crystalline domains existing between approximately 10 and -45°C. Physical hardening was observed in asphalts at broad range of temperatures. Physical aging, i.e. structural relaxation of the glass, was identified as a major process contributing to physical hardening. Direct effect of crystallization was rather insignificant in the temperature range of glass transition. However, the presence of crystals was suggested to affect the molecular mobility of the amorphous phase and thus increase the hardening rate and also extent the phenomenon to higher temperatures outside the normal glass transition range. The concept of rigid amorphous phase was offered. The effect of the physical hardening could generally be reversed upon heating to higher temperature. Although for semi-crystalline asphalt, temperature higher by 50°C than the isothermal storage temperature, was found not to be sufficient to successfully reverse the hardening. Effect of thermal stress on the hardening rate was studied. It was found that the imposed stress was either not significant factor affecting the asphalt hardening or the imposed stress was too low to affect hardening rate significantly. Rheological model able to capture the dependence of relaxation times on the isothermal storage time, reference temperature

  4. Rheological properties of asphalts with particulate additives

    SciTech Connect

    Shashidhar, N.; Chollar, B.H.

    1996-12-31

    The Superpave asphalt binder specifications are performance-based specifications for purchasing asphalt binders for the construction of roads. This means that the asphalt is characterized by fundamental material (rheological) properties that relate to the distress modes of the pavements. The distress modes addressed are primarily rutting, fatigue cracking and low temperature cracking. For example, G*/sin({delta}) is designed to predict the rutting potential of pavements, where G* is the magnitude of the complex shear modulus and 6 is the phase angle. The binder for a road that is situated in a certain climatic zone requires the binder to have a minimum G*/sin({delta}) of 2200 Pa at the highest consecutive 7-day average pavement temperature the road had experienced. Implicit in such a performance based specification is that the fundamental property, G*/sin({delta}), of the binder correlates with rutting potential of the pavement regardless of the nature of the binder. In other words, the specification is transparent to the fact that the binder can simply be an asphalt, or an asphalt modified by polymers, particulates and other materials that can form a two-phase mixture. This paper discusses the asphalt-particulate system.

  5. Exposure to ultrafine particles in asphalt work.

    PubMed

    Elihn, Karine; Ulvestad, Bente; Hetland, Siri; Wallen, Anna; Randem, Britt Grethe

    2008-12-01

    An epidemiologic study has demonstrated that asphalt workers show increased loss of lung function and an increase of biomarkers of inflammation over the asphalt paving season. The aim of this study was to investigate which possible agent(s) causes the inflammatory reaction, with emphasis on ultrafine particles. The workers' exposure to total dust, polycyclic aromatic hydrocarbons, and NO(2) was determined by personal sampling. Exposure to ultrafine particles was measured by means of particle counters and scanning mobility particle sizer mounted on a van following the paving machine. The fractions of organic and elemental carbon were determined. Asphalt paving workers were exposed to ultrafine particles with medium concentration of about 3.4 x 10(4)/cm(3). Ultrafine particles at the paving site originated mainly from asphalt paving activities and traffic exhaust; most seemed to originate from asphalt fumes. Oil mist exceeded occupational limits on some occasions. Diesel particulate matter was measured as elemental carbon, which was low, around 3 microg/m(3). NO(2) and total dust did not exceed limits. Asphalt pavers were exposed to relatively high concentrations of ultrafine particles throughout their working day, with possible adverse health effects.

  6. Asphalt: paving the way to development

    SciTech Connect

    Not Available

    1984-02-22

    Synthetic asphalt (extracted from the residual-fuel output of refineries as opposed to naturally occurring Gilsonite) is priced below that of the original barrel of crude in many countries; in such circumstances, it is virtually a waste product. Energy planners recognize the illogic of allowing any vital, nonrenewable natural resource such as petroleum to generate any unnecessary waste. Coking units, such as the US $1.2-billion unit at Pascagoula, MS, convert the resid end of the barrel to gasoline, distillates, and coke, virtually eliminating the former waste. Although asphalt is an integral part of a country's national transportation system, and therefore of infrastructure and economic well-being, its constructive use still must surmount its traditional position as a mere by-product of refining. Asphalt's value also goes to motor-fuel efficiency, and the effects of highway conditions on vehicles. Poor roads waste fuel not only in driving, but in burning of fuel to heat and transport asphalt when repairs must be frequent. Since the finding cost alone of new oil in oil-producing countries is in the area of US $14 per barrel, it is probable that asphalt prices will eventually rise. Domestic asphalt prices in 23 nations are compared. Lowest prices are found in oil-exporting, developing countries; highest prices are usually found in oil-importing countries, whether industrialized or not. This issue presents the fuel price/tax series and the industrial fuel prices for February for countries of the Western Hemisphere.

  7. Rapid determination of actinides in asphalt samples

    DOE PAGES

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

    2014-01-12

    A new rapid method for the determination of actinides in asphalt samples has been developed that can be used in emergency response situations or for routine analysis If a radiological dispersive device (RDD), Improvised Nuclear Device (IND) or a nuclear accident such as the accident at the Fukushima Nuclear Power Plant in March, 2011 occurs, there will be an urgent need for rapid analyses of many different environmental matrices, including asphalt materials, to support dose mitigation and environmental clean up. The new method for the determination of actinides in asphalt utilizes a rapid furnace step to destroy bitumen and organicsmore » present in the asphalt and sodium hydroxide fusion to digest the remaining sample. Sample preconcentration steps are used to collect the actinides and a new stacked TRU Resin + DGA Resin column method is employed to separate the actinide isotopes in the asphalt samples. The TRU Resin plus DGA Resin separation approach, which allows sequential separation of plutonium, uranium, americium and curium isotopes in asphalt samples, can be applied to soil samples as well.« less

  8. Observation of asphalt binder microstructure with ESEM.

    PubMed

    Mikhailenko, P; Kadhim, H; Baaj, H; Tighe, S

    2017-09-01

    The observation of asphalt binder with the environmental scanning electron microscope (ESEM) has shown the potential to observe asphalt binder microstructure and its evolution with binder aging. A procedure for the induction and identification of the microstructure in asphalt binder was established in this study and included sample preparation and observation parameters. A suitable heat-sampling asphalt binder sample preparation method was determined for the test and several stainless steel and Teflon sample moulds developed, finding that stainless steel was the preferable material. The magnification and ESEM settings conducive to observing the 3D microstructure were determined through a number of observations to be 1000×, although other magnifications could be considered. Both straight run binder (PG 58-28) and an air blown oxidised binder were analysed; their structures being compared for their relative size, abundance and other characteristics, showing a clear evolution in the fibril microstructure. The microstructure took longer to appear for the oxidised binder. It was confirmed that the fibril microstructure corresponded to actual characteristics in the asphalt binder. Additionally, a 'bee' micelle structure was found as a transitional structure in ESEM observation. The test methods in this study will be used for more comprehensive analysis of asphalt binder microstructure. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  9. Rapid determination of actinides in asphalt samples

    SciTech Connect

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

    2014-01-12

    A new rapid method for the determination of actinides in asphalt samples has been developed that can be used in emergency response situations or for routine analysis If a radiological dispersive device (RDD), Improvised Nuclear Device (IND) or a nuclear accident such as the accident at the Fukushima Nuclear Power Plant in March, 2011 occurs, there will be an urgent need for rapid analyses of many different environmental matrices, including asphalt materials, to support dose mitigation and environmental clean up. The new method for the determination of actinides in asphalt utilizes a rapid furnace step to destroy bitumen and organics present in the asphalt and sodium hydroxide fusion to digest the remaining sample. Sample preconcentration steps are used to collect the actinides and a new stacked TRU Resin + DGA Resin column method is employed to separate the actinide isotopes in the asphalt samples. The TRU Resin plus DGA Resin separation approach, which allows sequential separation of plutonium, uranium, americium and curium isotopes in asphalt samples, can be applied to soil samples as well.

  10. Mutagenicity of bitumen and asphalt fumes.

    PubMed

    Heikkilä, P R; Väänänen, V; Hämeilä, M; Linnainmaa, K

    2003-08-01

    The mutagenicity of asphalt fumes was tested with the Salmonella bioassays. The aim was to investigate if recycled additives modify the genotoxicity of emissions. Recycling of old asphalt is increasing, and we studied also the mutagenicity of emissions sampled during the re-use of asphalt. The composition of vapours and fumes were analysed by gas chromatography and by liquid chromatography. Bitumens containing coal fly ash (CFA) or waste plastics were heated to the paving temperatures in the laboratory. In the field, bitumen fumes were collected during paving of stone mastic asphalts (lime or CFA as a filler), remixing of stone mastic asphalt (lime or CFA as a filler), and of asphalt concrete. All the lab-generated vapour fractions were non-mutagenic. The particulate fractions were mutagenic with TA98 in the presence of the S9 activation. In addition, the lab-fumes from bitumen containing waste plastics were positive with both strains without S9. Only particulate fractions sampled in the field were tested. They were mutagenic with and without metabolic activation with both strains. The mutagenic potency of the field samples was higher than that of the lab-generated fumes without S9, and the remixing fumes were more mutagenic than the normal paving and lab-generated fumes with S9. The use of inorganic additive, CFA, did not change the mutagenicity of the fumes, whereas the organic additive, waste plastics, increased the mutagenicity of the laboratory emissions significantly.

  11. Hei-way general purpose recycled asphalt material (RHM). Final report

    SciTech Connect

    Dash, U.

    1993-02-01

    Utilization of Reclaimed Asphalt Pavement (RAP) in paving projects is a popular concept. It conserves material and can often provide an economical alternative to using virgin materials. The research summarizes the utilization of about 8000 tons of RAP in a project in Armstrong County (SR 3011 and SR 3013) using a proprietary process by Heilman Pavement Specialities. The mix is called Recycled Heilman Mix (RHM), which is prepared using a proprietary blend of asphalt cement (AC-5) and a rejuvenator mixed with equal weights of RAP and virgin aggregates in a batch-type pugmill. A control mix was produced by using 9.6 gallons per ton of E-5 emulsion and a blend of equal weights of RAP and coarse aggregates. The construction of the two sites were completed in September 1988 without any significant problems. A three-wheeled roller, ballasted rubber-tired roller and a second 1-ton tandem roller was used for compaction. There were no significant construction problems. RHM performed well on this project. The method of recycling asphalt pavements appears to be viable. RHM is stockpileable. Although RHM was 40 to 50 percent more expensive on the project, the life cycle costs on larger projects can be more competitive, especially when the cost of a seal coat is either avoided or delayed on RHM jobs when compared to E-5 mixes as control.

  12. Microwave Mixing and if Bandwidth in Sub-Micron Long High -T(sub c) Hot - Electron Bolometers

    NASA Technical Reports Server (NTRS)

    Harnack, Oliver; Karasik, Boris; McGrath, William; Kleinsasser, Alan; Barner, Jeff

    2000-01-01

    The hot-electron bolometer (HEB) mixer made from a high-T(sub c) superconductor (HTS) was introduced recently as a competing alternative to a Schottky mixer. The HEB mixer would require 100-times less LO power and thus would be a desirable candidate for long-term observational missions such as atmospheric remote-sensing and planetary science. The required cooling temperatures between 65 K and 75 K can be achieved with available space-qualified coolers or even with passive radiative coolers.

  13. [Nutrient accumulation and cycling in pure and mixed plantations of Azadirachta indica and Acacia auriculiformis in a dry-hot valley, Yunnan Province, southwest China].

    PubMed

    Gao, Cheng-Jie; Li, Kun; Tang, Guo-Yong; Zhang, Chun-Hua; Li, Bin

    2014-07-01

    To ease the implementation of effective nutrient management for plantations with different vegetation restoration patterns and to assist in the selection of appropriate species and forestation patterns, nutrient (N, P, K, Ca and Mg) accumulation and cycling were investigated and compared in three plantations (10-year-old Azadirachta indica, Acacia auriculiformis and mixed A. indica--A. auriculiformis plantations) in Yuanmou Valley, a dry-hot valley of Yunnan Province, Southwestern China. The result showed that total nutrient accumulations were 333.05, 725.61 and 533.85 kg x hm(-2) in pure plantations of A. indica and A. auriculiformis, and in A. indica--A. auriculiformis mixed plantation, respectively. The nutrient accumulation of various organs was ranked as branches > stems > roots > leaves > bark in the A. indica plantation and branches > stems > leaves > roots > bark both in the A. auriculiformis plantation and in the mixed plantation. Changes in accumulation of various nutrients in the mixed plantation were similar to that in the A. auriculiformis plantation (Ca > N > K > Mg > P), which were different from the A. indica plantation (Ca > K > N > Mg > P). Annual net nutrient accumulation, return and absorption in these plantations ranged from 62.72 to 162.19 kg x hm(-2) x a(-1), 48.82 to 88.86 kg x hm-2 a-1 and 111.54 to 251.05 kg x hm(-2) x a(-1), respectively, which were all the highest in the A. auriculiformis planta- tion, followed by the mixed plantation, and were the lowest in the A. indica plantation. The nutrient utilization coefficient, the cycling coefficient and the recycling period were estimated to be from 0.34 to 0.39, 0.35 to 0.44, and 6.54 to 8.17 a, respectively. The lower nutrient return and circulation rate of N or P in the A. indica plantation showed that this plantation had a poor ability to maintain soil fertility, while the highest nutrient circulation rate of N or P was observed in the A. auriculiformis plantation that displayed the

  14. Dermal exposure and urinary 1-hydroxypyrene among asphalt roofing workers

    SciTech Connect

    McClean, M.D.; Rinehart, R.D.; Sapkota, A.; Cavallari, J.M.; Herrick, R.F.

    2007-07-01

    The primary objective of this study was to identify significant determinants of dermal exposure to polycyclic aromatic compounds (PACs) among asphalt roofing workers and use urinary 1-hydroxyprene (1-OHP) measurements to evaluate the effect of dermal exposure on total absorbed dose. The study population included 26 asphalt roofing workers who performed three primary tasks: tearing off old roofs, putting down new roofs, and operating the kettle at ground level. During multiple consecutive work shifts, dermal patch samples were collected from the underside of each worker's wrists and were analyzed for PACs, pyrene, and benzo(a)pyrene (BAP). During the same work week, urine samples were collected at pre-shift, post-shift, and bedtime each day and were analyzed for 1-OHP (205 urine samples). Linear mixed effects models were used to evaluate the dermal measurements for the purpose of identifying important determinants of exposure, and to evaluate urinary 1-OHP measurements for the purpose of identifying important determinants of total absorbed dose. Dermal exposures to PAC, pyrene, and BAP were found to vary significantly by roofing task and by the presence of an old coal tar pitch roof. For each of the three analytes, the adjusted mean dermal exposures associated with tear-off were approximately four times higher than exposures associated with operating the kettle. Exposure to coal tar pitch was associated with a 6-fold increase in PAC exposure, an 8-fold increase in pyrene exposure and a 35-fold increase in BAP exposure. The presence of coal tar pitch was the primary determinant of dermal exposure, particularly for exposure to BAP. However, the task-based differences that were observed while controlling for pitch suggest that exposure to asphalt also contributes to dermal exposures.

  15. Analysis of asphalt-based roof systems using thermal analysis

    SciTech Connect

    Paroli, R.M.; Delgado, A.H.

    1996-12-31

    Asphalt has been used in the construction of roads and houses for thousands of years. The properties of asphalt has rendered it quite useful in roofing and waterproofing applications. The most popular use of asphalt in industrial roofing is in the form of a built-up roof or modified-bituminous sheet. This type of roof consists of asphalt, reinforcement and aggregate which is used to protect the asphalt from ultraviolet rays. All materials have their weaknesses and asphalt is no exception. A good asphalt (e.g., low asphaltene content) must be used to ensure the quality and low-temperature performance of roofing asphalts. Polymer additives can be added. The objective of this work was to demonstrate the utility of termogravimetry and dynamic mechanical analysis in establishing the durability of modified bituminous membranes.

  16. Preparation and rheological behavior of polymer-modified asphalts

    NASA Astrophysics Data System (ADS)

    Yousefi, Ali Akbar

    1999-09-01

    Different materials and methods were used to prepare and stabilize polymer-modified asphalts. Addition of thermoplastic elastomers improved some technically important properties of asphalt. Due to inherent factors like large density difference between asphalt and polyethylene, many physical methods in which the structure of asphalt is unchanged, failed to stabilize this system. The effect of addition of copolymers and a pyrolytic oil residue derived from used tire rubber were also studied and found to be ineffective on the storage stability of the polymer-asphalt emulsions while high and moderate temperature properties of the asphalt were found to be improved. Finally, the technique of catalytic grafting of polymer on the surface of high-density particles (e.g. carbon black) was used to balance the large density difference between asphalt and polymer. The resulting polymer-asphalts were stable at high temperatures and showed enhanced properties at low and high temperatures.

  17. SITE DEMONSTRATION CAPSULE --MATCON MODIFIED ASPHALT FOR WASTE CONTAINMENT

    EPA Science Inventory

    MatCon is a polymer modified asphalt material designed specifically for waste contaminment applications. The modifications to the material differentiate it from conventional paving asphalt by minimizing the damaging effects of environmental exposure that could detract from the d...

  18. Investigation of fatigue failure in bituminous base mixes

    NASA Astrophysics Data System (ADS)

    Maupin, G. W., Jr.

    1980-02-01

    A correlation between the results obtained with the fatigue test and those from the indirect tensile test on two base mixes was attempted in anticipation of the possible use of the latter test to design base mixes for maximum fatigue life. Two base mixes at several asphalt contents were tested at two test temperatures. Flexural fatigue tests and indirect tensile tests were performed for each mix and temperature condition. The asphalt content corresponding to the maximum fatigue life agreed generally with the asphalt content corresponding to maximum work in the indirect tensile test. The work computed from the indirect tensile test is useful in selecting the asphalt content for the maximum fatigue life of base mixes.

  19. Using urinary biomarkers of polycyclic aromatic compound exposure to guide exposure-reduction strategies among asphalt paving workers.

    PubMed

    McClean, Michael D; Osborn, Linda V; Snawder, John E; Olsen, Larry D; Kriech, Anthony J; Sjödin, Andreas; Li, Zheng; Smith, Jerome P; Sammons, Deborah L; Herrick, Robert F; Cavallari, Jennifer M

    2012-11-01

    Paving workers are exposed to polycyclic aromatic compounds (PACs) while working with hot-mix asphalt (HMA). Further characterization of the source and route of these exposures is necessary to guide exposure-reduction strategies. Personal air (n=144), hand-wash (n=144), and urine (n=480) samples were collected from 12 paving workers over 3 workdays during 4 workweeks. Urine samples were collected at preshift, postshift, and bedtime and analyzed for 10 hydroxylated PACs (1-OH-pyrene; 1-, 2-, 3-, 4-OH-phenanthrene; 1-, 2-OH-naphthalene; 2-, 3-, 9-OH-fluorene) by an immunochemical quantification of PACs (I-PACs). The air and hand-wash samples were analyzed for the parent compounds corresponding to the urinary analytes. Using a crossover study design, each of the 4 weeks represented a different exposure scenario: a baseline week (normal conditions), a dermal protection week (protective clothing), a powered air-purifying respirator (PAPR) week, and a biodiesel substitution week (100% biodiesel provided to replace the diesel oil normally used by workers to clean tools and equipment). The urinary analytes were analyzed using linear mixed-effects models. Postshift and bedtime concentrations were significantly higher than preshift concentrations for most urinary biomarkers. Compared with baseline, urinary analytes were reduced during the dermal protection (29% for 1-OH-pyrene, 15% for I-PACs), the PAPR (24% for 1-OH-pyrene, 15% for I-PACs), and the biodiesel substitution (15% for 1-OH-pyrene) weeks. The effect of PACs in air was different by exposure scenario (biodiesel substitution>dermal protection>PAPR and baseline) and was still a significant predictor of most urinary analytes during the week of PAPR use, suggesting that PACs in air were dermally absorbed. The application temperature of HMA was positively associated with urinary measures, such that an increase from the lowest application temperature (121°C) to the highest (154°C) was associated with a 72% increase in

  20. Effects of preparation process on performance of rubber modified asphalt

    NASA Astrophysics Data System (ADS)

    Liu, Hanbing; Luo, Guobao; Wang, Xianqiang; Jiao, Yubo

    2015-06-01

    The rational utilization of waste rubber tire is essential for the environmental protection. Utilizing rubber particles to modify asphalt can not only improve asphalt performance, but also help the recycling of waste materials. Considering the effect of different preparation process parameters on the performance of rubber modified asphalt, this paper analyzes the effects of the shear temperature, shear time and shear rate on the performance of rubber modified asphalt, and provided a reference for its preparation.

  1. Fabrication and Characterization of Ultrathin PBCO/YBCO/PBCO Constrictions for Hot Electron Bolometer THz Mixing Application

    NASA Astrophysics Data System (ADS)

    Peroz, Christophe; Degardin, Annick F.; Villegier, Jean-Claude; Kreisler, Alain J.

    2007-06-01

    Superconducting Hot Electron Bolometer (HEB) mixers are a competitive alternative to conventional mixer technologies in the terahertz range because of their ultrawide bandwidth, high conversion gain, and low intrinsic noise level, even at 77 K. A technological process to realize HEBs based on high-Tc YBa2Cu3O7-delta (YBCO) materials is described. Ultra-thin 12 to 40 nm layers were sputtered on MgO (100) substrates, sub-micrometer constrictions (0.5 mum times 0.5 mum) were etched on these and log-periodic gold antennas were then integrated. Good superconducting properties were measured after the whole process. Electrical transport characteristics of the device are discussed, aging effects are considered and regular bolometric THz response results are given.

  2. 40 CFR 52.2054 - Control of asphalt paving material.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 5 2013-07-01 2013-07-01 false Control of asphalt paving material. 52... asphalt paving material. (a) Notwithstanding any provisions to the contrary in the Pennsylvania Implementation Plan, the Pennsylvania Department of Transportation shall restrict the annual usage of asphalts to...

  3. 7 CFR 3201.76 - Asphalt and tar removers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Asphalt and tar removers. 3201.76 Section 3201.76... Designated Items § 3201.76 Asphalt and tar removers. (a) Definition. Cleaning agents designed to remove asphalt or tar from equipment, roads, or other surfaces. (b) Minimum biobased content. The Federal...

  4. 7 CFR 3201.65 - Concrete and asphalt cleaners.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Concrete and asphalt cleaners. 3201.65 Section 3201... PROCUREMENT Designated Items § 3201.65 Concrete and asphalt cleaners. (a) Definition. Chemicals used in..., rust, and dirt from concrete, asphalt, stone and other hard porous surfaces. Products within this item...

  5. 7 CFR 3201.65 - Concrete and asphalt cleaners.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Concrete and asphalt cleaners. 3201.65 Section 3201... PROCUREMENT Designated Items § 3201.65 Concrete and asphalt cleaners. (a) Definition. Chemicals used in..., rust, and dirt from concrete, asphalt, stone and other hard porous surfaces. Products within this item...

  6. 7 CFR 3201.76 - Asphalt and tar removers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Asphalt and tar removers. 3201.76 Section 3201.76... Designated Items § 3201.76 Asphalt and tar removers. (a) Definition. Cleaning agents designed to remove asphalt or tar from equipment, roads, or other surfaces. (b) Minimum biobased content. The Federal...

  7. 40 CFR 52.2054 - Control of asphalt paving material.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 5 2012-07-01 2012-07-01 false Control of asphalt paving material. 52... asphalt paving material. (a) Notwithstanding any provisions to the contrary in the Pennsylvania Implementation Plan, the Pennsylvania Department of Transportation shall restrict the annual usage of asphalts to...

  8. 40 CFR 52.2054 - Control of asphalt paving material.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 5 2014-07-01 2014-07-01 false Control of asphalt paving material. 52... asphalt paving material. (a) Notwithstanding any provisions to the contrary in the Pennsylvania Implementation Plan, the Pennsylvania Department of Transportation shall restrict the annual usage of asphalts to...

  9. Full-Depth Asphalt Pavements for Parking Lots and Driveways.

    ERIC Educational Resources Information Center

    Asphalt Inst., College Park, MD.

    The latest information for designing full-depth asphalt pavements for parking lots and driveways is covered in relationship to the continued increase in vehicle registration. It is based on The Asphalt Institute's Thickness Design Manual, Series No. 1 (MS-1), Seventh Edition, which covers all aspects of asphalt pavement thickness design in detail,…

  10. 7 CFR 3201.65 - Concrete and asphalt cleaners.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Concrete and asphalt cleaners. 3201.65 Section 3201... PROCUREMENT Designated Items § 3201.65 Concrete and asphalt cleaners. (a) Definition. Chemicals used in..., rust, and dirt from concrete, asphalt, stone and other hard porous surfaces. Products within this item...

  11. 40 CFR 52.2054 - Control of asphalt paving material.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 4 2011-07-01 2011-07-01 false Control of asphalt paving material. 52... asphalt paving material. (a) Notwithstanding any provisions to the contrary in the Pennsylvania Implementation Plan, the Pennsylvania Department of Transportation shall restrict the annual usage of asphalts...

  12. 40 CFR 52.2054 - Control of asphalt paving material.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control of asphalt paving material. 52... asphalt paving material. (a) Notwithstanding any provisions to the contrary in the Pennsylvania Implementation Plan, the Pennsylvania Department of Transportation shall restrict the annual usage of asphalts...

  13. High Modulus Asphalt Concrete with Dolomite Aggregates

    NASA Astrophysics Data System (ADS)

    Haritonovs, V.; Tihonovs, J.; Smirnovs, J.

    2015-11-01

    Dolomite is one of the most widely available sedimentary rocks in the territory of Latvia. Dolomite quarries contain about 1,000 million tons of this material. However, according to Latvian Road Specifications, this dolomite cannot be used for average and high intensity roads because of its low quality, mainly, its LA index (The Los Angeles abrasion test). Therefore, mostly the imported magmatic rocks (granite, diabase, gabbro, basalt) or imported dolomite are used, which makes asphalt expensive. However, practical experience shows that even with these high quality materials roads exhibit rutting, fatigue, and thermal cracks. The aim of the research is to develop a high performance asphalt concrete for base and binder courses using only locally available aggregates. In order to achieve resistance against deformations at a high ambient temperature, a hard grade binder was used. Workability, fatigue and thermal cracking resistance, as well as sufficient water resistance is achieved by low porosity (3-5%) and higher binder content compared to traditional asphalt mixtures. The design of the asphalt includes a combination of empirical and performance based tests, which in laboratory circumstances allow simulating traffic and environmental loads. High performance AC 16 base asphalt concrete was created using local dolomite aggregate with polymer modified (PMB 10/40-65) and hard grade (B20/30) bitumen. The mixtures were specified based on fundamental properties in accordance with EN 13108-1 standard.

  14. Current practices for modification of paving asphalts

    SciTech Connect

    Bahia, H.U.; Perdomo, D.

    1996-12-31

    The Superpave binder specification, AASHTO MP1, has introduced new concepts for selecting paving asphalt binders. The specification, in addition to using rheological and failure measurements that are more related to performance, is based on the idea that the criteria to maintain a satisfactory contribution of asphalt binders to the resistance of pavement failures remains the same but have to be satisfied at critical application temperatures. The test procedures require that the material be characterized within certain ranges of strains or stresses to ensure that material and geometric non-linearities are not confounded in the measurements. These new specification concepts have resulted in re-evaluation of asphalt modification by the majority of modified asphalt suppliers. The philosophy of asphalt modification is expected to change, following these new concepts, from a general improvement of quality to more focus on using modifiers based on the most critical need as defined by two factors: (1) The application temperature domain and (2) the type of distress to be remedied. The new specification requirements should result in a more effective use of modifiers as the amount and type of modifier will be directly related to the application environment and the engineering requirements.

  15. Asphalt and risk of cancer in man.

    PubMed Central

    Chiazze, L; Watkins, D K; Amsel, J

    1991-01-01

    Epidemiological publications regarding the carcinogenic potential of asphalt (bitumen) are reviewed. In 1984 the International Agency for Research on Cancer (IARC) stated that there is "inadequate evidence that bitumens alone are carcinogenic to humans." They did, however, conclude that animal data provided sufficient evidence for the carcinogenicity of certain extracts of steam refined and air refined bitumens. In the absence of data on man, IARC considered it reasonable to regard chemicals with sufficient evidence of carcinogenicity in animals as if they presented a carcinogenic risk to man. Epidemiological data for man accumulated since the IARC report do not fulfil the criteria for showing a causal association between exposure to asphalt and development of cancer. The studies cited all suffer from a lack of data on exposure or potential confounders, which are necessary to establish whether or not such an association may or may not exist. In view of the evidence (or lack thereof) regarding asphalt today, an appropriate public health attitude suggests at least that action be taken to protect those working with asphalt by monitoring the workplace, taking whatever steps are possible to minimise exposures and to inform workers of potential hazards. At the same time, a need exists for well designed analytical epidemiological studies to determine whether a risk of cancer in man exists from exposure to asphalt. PMID:1878310

  16. Effect of Warm Asphalt Additive on the Creep and Recovery Behaviour of Aged Binder Containing Waste Engine Oil

    NASA Astrophysics Data System (ADS)

    Hassan, Norhidayah Abdul; Kamaruddin, Nurul Hidayah Mohd; Rosli Hainin, Mohd; Ezree Abdullah, Mohd

    2017-08-01

    The use of waste engine oil as an additive in asphalt mixture has been reported to be able to offset the stiffening effect caused by the recycled asphalt mixture. Additionally, the fumes and odor of the waste engine oil has caused an uncomfortable condition for the workers during road construction particularly at higher production temperature. Therefore, this problem was addressed by integrating chemical warm asphalt additive into the mixture which functions to reduce the mixing and compaction temperature. This study was initiated by blending the additive in the asphalt binder of bitumen penetration grade 80/100 prior to the addition of pavement mixture. The effect of chemical warm asphalt additive, Rediset WMX was investigated by modifying the aged binder containing waste engine oil with 0%, 1%, 2% and 3% by weight of the binder. The samples were then tested for determining the rutting behaviour under different loading stress levels of 3Pa (low), 10Pa (medium) and 50Pa (high) using Dynamic Shear Rheometer (DSR). A reference temperature of 60 °C was fixed to reflect the maximum temperature of the pavement. The results found that the addition of Rediset did not affect the creep and recovery behavior of the modified binder under different loading. On the other hand, 2% Rediset resulted a slight decrease in its rutting resistance as shown by the reduction of non-recoverable compliance under high load stress. However, overall, the inclusion of chemical warm asphalt additive to the modified binder did not adversely affect the rutting resistance which could be beneficial in lowering the temperature of asphalt production and simultaneously not compromising the binder properties.

  17. Thiol/disulfide homeostasis in asphalt workers.

    PubMed

    Yilmaz, Ömer Hınç; Bal, Ceylan; Neşelioglu, Salim; Büyükşekerci, Murat; Gündüzöz, Meşide; Eren, Funda; Tutkun, Lutfiye; Yilmaz, Fatma Meric

    2016-09-02

    The aim of this study was to investigate thiol/disulfide homeostasis in asphalt workers who are exposed to polycyclic aromatic hydrocarbons occupationally. The study was carried out in 34 nonsmoker asphalt workers. Additionally, 35 healthy nonsmoker volunteers were recruited as control group. Thiol and disulfide concentrations were determined using the novel automated measurement method. Levels of urinary 1-OH-pyrene were analyzed by liquid chromatography. Disulfide/thiol ratio was significantly higher in exposed group (p = .034). Also, a positive correlation was detected between disulfide/thiol ratio and 1-OH-pyrene values (r = .249, p = .036). Thiol/disulfide homeostasis was found to be disturbed in asphalt workers. The novel test used in this study may be useful for evaluating the oxidative status in polycyclic aromatic hydrocarbon (PAH) exposure.

  18. Pneumoproteins and inflammatory biomarkers in asphalt pavers.

    PubMed

    Ellingsen, Dag G; Ulvestad, Bente; Andersson, Lena; Barregard, Lars

    2010-09-01

    Pneumoproteins, biomarkers of systemic inflammation and endothelial activation were studied across a season in 72 asphalt pavers, 32 asphalt plant operators and 19 asphalt engineers. Smokers had lower concentrations of Clara cell protein (CC-16) and surfactant protein A, but higher concentrations of surfactant protein D, interleukin 6, C-reactive protein, fibrinogen and intercellular adhesion molecule (ICAM)-1 than non-smokers. Smokers reporting wheezing had lower mean CC-16 concentration than smokers not reporting wheezing (5.7 vs 8.6 microg l(-1); p = 0.05). Cholesterol, P-selectin and ICAM-1 were lower in pavers and operators at the end compared with the start of the season. This may be related to increased physical activity during the season.

  19. Practical experiences with new types of highly modified asphalt binders

    NASA Astrophysics Data System (ADS)

    Špaček, Petr; Hegr, Zdeněk; Beneš, Jan

    2017-09-01

    As a result of steadily increasing traffic load on the roads in the Czech Republic, we should be focused on the innovative technical solutions, which will lead to extending the life time of asphalt pavements. One of these ways could be the future use of bitumen with a higher degree of polymer modification. This paper discusses experience with comparison of new highly polymer modified asphalt binder type with conventional polymer modified asphalt binder and unmodified binder with penetration grade 50/70. There are compared the results of various types laboratory tests of asphalt binders, as well as the results of asphalt mixtures laboratory tests. The paper also mentions the experience with workability and compactability of asphalt mixture with highly polymer modified asphalt binder during the realization of the experimental reference road section by the Skanska company in the Czech Republic.

  20. State-of-the-art and prospect for self-healing asphalt concrete

    NASA Astrophysics Data System (ADS)

    Xiao, Dong

    2017-08-01

    In order to solve the problem of asphalt concrete pavement cracks, this paper summarizes the principle of self-healing asphalt concrete, and describes asphalt concrete self-healing technology in various countries. This paper also analyses the factors of influencing the self-healing ability of asphalt concrete and the evaluation index, and describes the prospect of asphalt concrete self-healing technology.

  1. Evaluation of Fatigue Performance of Asphalt Based on Constant Strain DSR Test

    NASA Astrophysics Data System (ADS)

    Zhu, H. Z.; Yan, E. H.; Lu, Z. T.

    2017-02-01

    Asphalt performance has important effect on the fatigue resistance performance of asphalt mixture. This research based on the DSR time scanning mode, investigated the constant strain performance of 70 # matrix asphalt and SBS modified asphalt. Based on 50% G* 0 to simulate the fatigue performance of two kinds of the asphalt.

  2. Bounding Estimate for the 'Hot' Channel Temperature and Preliminary Calculation of Mixing in the Lower Plenum for the NGNP Point Design Using CFD

    SciTech Connect

    Richard W. Johnson; R. R. Schultz

    2004-12-01

    The power density in the core of the block next generation nuclear power plant (NGNP) will not be uniform due to geometry, core layout and fuel pin design. Recent calculations performed to optimize the core design indicate that the maximum radial variation will be 1.25 times the average. This significant radial variation in the local power density will create a variation in the temperature of the helium coolant as it cools the core. The coolant channel with the highest outlet temperature is referred to as the ‘hot’ channel. The concern is that the high temperature channels, which exit into the lower plenum as jets, called ‘hot streaking,’ will adversely affect materials in the lower plenum, the exit duct and the turbine, as well as affect the performance of the turbine. The objective of the present study is to determine or bound the maximum exit temperature of the ‘hot’ channel. The maximum hot channel temperature depends on the total coolant flow rate, which has not yet been fixed. Experiments need to be designed to capture the complex physics of the lower-plenum flow to allow assessment and validation of numerical simulations. While preliminary CFD simulations are not yet validated, they can be of use in the planning of the experiments, particularly in estimating where there are regions of high and low turbulence intensity. Mixing of the coolant is related to the turbulence intensity as well as to the overall nature of the mean flow. The purpose of the present task is to provide preliminary flow calculations of the coolant in the lower plenum to examine flow patterns and turbulence intensity.

  3. Petroleum degradation and associated microbial signatures at the Chapopote asphalt volcano, Southern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Schubotz, Florence; Lipp, Julius S.; Elvert, Marcus; Kasten, Sabine; Mollar, Xavier Prieto; Zabel, Matthias; Bohrmann, Gerhard; Hinrichs, Kai-Uwe

    2011-08-01

    At the Chapopote Knoll in the Southern Gulf of Mexico, deposits of asphalt provide the substrate for a prolific cold seep ecosystem extensively colonized by chemosynthetic communities. This study investigates microbial life and associated biological processes within the asphalts and surrounding oil-impregnated sediments by analysis of intact polar membrane lipids (IPLs), petroleum hydrocarbons and stable carbon isotopic compositions (δ 13C) of hydrocarbon gases. Asphalt samples are lightly to heavily biodegraded suggesting that petroleum-derived hydrocarbons serve as substrates for the chemosynthetic communities. Accordingly, detection of bacterial diester and diether phospholipids in asphalt samples containing finely dispersed gas hydrate suggests the presence of hydrocarbon-degrading bacteria. Biological methanogenesis contributes a substantial fraction to the methane captured as hydrate in the shallow asphalt deposits evidenced by significant depletion in 13C relative to background thermogenic methane. In sediments, petroleum migrating from the subsurface stimulates both methanogenesis and methanotrophy at a sulfate-methane transition zone 6-7 m below the seafloor. In this zone, microbial IPLs are dominated by archaeal phosphohydroxyarchaeols and archaeal diglycosidic diethers and tetraethers. Bacterial IPLs dominate surface sediments that are impregnated by severely biodegraded oil. In the sulfate-reduction zone, diagnostic IPLs indicate that sulfate-reducing bacteria (SRB) play an important role in petroleum degradation. A diverse mixture of phosphohydroxyarchaeols and mixed phospho- and diglycosidic archaeal tetraethers in shallow oil-impregnated sediments point to the presence of anaerobic methane-oxidizing ANME-2 and ANME-1 archaea, respectively, or methanogens. Archaeal IPLs increase in relative abundance with increasing sediment depth and decreasing sulfate concentrations, accompanied by a shift of archaeol-based to tetraether-based archaeal IPLs. The

  4. Lignite slime as activator in production of oxidized asphalts

    SciTech Connect

    Gureev, A.A.; Gorlov, E.G.; Leont'eva, O.B.; Zotova, O.V.

    1988-03-01

    The possibility of activation of the oxidation of straight-run resids to asphalts by the addition of lignite slimes obtained in the liquefaction of coals of the Kansk-Achinsk basin was studied on the basis of a hypothesis formulated with due regard for the principles of physicochemical mechanics of petroleum disperse systems. A reduction of the air bubble size in the oxidizing vessel should lead to an increase in the total surface of oxidation and hence to a shortening of the time required for oxidation of the feed. A straight-run vacuum resid from mixed West Siberian and Ukhta crudes was used. The resid was oxidized with and without the addition of slime.

  5. Microstructural Analysis and Rheological Modeling of Asphalt Mixtures Containing Recycled Asphalt Materials

    PubMed Central

    Cannone Falchetto, Augusto; Moon, Ki Hoon; Wistuba, Michael P.

    2014-01-01

    The use of recycled materials in pavement construction has seen, over the years, a significant increase closely associated with substantial economic and environmental benefits. During the past decades, many transportation agencies have evaluated the effect of adding Reclaimed Asphalt Pavement (RAP), and, more recently, Recycled Asphalt Shingles (RAS) on the performance of asphalt pavement, while limits were proposed on the amount of recycled materials which can be used. In this paper, the effect of adding RAP and RAS on the microstructural and low temperature properties of asphalt mixtures is investigated using digital image processing (DIP) and modeling of rheological data obtained with the Bending Beam Rheometer (BBR). Detailed information on the internal microstructure of asphalt mixtures is acquired based on digital images of small beam specimens and numerical estimations of spatial correlation functions. It is found that RAP increases the autocorrelation length (ACL) of the spatial distribution of aggregates, asphalt mastic and air voids phases, while an opposite trend is observed when RAS is included. Analogical and semi empirical models are used to back-calculate binder creep stiffness from mixture experimental data. Differences between back-calculated results and experimental data suggest limited or partial blending between new and aged binder. PMID:28788190

  6. Microstructural Analysis and Rheological Modeling of Asphalt Mixtures Containing Recycled Asphalt Materials.

    PubMed

    Falchetto, Augusto Cannone; Moon, Ki Hoon; Wistuba, Michael P

    2014-09-02

    The use of recycled materials in pavement construction has seen, over the years, a significant increase closely associated with substantial economic and environmental benefits. During the past decades, many transportation agencies have evaluated the effect of adding Reclaimed Asphalt Pavement (RAP), and, more recently, Recycled Asphalt Shingles (RAS) on the performance of asphalt pavement, while limits were proposed on the amount of recycled materials which can be used. In this paper, the effect of adding RAP and RAS on the microstructural and low temperature properties of asphalt mixtures is investigated using digital image processing (DIP) and modeling of rheological data obtained with the Bending Beam Rheometer (BBR). Detailed information on the internal microstructure of asphalt mixtures is acquired based on digital images of small beam specimens and numerical estimations of spatial correlation functions. It is found that RAP increases the autocorrelation length (ACL) of the spatial distribution of aggregates, asphalt mastic and air voids phases, while an opposite trend is observed when RAS is included. Analogical and semi empirical models are used to back-calculate binder creep stiffness from mixture experimental data. Differences between back-calculated results and experimental data suggest limited or partial blending between new and aged binder.

  7. Building America Residential System Research Results: Achieving 30% Whole House Energy Savings Level in the Hot-Dry and Mixed-Dry Climates

    SciTech Connect

    Building Industry Research Alliance; Building Science Consortium; Consortium for Advanced Residential Buildings; Davis Energy Group; Florida Solar Energy Center; IBACOS; National Association of Home Builders Research Center; National Renewable Energy Laboratory

    2006-01-01

    The Building America program conducts the system research required to reduce risks associated with the design and construction of homes that use an average of 30% to 90% less total energy for all residential energy uses than the Building America Research Benchmark, including research on homes that will use zero net energy on annual basis. To measure the program's progress, annual research milestones have been established for five major climate regions in the United States. The system research activities required to reach each milestone take from 3 to 5 years to complete and include research in individual test houses, studies in pre-production prototypes, and research studies with lead builders that provide early examples that the specified energy savings level can be successfully achieved on a production basis. This report summarizes research results for the 30% energy savings level and demonstrates that lead builders can successfully provide 30% homes in the Hot-Dry/Mixed-Dry Climate Region on a cost neutral basis.

  8. Asphalt Flows on Chapopote, a Knoll in the Campeche Bay, Southern Gulf of Mexico - new Results From ROV Investigations

    NASA Astrophysics Data System (ADS)

    Brüning, M.; Bohrmann, G.; Sahling, H.; MacDonald, I. R.; Escobar Briones, E. G.

    2007-05-01

    During the German expeditions SO174 in 2003 and M67 in 2006 swath mapping was carried out in the salt diapir province in the Campeche Bay. The seafloor morphology in the north of the area is dominated by elongated hills, called knolls. Asphalts have been discovered at two of the 400 m high knolls during video surveys, but more findings are likely. During M67 dives with the ROV QUEST were carried out at one of the knolls, named "Chapopote", in about 3000 m water depth. Chapopote has a caldera-like central depression with a rim that is depressed in the north and south. The distribution of asphalts is patchy, with a major field south-east of the central depression and several smaller areas some hundred meters apart from each other at the rim. Asphalts cover about 0.5 km2. The main field appears to be the most recent outflow of asphalt. The flow pattern of this asphalt is ropy with little signs for degradation. At the other fields the asphalts are degraded to blocks without visible flow structures and are covered with hemipelagic sediments. Based on detailed observations, we put an earlier model by Hovland et al., EOS, 86, 42, 2006, in question. This model proposes supercritical water transporting hydrocarbons leading to the expulsion of warm or hot asphalts at the seafloor. Alternatively, we favour the view that cold hydrocarbons flew out at several locations at Chapopote. In a subsequent alteration process, the hydrocarbons lose the more volatile components leading to the observed residue of asphalts on top of the sediments. We found evidence of seepage at Chapopote: outflow of gas bubbles, occurrence of gas hydrates and release of oil while sampling. At one site, we observed a package of individual flows stacked on top of each other. This structure suggests that the expelled hydrocarbons, can flow into the water as a viscous fluid, which is positive buoyant. During the alteration the flows get heavier and lay down at the sediments and partly keep on flowing

  9. A Study on the Rheological Properties of Recycled Rubber-Modified Asphalt Mixtures

    PubMed Central

    Karacasu, Murat; Er, Arzu

    2015-01-01

    Using waste rubber in asphalt mixes has become a common practice in road construction. This paper presents the results of a study on the rheological characteristics of rubber-modified asphalt (RMA) concrete under static and dynamic loading conditions. A number of static and dynamic creep tests were conducted on RMA mix specimens with different rubber sizes and contents, and a series of resonant column tests were conducted to evaluate the shear modulus and damping values. To simulate the stress-strain response of traffic-induced loading, the measurements were taken for different confining pressures and strain levels. The results of the study indicated that rubber modification increases stiffness and damping ratio, making it a very attractive material for use in road construction. However the grain size of the rubber is very important. Although RMA may cost up to 100% more than regular asphalt, the advantages it brings, such as an increased service life of the road and proper waste utilization contributing to a more sustainable infrastructure, may justify the added cost. PMID:25695096

  10. A study on the rheological properties of recycled rubber-modified asphalt mixtures.

    PubMed

    Karacasu, Murat; Okur, Volkan; Er, Arzu

    2015-01-01

    Using waste rubber in asphalt mixes has become a common practice in road construction. This paper presents the results of a study on the rheological characteristics of rubber-modified asphalt (RMA) concrete under static and dynamic loading conditions. A number of static and dynamic creep tests were conducted on RMA mix specimens with different rubber sizes and contents, and a series of resonant column tests were conducted to evaluate the shear modulus and damping values. To simulate the stress-strain response of traffic-induced loading, the measurements were taken for different confining pressures and strain levels. The results of the study indicated that rubber modification increases stiffness and damping ratio, making it a very attractive material for use in road construction. However the grain size of the rubber is very important. Although RMA may cost up to 100% more than regular asphalt, the advantages it brings, such as an increased service life of the road and proper waste utilization contributing to a more sustainable infrastructure, may justify the added cost.

  11. Use of plastic waste (poly-ethylene terephthalate) in asphalt concrete mixture as aggregate replacement.

    PubMed

    Hassani, Abolfazl; Ganjidoust, Hossein; Maghanaki, Amir Abedin

    2005-08-01

    One of the environmental issues in most regions of Iran is the large number of bottles made from poly-ethylene terephthalate (PET) deposited in domestic wastes and landfills. Due to the high volume of these bottles, more than 1 million m3 landfill space is needed for disposal every year. The purpose of this experimental study was to investigate the possibility of using PET waste in asphalt concrete mixes as aggregate replacement (Plastiphalt) to reduce the environmental effects of PET disposal. For this purpose the mechanical properties of plastiphalt mixes were compared with control samples. This study focused on the parameters of Marshall stability, flow, Marshall quotient (stability-to-flow ratio) and density. The waste PET used in this study was in the form of granules of about 3 mm diameter which would replace (by volume) a portion of the mineral coarse aggregates of an equal size (2.36-4.75 mm). In all prepared mixes the determined 6.6% optimum bitumen content was used. In this investigation, five different percentages of coarse aggregate replacement were used. The results showed that the aggregate replacement of 20% by volume with PET granules would result in a reduction of 2.8% in bulk compacted mix density. The value of flow in the plastiphalt mix was lower than that of the control samples. The results also showed that when PET was used as partial aggregate replacement, the corresponding Marshall stability and Marshall quotient were almost the same as for the control samples. According to most of specification requirement, these results introduce an asphalt mix that has properties that makes it suitable for practical use and furthermore, the recycling of PET for asphalt concrete roads helps alleviate an environmental problem and saves energy.

  12. Modeling of Thermal Runoff From an Asphalt-Paved Plot in the Framework of the Mass Response Functions

    NASA Astrophysics Data System (ADS)

    Kim, K.; Thompson, A. M.; Botter, G.

    2007-12-01

    During hot summer months, impervious surfaces within urban areas may store significant amounts of thermal energy, which may be rapidly transferred to stream waters during runoff events. Modeling of heat release from impervious areas to stream waters thus represents a first, necessary step to quantify possible negative impacts of increased stream water temperature on nearby aquatic ecosystems. In this paper, a stochastic Lagrangian approach is developed to simulate heat transfer from an impermeable surface to runoff. The approach is based on the framework of the mass response functions (MRFs), which was originally developed for modeling non-point source pollutant transport in watersheds. The MRF approach has been adapted to describe heat transfer from impervious surfaces to runoff by coupling a heat balance at the asphalt/water interface and a one-dimensional heat diffusion equation within the asphalt. The model incorporates a simplified, physically based description of all the heat fluxes possibly affecting the ensuing thermal response of impervious areas (e.g., solar radiation, evaporation). The model was applied to an artificial asphalt-paved plot of 90 m2 where it was able to accurately reproduce the temperature variation of the asphalt surface and runoff during an artificially produced rainfall event. The effect of the heat diffusivity on the surface temperature response to rainfall input was also examined, showing that the effect could be significant depending on vertical temperature distributions of the plot.

  13. Mechanical properties of gutta-percha sulfide modified asphalt

    NASA Astrophysics Data System (ADS)

    Zou, X. Y.; Gu, X. Y.; Wang, X. W.

    2017-01-01

    Gutta-percha is the isomer of caoutchouc and can be used to enhance the performance of asphalt. In this paper, the produce proceedings of gutta-percha sulfide and gutta-percha sulfide modified asphalt are introduced. The performance indices of gutta-percha sulfide modified asphalt samples with different proportions are examined based on laboratory tests and the optimum ratio of gutta-percha and sulfur is decided.The micromechanism, temperature sensitivity, high and low temperature properties and viscoelasticity of the polymer modified asphalt are analyzed to discuss the modified mechanism and to decide the optimal polymer content. Low temperature bending tests are carried out to verify the low temperature performance of gutta-percha sulfide modified asphalt mixture. Research results showed that gutta-percha sulfide modified asphalt has good low temperature performance and a promising application prospect in the cold regions.

  14. Analysis of asphalt-based roof systems using thermal analysis

    SciTech Connect

    Paroli, R.M.; Delgado, A.H.

    1996-10-01

    Asphalt is used extensively in roofing applications. Traditionally, it is used in a built-up roof system, where four or five plies are applied in conjunction with asphalt. This is labour intensive and requires good quality assurance on the roof top. Alternatively, asphalt can be used in a polymer-modified sheet where styrene-butadiene-styrene (SBS) or atactic polypropylene (APP) are added to the asphalt shipped in a roll where reinforcement (e.g., glass fibre mat) has been added. Regardless of the system used, the roof must be able to withstand the environmental loads such UV, heat, etc. Thermoanalytical techniques such as DSC, DMA, TMA and TG/DTA are ideally suited to monitor the weathering of asphalt. This paper presents data obtained using these techniques and shows how the performance of asphalt-based roof systems can be followed by thermal analysis.

  15. Rheo-mechanical model for self-healing asphalt pavement

    NASA Astrophysics Data System (ADS)

    Gömze, A. L.; Gömze, L. N.

    2017-01-01

    Examining the rheological properties of different asphalt mixtures at different temperatures, pressures and deformation conditions on the combined rheo-tribometers the authors have found that the generally used Burgers-model doesn’t explain the deformation properties of asphalt mixtures and pavements under loading forces and loading pressures. To understand better the rheological and deformation properties of such complex materials like asphalt mixtures and pavements the authors used Malvern Mastersizer X laser granulometer, Bruker D8 Advance X-ray diffractometer, Hitachi TM 1000 Scanning Elektronmicroscope, Tristar 3000 specific surface tester and the combined rheo-tribometer developed and patented by the authors. After the complex investigation of different asphalt mixtures the authors have found a new, more complex rheological model for the asphalts including self-healing asphalt pavements.

  16. Manufacture of road paving asphalt using coal tar

    SciTech Connect

    Yan, T.Y.

    1986-09-01

    Coal tar is a ready source of asphaltenes needed in asphalt production. Coal tar pitch itself, however, is unsuitable for making road-paving asphalt, since the resulting material has low ductility, high temperature sensitivity, and low resistance to wear. For this reason, in England, where replacing imported petroleum with local products was important 10 to 20 years ago, it was required that no more than 10 to 20 percent coal tar pitch be incorporated in road pavement. At higher concentrations, the pitch separates from the petroleum-derived asphalt, causing brittleness and cracking. To make a good asphalt from coal tar pitch, chemical modification or blending with additives appears necessary. In this study, the potentials are for producing road-paving asphalt from coal tar and available inexpensive petroleum fractions are explored. The objective of the study is to develop new uses of coal tar for asphalt production and to free the petroleum residue for upgrading to gasoline and diesel fuels.

  17. DEVELOPMENT OF NEW FUNCTIONAL ASPHALT-NANOCARBONS COMPOSITES

    NASA Astrophysics Data System (ADS)

    Shirakawa, Tatsuo; Tada, Akio; Okazaki, Noriyasu

    Nanocarbon materials such as carbon nanotubes are well known for their superior performances in thermal, mechanical, electrical and optical properties. The purpose of this study is to prepare new asphalt composites improved by adding nanocarbons and to find new features that reflect the characteristics of nanocarbons in the asphalt composites. Such composites were prepared using several types of asphalt emulsions as a source of asphalt. Both nonionic and anionic emulsions maintained dispersed state well, when combined with nanocarbons. Cationic emulsion, however, failed to keep dispersed state. After several systematic experiments, it was found that cationic emulsion also succeeded in maintaining well-dispersed state, when combined with acid solution-pretreated nanocarbons. Asphalt-nanocarbons composites showed higher performances in both penetration and microwave-absorption tests than asphalt composites including carbon black powder instead of nanocarbons, when the mass percentage of both carbon materials was the same.

  18. Study of asphalt performance impact with ultraviolet aging

    NASA Astrophysics Data System (ADS)

    Luo, Min

    2017-09-01

    To solve the problem of strong ultraviolet radiation on the road asphalt aging, ultraviolet aging environment box analog wild aging condition to be used to experiment, Through dynamic shear rheometer respectively to study the effect of SBS modified asphalt and asphalt matrix high temperature, low temperature and fatigue performance with the aging time to change. The results show that SBS modified asphalt can produce serious aging under strong ultraviolet light, the Main aspects is fatigue performance and low temperature performance greatly reduced, high temperature performance is further improved, They have a closer relationship with aging time; At the same time, along with the test temperature, aging time on the influence of G*/sinδ, G*sinδ of amplitude decreases. That ultraviolet on SBS modified asphalt aging has temperature sensitivity. The research conclusion can choose the light aging resistance of airport pavement asphalt to provide good technical support.

  19. Effects of SBS Content on the Performance of Modified Asphalt

    NASA Astrophysics Data System (ADS)

    Zhuang, Chuanyi; Li, Ning; Zhao, Wei; Cai, Chuanfeng

    2017-06-01

    The effects of different dosage SBS (Styrene-butadiene-styrene) modifiers on the properties of asphalt were compared and analyzed from the temperature sensitivity, high temperature performance and low temperature performance of modified asphalt. The results show that with the increase of the content of SBS modifier, the softening point and kinematic viscosity of SBS modified asphalt are increased and the high temperature performance is improved. The low temperature ductility is improved; the penetration of modified asphalt is reduced, the temperature sensitivity of the asphalt is reduced. However, when the content of modifier is more than 4%, the penetration index of SBS modified asphalt decreases linearly with the increase of the content of modifier, and the temperature sensitivity increases. The engineering application should be determined according to the specific technical requirements.

  20. Seal coats and asphalt recycling. Transportation research record

    SciTech Connect

    1995-12-31

    The papers in this volume deal with various facets of seal coats and asphalt recycling; they should be of interest to state and local construction, design, materials, maintenance, and research engineers as well as contractors and material producers. Authors describe their work related to the design, construction, and performance of seal coats. The relationship between asphalt mixture characteristics and design and the frictional resistance of bituminous wearing course mixtures is reported, and research efforts related to asphalt recycling are explained.

  1. 40 CFR 60.90 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... for Hot Mix Asphalt Facilities § 60.90 Applicability and designation of affected facility. (a) The affected facility to which the provisions of this subpart apply is each hot mix asphalt facility. For the purpose of this subpart, a hot mix asphalt facility is comprised only of any combination of the following...

  2. 40 CFR 60.90 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... for Hot Mix Asphalt Facilities § 60.90 Applicability and designation of affected facility. (a) The affected facility to which the provisions of this subpart apply is each hot mix asphalt facility. For the purpose of this subpart, a hot mix asphalt facility is comprised only of any combination of the following...

  3. 40 CFR 60.90 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... for Hot Mix Asphalt Facilities § 60.90 Applicability and designation of affected facility. (a) The affected facility to which the provisions of this subpart apply is each hot mix asphalt facility. For the purpose of this subpart, a hot mix asphalt facility is comprised only of any combination of the...

  4. 40 CFR 60.90 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... for Hot Mix Asphalt Facilities § 60.90 Applicability and designation of affected facility. (a) The affected facility to which the provisions of this subpart apply is each hot mix asphalt facility. For the purpose of this subpart, a hot mix asphalt facility is comprised only of any combination of the...

  5. 40 CFR 60.90 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... for Hot Mix Asphalt Facilities § 60.90 Applicability and designation of affected facility. (a) The affected facility to which the provisions of this subpart apply is each hot mix asphalt facility. For the purpose of this subpart, a hot mix asphalt facility is comprised only of any combination of the...

  6. Investigation of porous asphalt microstructure using optical and electron microscopy.

    PubMed

    Poulikakos, L D; Partl, M N

    2010-11-01

    Direct observations of porous asphalt concrete samples in their natural state using optical and electron microscopy techniques led to useful information regarding the microstructure of two mixes and indicated a relationship between microstructure and in situ performance. This paper presents evidence that suboptimal microstructure can lead to premature failure thus making a first step in defining well or suboptimal performing pavements with a bottom-up approach (microstructure). Laboratory and field compaction produce different samples in terms of the microstructure. Laboratory compaction using the gyratory method has produced more microcracks in mineral aggregates after the binder had cooled. Well-performing mixes used polymer-modified binders, had a more homogeneous void structure with fewer elongated voids and better interlocking of the aggregates. Furthermore, well-performing mixes showed better distribution of the mastic and better coverage of the aggregates with bitumen. Low vacuum scanning electron microscopy showed that styrene butadiene styrene polymer modification in binder exists in the form of discontinuous globules and not continuous networks. A reduction in the polymer phase was observed as a result of aging and in-service use. © 2010 The Authors Journal compilation © 2010 The Royal Microscopical Society.

  7. Asphalt compatibility testing using the automated Heithaus titration test

    SciTech Connect

    Pauli, A.T.

    1996-12-31

    The Heithaus titration test or variations of the test have been used for over 35 years to predict compatibilities of blends of asphalts from different crude sources. Asphalt compatibility is determined from three calculated parameters that measure the state of peptization of an asphalt or asphalt blend. The parameter p{sub a} is a measure of the peptizability of the asphaltenes. The parameter p{sub a} is a measure of the peptizing power of the maltenes, and the parameter P, derived from p{sub a} and p{sub o} values, is a measure of the overall state of peptization of the asphalt or asphalt blend. In Heithaus original procedure, samples of asphalt were dissolved in toluene and titrated with n-heptane in order to initiate flocculation. The onset of flocculation was detected either by photography or by spotting a filter paper with a small amount of the titrated solution. Recently, an {open_quotes}automated{close_quotes} procedure, after Hotier and Robin, has been developed for use with asphalt. In the automated method UV-visible spectrophotometric detection measures the onset of flocculation as a peak with the percent transmittance plotted as a function of the volume of titrating solvent added to a solution of asphalt. The automated procedure has proven to be less operator dependent and much faster than the original Heithaus procedure. Results from the automated procedure show the data to be consistent with results from the original, {open_quotes}classical{close_quotes} Heithaus procedure.

  8. Lung function in asphalt pavers: a longitudinal study.

    PubMed

    Ulvestad, Bente; Randem, Britt Grethe; Skare, Øivind; Aaløkken, Trond Mogens; Myranek, Georg Karl; Elihn, Karine; Lund, May Brit

    2017-01-01

    To study longitudinal changes in lung function in asphalt pavers and a reference group of road maintenance workers, and to detect possible signs of lung disease by high-resolution computed tomography (HRCT) scans. Seventy-five asphalt pavers and 71 road maintenance workers were followed up with questionnaires and measurements of lung function. Not every worker was tested every year, but most of them had four or more measurement points. The 75 asphalt pavers were also invited to have HRCT scans of the lungs at the end of the follow-up period. Mean annual decline in forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) of the asphalt pavers was 58 and 35 ml, respectively. Adjusted for age at baseline, packyears of smoking and BMI, the asphalt pavers had a significant excess annual decline in FVC and FEV1 compared to the references. The screedmen, the most exposed group of the asphalt pavers, showed a significantly larger decline in FVC than the other asphalt pavers (P = 0.029). Fine intralobular fibrosis without evident cysts was identified with HRCT in three subjects (4 %). We conclude that our findings may indicate an excess annual decline in FVC and FEV1 related to exposure to asphalt fumes. The screedmen, who carry out their work behind and close to the paving machine, had the largest decline in lung function. The finding of adverse pulmonary effects in asphalt pavers calls for better technological solutions to prevent exposure.

  9. Detection of asphalt pavement cracks using remote sensing techniques

    NASA Astrophysics Data System (ADS)

    Mettas, Christodoulos; Agapiou, Athos; Themistocleous, Kyriacos; Neocleous, Kyriacos; Hadjimitsis, Diofantos G.

    2016-10-01

    Deterioration of asphalt road pavements is inevitable throughout its life cycle. There are several types of deterioration that take place on these surfaces, like surface defects and deformations. One of the most common asphalt defects is cracking. Fatigue, transverse, longitudinal, reflective, edge, block and slippage are types of cracking that can be observed anywhere in the world. Monitoring and preventative/periodic maintenance of these types of wears are two very important actions that have to take place to avoid "costly" solutions. This paper aims to introduce the spectral characteristics of uncracked (healthy) and cracked asphalt surfaces which can give a new asphalt crack index. This is performed through remote sensing applications in the area of asphalt pavements. Multispectral images can be elaborated using the index to enhance crack marks on asphalt surfaces. Ground spectral signatures were acquired from both uncracked and cracked asphalted areas of Cyprus (Limassol). Evaluation separability indices can be used to identify the optimum wavelength regions that can distinguish better the uncracked and cracked asphalt surfaces. The results revealed that the spectral sensitivity for the enhancement of cracked asphalt was detected using the Euclidean, Mahalanobis and Cosine Distance Indices in the Vis range (approximately at 450 nm) and in the SWIR 1 range (approximately at 1750 nm).

  10. Hanford Permanent Isolation Barrier Program: Asphalt technology development

    SciTech Connect

    Freeman, H.D.; Romine, R.A.

    1994-11-01

    An important component of the Hanford Permanent Isolation Barrier is the use of a two-layer composite asphalt system, which provides backup water diversion capabilities if the primary capillary barrier fails to meet infiltration goals. Because of asphalt`s potential to perform to specification over the 1000-year design life criterion, a composite asphalt barrier (HMAC/fluid-applied polymer-modified asphalt) is being considered as an alternative to the bentonite clay/high density poly(ethylene) barriers for the low-permeability component of the Hanford Permanent Isolation Barrier. The feasibility of using asphalt as a long-term barrier is currently being studied. Information that must be known is the ability of asphalt to retain desirable physical properties over a period of 1000 years. This paper presents the approach for performing accelerated aging tests and evaluating the performance of samples under accelerated conditions. The results of these tests will be compared with asphalt artifact analogs and the results of modeling the degradation of the selected asphalt composite to make life-cycle predictions.

  11. Field testing of asphalt-emulsion radon-barrier system

    SciTech Connect

    Hartley, J.N.; Freeman, H.D.; Baker, E.G.; Elmore, M.R.; Nelson, D.A.; Voss, C.F.; Koehmstedt, P.L.

    1981-09-01

    Three years of laboratory and field testing have demonstrated that asphalt emulsion seals are effective radon diffusion barriers. Both laboratory and field tests in 1979, 1980 and 1981 have shown that an asphalt emulsion seal can reduce radon fluxes by greater than 99.9%. The effective diffusion coefficient for the various asphalt emulsion admix seals averages about 10/sup -6/ cm/sup 2//s. The 1981 joint field test is a culmination of all the technology developed to date for asphalt emulsion radon barrier systems. Preliminary results of this field test and the results of the 1980 field test are presented. 18 figures, 6 tables.

  12. Rapid Radiochemical Methods for Asphalt Paving Material ...

    EPA Pesticide Factsheets

    Technical Brief Validated rapid radiochemical methods for alpha and beta emitters in solid matrices that are commonly encountered in urban environments were previously unavailable for public use by responding laboratories. A lack of tested rapid methods would delay the quick determination of contamination levels and the assessment of acceptable site-specific exposure levels. Of special concern are matrices with rough and porous surfaces, which allow the movement of radioactive material deep into the building material making it difficult to detect. This research focuses on methods that address preparation, radiochemical separation, and analysis of asphalt paving materials and asphalt roofing shingles. These matrices, common to outdoor environments, challenge the capability and capacity of very experienced radiochemistry laboratories. Generally, routine sample preparation and dissolution techniques produce liquid samples (representative of the original sample material) that can be processed using available radiochemical methods. The asphalt materials are especially difficult because they do not readily lend themselves to these routine sample preparation and dissolution techniques. The HSRP and ORIA coordinate radiological reference laboratory priorities and activities in conjunction with HSRP’s Partner Process. As part of the collaboration, the HSRP worked with ORIA to publish rapid radioanalytical methods for selected radionuclides in building material matrice

  13. Microbial Diversity in Natural Asphalts of the Rancho La Brea Tar Pits▿

    PubMed Central

    Kim, Jong-Shik; Crowley, David E.

    2007-01-01

    Bacteria commonly inhabit subsurface oil reservoirs, but almost nothing is known yet about microorganisms that live in naturally occurring terrestrial oil seeps and natural asphalts that are comprised of highly recalcitrant petroleum hydrocarbons. Here we report the first survey of microbial diversity in ca. 28,000-year-old samples of natural asphalts from the Rancho La Brea Tar Pits in Los Angeles, CA. Microbiological studies included analyses of 16S rRNA gene sequences and DNA encoding aromatic ring-hydroxylating dioxygenases from two tar pits differing in chemical composition. Our results revealed a wide range of phylogenetic groups within the Archaea and Bacteria domains, in which individual taxonomic clusters were comprised of sets of closely related species within novel genera and families. Fluorescent staining of asphalt-soil particles using phylogenetic probes for Archaea, Bacteria, and Pseudomonas showed coexistence of mixed microbial communities at high cell densities. Genes encoding dioxygenases included three novel clusters of enzymes. The discovery of life in the tar pits provides an avenue for further studies of the evolution of enzymes and catabolic pathways for bacteria that have been exposed to complex hydrocarbons for millennia. These bacteria also should have application for industrial microbiology and bioremediation. PMID:17416692

  14. Coating green slash asphalt and wax prevent drying

    Treesearch

    Harry E. Schimke; Ronald H. Dougherty

    1967-01-01

    Dry logging slash has been successfully kept dry for later burning by spraying it with asphalt and wax emulsions. The same treatments were tried on green slash. Tests made by applying SS-1 grade asphalt emulsion and a lumber wax on green slash showed that these protective coatings prevented the slash from drying satisfactorily.

  15. 7 CFR 3201.36 - Concrete and asphalt release fluids.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Concrete and asphalt release fluids. 3201.36 Section... PROCUREMENT Designated Items § 3201.36 Concrete and asphalt release fluids. (a) Definition. Products that are designed to provide a lubricating barrier between the composite surface materials (e.g., concrete...

  16. 7 CFR 2902.36 - Concrete and asphalt release fluids.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 15 2011-01-01 2011-01-01 false Concrete and asphalt release fluids. 2902.36 Section... PROCUREMENT Designated Items § 2902.36 Concrete and asphalt release fluids. (a) Definition. Products that are designed to provide a lubricating barrier between the composite surface materials (e.g., concrete...

  17. 7 CFR 3201.36 - Concrete and asphalt release fluids.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Concrete and asphalt release fluids. 3201.36 Section... PROCUREMENT Designated Items § 3201.36 Concrete and asphalt release fluids. (a) Definition. Products that are designed to provide a lubricating barrier between the composite surface materials (e.g., concrete...

  18. 7 CFR 2902.36 - Concrete and asphalt release fluids.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Concrete and asphalt release fluids. 2902.36 Section... PROCUREMENT Designated Items § 2902.36 Concrete and asphalt release fluids. (a) Definition. Products that are designed to provide a lubricating barrier between the composite surface materials (e.g., concrete...

  19. 7 CFR 3201.36 - Concrete and asphalt release fluids.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Concrete and asphalt release fluids. 3201.36 Section... PROCUREMENT Designated Items § 3201.36 Concrete and asphalt release fluids. (a) Definition. Products that are designed to provide a lubricating barrier between the composite surface materials (e.g., concrete...

  20. Good news from the bottom: US asphalt market 1993

    SciTech Connect

    Not Available

    1993-09-22

    For US refiners faced with numerous tough challenges in 1993, the US asphalt market recovery may have provided some welcome news for those watching the bottom line. Higher prices and increased sales made the asphalt market a summertime profit center for many US refiners and marketers -- for the first time in years.

  1. Alternate/Modified Binders for Asphalt Airfield Pavements

    DTIC Science & Technology

    1990-11-01

    ing volume of aircraft traffic, higher tire pressures, heavier load capaci- ties, and substandard construction materials. These problems are...ing asphalt cements to increase resistance to rutting from high pressure tires , (3) improving the rheological properties of the asphalt, and (4...and rehabilitation have become increasingly difficult from a materials design standpoint. Air- craft design changes such as increasing tire pressures

  2. Comparing Urinary Biomarkers of Airborne and Dermal Exposure to Polycyclic Aromatic Compounds in Asphalt-Exposed Workers

    PubMed Central

    Sobus, Jon R.; McClean, Michael D.; Herrick, Robert F.; Waidyanatha, Suramya; Nylander-French, Leena A.; Kupper, Lawrence L.; Rappaport, Stephen M.

    2009-01-01

    When working with hot mix asphalt, road pavers are exposed to polycyclic aromatic hydrocarbons (PAHs) through the inhalation of vapors and particulate matter (PM) and through dermal contact with PM and contaminated surfaces. Several PAHs with four to six rings are potent carcinogens which reside in these particulate emissions. Since urinary biomarkers of large PAHs are rarely detectable in asphalt workers, attention has focused upon urinary levels of the more volatile and abundant two-ring and three-ring PAHs as potential biomarkers of PAH exposure. Here, we compare levels of particulate polycyclic aromatic compounds (P-PACs, a group of aromatic hydrocarbons containing PAHs and heterocyclic compounds with four or more rings) in air and dermal patch samples from 20 road pavers to the corresponding urinary levels of naphthalene (U-Nap) (two rings), phenanthrene (U-Phe) (three rings), monohydroxylated metabolites of naphthalene (OH-Nap) and phenanthrene (OH-Phe), and 1-hydroxypyrene (OH-Pyr) (four rings), the most widely used biomarker of PAH exposure. For each worker, daily breathing-zone air (n = 55) and dermal patch samples (n = 56) were collected on three consecutive workdays along with postshift, bedtime, and morning urine samples (n = 149). Measured levels of P-PACs and the urinary analytes were used to statistically model exposure–biomarker relationships while controlling for urinary creatinine, smoking status, age, body mass index, and the timing of urine sampling. Levels of OH-Phe in urine collected postshift, at bedtime, and the following morning were all significantly associated with levels of P-PACs in air and dermal patch samples. For U-Nap, U-Phe, and OH-Pyr, both air and dermal patch measurements of P-PACs were significant predictors of postshift urine levels, and dermal patch measurements were significant predictors of bedtime urine levels (all three analytes) and morning urine levels (U-Nap and OH-Pyr only). Significant effects of

  3. 40 CFR 443.20 - Applicability; description of the asphalt concrete subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... asphalt concrete subcategory. 443.20 Section 443.20 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.20 Applicability; description of the asphalt concrete subcategory. The provisions of this subpart are applicable to...

  4. 40 CFR 443.20 - Applicability; description of the asphalt concrete subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... asphalt concrete subcategory. 443.20 Section 443.20 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.20 Applicability; description of the asphalt concrete subcategory. The provisions of this subpart are applicable to...

  5. 40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt...

  6. 40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt subcategory. The...

  7. 40 CFR Table 1 of Subpart Aaaaaaa... - Emission Limits for Asphalt Processing (Refining) Operations

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 15 2014-07-01 2014-07-01 false Emission Limits for Asphalt Processing... Area Sources: Asphalt Processing and Asphalt Roofing Manufacturing Other Requirements and Information... of Part 63—Emission Limits for Asphalt Processing (Refining) Operations For * * * You must meet the...

  8. 40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt...

  9. 40 CFR 443.10 - Applicability; description of the asphalt emulsion subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... asphalt emulsion subcategory. 443.10 Section 443.10 Protection of Environment ENVIRONMENTAL PROTECTION... ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.10 Applicability; description of the asphalt emulsion subcategory. The provisions of this subpart are applicable to...

  10. 40 CFR 443.10 - Applicability; description of the asphalt emulsion subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... asphalt emulsion subcategory. 443.10 Section 443.10 Protection of Environment ENVIRONMENTAL PROTECTION... ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.10 Applicability; description of the asphalt emulsion subcategory. The provisions of this subpart are applicable to...

  11. 40 CFR 443.20 - Applicability; description of the asphalt concrete subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... asphalt concrete subcategory. 443.20 Section 443.20 Protection of Environment ENVIRONMENTAL PROTECTION... ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.20 Applicability; description of the asphalt concrete subcategory. The provisions of this subpart are applicable to...

  12. 40 CFR 443.30 - Applicability; description of the asphalt roofing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... asphalt roofing subcategory. 443.30 Section 443.30 Protection of Environment ENVIRONMENTAL PROTECTION... ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.30 Applicability; description of the asphalt roofing subcategory. The provisions of this subpart are applicable to...

  13. 40 CFR Table 1 of Subpart Aaaaaaa... - Emission Limits for Asphalt Processing (Refining) Operations

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 15 2013-07-01 2013-07-01 false Emission Limits for Asphalt Processing... Area Sources: Asphalt Processing and Asphalt Roofing Manufacturing Other Requirements and Information... of Part 63—Emission Limits for Asphalt Processing (Refining) Operations For * * * You must meet the...

  14. 40 CFR Table 1 of Subpart Aaaaaaa... - Emission Limits for Asphalt Processing (Refining) Operations

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 15 2012-07-01 2012-07-01 false Emission Limits for Asphalt Processing... Area Sources: Asphalt Processing and Asphalt Roofing Manufacturing Other Requirements and Information... of Part 63—Emission Limits for Asphalt Processing (Refining) Operations For * * * You must meet the...

  15. 40 CFR 443.30 - Applicability; description of the asphalt roofing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... asphalt roofing subcategory. 443.30 Section 443.30 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.30 Applicability; description of the asphalt roofing subcategory. The provisions of this subpart are applicable to discharges...

  16. 40 CFR 443.30 - Applicability; description of the asphalt roofing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... asphalt roofing subcategory. 443.30 Section 443.30 Protection of Environment ENVIRONMENTAL PROTECTION... ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.30 Applicability; description of the asphalt roofing subcategory. The provisions of this subpart are applicable to...

  17. 40 CFR 443.10 - Applicability; description of the asphalt emulsion subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... asphalt emulsion subcategory. 443.10 Section 443.10 Protection of Environment ENVIRONMENTAL PROTECTION... ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.10 Applicability; description of the asphalt emulsion subcategory. The provisions of this subpart are applicable to...

  18. 40 CFR 443.30 - Applicability; description of the asphalt roofing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... asphalt roofing subcategory. 443.30 Section 443.30 Protection of Environment ENVIRONMENTAL PROTECTION... ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.30 Applicability; description of the asphalt roofing subcategory. The provisions of this subpart are applicable to...

  19. 40 CFR 443.20 - Applicability; description of the asphalt concrete subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... asphalt concrete subcategory. 443.20 Section 443.20 Protection of Environment ENVIRONMENTAL PROTECTION... ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.20 Applicability; description of the asphalt concrete subcategory. The provisions of this subpart are applicable to...

  20. 40 CFR 443.20 - Applicability; description of the asphalt concrete subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... asphalt concrete subcategory. 443.20 Section 443.20 Protection of Environment ENVIRONMENTAL PROTECTION... ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.20 Applicability; description of the asphalt concrete subcategory. The provisions of this subpart are applicable to...

  1. 40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt...

  2. 40 CFR 443.10 - Applicability; description of the asphalt emulsion subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... asphalt emulsion subcategory. 443.10 Section 443.10 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.10 Applicability; description of the asphalt emulsion subcategory. The provisions of this subpart are applicable to...

  3. 40 CFR 443.30 - Applicability; description of the asphalt roofing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... asphalt roofing subcategory. 443.30 Section 443.30 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.30 Applicability; description of the asphalt roofing subcategory. The provisions of this subpart are applicable to...

  4. 40 CFR 443.10 - Applicability; description of the asphalt emulsion subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... asphalt emulsion subcategory. 443.10 Section 443.10 Protection of Environment ENVIRONMENTAL PROTECTION... MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.10 Applicability; description of the asphalt emulsion subcategory. The provisions of this subpart are applicable to...

  5. Respiratory symptoms and airflow limitation in asphalt workers

    PubMed Central

    Randem, B; Ulvestad, B; Burstyn, I; Kongerud, J

    2004-01-01

    Aims: To assess the occurrence of respiratory symptoms and signs of airflow limitations in a group of asphalt workers. Methods: All 64 asphalt workers and a reference group of 195 outdoor construction workers from the same company participated in a cross-sectional study. Spirometric tests and a questionnaire on respiratory symptoms and smoking habits were administered. Respiratory symptoms and lung function were adjusted for age and smoking. Results: The FEV1/FVC% ratio was significantly lower in the asphalt workers than in the referents. Symptoms of eye irritation, chest tightness, shortness of breath on exertion, chest wheezing, physician diagnosed asthma, and chronic obstructive pulmonary disease (COPD) were all significantly more prevalent among the asphalt workers. Conclusion: In asphalt workers there is an increased risk of respiratory symptoms, lung function decline, and COPD compared to other construction workers. PMID:15031397

  6. Experimental evaluation of high performance base course and road base asphalt concrete with electric arc furnace steel slags.

    PubMed

    Pasetto, Marco; Baldo, Nicola

    2010-09-15

    The paper presents the results of a laboratory study aimed at verifying the use of two types of electric arc furnace (EAF) steel slags as substitutes for natural aggregates, in the composition of base course and road base asphalt concrete (BBAC) for flexible pavements. The trial was composed of a preliminary study of the chemical, physical, mechanical and leaching properties of the EAF steel slags, followed by the mix design and performance characterization of the bituminous mixes, through gyratory compaction tests, permanent deformation tests, stiffness modulus tests at various temperatures, fatigue tests and indirect tensile strength tests. All the mixtures with EAF slags presented better mechanical characteristics than those of the corresponding asphalts with natural aggregate and satisfied the requisites for acceptance in the Italian road sector technical standards, thus resulting as suitable for use in road construction.

  7. Investigation of the Microstructural Mechanisms of Relaxation and Fracture Healing in Asphalt

    DTIC Science & Technology

    1991-10-30

    asphalt concrete. The methodology has been verified by testing ’ thirteen’ differe~nt asphalts with widely varying compositions and chemistries. This... method of establishing the amount of fracture healing that occurs in asphalt concrete as the result’ of rest periods is being used to establish the...Process .......... ... ... ..... 24 Task 5 - Relaxation and Healing Testing of Asphalt’ Samples . . 26 m Task 6 - Produce Specific Asphalts by

  8. Air sampling methodology for asphalt fume in asphalt production and asphalt roofing manufacturing facilities: total particulate sampler versus inhalable particulate sampler.

    PubMed

    Calzavara, Thomas S; Carter, Charles M; Axten, Charles

    2003-05-01

    In 2000, the American Conference of Governmental Industrial Hygienists (ACGIH(R)) changed its 1971 threshold limit value (TLV) for 8-hour time-weighted average (TWA) exposure to asphalt from 5 mg/m(3) total particulate (generally < or =40 micrometer [microm] diameter) to 0.5 mg/m(3) inhalable particulate (< or =100 microm aerodynamic diameter) as benzene-soluble aerosol. To date, no inhalable particulate sampling method has been standardized and validated for asphalt fume. Furthermore, much of the historical data were collected using total particulate samplers, and the comparability of total versus inhalable size fractions of asphalt fume is not known. Therefore, the present study compared results from two types of asphalt fume samplers: 1) a traditional total particulate sampler with a 37-mm filter in a closed-face cassette with a 4-mm orifice (NIOSH 5042) versus (2) an inhalable particulate sampler designed by the IOM with a 15-mm orifice. A total of 75 simultaneous pairs of samples were collected, including personal and area samples from 19 roofing and asphalt production facilities operated by 7 different manufacturers. Each sample was analyzed for total mass collected and for benzene-soluble mass. Data from the two sampling methods (total versus inhalable) were comparable for asphalt fumes up to an aerosol concentration of 10 mg/m(3). However, we conclude that the traditional total particulate method is preferable, for this reason: The vast majority of asphalt fume particles are <12.5 microm in diameter. The traditional sampler is designed to collect primarily particles < or =40 microm, while the IOM sampler is optimized for collecting particles < or =100 microm. Thus, the traditional sampler is less likely than the IOM sampler to collect the larger-size fraction of airborne particles, most of which are non-asphalt dust.

  9. Characterisation of Asphalt Concrete Using Nanoindentation.

    PubMed

    Barbhuiya, Salim; Caracciolo, Benjamin

    2017-07-18

    In this study, nanoindentation was conducted to extract the load-displacement behaviour and the nanomechanical properties of asphalt concrete across the mastic, matrix, and aggregate phases. Further, the performance of hydrated lime as an additive was assessed across the three phases. The hydrated lime containing samples have greater resistance to deformation in the mastic and matrix phases, in particular, the mastic. There is strong evidence suggesting that hydrated lime has the most potent effect on the mastic phase, with significant increase in hardness and stiffness.

  10. Characterisation of Asphalt Concrete Using Nanoindentation

    PubMed Central

    Barbhuiya, Salim; Caracciolo, Benjamin

    2017-01-01

    In this study, nanoindentation was conducted to extract the load-displacement behaviour and the nanomechanical properties of asphalt concrete across the mastic, matrix, and aggregate phases. Further, the performance of hydrated lime as an additive was assessed across the three phases. The hydrated lime containing samples have greater resistance to deformation in the mastic and matrix phases, in particular, the mastic. There is strong evidence suggesting that hydrated lime has the most potent effect on the mastic phase, with significant increase in hardness and stiffness. PMID:28773181

  11. Observation of a network structure in asphalt cements

    SciTech Connect

    Rozeveld, J.; Shin, E.E.; Bhurke, A.; Drzal, L.T.

    1996-12-31

    Paving asphalts are often judged and selected based on their rheological behavior at prescribed temperatures or aging response. Asphalts are considered as a colloidal mixture, where clusters of polar, aromatic molecules are dispersed in a less polar solvent. Thus, the extent to which the solvent phase disperses the associating molecules will determine many of the fundamental asphalt properties. Asphalts are typically divided into four major groups, namely: asphaltenes, resins, aromatics, ans saturates. Asphaltenes are the highest molecular weight group and constitute {approximately}25% of the total asphalt. Resins are very polar in nature and act as a dispersing agent or peptisers for the asphaltenes. The solvent or oily phase (aromatics and saturates) are the lightest molecular weight group and are the bulk of the total asphalt (40-50%). The dispersion of the asphaltenes within the oily solvent is an important property and has been studied by separation and titration methods. In this study, asphalt cements were examined using an Environmental Scanning Electron Microscopy (ESEM) (ElectroScan 2020), and confocal Laser Scanning Microscope (LSM) (Zeiss 10).

  12. The effects of free and bonded sulfur both in the presence and absence of vulcanization accelerators on the rheological, technological, aging, and thermal stability of asphalts

    SciTech Connect

    Onabajo, A.; Kopsch, H.

    1987-01-01

    Rheological and technological experiments have been carried out on sulfur-modified asphalts in the temperature range of 353 K to 453 K over a wide range of shear rates (0-4800 sec/sup -1/). The results indicated that the activation energy of the viscous flow increased with increasing amount of bonded sulfur. The irreversible shear degradation observed in sulfur-modified asphalts is caused by the high shear forces which rupture the aggregated molecules. Thermogravimetric analysis and aging experiments on asphalts and their sulfurized products, containing varying amounts of free sulfur (0-5.5 wt.-%) and vulcanization accelerators (0.5-2.5 wt.-%), have shown that mixes containing vulcanization accelerators have higher thermal stabilities and are more resistant to thermal and non-thermal aging than the unaccelerated asphalt-sulfur mixed prepared at the same or higher temperatures. The changes in the rheological and physical properties of the mixes with time is not only explained by the changes in the physical state of unreacted free sulfur, that is, from plastic to crystalline state (physical process), but also attributable to the effect of chemical reactions.

  13. Hot Flashes

    MedlinePlus

    ... are due to menopause — the time when menstrual periods become irregular and eventually stop. In fact, hot flashes are the most common symptom of the menopausal transition. How often hot flashes occur varies among women ...

  14. Hot microswimmers

    NASA Astrophysics Data System (ADS)

    Kroy, Klaus; Chakraborty, Dipanjan; Cichos, Frank

    2016-11-01

    Hot microswimmers are self-propelled Brownian particles that exploit local heating for their directed self-thermophoretic motion. We provide a pedagogical overview of the key physical mechanisms underlying this promising new technology. It covers the hydrodynamics of swimming, thermophoresis and -osmosis, hot Brownian motion, force-free steering, and dedicated experimental and simulation tools to analyze hot Brownian swimmers.

  15. Hot Flashes

    MedlinePlus

    Diseases and Conditions Hot flashes By Mayo Clinic Staff Hot flashes are sudden feelings of warmth, which are usually most intense over the ... skin may redden, as if you're blushing. Hot flashes can also cause profuse sweating and may ...

  16. Low permeability asphalt concrete gamma ray shielding properties.

    PubMed

    Binney, S E; Sykes, K L

    1997-01-01

    Energy-dependent gamma ray shielding properties were measured as a function of gamma ray energy for a low permeability asphalt concrete that is used as a cap to prevent water infiltration into radioactive waste sites. Experimental data were compared to ISO-PC point kernel shielding calculations. Calculated dose equivalent rates compared well with experimental values, especially considering the poor detector resolution involved. The shielding properties of the asphalt concrete closely resembled those of aluminum. The results presented can be used to determine the asphalt concrete thickness required to reduce dose equivalent rates from several gamma ray emitting radionuclides.

  17. Influence of ferrous materials on crumb rubber modified asphalts

    NASA Astrophysics Data System (ADS)

    Capelo, M.; Reina, V.; Naranjo, F.; Carrión, L.; Arroyo, Carlos R.; Narváez-Muñoz, C.

    2017-09-01

    This research investigated the properties of crumb rubber modified asphalt mixtures, using a wet process. Different size of crumb rubber particles have been used to analyze their effects on modified asphalt. Moreover, two types of crumb rubber were use; one was used without any change (powder 1), while the other one the ferrous material was removed (powder 2). The tests of chemical compositions and microstructure were performed by Scanning electronic microscope (SEM) and optical microscope, respectively. Finally, the results obtained confirm that the rheology of this modified asphalt depends on the chemical compositions of the crumb rubber at low temperatures.

  18. In hot water, again

    NASA Astrophysics Data System (ADS)

    Basden, Alastair; Watkins, Sheila

    2009-10-01

    Regarding Norman Willcox's letter about the problems of using solar panels for domestic heating (August p21), I also have thermal solar panels installed. However, contrary to his disappointing experience, I have found that they provide my family with a useful amount of hot water. In our system, the solar energy is used to heat a store of water, which has no other source of heat. Mains-pressure cold water passes through this store via a heat exchanger, removing heat from it and warming up. If the water becomes warm enough, an unpowered thermostatic valve allows it to go straight to the hot taps (mixing it with cold if it is too hot). However, if it is not hot enough, then the water is directed first through our previously installed gaspowered combination boiler and then to the taps.

  19. 12. VIEW NORTH, ACROSS DECK CENTER AREA SHOWING ASPHALT AND ...

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

    12. VIEW NORTH, ACROSS DECK CENTER AREA SHOWING ASPHALT AND NORTH SIDE GUARD WALL - Route 1 Extension, South Street Viaduct, Spanning Conrail & Wheeler Point Road at South Street, Newark, Essex County, NJ

  20. Comprehensive research program: Wind resistance of asphalt shingles

    SciTech Connect

    Jones, J.E.; Metz, R.E.

    1999-07-01

    This paper describes the Asphalt Roofing Manufacturers Association's comprehensive research program which has resulted in a validated wind load model that can be used to calculate the uplift pressure on asphalt shingles as a function of approach wind velocities and other wind and building conditions. Also, a tab uplift resistance test method has been developed to measure the ability of asphalt shingles to withstand the imposed pressures due to the wind. In combination, the results of these two efforts provide the shingle manufacturers with the methodology to evaluate and improve their products. The results are not only of interest to the roofing manufacturers, but also to contractors, code officials, insurance companies, roofing specifiers and other professionals in the roofing industry. The results of this work should provide building owners and homeowners with high performance asphalt shingles for extreme wind conditions.

  1. 4. LOOKING SOUTHWEST AT LATTICED GUARDRAIL, DIAGONALS, ASPHALT DECK AND ...

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

    4. LOOKING SOUTHWEST AT LATTICED GUARDRAIL, DIAGONALS, ASPHALT DECK AND LACED ANGLES ON VERTICALS - Wayne County Bridge No. 122, Spanning West Fork Whitewater River at Main Street, Milton, Wayne County, IN

  2. 5. VIEW OF SECOND ELEVATOR WITH WOODFRAME HEADHOUSE AND ASPHALTIC ...

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

    5. VIEW OF SECOND ELEVATOR WITH WOOD-FRAME HEADHOUSE AND ASPHALTIC SIDING, LOOKING WEST. - Lockport DuPage Farmer's Elevator Company Grain Elevator, South of Romeoville Road, Lockport, Will County, IL

  3. Bettis Asphalt and Construction, Inc. - Clean Water Act Public Notice

    EPA Pesticide Factsheets

    The EPA is providing notice of a proposed Administrative Penalty Assessment against Bettis Asphalt and Construction, Inc. for alleged violations at its facility located at 2350 Northwest Water Works Drive, Topeka, KS 66606.

  4. Rapid Method for Sodium Hydroxide Fusion of Asphalt ...

    EPA Pesticide Factsheets

    Technical Brief--Addendum to Selected Analytical Methods (SAM) 2012 The method will be used for qualitative analysis of americium-241, plutonium-238, plutonium-239, radium-226, strontium-90, uranium-234, uranium-235 and uranium-238 in asphalt matrices samples.

  5. Effect of moisture on the aging behavior of asphalt binder

    NASA Astrophysics Data System (ADS)

    Ma, Tao; Huang, Xiao-Ming; Mahmoud, Enad; Garibaldy, Emil

    2011-08-01

    The moisture aging effect and mechanism of asphalt binder during the in-service life of pavement were investigated by laboratory simulating tests. Pressure aging vessel (PAV) test simulating the long-term aging of binder during the in-service life of pavement was modified to capture the long-term moisture aging effect of binder. Penetration grade tests including penetration test, soften point test, and ductility test as well as Superpave™ performance grade tests including viscosity test, dynamic shear rheometer test, and bending beam rheometer test were conducted to fully evaluate the moisture aging effect of binder. Fourier transform infrared spectroscopy test and Gel-permeation chromatography test were applied to provide a fundamental understanding of the moisture aging mechanism of binder. The results indicate that moisture condition can accelerate the aging of asphalt binder and shorten the service life of asphalt binder. The modified PAV test with moisture condition can well characterize the moisture aging properties of asphalt binder.

  6. Recycled brake linings as partial aggregate substitute in asphalt paving. Construction and final report. Report for July 1992-August 1996

    SciTech Connect

    Miller, P.A.; Sukley, R.

    1996-09-01

    The purpose of this project was to evaluate the performance of asphalt containing various percentages of brake lining as an aggregate, and compare its performance to that of normal asphalt containing natural aggregate. This project is an effort to explore alternate ways to use waste product. Four test section of FB-2 Modified mix containing brake lining materials were placed in July 1992 along with one control section on SR 3022 in Mercer county. To date all sections are performing satisfactory, and Brake linings should be recommended as a viable partial replacement of aggregate in bituminous materials. This study only considered the performance of only off-spec brake linings, therefore, any performance data or enviromental effects of placement of used brake material should be addressed.

  7. Modeling of thermal runoff response from an asphalt-paved plot in the framework of the mass response functions

    NASA Astrophysics Data System (ADS)

    Kim, Kyunghyun; Thompson, Anita M.; Botter, Gianluca

    2008-11-01

    During hot summer months, impervious surfaces within urban areas may store significant amounts of thermal energy, which may be rapidly transferred to stream waters during runoff events. Modeling of heat release from impervious areas to stream waters thus represents a first, necessary step to quantify possible negative impacts of increased stream water temperature on nearby aquatic ecosystems. In this paper, a stochastic Lagrangian approach is developed to simulate heat transfer from an impermeable surface to runoff. The approach is based on the framework of the mass response functions (MRFs), which was originally developed for modeling nonpoint source pollutant transport in watersheds. The MRF approach has been adapted to describe heat transfer from impervious surfaces to runoff by coupling a heat balance at the asphalt/water interface and a one-dimensional heat diffusion equation within the asphalt. The model incorporates a simplified, physically based description of all the heat fluxes possibly affecting the ensuing thermal response of impervious areas (e.g., solar radiation and evaporation). The model was applied to an asphalt-paved plot of 90 m2 where it was able to accurately reproduce the temperature variation of the asphalt surface and runoff during an artificially produced rainfall event. Model prediction uncertainty introduced by the estimate of some key parameters involved in the heat balance is analyzed by sensitivity analysis and by checking a posteriori the consistency of the estimated heat fluxes through an overall heat conservation equation. The effect of the heat diffusivity on the surface temperature response to rainfall input was also examined, showing that the effect could be significant depending on vertical temperature distributions of the plot.

  8. Wavelet-based asphalt concrete texture grading and classification

    NASA Astrophysics Data System (ADS)

    Almuntashri, Ali; Agaian, Sos

    2011-03-01

    In this Paper, we introduce a new method for evaluation, quality control, and automatic grading of texture images representing different textural classes of Asphalt Concrete (AC). Also, we present a new asphalt concrete texture grading, wavelet transform, fractal, and Support Vector Machine (SVM) based automatic classification and recognition system. Experimental results were simulated using different cross-validation techniques and achieved an average classification accuracy of 91.4.0 % in a set of 150 images belonging to five different texture grades.

  9. Evaluation of Asphalt Rubber Binders in Porous Friction Courses

    DTIC Science & Technology

    1992-05-01

    5RE, AC-5R, and AC-20R for all tests in this study. The crumb rubber used in each asphalt rubber blend was made of 100 percent reclaimed waste tires ...binder’s tendency to age harden at the asphalt plant . The exception to this statement may be when an extender oil is added with the crumb rubber such as...equipment ......................... 40 21 Crumb rubber after milling .......................................... 43 22 Absolute viscosity test results

  10. Impulse radar evaluation of concrete, asphalt and waterproofing membrane

    NASA Astrophysics Data System (ADS)

    Chung, T.; Carter, C. R.; Masliwec, T.; Manning, D. G.

    1994-04-01

    Impulse radar has proved to be effective in the nondestructive testing of bridge decks composed of layers of dielectric materials such as asphalt, waterproofing membrane, and reinforced concrete. In this work, the waveforms reflected from these materials are modeled and analyzed theoretically. The relative dielectric constants are measured using sample blocks, and the reflected radar waveforms are related to the actual physical structures. It is found that asphalt thickness and cover over reinforcement can be accurately determined.

  11. BEHAVIOR OF MODEL ASPHALT PAVEMENT CONTAINING A HYDRAULIC, GRADED IRON AND STEEL SLAG BASE-COURSE UNDER REPEATED PLATE-LOADING

    NASA Astrophysics Data System (ADS)

    Yoshida, Nobuyuki; Sugisako, Yasunari

    In this paper, the dynamic response of asphalt pave ment containing a hydraulic, graded iron and steel slag (hereafter called HMS) base-course under repeated plate-loading was investigated using a model asphalt pavement and the influence of hydraulicity on th e pavement behavior was discussed. The model pavement constructed was a 4-layer system consis ting of a dense-graded asphalt mix surface layer, a dense-graded asphalt mix binder-course, a HMS base-course and a Masado (heavily-weathered granitic sand) subgrade. A repeated plate-loading test was carri ed out so as to achieve a resilient state. It is shown that surface resilient deflection decreases as curing progresses and after 90 days, the deflection becomes almost half of the initial. Large horizontal tensile strains develop at the bottoms of binder- and base-course, which decrease significantly with curing. It is indicative that HMS base-course behaves like a stiffer plate resulting in a hard-to-deflect state due to the development of hydraulicity.

  12. The use of waste materials in asphalt concrete mixtures.

    PubMed

    Tuncan, Mustafa; Tuncan, Ahmet; Cetin, Altan

    2003-04-01

    The purpose of this study was to investigate (a) the effects of rubber and plastic concentrations and rubber particle sizes on properties of asphalt cement, (b) on properties of asphalt concrete specimens and (c) the effects of fly ash, marble powder, rubber powder and petroleum contaminated soil as filler materials instead of stone powder in the asphalt concrete specimens. One type of limestone aggregate and one penetration-graded asphalt cement (75-100) were used. Three concentrations of rubber and plastic (i.e. 5%, 10% and 20% of the total weight of asphalt cement), three rubber particle sizes (i.e. No. 4 [4.75mm] - 20 [0.85 mm], No. 20 [0.85mm] - 200 [0.075mm] and No. 4 [4.75mm] - 200 [0.075mm]) and one plastic particle size (i.e. No. 4 [4.75mm] - 10 [2.00mm]) were also used. It was found that while the addition of plastic significantly increased the strength of specimens, the addition of rubber decreased it. No. 4 [4.75mm] - 200 [0.075mm] rubber particles showed the best results with respect to the indirect tensile test. The Marshall stability and indirect tensile strength properties of plastic modified specimens increased. Marble powder and fly ash could be used as filler materials instead of stone powder in the asphalt concrete pavement specimens.

  13. X-ray phase determination of solid paraffins in asphalts

    SciTech Connect

    Biktimirova, T.G.; Aleksandrova, S.L.; Fryazinov, V.V.

    1984-03-01

    This article discusses the attempt to increase the sensitivity of the x-ray phase analysis and to broaden the field of its application in determining the content of paraffins in petroleum asphalts and residual stocks from various raw materials. Samples were prepared by blending technical-grade paraffin wax with a paraffin-free asphalt. The influence of the cooling time on the intensity of the paraffin lines was determined for the various asphalt samples. In order to improve the reproducibility of the line intensity, 1% microcrystalline wax with a known content of paraffins was added to each reference sample. Artificial mixtures of paraffins with model asphalts having various group compositions were prepared in order to determine the influence of the composition of the various asphalts on the intensity of the paraffin reflections under the preparation conditions (heating and cooling). It is established that with increasing takeoff of distillate in the vacuum distillation of atmospheric resids, or in the course of oxidation of residual stocks to produce asphalts, the paraffin content drops. Includes 2 tables.

  14. Application of Common Mid-Point Method to Estimate Asphalt

    NASA Astrophysics Data System (ADS)

    Zhao, Shan; Al-Aadi, Imad

    2015-04-01

    3-D radar is a multi-array stepped-frequency ground penetration radar (GPR) that can measure at a very close sampling interval in both in-line and cross-line directions. Constructing asphalt layers in accordance with specified thicknesses is crucial for pavement structure capacity and pavement performance. Common mid-point method (CMP) is a multi-offset measurement method that can improve the accuracy of the asphalt layer thickness estimation. In this study, the viability of using 3-D radar to predict asphalt concrete pavement thickness with an extended CMP method was investigated. GPR signals were collected on asphalt pavements with various thicknesses. Time domain resolution of the 3-D radar was improved by applying zero-padding technique in the frequency domain. The performance of the 3-D radar was then compared to that of the air-coupled horn antenna. The study concluded that 3-D radar can be used to predict asphalt layer thickness using CMP method accurately when the layer thickness is larger than 0.13m. The lack of time domain resolution of 3-D radar can be solved by frequency zero-padding. Keywords: asphalt pavement thickness, 3-D Radar, stepped-frequency, common mid-point method, zero padding.

  15. Investigation of Primary Causes of Load-Related Cracking in Asphalt Concrete Pavement in North Carolina

    NASA Astrophysics Data System (ADS)

    Park, Hong Joon

    This dissertation presents causes of cracking in asphalt concrete pavement in North Carolina through field investigation and laboratory experiments with field extracted material. North Carolina is experiencing higher than anticipated rates of fatigue cracking compared to other state. These higher than expected rates could be reflective of the national trends in mix design practice or could be caused by structural pavement failures. The problems associated with premature cracking in North Carolina pavements point to the need to evaluate the North Carolina Department of Transportation (NCDOT) mixes, processes, and measures to ensure that these factors properly balance the goals of preventing cracking and minimizing permanent deformation. Without solid data from in-service pavements, any conclusions regarding the causes of these failures might be pure conjecture. Accordingly, this research examines material properties through laboratory experiments using field-extracted materials and investigates in situ pavements and pavement structure. In order to assess condition of existing pavement, alligator cracking index (ACI) was developed. The asphalt content in the top layer that exhibits top-down cracking or bottom-up cracking has a proportional relationship to ACI values. The air void content in a bottom layer that exhibits top-down cracking or bottom-up cracking shows an inverse proportional relationship to ACI values. These observations reflect reasonable results. A comparison between ACI and asphalt film thickness values does not produce noteworthy findings, but somewhat reasonable results are evident once the range of comparison is narrowed down. Thicker film thicknesses show higher ACI values. From field core visual observations, road widening is identified as a major cause of longitudinal cracking. Regions with observed layer interface separation tend to have low ACI values. Through tensile strain simulation based on actual field conditions, it is observed that

  16. Asphalt Volcanism as a Model to Understand the Geochemical Nature of Pitch Lake, a Planetary Analog for Titan and the Implications towards Methane Flux into Earth's Atmosphere.

    NASA Astrophysics Data System (ADS)

    Khan, A.

    2016-12-01

    Pitch Lake is located in the southwest peninsula of the island near La Brea in Trinidad and Tobago, covering an area of approximately 46 hectares. It was discovered in the year 1595 and is the largest of three natural asphalt lakes that exist on Earth. Pitch Lake is a large oval shaped reservoir composed of dominantly hydrocarbon compounds, but also includes minor amounts of clay and muddy water. It is a natural liquid asphalt desert, which is nourished by a form of petroleum consisting of mostly asphaltines from the surrounding oil-rich region. The hydrocarbons mix with mud and gases under high pressure during upward seepage, and the lighter portion evaporates or is volatilized, which produces a high-viscosity liquid asphalt residue. The residue on and near the surface is a hydrocarbon matrix, which poses extremely challenging environmental conditions to microorganisms characterized by an average low water activity in the range of 0.49 to 0.75, recalcitrant carbon substrates, and toxic chemical compounds. Nevertheless, an active microbial community of archaea and bacteria, many of them novel strains, was found to inhabit the liquid hydrocarbon matrix of Pitch Lake. Geochemical analyses of minerals, done by our team, which revealed sulfates, sulfides, silicates, and metals, normally associated with deep-water hydrothermal vents leads to our new hypothetical model to describe the origins of Pitch Lake and its importance to atmospheric and earth sciences. Pitch Lake is likely the terrestrial equivalent of an offshore submarine asphalt volcano just as La Brea Tar Pits are in some ways an on-land version of the asphalt volcanoes discovered off shore of Santa Barbara by Valentine et al. in 2010. Asphalt volcanism possibly also creates the habitat for chemosynthetic life that is widespread in this lake, as reported by Schulze-Makuch et al. in 2011 and Meckenstock et al. in 2014.

  17. Criteria for Asphalt-Rubber Concrete in Civil Airport Pavements. Volume 2. Evaluation of Asphalt-Rubber Concrete.

    DTIC Science & Technology

    1987-03-01

    194 ix LIST OF TABLES Table Page 1 1977 FAA Aggregate Grading Band for Bituminous Surface Course with 1/2" (12.5m) Maximum Particle Size* ...... 6 2...Asphalt Concrete and Asphalt-Rubber Concrete. . . . . . . . . . . . . . . . . . . . . . . . . 106 xi LIST OF FthJiJRf1 Figure Page 1 1977 FAA...were blended to meet the 1977 FAA aggregate grading specification for pavements with a bituminous surface course and designed to accommodate aircraft

  18. Quantitative exposure matrix for asphalt fume, total particulate matter, and respirable crystalline silica among roofing and asphalt manufacturing workers.

    PubMed

    Fayerweather, William E; Trumbore, David C; Johnson, Kathleen A; Niebo, Ronald W; Maxim, L Daniel

    2011-09-01

    This paper summarizes available data on worker exposures to asphalt fume (soluble fraction), total particulate matter, and respirable crystalline silica (quartz) [hereinafter RCS] over a 30-year period in Owens Corning's asphalt production and roofing manufacturing plants. For the period 1977 through 2006, the air-monitoring database contains more than 1,400 personal samples for asphalt fume (soluble fraction), 2,400 personal samples for total particulate, and 1,300 personal samples for RCS. Unique process-job categories were identified for the asphalt production and roofing shingle manufacturing plants. Quantitative exposures were tabulated by agent, process-job, and calendar period to form an exposure matrix for use in subsequent epidemiologic studies of the respiratory health of these workers. Analysis of time trends in exposure data shows substantial and statistically significant exposure reductions for asphalt fume (soluble fraction), total particulate matter, and respirable crystalline silica at Owens Corning plants. Cumulative distribution plots for the most recent sampling period (2001-2006) show that 95% of the asphalt fume (soluble fraction) measurements were less than 0.25 mg/m3; 95% of the total particulate measurements were less than 2.2 mg/m3; and 95% of the RCS measurements were less than 0.05 mg/m3. Several recommendations are offered to improve the design of future monitoring efforts.

  19. 40 CFR 436.60 - Applicability; description of the asphaltic mineral subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... asphaltic mineral subcategory. 436.60 Section 436.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) MINERAL MINING AND PROCESSING POINT SOURCE CATEGORY Asphaltic Mineral Subcategory § 436.60 Applicability; description of the...

  20. 40 CFR 436.60 - Applicability; description of the asphaltic mineral subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... asphaltic mineral subcategory. 436.60 Section 436.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) MINERAL MINING AND PROCESSING POINT SOURCE CATEGORY Asphaltic Mineral Subcategory § 436.60 Applicability; description of the...

  1. 40 CFR 436.60 - Applicability; description of the asphaltic mineral subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... asphaltic mineral subcategory. 436.60 Section 436.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) MINERAL MINING AND PROCESSING POINT SOURCE CATEGORY Asphaltic Mineral Subcategory § 436.60 Applicability; description of the...

  2. 40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... FOR EXISTING SOURCES AND STANDARDS OF PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt...

  3. Hot Groups.

    ERIC Educational Resources Information Center

    Vail, Kathleen

    1996-01-01

    Collaborators sparked by creative ideas and obsessed by a common task may not realize they're part of a "hot group"--a term coined by business professors Harold J. Leavitt and Jean Lipman-Blumen. Spawned by group decision making and employee empowerment, hot groups can flourish in education settings. They're typically small, short lived,…

  4. Elucidation and visualization of solid-state transformation and mixing in a pharmaceutical mini hot melt extrusion process using in-line Raman spectroscopy.

    PubMed

    Van Renterghem, Jeroen; Kumar, Ashish; Vervaet, Chris; Remon, Jean Paul; Nopens, Ingmar; Vander Heyden, Yvan; De Beer, Thomas

    2017-01-30

    Mixing of raw materials (drug+polymer) in the investigated mini pharma melt extruder is achieved by using co-rotating conical twin screws and an internal recirculation channel. In-line Raman spectroscopy was implemented in the barrels, allowing monitoring of the melt during processing. The aim of this study was twofold: to investigate (I) the influence of key process parameters (screw speed - barrel temperature) upon the product solid-state transformation during processing of a sustained release formulation in recirculation mode; (II) the influence of process parameters (screw speed - barrel temperature - recirculation time) upon mixing of a crystalline drug (tracer) in an amorphous polymer carrier by means of residence time distribution (RTD) measurements. The results indicated a faster mixing endpoint with increasing screw speed. Processing a high drug load formulation above the drug melting temperature resulted in the production of amorphous drug whereas processing below the drug melting point produced solid dispersions with partially amorphous/crystalline drug. Furthermore, increasing the screw speed resulted in lower drug crystallinity of the solid dispersion. RTD measurements elucidated the improved mixing capacity when using the recirculation channel. In-line Raman spectroscopy has shown to be an adequate PAT-tool for product solid-state monitoring and elucidation of the mixing behavior during processing in a mini extruder. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Exposure, lung function decline and systemic inflammatory response in asphalt workers.

    PubMed

    Ulvestad, Bente; Randem, Britt Grethe; Hetland, Siri; Sigurdardottir, Gudmunda; Johannessen, Egil; Lyberg, Torstein

    2007-04-01

    The aim of this study was to determine the association between exposures in asphalt work and changes in lung function, blood concentrations of interleukin-6 (IL-6), micro-C-reactive protein, and fibrinogen among asphalt workers during a work season. Blood samples from all asphalt workers (N=140) in Norway's largest road construction and maintenance company were taken in April-May 2005 and again in September-October 2005. Spirometric tests of the asphalt workers and a reference group (heavy construction workers, N=126) were carried out before the asphalt season, and the asphalt workers were tested again at the end of the season. Exposure to total dust, oil mist, polycyclic aromatic hydrocarbons, and gases was measured by personal samplers during the asphalt season. The asphalt workers had a significantly a lower forced expiratory volume in 1 second (FEV(1)) and forced expiratory flow rate of 50% of the forced vital capacity than the reference group at the beginning of the season. The asphalt workers were divided according to their exposure into two groups, asphalt pavers (N=81) and asphalt plant operators and truck drivers (N=54). The screedmen, a group of the asphalt pavers, had a statistically significant lower FVC and FEV(1) after one season of asphalt work than all of the other asphalt workers (P<0.05). The mean plasma concentration of IL-6 increased among the asphalt pavers from 1.55 pg/ml before the season to 2.67 pg/ml at the season's end (P=0.04, adjusted for current smoking). Exposure in asphalt paving may enhance the risk of lung function decline.

  6. Design of open graded friction courses with sulfur extended asphalt binders

    NASA Astrophysics Data System (ADS)

    Saylak, D.; Ho, K. K.; Gallaway, B. M.; Little, D. N.

    1982-09-01

    The combination of the anticipated shortage of asphalt cement and the projected abundance of sulfur has led to the investigation of the potential for substituting this element for the former in the paving industry. Sulfur was incorporated with asphalt to form sulfur-extended asphalt (SEA) binders for use in open graded friction course mixtures. The experimental design variable included aggregated type, asphalt cement, level of sulfur contents in the binder and method of preparing SEA binders.

  7. 40 CFR Table 2 of Subpart Aaaaaaa... - Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Manufacturing (Coating) Operations 2 Table 2 of Subpart AAAAAAA of Part 63 Protection of Environment... Pollutants for Area Sources: Asphalt Processing and Asphalt Roofing Manufacturing Other Requirements and... AAAAAAA of Part 63—Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations For * * *...

  8. 40 CFR Table 2 of Subpart Aaaaaaa... - Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Manufacturing (Coating) Operations 2 Table 2 of Subpart AAAAAAA of Part 63 Protection of Environment... Pollutants for Area Sources: Asphalt Processing and Asphalt Roofing Manufacturing Other Requirements and... AAAAAAA of Part 63—Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations For * * *...

  9. 40 CFR Table 2 of Subpart Aaaaaaa... - Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Manufacturing (Coating) Operations 2 Table 2 of Subpart AAAAAAA of Part 63 Protection of Environment... Pollutants for Area Sources: Asphalt Processing and Asphalt Roofing Manufacturing Other Requirements and... AAAAAAA of Part 63—Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations For * * *...

  10. 40 CFR 436.60 - Applicability; description of the asphaltic mineral subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... asphaltic mineral subcategory. 436.60 Section 436.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS MINERAL MINING AND PROCESSING POINT SOURCE CATEGORY Asphaltic Mineral Subcategory § 436.60 Applicability; description of the asphaltic mineral subcategory....

  11. 40 CFR 436.60 - Applicability; description of the asphaltic mineral subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... asphaltic mineral subcategory. 436.60 Section 436.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS MINERAL MINING AND PROCESSING POINT SOURCE CATEGORY Asphaltic Mineral Subcategory § 436.60 Applicability; description of the asphaltic mineral subcategory....

  12. ASPHALT FOR OFF-STREET PAVING AND PLAY AREAS, 3RD EDITION.

    ERIC Educational Resources Information Center

    Asphalt Inst., College Park, MD.

    THIS PAMPHLET DISCUSSES THE ALTERNATIVE METHODS, APPLICATIONS, AND TECHNICAL CONSIDERATIONS FOR OFF-STREET PAVING AND PLAY AREAS. OFF-STREET PAVING INCLUDES--(1) ASPHALT-PAVED PARKING AREAS, (2) ROOF DECK PARKING AREAS, (3) ASPHALT-PAVED DRIVEWAYS, (4) ASPHALT-PAVED SERVICE STATION LOTS, AND (5) SIDEWALKS. THE DISCUSSION OF PLAY AREAS…

  13. Using the poker-chip test for determining the bulk modulus of asphalt binders

    NASA Astrophysics Data System (ADS)

    Motamed, Arash; Bhasin, Amit; Liechti, Kenneth M.

    2014-02-01

    The properties of asphalt binders strongly influence the overall mechanical response of asphalt mixture composites. A thorough understanding of the mechanistic behavior of asphalt binders is important in order to fully and accurately characterize the behavior of the asphalt mixture. The mechanical properties of the asphalt binder, the matrix in the asphalt mixture composite, are time and temperature dependent and have a lower stiffness compared to the inclusions (aggregate particles). However, computational methods used to model the micromechanics of asphalt mixtures typically assume a constant bulk modulus or Poisson's ratio for asphalt binders. This research investigates the time-dependence of the bulk modulus of asphalt binders. Several approaches for measuring the bulk modulus were explored and the poker-chip geometry was found to be the most suitable one. The boundary value problem for the poker-chip geometry was solved to determine the bulk modulus and Poisson's ratio of asphalt binders as a function of time. The findings from this research improve our understanding of the viscoelastic behavior of asphaltic materials, and also guide important assumptions that are typically made during computational modeling of asphaltic materials.

  14. Research on fracture performance of epoxy asphalt concrete based on double-K fracture criterion

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Qian, Z. D.; Xue, Y. C.

    2017-01-01

    After cracks appear on steel bridge deck epoxy asphalt concrete pavement, cracks propagate fast under vehicle load. This paper studied the fracture performance of epoxy asphalt concrete, utilized single edge notched beam (SEB) three-point bending test, measured the load (P) exerted on epoxy asphalt SEB; utilized digital camera to record the fracture process of epoxy asphalt SEB, extracted the images according to the required sampling frequency and utilized Image-Pro Plus to measure the crack mouth opening displacement (CMOD) of epoxy asphalt SEB on the extracted images; calculated the double-K fracture parameters according to the P-CMOD curve. Results indicate that of epoxy asphalt concrete is 1.11 MPa and of epoxy asphalt concrete is 2.31 MPa at -15°C of epoxy asphalt concrete is 1.02 MPa and of epoxy asphalt concrete is 1.83 MPa at -5°C of epoxy asphalt concrete is 0.77 MPa and of epoxy asphalt concrete is 1.82 MPa at 5°C. The double-K fracture parameters of epoxy asphalt concrete increase slightly when the temperature decreases at the scope of -15°C to 5°C. The relation of and is .

  15. On the representative volume element of asphalt concrete at low temperature

    NASA Astrophysics Data System (ADS)

    Marasteanu, Mihai; Cannone Falchetto, Augusto; Velasquez, Raul; Le, Jia-Liang

    2016-08-01

    The feasibility of characterizing asphalt mixtures' rheological and failure properties at low temperatures by means of the Bending Beam Rheometer (BBR) is investigated in this paper. The main issue is the use of thin beams of asphalt mixture in experimental procedures that may not capture the true behavior of the material used to construct an asphalt pavement.

  16. 40 CFR Table 2 of Subpart Aaaaaaa... - Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    .... Coater-only production lines a. Limit PAH emissions to 0.0002 lb/ton of asphalt roofing product...-only production lines a. Limit PAH emissions to 0.0007 lb/ton of asphalt roofing product manufactured... saturator/coater production lines a. Limit PAH emissions to 0.0009 lb/ton of asphalt roofing...

  17. 40 CFR Table 2 of Subpart Aaaaaaa... - Emission Limits for Asphalt Roofing Manufacturing (Coating) Operations

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... Coater-only production lines a. Limit PAH emissions to 0.0002 lb/ton of asphalt roofing product...-only production lines a. Limit PAH emissions to 0.0007 lb/ton of asphalt roofing product manufactured... saturator/coater production lines a. Limit PAH emissions to 0.0009 lb/ton of asphalt roofing...

  18. Asphalt fume exposure levels in North American asphalt production and roofing manufacturing operations.

    PubMed

    Axten, Charles W; Fayerweather, William E; Trumbore, David C; Mueller, Dennis J; Sampson, Arthur F

    2012-01-01

    This study extends by 8 years (1998-2005) a previous survey of asphalt fume exposures within North American asphalt processing and roofing product manufacturing workers. It focuses on characterizing personal, full-shift samples and seeks to address several limitations of the previous survey. Five major roofing manufacturers with established occupational health programs submitted workplace asphalt fume sampling results to a central repository for review and analysis. A certified industrial hygienist-led quality assurance team oversaw the data collection, consolidation, and analysis efforts. The analysis dataset consisted of 1261 personal exposure samples analyzed for total particulate (TP) and benzene soluble fraction (BSF) using existing NIOSH methods. For BSF, the survey's arithmetic (0.25 mg/m(3), SD = 0.62) and geometric (0.12 mg/m(3), GSD = 2.88) means indicate that the industry has sustained the control levels achieved in the late 1980s, early 1990s. Similar results were found for TP. The survey-wide summary statistics are consistent with other post-1990 multi-company exposure studies. Although these findings indicate that currently available controls are capable of achieving substantial (95%) compliance with the current threshold limit value in asphalt processing and inorganic shingle and roll plants, they also show that the majority of plants are not achieving this level of exposure control, and that exposures are significantly higher in plants making other product lines, particularly organic felt products. The current retrospective survey of existing company exposure data, like its predecessor, has several important limitations. These include lack of data on smaller manufacturers and on several commercially important product lines; insufficient information on the prevalence and effectiveness of engineering controls; no standard criteria by which to define and assess exposures in non-routine operations; and a paucity of exposure data collected as part of a

  19. Asphalt mounds and associated biota on the Angolan margin

    NASA Astrophysics Data System (ADS)

    Jones, Daniel O. B.; Walls, Anne; Clare, Michael; Fiske, Mike S.; Weiland, Richard J.; O'Brien, Robert; Touzel, Daniel F.

    2014-12-01

    Release of hydrocarbons from sediments is important in increasing habitat heterogeneity on deep ocean margins. Heterogeneity arises from variation in abiotic and biotic conditions, including changes in substratum, geochemistry, fluid flow, biological communities and ecological interactions. The seepage of heavy hydrocarbons to the seafloor is less well studied than most other cold seep systems and may lead to the formation of asphalt mounds. These have been described from several regions, particularly the Gulf of Mexico. Here, we describe the structure, potential formation and biology of a large asphalt mound province in Block 31SE Angola. A total of 2254 distinct mound features was identified by side-scan sonar, covering a total area of 3.7 km2 of seafloor. The asphalt mounds took a number of forms from small (<0.5 m diameter; 13% observations) mounds to large extensive (<50 m diameter) structures. Some of the observed mounds were associated with authigenic carbonate and active seepage (living chemosynthetic fauna present in addition to the asphalt). The asphalt mounds are seabed accumulations of heavy hydrocarbons formed from subsurface migration and fractionation of reservoir hydrocarbons primarily through a network of faults. In Angola these processes are controlled by subsurface movement of salt structures. The asphalt mounds were typically densely covered with epifauna (74.5% of mounds imaged had visible epifauna) although individual mounds varied considerably in epifaunal coverage. Of the 49 non-chemosynthetic megafaunal taxa observed, 19 taxa were only found on hard substrata (including asphalt mounds), 2 fish species inhabited the asphalt mounds preferentially and 27 taxa were apparently normal soft-sediment fauna. Antipatharians (3.6±2.3% s.e.) and poriferans (2.6±1.9% s.e.) accounted for the highest mean percentage of the observed cover, with actinarians (0.9±0.4% s.e.) and alcyonaceans (0.4±0.2% s.e.) covering smaller proportions of the area

  20. Laboratory Measurements of Particulate Matter Concentrations from Asphalt Pavement Abrasion

    NASA Astrophysics Data System (ADS)

    Fullová, Daša; Đurčanská, Daniela

    2016-12-01

    The issue of emissions from road traffic is compounded by the fact that the number of vehicles and driven kilometres increase each year. Road traffic is one of the main sources of particulate matter and traffic volume is still increasing and has unpleasant impact on longevity of the pavements and the environment. Vehicle motions cause mechanical wearing of the asphalt pavement surface - wearing course by vehicle tyres. The contribution deals with abrasion of bituminous wearing courses of pavements. The asphalt mixtures of wearing courses are compared in terms of mechanically separated particulate matter. The samples of asphalt mixtures were rutted in wheel tracking machine. The particulate matter measurements were performed in laboratory conditions. The experimental laboratory measurements make it possible to sample particulates without contamination from exhaust emissions, abraded particles from vehicles, resuspension of road dust and climate affects. The contribution offers partial results of measurements on six trial samples of asphalt mixtures with different composition. It presents particulate matter morphology and the comparison of rutted asphalt samples in terms of PM mass concentrations and chemical composition.