Laboratory Evaluation Of Warm Mix Asphalt Influence On Theoretical Maximum Specific Gravity
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Laboratory Evaluation Of Warm Mix Asphalt Influence On Theoretical Maximum Specific Gravity
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Author : Jianhua Yu
language : en
Publisher:
Release Date : 2012
Laboratory Evaluation Of Warm Mix Asphalt Influence On Theoretical Maximum Specific Gravity written by Jianhua Yu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Asphalt concrete categories.
Warm mix asphalt (WMA) technology provides sufficient workability for asphalt mixtures at reduced mixing and compaction temperatures. Depending on the WMA technology, the typical temperature reduction range is 20 °C to 55 °C below hot mix asphalt (HMA) production temperatures. WMA involves chemical and wax additives that are added to an asphalt binder or incorporated through the use of foaming technology. The main advantages of WMA are reduced emissions and a reduction in combustible fuel consumption. Ongoing WMA research projects have documented some differences between HMA and WMA mixes, prompting numerous research projects that are investigating these concerns. The purpose of this research is to evaluate the volumetric properties by directly comparing laboratory produced WMA and HMA mixes. This study investigates the impact of WMA additives on the volumetric properties, specifically, the theoretical maximum specific gravity (Gmm). The Gmm testing followed the procedure of ASTM D2041. Two mix designs with HMA binder were produced, one without recycled asphalt pavement (RAP) and the other with 30 % RAP. After the mix designs were completed, no additional changes were made to account for the addition of the WMA technology. The mixes included the WMA technologies Sasobit and Advera, as well as an HMA control, for a total of six different laboratory produced mixes. Each mix was produced at 120 °C, 135 °C, and 150 °C, and each mix was oven cured for 1, 2, and 4 h. The test results were analyzed using statistical principles to determine whether differences in the Gmm values were statistically significant. The results show that temperature has little impact on Gmm. Gmm was not affected by curing times of 1 and 2 h, but the longer curing time of 4 h resulted in a statistically significant increase in Gmm. Further analysis revealed that the mix sensitivity to curing time depends on the amount of RAP in the mix. For the mix designs studied, the Advera Gmm values were similar to the HMA values, but the Sasobit Gmm values were statistically lower than the Advera values.
Laboratory Evaluation Of Warm Mix Asphalt
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Author : Zhanping Yuo
language : en
Publisher:
Release Date : 2011
Laboratory Evaluation Of Warm Mix Asphalt written by Zhanping Yuo and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Asphalt emulsion mixtures categories.
Hot Mix Asphalt (HMA) has been traditionally produced at a discharge temperature of between 280° F (138° C) and 320° F (160° C), resulting in high energy (fuel) costs and generation of greenhouse gases. The goal for Warm Mix Asphalt (WMA) is to use existing HMA plants and specifications to produce quality dense graded mixtures at significantly lower temperatures. Europeans are using WMA technologies that allow the mixture to be placed at temperatures as low as 250° F (121° C). It is reported that energy savings on the order of 30%, with a corresponding reduction in CO2 emissions of 30%, are realized when WMA is used compared to conventional HMA. Although numerous studies have been conducted on WMA, only limited laboratory experiments are available and most of the current WMA laboratory test results are inconsistent and not compatible with field performance The main objectives of this study are: The main objectives of this study are: 1) review and synthesize information on the available WMA technologies; 2) measure the complex/dynamic modulus of WMA and the control mixtures (HMA) for comparison purpose and for use in mechanistic-empirical (ME) design comparison; 3) assess the rutting and fatigue potential of WMA mixtures; and 4) provide recommendation for the proper WMA for use in Michigan considering the aggregate, binder, and climatic factors. The testing results indicated that most of the WMA has higher fatigue life and TSR which indicated WMA has better fatigue cracking and moisture damage resistant; however, the rutting potential of most of the WMA tested were higher than the control HMA. In addition, the WMA design framework was developed based on the testing results, and presented in this study to allow contractors and state agencies to successfully design WMA around the state of Michigan.
Laboratory Evaluation Of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders
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Author : Ayman W. Ali
language : en
Publisher:
Release Date : 2010
Laboratory Evaluation Of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders written by Ayman W. Ali and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Asphalt categories.
Warm Mix Asphalt (WMA) is a name given to different technologies that have the common purpose of reducing the viscosity of the asphalt binders. This reduction in viscosity offers the advantage of producing asphalt-aggregate mixtures at lower mixing and compaction temperatures, and subsequently reducing energy consumption and pollutant emissions during asphalt mix production and placement. WMA technologies can be classified into two groups. The first group reduces the asphalt binders' viscosity through the addition of organic or chemical additives, while the second group reduces the viscosity of the asphalt binders through the addition of water. The latter has received increased attention in Ohio since it does not require the use of costly additives. In spite of the above-mentioned advantages for WMA mixtures, many concerns have been raised regarding the susceptibility of this material to moisture-induced damage and permanent deformation due to the reduced temperature level used during WMA production. Therefore, this study was conducted to develop a laboratory procedure to produce WMA mixtures prepared using foamed asphalt binders (WMA-FA), and to evaluate their performance in comparison to conventional Hot Mix Asphalt (HMA). This study involved two types of aggregates (natural gravel and crushed limestone) and two types of asphalt binders (PG 64-22 and PG 70-22M). A laboratory scale asphalt binder foaming device called WLB10, produced by Wirtgen, Inc., was used to foam the asphalt binders. The aggregate gradation met the Ohio Department of Transportation (ODOT) Construction and Materials Specification (C&MS) requirements for Item 441 Type 1 Surface Course for Medium Traffic. The resistance of WMA-FA and HMA mixtures to moisture-induced damage was measured using AASHTO T-283, and the resistance to permanent deformation was measured using the Asphalt Pavement Analyzer (APA) and the Simple Performance Test (SPT). Based on the experimental test results and the subsequent analyses findings, the following conclusions were made: [1] WMA-FA mixtures are more workable and easily compacted than HMA mixtures even though they are produced at lower mixing and compaction temperatures; [2] WMA-FA mixtures are slightly more susceptible to moisture damage than HMA mixtures. However, the difference is statistically insignificant. Therefore, if designed properly, both mixtures are expected to meet ODOT's minimum TSR requirement for the proposed traffic level; [3] WMA-FA mixtures, especially those prepared using gravel aggregates and unmodified asphalt binders are more prone to rutting than the corresponding HMA mixtures. Therefore, it is recommended to include the APA test as part of the WMA mix design procedure to ensure satisfactory performance for rutting.
Evaluation Of Warm Mix Asphalt Versus Conventional Hot Mix Asphalt For Field And Laboratory Compacted Specimens
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Author : Abdulaziz Alossta
language : en
Publisher:
Release Date : 2011
Evaluation Of Warm Mix Asphalt Versus Conventional Hot Mix Asphalt For Field And Laboratory Compacted Specimens written by Abdulaziz Alossta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Asphalt concrete categories.
A recent joint study by Arizona State University and the Arizona Department of Transportation (ADOT) was conducted to evaluate certain Warm Mix Asphalt (WMA) properties in the laboratory. WMA material was taken from an actual ADOT project that involved two WMA sections. The first section used a foamed-based WMA admixture, and the second section used a chemical-based WMA admixture. The rest of the project included control hot mix asphalt (HMA) mixture. The evaluation included testing of field-core specimens and laboratory compacted specimens. The laboratory specimens were compacted at two different temperatures; 270 °F (132 °C) and 310 °F (154 °C). The experimental plan included four laboratory tests: the dynamic modulus (E*), indirect tensile strength (IDT), moisture damage evaluation using AASHTO T-283 test, and the Hamburg Wheel-track Test. The dynamic modulus E* results of the field cores at 70 °F showed similar E* values for control HMA and foaming-based WMA mixtures; the E* values of the chemical-based WMA mixture were relatively higher. IDT test results of the field cores had comparable finding as the E* results. For the laboratory compacted specimens, both E* and IDT results indicated that decreasing the compaction temperatures from 310 °F to 270 °F did not have any negative effect on the material strength for both WMA mixtures; while the control HMA strength was affected to some extent. It was noticed that E* and IDT results of the chemical-based WMA field cores were high; however, the laboratory compacted specimens results didn't show the same tendency. The moisture sensitivity findings from TSR test disagreed with those of Hamburg test; while TSR results indicated relatively low values of about 60% for all three mixtures, Hamburg test results were quite excellent. In general, the results of this study indicated that both WMA mixes can be best evaluated through field compacted mixes/cores; the results of the laboratory compacted specimens were helpful to a certain extent. The dynamic moduli for the field-core specimens were higher than for those compacted in the laboratory. The moisture damage findings indicated that more investigations are needed to evaluate moisture damage susceptibility in field.
Issues In Teaching And Education Policy Research And Special Topics 2013 Edition
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Author :
language : en
Publisher: ScholarlyEditions
Release Date : 2013-05-01
Issues In Teaching And Education Policy Research And Special Topics 2013 Edition written by and has been published by ScholarlyEditions this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-05-01 with Education categories.
Issues in Teaching and Education Policy, Research, and Special Topics: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Education Testing and Evaluation. The editors have built Issues in Teaching and Education Policy, Research, and Special Topics: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Education Testing and Evaluation in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Teaching and Education Policy, Research, and Special Topics: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Evaluation Of Warm Mix Additives For Use In Modified Asphalt Mixtures
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Author : Corina Borroel Wong
language : en
Publisher:
Release Date : 2011
Evaluation Of Warm Mix Additives For Use In Modified Asphalt Mixtures written by Corina Borroel Wong and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Thesis categories.
The intention of this research effort is to evaluate the use of warm mix additives with typical polymer-modified and terminal blend tire rubber asphalt mixtures from Nevada and California. The research effort is broken into three phases that are intended to evaluate the impacts of warm mix additives with typical polymer-modified and terminal blend tire rubber asphalt mixtures from Nevada and California: moisture damage, performance characteristics, and mechanistic analysis. In Phase I of this research effort, mixture resistance to moisture damage was evaluated using the indirect tensile test and the dynamic modulus at multiple freeze-thaw cycles. Laboratory testing was conducted to address the following: (1) the impact of warm mix additive and reduced production temperatures on the moisture damage resistance of asphalt mixtures, (2) the impact of residual aggregate moisture on the moisture damage resistance of WMA mixtures, (3) the impact of warm mix additives on the moisture damage resistance of anti-strip treated WMA mixtures, and (3) the impact of long-term aging on strength gain and the moisture damage resistance of WMA mixtures. A total of one aggregate source, four warm mix asphalt technologies (Advera, Sasobit, Revix and Foaming) and three asphalt binder types (neat, polymer-modified and terminal blend tire rubber modified asphalt binders) typically used in both Nevada and California are being evaluated in this study. This thesis will only summarize the test results and findings of the Phase I of the study for two warm-mix additives: Advera and Sasobit. The evaluation of the other two technologies (i.e. Revix and Foaming) as well as the Phase II testing are still in progress and have not been completed.
Determining The Limitations Of Warm Mix Asphalt By Water Injection In Mix Design Quality Control And Placement
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Author :
language : en
Publisher:
Release Date : 2013
Determining The Limitations Of Warm Mix Asphalt By Water Injection In Mix Design Quality Control And Placement written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Asphalt categories.
In this project, a comprehensive study was conducted to evaluate the laboratory performance of foamed WMA mixtures with regard to permanent deformation, moisture-induced damage, fatigue cracking, and low-temperature (thermal) cracking; and compare it to traditional HMA. In addition, the workability of foamed WMA and HMA mixtures was evaluated using a new device that was designed and fabricated at the University of Akron, and the compactability of both mixtures was examined by analyzing compaction data collected using the Superpave gyratory compactor. The effect of the temperature reduction, foaming water content, and aggregate moisture content on the performance of foamed WMA was also investigated. Furthermore, the rutting performance of plant-produced foamed WMA and HMA mixtures was evaluated in the Ohio University (OU) Accelerated Pavement Load Facility (APLF), and the long-term performance of pavement structures constructed using foamed WMA and HMA surface and intermediate courses was analyzed using the Mechanistic-Empirical Pavement Design Guide (MEPDG). The laboratory test results revealed comparable resistance to permanent deformation, moisture-induced damage, and fatigue cracking for foamed WMA and HMA mixtures. However, the HMA mixtures had significantly higher ITS values at 14°F ( -10°C) and comparable failure strains to the foamed WMA mixtures, which indicates that the traditional HMA mixtures have better resistance to low-temperature (thermal) cracking. The laboratory tests conducted to evaluate the effect of the temperature reduction, foaming water content, and aggregate moisture content revealed that the performance of foamed WMA mixtures prepared using 30°F (16.7°C) temperature reduction, 1.8% foaming water content, and fully dried aggregates was comparable to that of the HMA mixtures. However, reducing the production temperature of foamed WMA resulted in increased susceptibility to permanent deformation and moisture-induced damage. In addition, producing foamed WMA using moist aggregates resulted in inadequate aggregate coating leading to concerns with regard to long-term durability. Increasing the foaming water content (up to 2.6% of the weight of the asphalt binder) did not seem to have a negative effect on the rutting performance or moisture sensitivity of the foamed WMA. The rut depth measurements obtained at the OU APLF confirmed the laboratory APA test results. It was found through these tests that the foamed WMA mixtures have comparable rutting resistance to the HMA mixtures. Finally, the long-term pavement performance predictions obtained using the MEPDG showed comparable service lives for pavement structures constructed using foamed WMA and HMA surface and intermediate mixtures.
Evaluation Of Laboratory Conditioning Protocols For Warm Mix Asphalt
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Author : Fan Yin
language : en
Publisher:
Release Date : 2013
Evaluation Of Laboratory Conditioning Protocols For Warm Mix Asphalt written by Fan Yin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Warm-Mix Asphalt (WMA) refers to the asphalt concrete paving material produced and placed at temperatures approximately 50°F lower than those used for Hot-Mix Asphalt (HMA). Economic, environmental and engineering benefits have boosted the use of WMA technology across the world during the past decade. While WMA technology has been successfully utilized as a paving material, several specifications and mix design protocols remain under development. For example, currently, there is no consistent laboratory conditioning procedure for preparing WMA specimens for performance tests, despite being essential for mix performance. Based on previous studies, several candidate conditioning protocols for WMA Laboratory Mixed Laboratory Compacted (LMLC) and off-site Plant Mixed Laboratory Compacted (PMLC) specimens were selected, and their effects on mixture properties were evaluated. Mixture stiffness evaluated in a dry condition using the Resilient Modulus (MR) test (ASTM D-7369) was the main parameter used to select a conditioning protocol to simulate pavement stiffness in its early life. The number of Superpave Gyratory Compactor (SGC) gyrations to get 7±0.5% air voids (AV) was the alternative parameter. Extracted binder stiffness and aggregate orientation of field cores and on-site PMLC specimens were evaluated using the Dynamic Shear Rheometer (DSR) (AASHTO T315) and image analysis techniques, respectively. In addition, mixture stiffness in a wet condition was evaluated using the Hamburg Wheel-Track Test (HWTT) (AASHTO T324) stripping inflection point (SIP) and rutting depth at a certain number of passes. Several conclusions are made based on test results. LMLC specimens conditioned for 2 hours at 240°F (116°C) for WMA and 275°F (135°C) for HMA had similar stiffnesses as cores collected during the early life of field pavements. For off-site PMLC specimens, different conditioning protocols are recommended to simulate stiffnesses of on-site PMLC specimens: reheat to 240°F (116°C) for WMA with additives and reheat to 275°F (135°C) for HMA and foamed WMA. Additionally, binder stiffness, aggregate orientation, and overall AV had significant effects on mixture stiffness. Mixture stiffness results for PMFC cores and on-site PMLC specimens in a wet condition as indicated by HWTT agree with those in a dry condition in MR testing. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148143
Evaluation Of Warm Mix Asphalt Technology In Flexible Pavements
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Author : Louay Mohammad
language : en
Publisher:
Release Date : 2018
Evaluation Of Warm Mix Asphalt Technology In Flexible Pavements written by Louay Mohammad and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Civil engineering categories.
Evaluation Of Engineering Properties Of Rubberized Laboratory Mixes Containing Warm Mix Additives
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Author : Chandra K. Akisetty
language : en
Publisher:
Release Date : 2010
Evaluation Of Engineering Properties Of Rubberized Laboratory Mixes Containing Warm Mix Additives written by Chandra K. Akisetty and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Crumb rubber categories.
Warm mix asphalt (WMA) refers to technologies which allow a significant reduction of mixing and compaction temperatures of asphalt mixes. From previous studies, it is observed that warm mix additives work in different ways, either in reducing the viscosity of the asphalt binder or allowing better workability of the asphalt mix at lower temperatures through volume expansion in the binder. If the technologies of WMA are incorporated into rubberized asphalt mixes, which are generally produced and compacted at higher temperature than conventional mixes, it is possible to reduce the mixing and compaction temperatures of rubberized mixes to those of conventional mixes. This paper presents a limited study that characterizes the engineering properties of crumb rubber modifier (CRM) mixtures containing warm mix additives. Six CRM mixtures (two of control mixtures and four of warm mixtures) were prepared using two aggregate sources and two additives: Aspha-min® and Sasobit®. Evaluation of all mixtures included the following testing procedures: tensile strength ratio, asphalt pavement analyzer, resilient modulus, and resilient modulus after long-term oven aging. The results from this study showed that in general, there was no significant difference between the control and warm CRM mixtures for the properties evaluated in this study, indicating that the use of WMA technologies into CRM mixes is expected to have no negative effect on the mixture's engineering properties.