Laboratory Evaluation Of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders
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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.
Mechanical Properties Of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders
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Author : Ala R. Abbas
language : en
Publisher:
Release Date : 2011
Mechanical Properties Of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders written by Ala R. Abbas 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 categories.
Hot mix asphalt (HMA) is a mixture containing aggregates and asphalt binders prepared at specified proportions. The aggregates and asphalt binder proportions are determined through a mix design procedure such as the Marshall Mix Design or the Superpave Mix Design methods. Overall, the goal of determining such proportions is to establish an HMA mixture that will meet specific performance criteria. In addition, it is imperative to ensure that the asphalt binder will fully coat the aggregates and that the resulting mixture is workable and compactable. In order to ensure sufficient aggregate drying and coating, both the asphalt binder and the aggregates are heated to elevated temperatures ranging between 300oF and 325oF. The use of such high temperatures would result in lowering the viscosity of the asphalt binder which is the main factor affecting the coating and workability of asphalt mixtures. In recent years, a new group of technologies have been introduced to the United States that allow producing asphalt mixtures at temperatures 30 to 100oF lower than what is used in HMA. This group of technologies is commonly referred to as Warm Mix Asphalt (WMA). They are promoted as environmentally friendly green alternatives to HMA mixtures as they produce lower greenhouse gas emissions. This new group of technologies aims at reducing the viscosity of the asphalt binder through the addition of organic or chemical additives or by introducing cool water into the heated molten asphalt under controlled temperature and pressure conditions, resulting in so-called foamed asphalt binder. As a consequence, lower temperatures are needed during production for the asphalt binder to be absorbed by the aggregates.
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.
Performance Evaluation Of Foamed Warm Mix Asphalt Produced By Water Injection
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Author : Ayman Ali
language : en
Publisher:
Release Date : 2013
Performance Evaluation Of Foamed Warm Mix Asphalt Produced By Water Injection written by Ayman Ali 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 recent years, a new group of technologies has been introduced in the United States that allow producing asphalt mixtures at temperatures 30 to 100oF lower than what is used in traditional hot mix asphalt (HMA). These technologies are commonly referred to as Warm Mix Asphalt (WMA). From among these technologies, foamed WMA produced by water injection has gained increased attention from the asphalt paving industry in Ohio since it does not require the use of costly additives. This type of asphalt mixtures is advertised as an environmentally friendly alternative to traditional HMA and promoted to have better workability and compactability. In spite of these advantages, several concerns have been raised regarding the performance of foamed WMA because of the reduced production temperature and its impact on aggregate drying and asphalt binder aging. Main concerns include increased propensity for moisture-induced damage (durability) and increased susceptibility to permanent deformation (rutting). Other concerns include insufficient coating of coarse aggregates, and applicability of HMA mix design procedures to foamed WMA mixtures. This dissertation presents the results of a comprehensive study 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 Accelerated Pavement Load Facility (APLF) at Ohio University, 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). Based on the experimental test results and the subsequent analyses findings, the following are the main conclusions made: In general, comparable laboratory test results were obtained for foamed WMA and HMA mixtures prepared using 30°F (16.7°C) temperature reduction, 1.8% foaming water content, and fully dried aggregates. Therefore, the performance of the resulting foamed WMA is expected to be similar to that of the HMA. Surface foamed WMA mixtures had comparable rutting performance in the APLF to that of the HMA mixtures. This was also the case for intermediate foamed WMA and HMA mixtures. These results indicate the field performance of the foamed WMA mixtures is similar to that of the HMA mixtures.
Determining The Limitations Of Warm Mix Asphalt By Water Injection In Mix Design Quality Control And Placement
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Author : Ala R. Abbas
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 Ala R. Abbas 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.
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
Special Mixture Design Considerations And Methods For Warm Mix Asphalt
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Author :
language : en
Publisher: Transportation Research Board
Release Date : 2012
Special Mixture Design Considerations And Methods For Warm Mix Asphalt written by and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Science categories.
TRB's National Cooperative Highway Research Program (NCHRP) Report 714: Special Mixture Design Considerations and Methods for Warm-Mix Asphalt: A Supplement to NCHRP Report 673: A Manual for Design of Hot-Mix Asphalt with Commentary presents special mixture design considerations and methods used with warm-mix asphalt. NCHRP Report 714 is a supplement to NCHRP Report 673: A Manual for Design of Hot-Mix Asphalt. All references to chapters in NCHRP Report 714 refer to the corresponding chapters in NCHRP Report 673.
Properties Of Foamed Asphalt For Warm Mix Asphalt Applications
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Author : David E. Newcomb
language : en
Publisher:
Release Date : 2015
Properties Of Foamed Asphalt For Warm Mix Asphalt Applications written by David E. Newcomb and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Asphalt concrete categories.
"TRB's National Cooperative Highway Research Program (NCHRP) Report 807: Properties of Foamed Asphalt for Warm Mix Asphalt Applications presents methods for measuring the performance-related properties of foamed asphalts and designing foamed asphalt mixes with satisfactory aggregate coating and workability." --
Short Term Laboratory Conditioning Of Asphalt Mixtures
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Author : David Newcomb
language : en
Publisher:
Release Date : 2015
Short Term Laboratory Conditioning Of Asphalt Mixtures written by David Newcomb and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Asphalt categories.
This report develops procedures and associated criteria for laboratory conditioning of asphalt mixtures to simulate short-term aging. The report presents proposed changes to the American Association of State Highway and Transportation Officials (AASHTO) R 30, Mixture Conditioning of Hot-Mix Asphalt (HMA), and a proposed AASHTO practice for conducting plant aging studies. The report will be of immediate interest to materials engineers in state highway agencies and the construction industry with responsibility for design and production of hot and warm mix asphalt.