Evaluating The Performance Of The Asphalt Mixes Containing Reclaimed Asphalt Pavement By Considering The Effect Of Silo Storage Time
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Evaluating The Performance Of The Asphalt Mixes Containing Reclaimed Asphalt Pavement By Considering The Effect Of Silo Storage Time
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Author : Hawraa Kadhim
language : en
Publisher:
Release Date : 2020
Evaluating The Performance Of The Asphalt Mixes Containing Reclaimed Asphalt Pavement By Considering The Effect Of Silo Storage Time written by Hawraa Kadhim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Asphalt pavements categories.
The use of reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) has been increasing in the last few decades because of its cost benefits and because of a compelling need to preserve the environment and natural resources. It is commonly assumed that HMA containing RAP (HMA-RAP) has an improved resistance to permanent deformation (rutting) and decreased resistance to the fatigue cracking. This is due to the fact that asphalt binder contained in the RAP has been oxidized over the years and is typically stiffer than virgin asphalt binder. However, during the production stage of the HMA-RAP, the blending between aged and virgin asphalt binders would be incomplete or partial, which would lead to heterogeneous distribution of the aged and virgin asphalt binders within the asphalt mix with RAP. Therefore, the purpose of this article is to evaluate the effect of silo storage on the blending mechanism between virgin and RAP asphalt binders and the impact that this would have on performance of the mix. Two plant-produced asphalt mixes (HL-3 and HL-8), typically used in the province of Ontario for surface and base courses in flexible pavements, were considered in this study. The mixes were designed with 15 and 30 % RAP, respectively, and the samples were collected immediately after the production (0 h) or at different silo storage times (1, 4, 8, and 12 h). The temperatures of the collected materials were closely monitored and recorded. The findings of this research indicated that silo-stored samples exhibited some improvement in their rutting and fatigue resistance. The examination of the dynamic modulus master curves indicated that the rheology of the mixes evolved with silo storage and that blending between the aged and the virgin binders has been improved.
Improving Durability Of Asphalt Mixes Produced With Reclaimed Asphalt Pavement Rap By Enhancing Binder Blending
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Author : Hawraa Kadhim
language : en
Publisher:
Release Date : 2019
Improving Durability Of Asphalt Mixes Produced With Reclaimed Asphalt Pavement Rap By Enhancing Binder Blending written by Hawraa Kadhim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Asphalt concrete categories.
Reclaimed Asphalt Pavement (RAP) has been favoured over virgin materials in the light of the unstable cost of virgin asphalt binders, shortage of quality aggregates, and compelling need to preserve the environment and natural resources. Mixes containing up to 20% RAP are commonly considered to have similar behaviour to virgin mixes. However, during the production process of HMA with RAP, the blending between aged and virgin binders would be partial, which would create heterogeneity in distribution of the aged recycled binder and the soft virgin binder in the HMA-RAP mixes. Hence, it is important to control the blending process between old and new binders to obtain more homogenous mix. Therefore, the main objectives of this research are to examine the kinematics of blending of aged and virgin binders by considering the time-temperature effect during mixing and silo-storage, and assess the thermo-mechanical behaviour of Hot Mix Asphalt (HMA) containing RAP at different blending states. The asphalt mixes used in this research were produced and collected at two plants (Plant 1) and (Plant 2) located in Ontario, Canada. Two Marshall mixes were produced and collected from Plant 1 including a surface course HL-3 containing 15 percent RAP and a base course HL-8 containing 30 percent RAP. These mixes were labelled as 1HL-3 and 1HL-8 respectively. In addition, two Marshall mixes were produced and collected from Plant 2 including a surface course HL-3 containing 20 percent RAP and a base course HL-8 containing 40 percent RAP. These mixes were labelled as 2HL-3 and 2HL-8 respectively. To investigate the impact of storage time on the blending progress and achieving a cohesive final binder, the mix samples were collected as a function of storage time in the silo. The first sampling was done immediately after production (t = 0-hour), and then at several time intervals of silo-storage; i.e., at 1, 4, 8, and 12 hours. In case of Plant 2, the samples were additionally collected after 24-hour of storage time. All samples were then kept in a storage room at 7ʻC until the day of compaction to minimize any further blending between aged and virgin binder. To understand the blending phenomena and its effect on the performance of the pavement, a multi-scale investigation is carried out. The blending was examined in terms of micro-mechanical and rheological properties. The microstructure of the blending zones were examined under The Environmental Scanning Electron Microscope (ESEM). In addition the effect of the silo-storage time on the rheology of the binders was investigated. The results indicate that increasing the interaction time and temperature between the aged and virgin binder significantly results in a better blending. The performance of RAP-HMA with respect to the silo-storage time was examined using Dynamic Modules Test, Thermal Stress Restrained Specimen Test (TSRST), Rutting Test, and Flexural Beam Fatigue Test. The experimental data indicates that samples collected after 12-hour of silo storage exhibited a reduction in the stiffness due to better blending of aged and virgin binder. In addition, the 12-hour samples showed enhancement in their fracture temperature, rutting depth, and fatigue life, accompanied with a better blending between their aged and virgin binder. On the other hand, the samples that collected after 24-hour silo-storage had a higher stiffness in comparison with the 8 and 12-hour samples. Moreover, the AASHTOWare Pavement Mechanistic-Empirical Design was utilized to examine the effect of the 12-hour silo-storage time on the long term performance of the pavements. Four pavement structures have been designed for this purpose. These pavements have the same structure of their granular A, granular B, and the subgrade. Yet, the first layer (surface course and base course) is a silo-storage time-dependent. The long-term field performance prediction indicates a slight improvement with the 12-hour pavements (Plant1 12hrs and Plant2 12hrs). However, it should be noted that AASHTOWare Pavement Mechanistic-Empirical Design does not appear to properly capture the effect of blending in the pavement performance. The collected experimental evidences unveils correlations between time-temperature effects and mixture performance. Based on these findings, the research provides practical recommendations to the professionals of the Canadian asphalt industry for a better use of RAP. Ultimately, this research recommends a 12-hour silo-storage time for the RAP-HMA for better performance and durability of the mixes.
Performance Assessment Of Asphalt Mixes Containing Reclaimed Asphalt Pavement And Tire Rubber
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Author : Shawn Shiangfeng Hung
language : en
Publisher:
Release Date : 2018
Performance Assessment Of Asphalt Mixes Containing Reclaimed Asphalt Pavement And Tire Rubber written by Shawn Shiangfeng Hung and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
The pavement community, including both agencies and industries, is moving toward more sustainable pavement designs and pavement network management. Increasing amounts of recycled materials, both reclaimed asphalt pavement (RAP) and recycled tire rubber, are expected to be used in new pavement construction projects in the future to reduce the use of virgin binder and aggregates. The main concern of using recycled materials in new asphalt pavement is the potential negative effect on the performance. Thus, the primary objective of this dissertation is to improve the current laboratory testing technologies and performance assessment approaches for characterizing the performance-related properties of asphalt mixes containing recycled materials and to improve understanding of how these properties affect the performance of asphalt pavements so that they can be designed and constructed better. A major challenge regarding the use of high RAP content mixes is the differences in the rheological properties of the virgin binder (mixes without RAP) and the blended binder (mixes with RAP). Traditionally, binder blending charts are used to determine the appropriate RAP content in asphalt mixes and the selection of virgin binder grade as part of the Superpave volumetric mix design procedures when RAP is incorporated in the mix. However, producing mixes based on blending charts that require testing of extracted and recovered RAP binders is expensive and hazardous. An alternative test approach for binder blending charts using fine aggregate matrix (FAM) mix testing is presented in this dissertation. The results demonstrated that the proposed approach could estimate the blended binder intermediate and low performance grading temperatures within ±3°C of the measured blended binder performance grading temperatures. Even though the proposed approach is not as accurate as the blending chart method (within ±2°C), it provides both cost and environmental benefits. Currently, the Superpave Performance Grading (PG) system cannot not be used to evaluate the performance-related properties of asphalt rubber binders produced using larger crumb rubber particles (maximum particle size passing 2.36 mm sieve) due to the limitations of parallel plate geometry. With the consideration of more open-graded or gap-graded rubberized hot mix asphalt (RHMA-O and RHMA-G) projects in the future, it is important to be able to perform Superpave PG testing on asphalt rubber binder and to establish performance-based contract acceptance criteria for the production of asphalt rubber binders. The test results indicated that the concentric cylinder geometry is an appropriate alternative geometry to parallel plates for quantifying the properties of asphalt rubber binders and specifically for assessing the high-temperature performance properties of binders containing crumb rubber particles larger than 250 [mu]m. Concerns have been raised with regard to incorporating reclaimed rubberized asphalt pavement (RRAP) into dense-graded new hot mix asphalt (HMA-DG) and RAP into new RHMA-G since the interactions between the virgin binder, age-hardened binder, and recycled tire rubber could considerably affect the rutting, fatigue cracking, and thermal cracking performances of new HMA-DG and RHMA-G. The fundamental differences between RAP and RRAP were identified and the performance of new mixes that contain these recycled materials were evaluated in this study. The experimental results showed that adding RRAP to HMA-DG mixes is ideal to resist rutting and low-temperature cracking based on the changes in mix stiffness. The HMA-DG mixes containing RRAP are better at resisting high tensile strain loadings than mixes containing RAP. In addition, adding RAP to RHMA-G mixes improves the rutting performance but diminishes the cracking performance, and potentially negating the benefits of selecting RHMA-G as an overlay to retard the rate of reflection cracking. Lastly, the effects of rest periods on asphalt fatigue performance considering asphalt thixotropy, non-linearity, self-heating, self-cooling, and steric hardening were also investigated in this research. The experimental test results showed that asphalt thixotropic softening and other biasing effects control the first 10 to 15 percent decrease in stiffness for unmodified binders and 15 to 35 percent decrease in stiffness for modified binders under cyclic loading, and this decrease in stiffness can be recovered with the introduction of rest periods. This means that most of the repeated loadings applied to test specimens within the thixotropic softening range do not caused any fatigue damage but only softening of the materials. Thus, by providing sufficient rest periods within the thixotropic softening range can effectively improve asphalt fatigue performance. Both the thixotropic softening range and the required time for thixotropic recovery (i.e., rest periods) need to be considered in asphalt fatigue test and mechanistic-empirical (ME) design for better evaluation of the true fatigue performance.
Evaluating The Effects Of Recycling Agents On Asphalt Mixtures With High Ras And Rap Binder Ratios
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Author : Amy Epps Martin
language : en
Publisher:
Release Date : 2020
Evaluating The Effects Of Recycling Agents On Asphalt Mixtures With High Ras And Rap Binder Ratios written by Amy Epps Martin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Asphalt categories.
"More than 90 percent of highways and roads in the United States are built using hot-mix asphalt (HMA) or warm-mix asphalt (WMA) mixtures, and these mixtures now recycle more than 99 percent of some 76.2 million tons of reclaimed asphalt pavement (RAP) and about 1 million tons of recycled asphalt shingles (RAS) each year. Cost savings in 2017 totaled approximately $2.2 billion with these recycled materials replacing virgin materials. The TRB National Cooperative Highway Research Program's NCHRP Research Report 927: Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios presents an evaluation of how commercially available recycling agents affect the performance of asphalt mixtures incorporating RAP and RAS at high recycled binder ratios."--
Evaluating The Effect Of High Rap Content On Asphalt Mixtures And Binders Fatigue Behavior
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Author : Umme Amina Mannan
language : en
Publisher:
Release Date : 2018
Evaluating The Effect Of High Rap Content On Asphalt Mixtures And Binders Fatigue Behavior written by Umme Amina Mannan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Asphalt categories.
One of the main concerns with the application of reclaimed asphalt pavement (RAP) in the asphalt concrete pavement is fatigue cracking due to the stiffness increase with the addition of aged and stiff RAP binder. The purpose of this study is to evaluate fatigue performance of asphalt binder and mixtures with different RAP percentages (0, 15, 25, 35 and 40 %). Among these, 35 and 40 % RAP mixes are considered as high RAP content. This study describes the results of laboratory fatigue response of asphalt mixtures and extracted binders containing RAP to define the effect of RAP on the fatigue performance. To achieve this objective, mixes and binders were tested using the beam fatigue test and the time-sweep test, respectively. Test results were analyzed using two different fatigue approaches, reduction in stiffness and dissipated energy criteria. Results showed that a higher initial stiffness and initial dissipated energy initiate the fatigue failure faster. Since both binders and mixes show an increase in the stiffness and energy consumed per loading cycle with the addition of RAP, resulting mixes containing higher RAP have a very short fatigue life. Also, the fatigue endurance limit decreases drastically with the addition of RAP in the mix. The results comparing two different RAP sources showed that the RAP source has more prominent effect on the mix fatigue performance than the binder fatigue performance. Finally, the traditional fatigue life prediction model is modified to incorporate the effect of RAP in the fatigue equation. The modified regression model predicted reasonable fatigue life of the mixture with a coefficient of determination (R2) close to 1. The measured and predicted fatigue life results were found close to each other for both mix and binder containing RAP.
Evaluation Of The Effect Of Homogeneity Of The Asphalt Binder On Performance Of A Recycled Mix
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Author :
language : en
Publisher:
Release Date : 2019
Evaluation Of The Effect Of Homogeneity Of The Asphalt Binder On Performance Of A Recycled Mix written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Asphalt categories.
The road to sustainability passes through the process of recycling a greater amount of asphalt pavement. Inclusion of additional amounts of reclaimed asphalt pavement (RAP) in new mixes has become a prominent method to promote sustainability. This research addresses some of the challenges related to high RAP content mixes. Among the factors considered are the impact of rejuvenator diffusion on binder stiffness, stiffness gradient, performance grade, homogeneity, and ultimately, their effects on mix performance.
Performance Evaluation Of Warm Mix Asphalt Mixtures Incorporating Reclaimed Asphalt Pavement
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Author : Brian Hill
language : en
Publisher:
Release Date : 2011
Performance Evaluation Of Warm Mix Asphalt Mixtures Incorporating Reclaimed Asphalt Pavement written by Brian Hill and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Sustainability is a cornerstone of today0́9s engineering world. Warm mix asphalt (WMA) and reclaimed asphalt pavement (RAP) are the most prominent sustainable materials in asphalt concrete pavements. WMA is a not a new concept, however new innovations and increased usage of WMA has been spurred by the increased focus on sustainable infrastructure systems. WMA enables reduced production temperatures through the use of wax, water, or other chemical packages. The effects of reduced production temperatures include fuel use and emissions reductions, improved compaction, and possible RAP concentration increases. RAP is the primary recycled product of the aged asphalt concrete pavements and its use leads to reductions in virgin aggregate and asphalt demand. However, significant performance issues can stem from the individual integration of WMA or RAP materials in asphalt concrete. In particular, WMA technologies can increase moisture and rutting susceptibility while RAP significantly increases the stiffness of the resulting mixture. Consequently, quality performance of sustainable asphalt pavements may require the combined use of WMA and RAP to produce mixtures with sufficient stiffness and moisture and fracture resistance. This study evaluates the potential of WMA technologies and their integration with RAP. Initially, an extensive literature review was completed to understand the advantages, disadvantages, and past field and lab performance of WMA and RAP mixtures. Rotational viscometer and bending beam rheometer tests were then used to evaluate Sasobit, Evotherm M1, and Advera WMA modified and unmodified binders. Finally, virgin and 45% RAP mixtures were designed and tested to examine the rutting, moisture, and fracture resistance of WMA and HMA mixtures. The results of this experiment provided several key observations. First, viscosity reductions may not be the primary cause for the availability of reduced production temperatures for WMA technologies. Second, WMA additive properties have a significant effect upon fracture, moisture, and rutting resistance. Furthermore, the addition of RAP to WMA mixtures improved the rutting and moisture sensitivity performance as characterized in the Hamburg and Tensile Strength Ratio testing procedures.
Laboratory Evaluation Of Asphalt Concrete Mixtures Containing High Contents Of Reclaimed Asphalt Pavement Rap And Binder
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Author :
language : en
Publisher:
Release Date : 2014
Laboratory Evaluation Of Asphalt Concrete Mixtures Containing High Contents Of Reclaimed Asphalt Pavement Rap And Binder written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Asphalt categories.
This study investigated the effect of added asphalt binder content on the performance and volumetric properties of asphalt concrete mixtures containing reclaimed asphalt pavement (RAP) in the amounts of 0%, 20%, and 40%. A laboratory-produced mixture containing 100% RAP was also evaluated. Performance of the mixtures was evaluated based on three criteria: stiffness (dynamic modulus), fatigue resistance, and rutting resistance (flow number and asphalt pavement analyzer). Results showed that a 0.5% increase in binder content improved both the fatigue and rutting resistance of the 0% and 20% RAP mixtures with only slight (insignificant) decreases in dynamic modulus. However, the addition of various amounts of binder to the 40% RAP mixture led to a significant decrease in rutting resistance with little or no improvement to fatigue resistance. Volumetric analysis was performed on all of the mixtures, and detailed results are presented. Based on the results of the study, the authors recommend that the Virginia Department of Transportation supplement current asphalt mixture design procedures that are based on mixture volumetric properties with laboratory-mixture performance testing.
Long Term Effectiveness Of Recycling Agents To Improve Performance Properties Of Asphalt Concrete
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Author : Mahsa Tofighian
language : en
Publisher:
Release Date : 2023
Long Term Effectiveness Of Recycling Agents To Improve Performance Properties Of Asphalt Concrete written by Mahsa Tofighian and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
Recycled materials such as reclaimed asphalt pavement (RAP) have been incorporated into asphalt mixtures for many years. However, their usage has increased over time as they are seen as a way to reduce the cost of asphalt mixtures, save energy, and protect the environment. Similarly, there has been a growing focus on the utilization of recycled asphalt shingles (RAS) in asphalt mixtures, a pursuit undertaken by various state highway agencies. However, unless appropriate precautions are taken, as the proportion of RAP and RAS in the asphalt mixture is raised, the mixture becomes more brittle, leading to a higher risk of cracking and raveling in the asphalt pavement. Furthermore, the mixture becomes less workable and more challenging to compact in the field, increasing the potential for premature field failure. One strategy to incorporate more RAP and RAS into asphalt mixtures involves the use of specialized recycling agents (RAs), known as rejuvenating agents. Over time, asphalt mixtures undergo aging during construction and over the extended service life of asphalt pavements, resulting in the oxidation of the mix and the loss of a significant portion of the maltenes in the binder composition. Maltenes contribute to the softening effect of the binder, and these recycling agents, when used appropriately, are expected to compensate for this reduction in maltenes. The ultimate result of this rebalancing of components is the softening of the aged binder and an improvement in its resistance to cracking. This study investigates the long-term impact of bio-based and petroleum-based recycling agents (RA's) on recycled asphalt binders with varying levels of reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) content, specifically low (15%) and high (30%) RAP content and 0% and 5% RAS content. The rejuvenated binders underwent short-term and long-term aging through the use of a Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV), respectively. The performance characteristics of these modified binders at various aging stages were assessed using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The study revealed that all RA's used in this research maintained their effectiveness even after long-term aging, though the degree of effectiveness varied. Additionally, the results indicated that the petroleum-based RA required a higher dosage to achieve the same effect as the bio-based RA's. The findings from this research also demonstrated that when rejuvenators are added to mixtures with a high RAP content or a combination of RAP and RAS, the mixture's performance is enhanced in terms of low-temperature cracking and fatigue cracking. Nevertheless, it is crucial to extend this work to field pilot projects to ensure the effective application of these rejuvenating products.
Evaluation Of The Combined Effects Of Reclaimed Asphalt Pavement Rap Reclaimed Asphalt Shingles Ras And Different Virgin Binder Sources On The Performance Of Blended Binders For Mixes With Higher Percentages Of Rap And Ras
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Author : M. Z. Alavi
language : en
Publisher:
Release Date : 2015
Evaluation Of The Combined Effects Of Reclaimed Asphalt Pavement Rap Reclaimed Asphalt Shingles Ras And Different Virgin Binder Sources On The Performance Of Blended Binders For Mixes With Higher Percentages Of Rap And Ras written by M. Z. Alavi 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.