Determination Of Recycled Asphalt Pavement Rap Content In Asphalt Mixes Based On Expected Mixture Durability
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Determination Of Recycled Asphalt Pavement Rap Content In Asphalt Mixes Based On Expected Mixture Durability
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Author : Osama Ahmed Abdulshafi
language : en
Publisher:
Release Date : 2002
Determination Of Recycled Asphalt Pavement Rap Content In Asphalt Mixes Based On Expected Mixture Durability written by Osama Ahmed Abdulshafi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Pavements, Asphalt categories.
This research project was directed toward determination of recycled asphalt pavement (RAP) content in hot-mixed asphalt (HMA). Intermediate course mixes used in Ohio were examined. The determination was based on testing of both binder and bituminous concrete specimens.
Experimental Study Of Hot Recycled Asphalt Mixtures With High Percentages Of Reclaimed Asphalt Pavement And Different Recycling Agents
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Author : Jinhai Yan
language : en
Publisher:
Release Date : 2014
Experimental Study Of Hot Recycled Asphalt Mixtures With High Percentages Of Reclaimed Asphalt Pavement And Different Recycling Agents written by Jinhai Yan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Analysis of variance categories.
Hot recycled mixture has been widely used as binder course on highways in the Jiangsu Province, China. The objectives of this study were to evaluate recycled mixture's performance with different Reclaimed Asphalt Pavement (RAP) contents and recycling agents (RA). At first, optimum RA contents were determined according to asphalt blending charts based on penetration index. Secondly, the performance of recycled mixtures and control virgin asphalt mixture was evaluated based on retained stability, Tensile Strength Ratio (TSR), dynamic stability (DS), failure strain, and fatigue life. Thirdly, statistical significance on the basis of analysis of variance was evaluated as a function of RAP contents and RA type. The results indicated that adding RA could improve moisture stability, low temperature cracking resistance, while decreasing high temperature stability and strength performance of recycled mixture. Recycled asphalt mixture Sup-20 with RA has similar performance compared to virgin asphalt mixture Sup-20. The former has better moisture stability and high temperature stability than that of the latter, with a slight reduction in low temperature cracking and fatigue resistance. With a fixed RA-2, TSR, and failure strain of recycled mixes decreases, and DS first slightly decreases and then increases, while fatigue life first increases and then decreases with increasing RAP contents. The results indicated that the interface status and blending level between recycled asphalt and aggregate is variable due to the mixing process and material compositions, which results in the varied performance results of recycled mixes due to the different test temperatures, loading modes, and testing periods, etc. Furthermore, the results of analysis of variance are consistent with the experimental test results.
Characterization Of Reclaimed Asphalt And Performance Based Evaluation Of Its Use In Recycled Mixtures
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Author : Jesse David Doyle
language : en
Publisher:
Release Date : 2011
Characterization Of Reclaimed Asphalt And Performance Based Evaluation Of Its Use In Recycled Mixtures written by Jesse David Doyle 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.
Reclaimed asphalt pavement (RAP) is a valuable resource that can be recycled into new asphalt mixtures. In recent years, the continued rise of raw material costs has generated considerable interest in increasing RAP usage. Warm mix asphalt (WMA) is a modern development in the asphalt industry that can potentially help increase RAP usage and achieve adequate mixture performance. The purpose of this dissertation is to: 1) develop a method to characterize the absorbed, inert and effective bituminous components in RAP; and 2) evaluate performance of high RAP-WMA mixtures for various pavement applications including airfield surfaces, highway surfaces and highway bases. A unique approach was taken to characterize RAP properties that coupled a dataset of 568 asphalt mix designs spanning five years of practice and testing 100% RAP with added virgin binder; 394 compacted specimens and 68 loose specimens were tested. A method to predict RAP absorbed asphalt was developed and shown to yield more reasonable results than conventional methods which were shown very likely to give incorrect absorbed asphalt contents in some conditions. The relative effectiveness of RAP surface asphalt was evaluated and estimates of inert and effective RAP asphalt were made for a variety of temperature, compactive effort, and warm mix additive conditions. Results showed different behaviors between RAP sources and between hot and warm mix temperatures. These results were also observed in volumetrics of high RAP mixtures. Performance evaluation was based on testing 75 slab specimens and more than 1100 gyratory specimens. Test data indicated a potential for decreased durability as RAP content increases; however 25% RAP highway surface mixtures and 50% RAP base mixtures had similar performance to current practice. Low temperature mixture stiffness testing and thermal cracking analysis indicated slightly increased stiffness with high RAP and 25% RAP highway surface mixtures that had comparable performance to current practice. Dry rut testing indicated high RAP mixtures are rut resistant. Moisture damage testing of high RAP mixtures indicated passing results in tensile strength ratio testing but potential for moisture damage in loaded wheel tracking. Overall, 25% RAP highway surface mixtures are recommended for immediate implementation.
Improved Mix Design Evaluation And Materials Management Practices For Hot Mix Asphalt With High Reclaimed Asphalt Pavement Content
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Author : Randy Clark West
language : en
Publisher: Transportation Research Board
Release Date : 2013
Improved Mix Design Evaluation And Materials Management Practices For Hot Mix Asphalt With High Reclaimed Asphalt Pavement Content written by Randy Clark West 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 2013 with Pavements, Asphalt categories.
TRB's National Cooperative Highway Research Program (NCHRP) Report 752: Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content describes proposed revisions to the American Association of State Highway and Transportation Officials (AASHTO) R 35, Superpave Volumetric Design for Hot Mix Asphalt, and AASHTO M 323, Superpave Volumetric Mix Design, to accommodate the design of asphalt mixtures with high reclaimed asphalt pavement contents.
Design Of A High Binder High Modulus Asphalt Mixture
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Author : G. W. Maupin
language : en
Publisher:
Release Date : 2006
Design Of A High Binder High Modulus Asphalt Mixture written by G. W. Maupin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Binders (Materials) categories.
Recent studies on long-life flexible pavements indicate that it may be advantageous to design and construct asphalt mixtures comprising the underlying layers in such a manner that very dense mixtures are produced. This will improve not only the fatigue characteristics but also durability through a decrease in air voids. A 19.0 mm mixture was designed and tested at asphalt contents (ACs) higher than the optimum design level. Stiffer binder and recycled asphalt pavement (RAP) were employed to help maintain stiffness in order to prevent instability. The field voids were predicted to decrease approximately 1.0 to 1.5 percent for each 0.4 percent increase in AC, which would improve durability. Flexural stiffness peaked for an 0.5 percent increase in AC, and fatigue life trended upward but needed approximately 1.0 percent additional asphalt for a major beneficial effect. Permeability improved slightly as AC was increased. The researchers think that the Hamburg test would have been more appropriate for this study than the tensile strength ratio test, which indicated no improvement in stripping susceptibility with an increased AC, because it might simulate field conditions better. In addition, the Mechanistic-Empirical Pavement Design Guide Software (Version 0.900) was used to evaluate trial pavement designs with several design alternatives, including varying the binder performance grade, effective binder volume, and air void content to determine the resultant changes in predicted fatigue cracking and rutting of hot-mix asphalt (HMA) layers. This theoretical pavement analysis indicated that increasing the binder content of the HMA intermediate layer beyond the design optimum and increasing the stiffness of the intermediate layer by increasing the high-temperature binder performance grade slightly decreased the predicted fatigue cracking and reduced the rutting of the HMA layers. The analysis also showed that more significant reductions in the predicted fatigue cracking could be realized by increasing the binder content of the HMA base layer slightly beyond the optimum and by reducing the in-place air void content of the HMA base layer. It was recommended that VTRC should further investigate the effects of higher binder contents and lower air voids on the performance of base mixes. Further study of current void criteria to verify optimum pavement performance is also recommended. This project provides a stepping stone to achieve long-lasting perpetual-type flexible pavement. Designs with a high binder content offer the potential to reduce fatigue cracking 20 to 60 percent by incorporating additional asphalt binder and reducing the void content of asphalt base. The use of RAP to maintain the necessary stiffness for high binder contents should provide comparable stiffness to an increasingly expensive PG 70-22 binder for base material. Some effort is taking place in 2007 for reducing voids in base mixes with high RAP content; however, quantification of the economic benefits from that endeavor will be a future goal.
Reclaimed Asphalt Pavement
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Author : Imad L. Al-Qadi
language : en
Publisher:
Release Date : 2007
Reclaimed Asphalt Pavement written by Imad L. Al-Qadi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Pavements, Asphalt categories.
Illinois has been recycling Reclaimed Asphalt Pavement (RAP) material into hot-mix asphalt (HMA) since 1980, this research project seeks to determine the appropriate level of contribution that should be given to the residual asphalt binder in RAP.
Development Of Quality Standards For Inclusion Of High Recycled Asphalt Pavement Content In Asphalt Mixtures
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Author : Hosin "David" Lee
language : en
Publisher:
Release Date : 2012
Development Of Quality Standards For Inclusion Of High Recycled Asphalt Pavement Content In Asphalt Mixtures written by Hosin "David" Lee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Pavements, Asphalt concrete categories.
The main objective of this research is to examine the effects that different methods of RAP stockpile fractionation would have on the volumetric mix design properties for high-RAP content surface mixes, with the goal of meeting all specified criteria for standard HMA mix designs. To determine the distribution of fine aggregates and binder in RAP stockpile, RAP materials were divided by each sieve size. The composition of RAP materials retained on each sieve was analyzed to determine the optimum fractionation method. Fractionation methods were designed to separate the stockpile at a specified sieve size to control the amount of fine RAP materials which contain higher amounts of fine aggregates and dust contents. These fine RAP materials were used in reduced proportions or completely eliminated, thereby decreasing the amount of fine aggregate materials introduced to the mix. Mix designs were performed using RAP materials from four different stockpiles and the two fractionated methods were used with high-RAP contents up to 50% by virgin binder replacement. By using a fractionation method, a mix with up to 50% RAP was successfully designed while meeting all Superpave criteria and asphalt film thickness requirement by controlling the dust content from RAP stockpiles.
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.
Performance Characterization Of Recycled Asphalt Pavements With Warm Mix Asphalt Technologies
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Author : Sandeep Pandey (Researcher in civil and environmental engineering)
language : en
Publisher:
Release Date : 2016
Performance Characterization Of Recycled Asphalt Pavements With Warm Mix Asphalt Technologies written by Sandeep Pandey (Researcher in civil and environmental engineering) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Electronic books categories.
This study evaluated the laboratory performance characteristics of Recycled Asphalt Pavements (RAP) with Warm Mix Asphalt (WMA) Technologies. RAP was introduced in mixtures at three levels: 0, 15 and 35% of RAP contents. Five WMA technologies were evaluated against all the mentioned levels of RAP content. The study was conducted in two phases, each phase with a separate aggregate and RAP source. Standard Marshall Mix design method was followed for the mix design purpose, with some modification to introduce RAP and WMA. Rheological properties of both the virgin and recovered asphalt binders were determined. Laboratory designed mixtures were evaluated for moisture resistance, dynamic modulus, rutting resistance and thermal resistance behavior. Moisture resistance of the mixtures were evaluated by performing the indirect tensile strength test for 0 and 1 freeze-thaw cycles. Resistance to rutting was evaluated by determining flow number using the Asphalt Mixture Performance Tester (AMPT) machine. Finally, thermal resistance of the mixtures were evaluated by conducting Uniaxial Thermal Stress and Strain Test (UTSST). The study determined that the moisture susceptibility of the mixtures increased with the increase in number of freeze thaw cycles. Dynamic modulus of the mixtures were higher for a higher RAP content. Further, HMA mixtures were determined to have higher dynamic modulus and tensile strengths than the WMA mixtures. Even though, the strength values for WMA mixtures were lower than the HMA mixtures, WMA mixtures satisfied the required criteria defined by agency. HMA mixtures were found to have higher rutting resistance than WMA mixtures, and this resistance increased with the increase in RAP content. Even though HMA mixtures with higher RAP content performed better in terms of rutting, such mixtures exhibited a huge drop in thermal resistance capacity. Varying aggregate source did not significantly influenced the performance of mixtures, except in the case of rutting. Further study is need in order to validate the use of higher RAP content in the mixtures.
Laboratory Testing And Economic Analysis Of High Rap Warm Mixed Asphalt
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Author : Isaac Lem Howard
language : en
Publisher:
Release Date : 2009
Laboratory Testing And Economic Analysis Of High Rap Warm Mixed Asphalt written by Isaac Lem Howard and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Asphalt industry categories.