In 2014, researchers at the Virginia Transportation Research Council initiated a study to evaluate the effectiveness of using high polymer-modified (HP) binders in surface asphalt concrete (AC) mixtures. The results were promising enough to support a field study investigating the use of HP binders in asphalt mixtures over jointed concrete pavement. Since 2015, HP AC overlays have been placed at several sections over existing jointed concrete pavement and cracked asphalt pavements in an effort to mitigate reflective cracking. The purpose of this study was to assess the viability of using HP AC mixtures in Virginia as a reflective crack mitigation technique or when deemed appropriate as a tool for increased crack resistance on higher volume facilities. Information on the state of the practice and lessons learned from the use of HP AC mixtures in the United States and Canada are also provided. In general, HP AC mixtures have been used in a wide range of applications under heavy traffic on interstates and slow-braking loads at intersections. No major field-related construction issues in terms of mixing temperatures and in-place compaction of HP AC mixtures were reported and standard construction practices and equipment were used. Good communication between the polymer/binder supplier and the contractor and solid planning prior to the work being conducted were important lessons learned with regard to paving with HP AC mixtures. The performance characteristics of conventional polymer-modified asphalt (PMA) and HP field-produced mixtures were evaluated in the laboratory in terms of durability and resistance to rutting and cracking. Based on the mixtures tested in this study, HP AC mixtures showed better performance when compared with PMA mixtures regardless of the mixture type (dense-graded surface mixtures and stone matrix asphalt [SMA]). Moreover, SMA mixtures showed better performance when compared with surface mixtures regardless of the asphalt binder type (PMA and HP). Overall, SMA-HP mixtures showed the most promising performance among all evaluated PMA and HP mixtures. Distress survey data collected from VDOT’s Pavement Management System of HP field sections were compiled, documented, and compared with that of their control PMA sections. The HP sections showed the most promising performance 5 years after construction (2015-2020) regardless of the traffic level and the pre-existing pavement conditions. In general, none of the evaluated mixtures (HP or PMA) was able to stop reflective cracking totally. Moreover, performance evaluations using the network-level pavement management data were conducted to estimate the life expectancy of HP AC overlays. Overall, PMA and HP AC overlays had an average predicted service life of 6.2 and 8.3 years, respectively, indicating a 34% extension of performance life of the AC overlays with HP modification. The study recommends continued assessment of the as-constructed properties in future HP projects for the purpose of compiling a materials characterization database. Further, the performance of all existing and future HP sections should be monitored. This will help in updating and revising the service life prediction models and the cost-effectiveness of using HP AC mixtures as the existing sections continue to age and more data are available. Finally, the use of the balanced mix design approach should be investigated to promote further the design of more durable and longer-lasting PMA and HP mixtures in Virginia.

Following the five-year study performed to investigate the behavior of binders and asphalt mixtures containing polymer modifiers, it was determined that an insufficient amount of time had elapsed to allow any determinations to be made based upon the special field test sections. The study reported herein was to extend that initial time and to study in depth those special test sections, using visual observations coupled with resulting tests performed on samples extracted from the sections and comparisons with the original data developed in the original research. The research includes laboratory testing of field samples, determining the aging effect on the control and modified binders and corresponding effect on the mixtures, and visual evaluations. Retained samples of the original asphalts were also evaluated for potential performance as determined by the performance-based asphalt binder specification developed by the Strategic Highway Research Program. Four hot mix pavement field projects were constructed in the Tyler, Lufkin, San Antonio, and Childress Districts (10, 11, 15, and 25, respectively), and two seal coat projects were placed in the Odessa and Bryan Districts (6 and 17).

Polymer modified asphalts have recently been the focus of much attention in the U.S. due to claims that polymer additives will lengthen the life of an asphalt pavement. Much of the published research on this topic has been concentrated on the effects of polymer modifiers on binder and mixture properties. The goal of this testing is to predict from laboratory testing the actual field performance of an asphalt concrete. Over the years, specifications have been developed for conventional asphalts that allow pavement performance to be predicted from certain binder tests. These conventional binder tests do not fully address the special characteristics of polymer modified asphalt binders and need revision to be an effective tool in predicting pavement service life. This paper presents the findings of a two-part laboratory research program intended to relate binder and mixture properties of polymer modified asphalts. The preliminary testing involved five asphalt binder types and a variety of binder and mixture tests. Promising test procedures were further investigated in the final testing program where ten asphalt binders were examined. Simple linear regression was used to determine the strength of a relationship between pairs of binder properties and mixture properties. The preliminary testing showed penetration, toughness and tenacity, and force ductility to have the most promise in predicting mixture performance. The final testing contained enough data to be analyzed with both simple linear regression and multiple regression. Penetration, toughness and tenacity, force ductility again were the test procedures that had binder properties that correlated well with mixture properties.

New developments in asphalt with bio-oil, rubber and polymer componentsEmpirical data and models on binders, aggregates, RAP, WMA, HMA for pavementSpecial section on asphalt paving research in IndiaFully-searchable text on CD-ROM (included) The latest volume of the AAPT series features over two dozen research presentations devoted to the chemistry, engineering, modeling and testing of asphalt materials and processing. Developments in the use of components like bio-oil are discussed, as are strategies for testing asphalt components for wear and durability at low and high temperatures. The book offers new data on the performance of reclaimed/recycled materials in asphalt paving. A special section focuses exclusively on discussions of binder modifications. The CD-ROM displays figures and illustrations in articles in full color along with a title screen and main menu screen. Each user can link to all papers from the Table of Contents and Author Index and also link to papers and front matter by using the global bookmarks which allow navigation of the entire CD-ROM from every article. Search features on the CD-ROM can be by full text including all key words, article title, author name, and session title. The CD-ROM has Autorun feature for Windows 2000 with Service Pack 4 or higher products along with the program for Adobe Acrobat Reader with Search 11.0. One year of technical support is included with your purchase of this product.