Effects of Asphalt Additives on Pavement Performance
Author(s):
J.W. Button, C.P. Hastings, D.N. Little
Publication Date:
November 1996
Abstract:
The overall objective of this study was to evaluate a variety of asphalt additives in the laboratory and in the field to determine their merit in reducing cracking and rutting. In the late 1980s, test pavements were constructed in Texarkana, Sherman, San Benito, and Ft. Worth, Texas. In 1995, cores were obtained from Texarkana and Sherman and evaluated in the laboratory. Asphalt binders, retained during construction and sealed in cans, were tested using the Superpave binder tests and certain chemical tests. Retained binders and aggregates were combined in accordance with the original mixture designs, compacted in the laboratory, and tested using the NCHRP AAMAS test protocols to assess relative resistance to fatigue cracking. The specific objective of the work reported herein was to test the binders and mixtures to determine what properties correlate with the field cracking. A secondary objective was to evaluate the ability of the laboratory tests to identify binders and mixtures susceptible to cracking. Asphalt additives included latex, ethylene vinyl acetate, styrene-butadiene styrene-block (SBS) copolymer, SBS vulcanized with asphalt, manganese organic complex, polyethylene, and carbon black.|Certain polymers when blended with the proper grade of asphalt will significantly reduce fatigue cracking. Field tests indicate that the addition of a polymer will reduce rutting when HMA is overasphalted or will allow the use of higher binder contents. Susceptibility to fatigue cracking was related to low loss tangent values from DSR testing, high levels of oxidation as measured by FT-IR, high amounts of large molecular size (LMS) material from GPC testing, and high asphaltene contents. Binders which failed the Superpave high temperature grading did not produce rut-susceptible mixtures, but did produce crack-resistant mixtures. AAMAS test results showed no correlation with the observed fatigue cracking.
Report Number:
187-26
Electronic Link(s):
Document/Product
http://tti.tamu.edu/documents/187-26.pdf
Publication/Product Request
TTI reports and products are available for download at no charge. If an electronic version is not available and no instructions on how to obtain it are given, contact the TTI Library.