Effectiveness of Using Polymer-Modified Asphalt Binders in Enhancing Fatigue Life of Asphalt Mixes Containing RAS and RAP

Abstract

AbstractIn view of its environmental and economic benefits, the use of Recycled Asphalt Shingles (RAS) and Reclaimed Asphalt Pavement (RAP) in Hot-Mix Asphalt (HMA) is on the rise. However, concerns over premature cracking and reduced fatigue life have limited their use in HMA. Polymer-modified asphalt binder is known to enhance the fatigue performance and resistance of HMA to cracking. This study was undertaken to evaluate the effectiveness of using a polymer-modified asphalt binder in asphalt mixes containing RAS and RAP to reduce fatigue cracking. For this purpose, two sets of HMA mixes, one set with a non-polymer-modified and the other set with a polymer-modified asphalt binder, both having identical gradations containing equal amounts of RAS and RAP were designed and tested for fatigue using a four-point bending beam method. It was found that polymer-modified asphalt binder effectively improved fatigue life of HMA mixes containing RAS, RAP, and their combinations. Also, use of RAP and a combination of RAS and RAP in asphalt mixes containing both non-polymer-modified and polymer-modified asphalt binders improved their fatigue lives. However, using only RAS resulted in an adverse effect relative to fatigue performance.KeywordsHot-mix asphalt (HMA)Reclaimed asphalt pavement (RAP)Recycled asphalt shingles (RAS)Fatigue life