Effect of Warm-Mix Additives and Lime on Intermediate-Temperature Fracture Property of RET- and PPA-Modified Asphalt Binder

Abstract

Asphalt binder phase plays a significant role in cracking resistance of asphaltic mixture. Therefore, selection of appropriate asphalt binder combination becomes important, especially when asphaltic pavement is expected to experience heavy traffic under intermediate-temperature conditions. Previous research shows that the use of polyphosphoric acid (PPA) along with reactive elastomeric terpolymer (RET) may improve various performance parameters; however, it may increase the energy requirement during the construction stage. To address this issue, use of warm-mix additives (WMAs) has been recommended. Therefore, the present study aimed at evaluating effects of different WMAs (wax, chemical, and zeolite based) on intermediate-temperature fracture properties of PPA- and RET-modified asphalt binder using a double-edge notched tension (DENT) test. It was found that chemical-based WMA may significantly improve the fracture properties of control binder. On the other hand, wax-based WMA may have a negative impact on the fracture properties of control binder. Likewise, zeolite-based WMA was found to improve the fracture properties of control binder by a marginal amount. Although the use of WMA may reduce the energy requirement, it may increase the moisture damage potential. To protect the asphaltic mixture from moisture damage, use of lime has been conventionally recommended. Therefore, the effect of lime on fracture properties of various asphalt binder combinations was also examined. It was found that irrespective of the asphalt binder combination, addition of lime may produce a negative impact on fracture properties of control binder with or without WMA.