Effects of Regular-Sized and Nanosized Hydrated Lime on Binder Rheology and Surface Free Energy of Adhesion of Foamed Warm Mix Asphalt

Abstract

Although foamed warm mix asphalt (WMA) offers many potential benefits, there are some performance concerns. Researchers are making efforts to study the usage of different additives as modifiers to meet standard specifications of asphalt mixes for paving applications; however, selection of an appropriate modifier is extremely important to better performing asphalt. In recent years, there has been a dramatic interest in research, technology, and production of nanoparticles (nanomaterials). The current study was conducted with the objective of addressing the potential benefits of using nanosized hydrated lime (NHL) compared with regular-sized hydrated lime (RHL) as a modifier to the WMA produced using an additive. This paper documents the findings of the effect of NHL and RHL on the asphalt binder rheology and provides an insight into their effect on the free energy of adhesion of the asphalt binder–aggregate system. The rheology of asphalt binder was investigated based on the dynamic shear rheometer (DSR) test, whereas the free energy of adhesion was quantified based on the surface free energy (SFE) measurements of the asphalt binders and aggregate. Rheology results showed that the addition of NHL in smaller amounts can provide improved characteristics as compared with RHL. In concurrence with the rheology results, the free energy of adhesion showed that the NHL is more competitive compared with the RHL. Foaming the asphalt binder adversely affects the asphalt binder-to-aggregate adhesion.