Impacts of colloidal and interfacial interactions on bonding strength of rubberized RAP asphalt binder

Abstract

Using crumb rubber modified binder to rejuvenate reclaimed asphalt pavement in a new pavement arouses great interest as a sustainable pavement technology that uses waste to recycle other waste. Besides the potential conservation of resources and mitigation of environmental burdens, this technology can also enhance the rheological and mechanical characteristics of asphalt binder and mixture. However, the performance greatly changes according to the material type and modifier dosage. Thus, a deep understanding of binder colloid and its interaction with aggregate is highly endorsed. This study investigates the impact of physical interactions inside the binder colloid and at the binder/aggregate interface on the cohesion strength and shear modulus of the asphalt binder. Thirty binders with different dosages of crumb rubber and reclaimed binder were prepared and tested. The interactions inside the binder colloid were evaluated from the perspective of rheological characteristics using the dynamic shear rheometer. Bond strengths of binders with three different mineral aggregates were measured using the pull-off test. A novel experimental method was developed for determining the influence of interfacial interaction on the binder colloid structure and cohesion strength. The results were explained from a perspective of nanoscale based on past studies. A prediction model was developed for the binder cohesion strength, where the crumb rubber interaction factors, interfacial interaction factor, and shear modulus of the base binder were significant predictors. It was also found that the shear modulus of the modified binder is attributed to colloidal interactions and the shear modulus of the base binder.