A Study on the Increase in the Durability of Asphalt Paving Mixtures

A novel approach of increasing the durability of the asphalt-paving mixtures was attempted in this study by pretreatment of the aggregate surface with styrene butadiene rubber (SBR) latex as an antistripping additive (ASA). The boiling water test showed that the pretreatment method could increase the asphalt-aggregate bond strength effectively. This result was confirmed by the indirect tensile test and the stiffness index measurement of the asphalt-paving mixtures. Even though the conventional method of direct addition of ASA to the asphalt could also improve the asphalt-aggregate bond strength compared to the asphalt paving mixtures without ASA, the performance was poorer than the pretreatment method because of its inherent disadvantages of losing the effectiveness of ASA in hot asphalt. Increase of pretreatment drying time, drying temperature, and ASA concentrations could improve the asphalt-aggregate bond strength confirmed by the boiling water test. Increase in pH of the contacting water showed a detrimental effect on the asphalt paving mixtures by dissociation of the acidic functionalities of the asphalt to disrupt the asphalt-aggregate bond.