Influence of using polymeric aggregate treatment on moisture damage in hot mix asphalt

Abstract

Moisture damage in hot mix asphalt (HMA) occurs due to a loss of adhesion and or cohesion, resulting in the reduced strength or stiffness of the HMA and the development of various forms of pavement distress. One of the convenient approaches to decreasing moisture sensitivity in HMA is coating the aggregate surface with a suitable agent. In this research, the effects of two types of polyethylene (PE), namely high density polyethylene (HDPE) and low density polyethylene (LDPE), on moisture damage of asphalt mixtures were evaluated. Two types of aggregates representing a considerable range in mineralogy (granite and limestone) were evaluated during the course of this study. To assess the impact of PE on moisture damage of HMA, control mixtures (without PE) and mixtures containing PE in dry and wet conditions were tested using indirect tensile strength (ITS) and indirect tensile stiffness modulus (ITSM) tests. The results showed that the ratio of wet/dry values of ITS and ITSM for mixtures containing limestone was higher than those of the samples with granite aggregate. The results of the laboratory tests indicate that PE increases the wettability of asphalt binder over the aggregate and the adhesion between the asphalt binder and aggregate, especially in the mixtures containing acidic (granite) aggregate prone to moisture damage. The aggregates treated with HDPE showed better resistance against moisture damage in both aggregates that were used in this study.