Evaluation of asphalt-aggregate adhesive characteristics using the binder bond strength device under variable curing conditions

Abstract

ABSTRACT Bonding strength between asphalt binder and aggregate is one of the major factors considered when developing flexible pavements. This study considered five factors to understand the most influential factor affecting the bonding strength at the asphalt aggregate interface and its impact on distresses in an attempt to limit their propagation. 60/70 penetration grade asphalt binder with different types of aggregate (basalt, granite, limestone, and marble) were investigated using the Binder Bond Strength (BBS) test. Three aging levels (unaged, RTFO, and PAV) with different curing temperatures (25, 40, and 60°C) and curing durations (24, 48, and 72 hr) were examined at two different curing conditions (dry and wet). Three-way analysis of variance (ANOVA) using SPSS software was utilised to quantify the significance of each factor on pull-off tensile strength (POTS) values. The results demonstrated that aging level, aggregate type, and curing temperature had a significant effect on bond strength. In contrast, curing type and curing duration did not show a significant effect as individual factors on the POTS values. It was found that increasing temperature had a detrimental effect on POTS for all combinations. On the other hand, short-term and long-term aging significantly increased the POTS values. Moreover, POTS values strongly depended on the aggregate type, as various aggregate types had different rankings. The POTS values decreased when samples were conditioned in water with a change in failure type. In dry conditions, the failure occurred within the asphalt (cohesive failure). The failure type changed from cohesion to adhesion after conditioning specimens in water.