The effects of gilsonite and crumb rubber on moisture damage resistance of stone matrix asphalt mixtures

Abstract

The current study was performed to investigate the influence of gilsonite on properties of binder and moisture resistance of SMA mixtures modified by Crumb Rubber (CR) additive. For this purpose, softening point, penetration, and Dynamic Shear Rheometer tests were implemented to investigate the performance of different binders. To evaluate the water sensitivity of modified mixtures, four different methods were performed, including Resilient Modulus Ratio (RMR), Fracture Energy Ratio (FER), Tensile Strength Ratio (TSR) and Texas boiling. To analyze the data, two-factor analysis of variance (ANOVA) was carried out. Based on the results, utilization of Gilsonite additive enhances the Resilient Modulus (Mr), Indirect Tensile Strength (ITS), and Fracture Energy (FE) of asphalt mixtures. The results also revealed that by utilization of CR, ITS and FE values increase. While, the MR values increase by addition of 10% CR, and by addition of higher percentages of CR (15 and 20%), the MR values decrease. Among different specimens fabricated, mixtures containing 30% Gilsonite and 20% CR have the highest ITS and FE values. Also, according to the results, 30% Gilsonite mixture modified by 20% CR has the highest TSR, and FER value, which indicates that the mentioned specimens have better resistance to water susceptibility.