Effects of material properties and environmental conditions on the adhesion performance and failure mode of CRMA

The interfacial interaction between asphalt and aggregate plays a pivotal role in determining the water stability of asphalt mixtures. This study investigates the effects of intrinsic material properties and environmental conditions on the adhesion behavior of crumb rubber modified asphalt (CRMA), utilizing the pull-off strength tests and image recognition methodologies. Multivariate analysis of variance (ANOVA) was conducted using SPSS software to statistically evaluate the significance of the effects of different material properties and environmental conditions on the adhesion performance of CRMA.The findings reveal that the adhesion strength between CRMA and aggregates decreases gradually with an increase in crumb rubber content. The smaller the crumb rubber particle size, the greater the interfacial adhesion strength. Under immersion conditions, the smaller crumb rubber particles reduce pull-off strength loss and strengthen the moisture resistance of the aggregates and asphalt interface, while lower content of crumb rubber maintains better water stability. Limestone and basalt aggregates demonstrate superior adhesion and resilience to moisture-induced degradation relative to their granite counterparts. Additionally, the cohesive failure area at the asphalt-aggregate interface decreases, shifting towards adhesive failure after immersion process based on the in-depth analysis of failure mode at the interface, including quantification of adhesion and cohesion failure area ratios. Among the examined factors, environmental moisture conditions (dry vs. wet) exert the most significant influence on the adhesion performance of CRMA. This comprehensive investigation establishes a theoretical foundation for optimizing the adhesion performance between CRMA and aggregates, thereby significantly enhancing the durability of asphalt pavement.