Experimental Mechanism Study on the Influence of Multi-Interface Pollution Factors on the Adhesion Performance between Layers of Asphalt Pavement

To investigate the formation mechanisms of soil, ice, and oil contamination between pavement layers, composite specimens containing soil, ice, and oil contamination were prepared separately and subjected to shear failure to obtain interlayer failure interfaces under different contamination conditions. Utilizing image recognition analysis, the coverage and distribution of soil and engine oil at the interlayer interface were determined. The process of ice adhesion at the interlayer interface was recorded using a strain gauge, and the formation of ice by water droplets at the interface was documented with a high-definition camera. The research results indicate that during the soil contamination process with a range of 0.3–0.9 kg/m², the contamination level transitioned from mild soil contamination to severe soil contamination. The average contaminated area per zone gradually increased, reaching a maximum of 5 cm² for an individual contaminated area. Additionally, introducing the concept of bonding failure efficiency revealed that when the soil contamination reached 0.9 kg/m², the interlayer bonding failure efficiency could reach a maximum of 40.66%. Shear failure tests revealed that the shear resistance of pre-formed ice specimens was weaker than that of naturally formed ice specimens. Observing the freezing process of water on the surface of the mixture based on the differences in thermal expansion coefficients between water/ice and the mixture, as well as the phase change expansion characteristics of water freezing, it was found that in low-temperature environments, water adhered to the mixture surface enters a supercooled state, resulting in a decrease in interface strain. As water begins to undergo phase change, the region where adhered water contacts the base surface freezes, leading to a rapid increase in interface strain. When the adhered water completely freezes into ice and the environmental temperature stabilizes, the interface stress at the ice-adhesion interface tends to stabilize. Based on the principles of the Lab mode, a detailed segmentation process of oil pollution and interlayer interfaces was obtained, and the distribution pattern of engine oil pollution at the interlayer interface was quantified using grayscale values. The defined modes of action for oil pollution at the interlayer were concentrated oil pollution areas and dispersed oil pollution areas. Studying the formation mechanisms of different contaminants between asphalt pavement layers contributes to elucidating the formation patterns of different contaminant factors at interfaces, providing theoretical support for pollution prevention in the engineering field.