Low-temperature damage and crack evolution mechanisms of hydraulic asphalt concrete with acidic aggregates under temperature-difference cycling

To promote the application of asphalt concrete with acidic aggregates in pumped-storage power stations and clarify its damage evolution and crack propagation mechanisms under extreme temperature-difference cycling, low-temperature direct tensile tests were conducted using digital image correlation, with alkaline aggregate asphalt concrete as the reference. The temperature-difference influence factor was introduced to quantify the degree of performance degradation of asphalt concrete under temperature-difference cycling, and in combination with analysis of variance revealed the influence patterns of multiple factors and their interactions on low-temperature mechanical behavior. Based on macroscopic performance indicators and the main-crack characteristic width ratio, a cross-scale synergistic damage model was constructed, elucidating how aggregate lithology governs interfacial adhesion and stress-transfer mechanisms across macroscopic and mesoscopic scales. Results indicate that, under temperature-difference cycling, the performance degradation process of asphalt concrete can be divided into three stages: thermal stress microdamage, hardening-damage interaction, and cumulative fatigue failure, and the plastic-to-brittle transition temperature shifted from −30 ℃ to −20 ℃. Analysis of variance indicates that temperature is the primary factor controlling changes in peak stress and peak strain, with contribution rates of 67.64% and 74.74% During the plastic failure stage (0 −60 cycles), granite asphalt concrete exhibits distinct transverse bands of high strain concentration. Crack initiation is strongly oriented toward the aggregate-asphalt interface. In contrast, the limestone aggregate-asphalt interface efficiently transfers stress and suppresses uncontrolled crack propagation because of its strong interfacial adhesion. The research results can provide a solid scientific basis for enabling the use of locally sourced materials in engineering and for the safe and widespread application of acidic aggregates.