Xingmin Liang, Yunchong Wei, Xin Yu, Lijian Huang, Jiale Mo, Jinghao Huang
Cracking in grouted composite pavements (GCP) limits their widespread application, particularly under heavy-load conditions. GCPs typically exhibit Type I, Type II, and I/II composite cracks, but research on Type II and composite cracks is limited. This study employs an enhanced semi-circular bending (SCB) test to develop a multi-mode fracture testing system for all three crack types. The effects of temperature (-10 °C, 25 °C) and asphalt-aggregate ratios (3.0%, 3.5%, and 4.0%) on the fracture performance of GCP mixtures (GCPM) are investigated. Digital image processing is applied to analyze crack propagation and interface failure modes. Results show that fracture mode and temperature are key factors influencing GCPM fracture behavior. At low temperatures, Type I cracks exhibit brittle failure, predominantly in the grout and interface adhesion zones. Type II cracks display greater deformability, sustaining larger displacements before failure. However, both Type II and I/II composite fractures are more susceptible under complex stress, being prone to tensile and shear stresses that accelerate crack propagation. At room temperature, composite crack mechanisms are more complex, and higher asphalt-aggregate ratios reduce crack resistance. Image analysis identifies three main failure types: grout fracture, aggregate/grout-asphalt interface adhesion failure, and asphalt cohesion failure. Low temperatures favor grout and interface adhesion failures, whereas at room temperature and higher asphalt-aggregate ratios, asphalt cohesion failure becomes more significant. This study provides insights into failure mechanisms under multi-mode fracture conditions and offers experimental guidance for optimizing GCP materials. Future research should focus on grout fracture and interface damage mechanisms to improve crack resistance.