Numerical analysis of failure behavior in mixed-molding method semi-flexible pavement material using a random aggregate model

Semi-flexible pavement (SFP) combines cement-based grout with porous asphalt mixture, but conventional SFP often suffers from low grouting efficiency, limited asphalt content and poor crack resistance. This study proposes a mixed-moulding SFP (M-SFP) and develops a mesoscale finite element model with randomly distributed aggregates, asphalt binder and cement mortar. Zero-thickness cohesive elements were embedded in the asphalt and mortar phases to simulate crack initiation and propagation. The model was validated by semicircular bending (SCB) tests and used to evaluate the effects of asphalt and mortar strength on fracture behaviour. The results show that asphalt cohesive properties strongly affect crack paths and peak load, while higher asphalt strength promotes tortuous cracking and improves fracture resistance. Mortar strength also governs mechanical response: moderate strength enhances crack resistance and energy dissipation, whereas excessive strength increases brittleness and reduces structural stability. The model provides insight into the fracture mechanism and material optimisation of M-SFP.