RETRACTED: Mechanical behavior and load-bearing capacity of a layered pavement composite by coal slurry-fly ash-slag hardened body and concrete

Coal slurry, a problematic mine solid waste, was innovatively utilized alongside fly ash and slag, activated by alkaline solutions, to fabricate a coal slurry hardened body (CSHB) with a uniaxial compressive strength (UCS) of 24.72 MPa. This CSHB was then overlaid with C30 concrete (UCS of 31.15 MPa) to form a novel composite pavement structure. Uniaxial compression and acoustic emission (AE) tests were conducted on composite specimens featuring varying CSHB-to-concrete height ratios at a loading rate of 0.01 mm/min. Concurrently, a discrete element model (DEM) based on Particle Flow Code (PFC) was developed to simulate mechanical and fracture behavior. Results indicated a staged damage progression. The CSHB height ratio critically governed the composite strength, crack development, and energy evolution. Both the compressive strength and the proportion of shear cracks exhibited a distinct ‘decrease–increase–decrease’ trend as the CSHB height decreased. A declining b-value derived from AE data served as a key precursor to failure. The optimal CSHB-to-concrete height ratio was determined to be 4:6, which provided the highest bearing capacity, reduced material costs by approximately 40.29% compared to full-concrete pavement, while maintaining structural performance. These findings offer practical insights for designing cost-effective and sustainable mine pavement systems. • The failure process of the CSHB-C30 concrete composite specimens exhibits distinct stages. • The height ratio of the CSHB layer significantly influences the specimen's strength, crack propagation pattern, energy evolution, and the anisotropy of internal contact forces. • A decreasing acoustic emission b-value serves as a key precursor to the failure of the composite structure. • An optimal CSHB-to-concrete height ratio of 4:6 is proposed for pavement design, achieving the best load performance and significant cost reduction.