Research on Mechanical Properties and Particle Crushing of Construction Solid Waste Concrete as Subgrade Filler

Construction solid waste is often used as subgrade filler, and its mechanical properties are greatly affected by moisture content and compaction degree. To explore the influence of these factors on the mechanical and particle crushing performance of construction solid waste, laboratory large-scale direct shear tests and particle screening tests were conducted. This study analyzed samples with varying moisture content and compaction degrees under a certain maximum dry density. The large-scale shear tests were carried out under three normal stress conditions: 50 kPa, 100 kPa, and 150 kPa, and the particle crushing characteristics of construction solid waste before and after shearing were analyzed. The results reveal notable changes in particle crushing form of the section before and after shearing of construction solid waste, which can be categorized into three types: rupture, abrasion, and grinding. The shear stress‑shear displacement curve shows a “jumping” phenomenon. The cohesion of construction solid waste increases with the decrease in moisture content or the increase in compaction degree. Similarly, the internal friction angle rises with decreased moisture content or a higher degree of compaction. The overall screening statistics of construction solid waste show that the particle gradation curve moves upward, and the relative crushing rate of particles increases as moisture content decreases, or compaction degree increases.