Investigation of Shear Properties and Particle Breakage Characteristics of Construction Waste as Roadbed Fill Material

This study evaluates the gradation changes occurring during the sample preparation process using two methods: impact compaction and vibratory compaction, and analyses the shear strength and deformation of samples produced by these two methods. Based on this analysis, we determined the most suitable method for laboratory testing. Utilizing the selected method and through data analysis and experimental observations, we further explore the mechanical properties and particle breakage characteristics of construction waste under varying gradations and brick contents when used as roadbed fill. Research findings indicate that the particle size distribution impact of vibratory compaction on samples is less than that of impact compaction. The stress–strain curves from the former demonstrate brittle characteristics more in line with the properties of construction waste. Under varying gradations, the peak strength is positively correlated with the content of coarse particles. At the same gradation, the brick content tends to decrease the maximum shear strength. Additionally, the primary breakage modes of construction waste particles are fragmentation, fracture, and abrasion, with the resultant particle shapes predominantly being flaky. When calculated based on the initial gradation, the relative breakage rate (Br) shows that particle breakage is positively correlated with the coarse particle and brick contents. When Br is computed using postsampling gradation, particle breakage is inversely related to the maximum dry density of the sample.