Review on shear strength of construction waste reclamation subgrade fillers

In recent years, construction waste including recycled concrete, bricks and mortar has been widely used in subgrade construction. The bearing capacity and stability of the subgrade mainly depend on the shear strength of the subgrade filler. Construction waste filler particles are characterized by a wide grading range, low strength, complex composition, etc., and their shear characteristics under service load are significantly different from those of traditional sand and gravel fillers. The existing research results are reviewed from three aspects: shear characteristics of recycled construction waste fillers, shear characteristics of construction waste - fine grained soil mixed fillers, and interface shear characteristics between recycled construction waste fillers and geomaterials. Based on existing research, it is found that changes in particle morphology and distribution of different types of construction waste determine the type and mode of particle breakage, and particle breakage significantly affects the shear strength during the shear process. On the premise of meeting subgrade filling strength requirements, it is necessary to further explore the influence mechanism of particle breakage laws of different construction wastes on shear strength. In addition, although the shear strength of construction waste can be improved when mixed with different fine-grained soils, the research on the optimal mixing ratio and interaction mechanism of mixed soils is still insufficient. Research on the interfacial shear strength between construction waste and geotechnical materials mainly focuses on recycled fillers such as concrete and blocks. Due to the differences in material composition and properties of construction waste, it is necessary to conduct indepth research on the interfacial shear mechanism of different construction waste fillers, so as to provide important theoretical support and technical reserves for the development of green and low-carbon transportation.