Shear characteristics of the interface between recycled concrete aggregate and geogrids

In the context of ongoing economic development and urban expansion, there is an urgent need to promote the resource utilization and recycling of construction waste. As a crushed material obtained from the screening of construction waste, recycled concrete aggregate has broad application prospects. This study focuses on four distinct particle size ranges of recycled concrete aggregate. By introducing the concept of aperture ratio, the shear characteristics of the interface between the recycled concrete aggregate and biaxial polypropylene geogrids are investigated through large-scale direct shear tests under three different vertical stresses and four different shear rates. The findings demonstrate that as the aperture ratio diminishes, the peak shear stress and residual shear stress at the shear interface increased, and the peak shear stress occurred at a later stage. Conversely, as the aperture ratio decreases, the peak apparent cohesion and residual apparent cohesion undergo a gradual increase, and the peak internal friction angle and residual internal friction angle also increase. The addition of geogrids effectively reduces the occurrence of shear dilation at the interface. By introducing the Kalhaway constitutive equation, the expression for shear stiffness is derived through linear and logarithmic fitting, and the shear stiffness corresponding to the stress state (σ_n, τ) is thereby obtained.