Strength and deformation performances of silt-based foamed concrete under triaxial shear loading

Abstract

Previous triaxial experiments have paid little attention to the shear strength and solid materials‒voids interaction of foamed concrete. Therefore, this study conducted comprehensive triaxial shear tests to investigate the strength and deformation characteristics of the silt-based foamed concrete, in which the silt was added to replace a portion of the cement. The results indicate that the deviatoric stress‒axial strain curves can be divided into the elastic stage, softening or hardening stage, and strength stability stage. In addition, the increasing confining pressure can gradually transform the type of stress‒strain curves from softening type to hardening type. The solid skeleton around the shear plane is broken into particle materials and then moves to fill the pores, while some residual solid skeletons still retain the characteristics of cementing binder. The volumetric strain of foamed concrete in triaxial shear loading presents a contraction feature. Moreover, as the confining pressure increased by 0.1 MPa, the peak strength and residual strength are observed to respectively rise on average by 0.075 MPa and 0.16 MPa. The cemented solid skeleton in foamed concrete primarily presents the cohesion in shear strength, which could be several hundred kPa. Furthermore, an equation is employed to describe the degradation of cohesion caused by the fracture of the cemented binder.