Experimental Research on Mechanical Properties of New-to-old Concrete Interface Under Direct Shear Condition

The shear performance of new-to-old concrete interface with different loading modes is the key to the reinforcement structure. Therefore, the experimental tests of dip angle and normal stress of new-to-old concrete interface on shear performance were carried out, and the shear failure characteristics were analyzed. The results showed that the curves of shear stress and shear displacement about new-to-old concrete were roughly divided into the linear elastic change stage, the failure stage, and the residual strength stage. The peak shear stress of new-to-old concrete increased exponentially with the increase of interface dip angle and linearly with the increase of normal stress. During the shear process of the specimen, the shear failure of new-to-old concrete was generally characterized by dilatancy and shrinkage. The dip angle and normal stress of interface had significant effects on the crack propagation mode and the crack distribution.