Experimental Study of Interfacial Bond Properties between CGM and Existing Concrete

To ensure that the cementitious grouting material (CGM) layer and existing concrete work together, the interfacial bond strength between CGM and normal concrete substrate was experimentally investigated by conducting direct and slant shear tests. The effects of connection interface form, concrete strength, interface shear key, and shear angle on the bond strength of CGM and normal concrete were discussed in detail. The results showed that for composite specimens, the interfacial bond strength was the highest for the triangular interface form, followed by the trapezoidal interface and smooth interface, which had the lowest. The interfacial bond strength increased as the existing concrete’s strength increased; the interfacial bond strength could be greatly improved under shear load in the slant section or when the shear key was set at the interface. Moreover, the interfacial bond strength increased with the increase in the shear angle. The interfacial bond–slip curves were analyzed, and a bond–slip model of the interface between CGM and concrete was proposed. A certain value of interfacial bond stiffness was also recommended.