Effects of Interfacial Treatment on Bonding Properties of MPC Mortar-NC Interface

The interfacial bonding strength and failure mechanism of magnesium phosphate cement （MPC） mortar and ordinary concrete （NC） are very important for the structural performance of MPC mortar to reinforce NC. In this paper， the double-sided shear test was used to study the influence of four different interface types on the bonding properties of the MPC mortar-NC interface， the failure process of the specimen was observed， the relationship curve between the bond strength and the slip amount was obtained， the failure mode and failure mechanism of the specimen were analyzed. The effects of curing ages（7 days and 28 days） as well as different compressive strengths （60 MPa and 55 MPa） on the interface bonding properties were compared. On the basis of theoretical analysis and combined with the experimental data， a calculation formula for the shear capacity of the bonded interface was proposed， suitable for different interface treatment conditions. In addition， a two-line constitutive model was established for the non-planting interface， and a three-line constitutive model was developed for the planting interface. This study provides theoretical support and design basis for the application of MPC in structural reinforcement engineering.