Experimental research and theoretical calculation of the shear performance of the MPCC-NC interface

Abstract

Magnesium phosphate cement concrete (MPCC) has a promising prospect in concrete repairment for its early-strength properties. However, the bonding performance between MPCC and normal concrete (NC) limits the safety of repaired structures; therefore, the study of bonding performance is of great significance for engineering applications. The research topic of this paper is to examine the shear performance of the interface between MPCC and NC with different interface treatment methods. A total of 14 push-off specimens were tested, where the interface treatment methods included the rough interface, the interface with a concrete block, and the interface strengthened with reinforcements. The results reveal that the interface strengthened with reinforcements has the maximum shear capacity, and the shear capacity is mainly controlled by the compressive strength of the localized concrete; the shear capacity of the interface with a concrete block is primarily controlled by the shear ability of the concrete block; the rough interface has the minimum shear capacity, which is mainly controlled by the chemical bonding action. Moreover, the shear calculation methods have been established based on the failure modes of the push-off tests, which has a good prediction effect on the interfacial shear capacity. This research provides a reference for the engineering design of MPCC.