Improvement effects of nano-silica on bonding performance of polymer concrete for repairing damaged concrete

Abstract

Bonding performance between polymer cement-based materials and old concrete is an important index for evaluating the repair effect. Adding nano-silica (NS) to the polymer concrete can effectively improve the bonding strength of the bonding surface. Based on the study of bond strength and failure mode of bond interfaces, this study analyzes the change regularity of bonding performance under different NS contents. The effect of the interface microstructure change on the macroscopic bond strength was analyzed by studying the microhardness of the bonding interface. The results showed that within a certain range of dosage, the bond strength increased with increasing NS content. NS changed the internal structure of the bonding interface and changed the mode of failure, which is the reason for the increase in interfacial bond strength. NS can reduce the thickness of the bonding interface transition zone, improve the growth of the hydration products, and generate a more high-density hydrated calcium silicate gel. Therefore, the microhardness of the transition zone was increased, and the microstructure of the transition zone and the integrity of the entire transition zone were improved, thereby improving the macroscopic bonding performance of the bonding surface.