PCM-Concrete Interfacial Tensile Behavior Using Nano-SiO₂ Based on Splitting-Tensile Test

Abstract

The purpose of this study is to improve the interfacial performance between the concrete and polymer cement mortar (PCM) by using nano-SiO₂. This study examined the bond properties of the inclusion of nano-SiO₂ in the PCM based on splitting-tensile tests. In addition, the bonding mechanism was investigated with SEM. The results demonstrate that the inclusion of 2% nano-SiO₂ in the PCM is beneficial to compressive strength and microstructure so as to obtain good interfacial bond strength as a repair layer mortar. The results also show that the increase in the surface roughness, the improvement of substrate concrete strength, vertical casting, and wet saturated interface state facilitate bond strength and change the failure mode of nano-SiO₂ PCM/concrete composite specimens. At that time, the interfacial strength is predominantly influenced by the interface roughness and the old concrete strength through one-way analysis of variance. The results of SEM present that the interface of nano-SiO₂ PCM/concrete composite specimen is more compact than that of the PCM/concrete composite specimen due to the transformation of harmful Ca(OH)₂ into more C-S-H gels and the formation of a better polymer film structure at the interface. As a result, mixing nano-SiO₂ into PCM accompanied by adopting effective treatment method of surface and higher compressive strength of substrate concrete is significantly beneficial to bond strength.