Comparative Study on the Effects of Five Nano-Metallic Oxide Particles on the Long-Term Mechanical Property and Durability of Cement Mortar

Abstract

Nano-metallic oxide particles have been found to be potentially effective microstructural reinforcements for cement mortar and have become a research hotspot in recent years for nano-modification technology of building materials. However, different conclusions have been obtained due to various researchers used different research methods, which have resulted in a deficiency for the performance comparison between different nano-metallic oxide particles. In the present study, the effects of five kinds of nano-metallic oxide particles, namely nano-MgO, nano-Al2O3, nano-ZrO2, nano-CuO, and nano-ZnO, on the performance of cement mortar at 28 days and 730 days in terms of mechanical, durability, microstructure, and pore size distribution properties by performing different experiments were investigated. Test results show that the dosage of nano-MgO, nano-Al2O3, nano-ZrO2, nano-CuO, and nano-ZnO is 2%, 1%, 1%, 1%, and 2%, respectively, where they can significantly prove the compressive and flexural strengths, decrease the porosity, drying shrinkage, and permeability, and refine the pore size distribution of cement mortar. It can be seen through SEM analysis that nano-metallic oxide particles can promote cement hydration, and also refine the size and distribution of Ca(OH)2 crystal, but the specific principles are different. The analysis concluded that the five kinds of nano-metallic oxide particles can play a filling role in cementitious materials to improve the denseness and surface activity role to promote the hydration of cement particles, thus improving the mechanical properties, durability, and pore size distribution of cementitious materials, with the order of their modification effect on cement-based materials being nano-ZrO2 > nano-MgO > nano-Al2O3 > nano-ZnO > nano-CuO.