Influence of SiO2 nanoparticles on the microstructure, mechanical properties, and thermal stability of Portland cement nanocomposites

Abstract

In the context of the microstructure of nano-SiO2 cement nanocomposites, information regarding the tricalcium silicate (C3S) and dicalcium silicate (C2S) phases during the hydration reaction remains inadequate. Therefore, in this research, the effects of different SiO2 nanoparticles contents on the microstructures, mechanical performance, and thermal stability of cement nanocomposites were investigated. The X-ray diffraction (XRD) results highlighted that the incorporation of nano-SiO2 enhanced the microstructure of the nanocomposites by decreasing the Ca(OH)2, C3S, and C2S peaks, leading to a higher production of calcium silicate hydrate (CSH) products. Moreover, the intensity of the unhydrated gypsum phase increased with the increase in the nano-SiO2 contents, which was suggestive of the retardation effect of nano-SiO2 on the aluminate phases and aluminate reaction. Furthermore, the addition of nano-SiO2 considerably enhanced the flexural strength and thermal stability of the nanocomposites compared to the control composites. The optimum ratio of nano-SiO2 was 1 wt%.