Effect of silica fume on corrosion resistance of cement-based materials under carbonic acid water environment

Abstract

The effect of silica fume (SF) on corrosion depth, mass loss and compressive strength of mortar specimens over time under carbonic acid water environment were studied in this study. In addition, the thermal gravimetric analysis (TG-DTG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to analyze the product evolution and microstructure of cement paste under such environment. Moreover, the corrosion process under carbonic acid water environment of cement-based materials was systematically discussed. A comprehensive explanation of the corrosion process was proposed, detailing the dynamic progression of CH leaching, carbonation, and deterioration over time and space. SF has different action mechanisms in different stages. On one hand, the addition of SF slightly increases the overall corrosion depth expansion rate due to reduced matrix alkalinity. In addition, it can promote the formation of calcium silicate hydrate (C-S-H) gels with a low Ca/Si ratio and densifies the microstructure of cement-based materials, thereby reducing mass loss and strength reduction and delaying the progression of deterioration depth under carbonic acid water environment. This study provides a comprehensive elucidation of the influence mechanism of SF on the carbonic acid water corrosion process in cementitious materials, offering new insights for enhancing concrete durability.