The rate of corrosion of hardened cement pastes and mortars with additive of silica fume in acids

Abstract

The rate of corrosion of hardened cement pastes (HCPs) and cement mortars in solutions of nitric acid and acetic acid were compared. Cement mortars were prepared with a different sand-to-cement ratio and fineness of sand. A study on the effect of silica fume on corrosion resistance of cement paste and mortars to acid solutions is also presented. The progress of corrosion was expressed in terms of depth of corrosion related to duration of acid attack. The rate of corrosion of all types of specimens was faster in nitric acid solution than in solution of acetic acid with the same concentration. Cement mortars corroded at a slower rate than HCPs, though the difference was minor. There was also some small difference between the rate of corrosion of different mortars. Corroded layers of cement mortars contained smaller, less observable cracks and shrank less than corroded layers of cement pastes. Addition of silica fume slightly reduced the corrosion rate of both HCP and mortar. The differences in the corrosion rate between various types of specimens were smaller in acetic acid than in nitric acid solutions. The specimens lost weight due to acid attack. Loss of weight per unit volume of cement pastes or mortars increased with the increase of the cement content.