This paper presents the effect of anion exchange resin (AER) on the adsorption of chloride ions in cement mortar. The kinetic and equilibrium behaviors of AER were investigated in distilled water and Ca(OH)₂ saturated solutions, and then the adsorption of chloride ions by the AER in the mortar specimen was determined. The AER was used as a partial replacement for sand in the mortar specimen. The mortar specimen was coated with epoxy, except for an exposed surface, and then immersed in a NaCl solution for 140 days. The chloride content in the mortar specimen was characterized by energy dispersive X-ray fluorescence analysis and electron probe microanalysis. The results showed that the AER could adsorb the chloride ions from the solution rapidly but had a relatively low performance when the pH of its surrounding environment increased. When the AER was mixed in the cement mortar, its chloride content was higher than that of the cement matrix around it, which confirms the chloride ion adsorption capacity of the AER.

In this study, γ-dicalcium silicate (γ-C₂S) was incorporated into ordinary Portland cement (OPC) to sequester CO₂ to enhance the carbonation resistance of cement-based composite materials. γ-C₂S can react with CO₂ rapidly to form vaterite and high dense SiO₂ gel which could block the pores off and then inhibit further diffusion of CO₂ into the system. Cement mortar specimens containing 0%, 5%, 10%, 20%, and 40% γ-C₂S as cement replacement were prepared. After water curing for 28 days followed by curing in an environmental chamber for 28 days, the specimens were then exposed to an accelerated carbonation with 5% CO₂ concentration for 28 days. The carbonation depth of the cement mortar with a low replacement rate (5% and 10%) was lower than that of the OPC mortar at all ages due to the sequestration of CO₂ by γ-C₂S. However, the cement mortar with a high replacement rate (20% and 40%) showed less carbonation resistance due to the dilution effect of γ-C₂S replacement and increase in initial porosity caused by nonhydraulic characteristic of γ-C₂S.