Performance of CO2-Cured Alkali-Activated Slag Pastes During Curing and Exposure
Yubin Jun, Seong Ho Han, Jae Hong Kim
Abstract
Abstract This study investigated the efficiency of CO 2 curing in blast-furnace slag pastes activated with three concentrations of KOH solution (3, 4, and 5 M). The CO 2 curing was applied into the alkali-activated slag paste for 3 days. The CO 2 -cured pastes were subjected to subsequent curing in a water bath or exposed to seawater. The mechanical properties and characteristics of the reaction products were compared. Full strength can be obtained within 3 days of the early CO 2 curing. The strength remained almost constant regardless of the activator concentration. The CO 2 -cured samples produced more CaCO 3 after exposure to the seawater. The carbonates filled the micropores of the samples, and no strength reduction was observed. The hydrates Ca(OH) 2 and C–S–H(I) are carbonated, forming calcite and amorphous CaCO 3 during the subsequent curing and exposure to seawater as well as the CO 2 curing. A less dense matrix with a lower activator concentration facilitated the diffusion of CO 2 and promoted early carbonation in the paste. The polymerization of C–S–H(I) was relatively slow with low activity, and within the period of CO 2 curing, more carbonates were produced in the sample prepared at a low activator concentration.