Compositions and microstructures of hardened cement paste with carbonation curing and further water curing

Abstract This study investigates the influence of degree of carbonation on the carbonation products and the mechanism of further water curing by tracing the compositions and microstructures of the hardened cement pastes. The results indicated that amorphous CaCO3 were the main carbonation products when the degree of hydration was low, while aragonite was also formed as the degree of carbonation increased. In addition, excessive carbonation resulted in the decomposition of C-S-H gel and the coarsening of the pore structure. In the subsequent water curing for 28 d, a 72-h carbonation time almost completely prevented cement hydration, but the pore structure was still refined, which may have been due to the absorption of water in the C-S-H gel.