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

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. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study found that the degree of carbonation affects the type of carbonation products, with excessive carbonation leading to the decomposition of C-S-H gel and coarsening of the pore structure. In subsequent water curing, reducing the carbonation time can prevent cement hydration while still refining the pore structure.