Microstructural densification and CO2 uptake promoted by the carbonation curing of belite-rich Portland cement

The present study investigates the effects of the belite content and carbonation curing on the physicochemical properties of cement mortar. The results provide new insight, demonstrating that a higher belite content in cement increases CO2 uptake during the carbonation curing process and thus promotes microstructural densification. Carbonation-cured cement with a high alite content showed increased pore connectivity, while the cement with a high belite content experienced reduced pore connectivity and more instances of pore closure, resulting in a complex microstructure. The belite phase was mostly consumed by the carbonation reaction during the curing process, resulting in the production of calcite. As a result, the mechanical strength of the carbonation-cured belite-rich Portland cement mortar was significantly improved in comparison with that after normal curing for an identical period. In particular, the reaction of the belite phase influenced by hydration/carbonation interaction at an early age is discussed along with the experimental results.