Accelerated curing of cement mortar: In-situ carbonation utilising CO₂-impregnated faujasite

This study explores the use of in-situ carbonation using CO₂-impregnated faujasite (FAU) for accelerating the curing of cement mortar. Results indicate that adding 3–12 wt% CO₂-impregnated FAU reduces the setting time of the mortars by 2–11% and significantly enhances the compressive strength of the mortars at 1, 7, and 28 days, compared to plain FAU. Microstructural analyses reveal that the in-situ carbonation promotes the hydration of cement by providing additional calcium carbonate nucleation sites for the C-S-H precipitation. This increases the formation of hydration products, which leads to the refinement of the pore structure. Additionally, the in-situ carbonation results in the formation of calcium carbonate crystals with a particle size of 150–200 nm at 28 days, with the calcium carbonate content increased by 1.9 wt% at an addition level of 12 wt% CO₂-impregnated FAU. Overall, the in-situ carbonation technique shows great promise as an alternative method for accelerating the curing of cement-based materials, particularly for cast-in-place concrete.