Carbonation hardening of Portland limestone cement: from laboratory testing to industrial applications

Carbonation hardening accelerates the early reaction of calcium silicate phases, binding CO2 and resulting in a significant increase in product volume and reduction in porosity. This process forms a mechanically efficient microstructure, enhancing early compressive strength. The inclusion of limestone shows limited impact on carbonation kinetics and the products formed; the accelerating effect of limestone on the carbonation reaction (filler effect) could not be confirmed. The comparison of carbonation progress revealed a difference between results obtained at the paste and concrete levels. Limestone composite cements show a higher degree of carbonation in concrete, while such difference is not observed for neat Portland cement. Industrial trials validate the laboratory findings, demonstrating the feasibility of scaling up carbonation hardening for commercial production. The research highlights the potential of carbonation curing to reduce the environmental impact of the building industry by sequestering CO2 and improving the mechanical properties of Portland cement based concrete. HighlightsCarbonation hardening boosts early compressive strength compared to hydrationLimestone in Portland cement improves microstructure and mechanical performance.Industrial trials show carbonation hardening can be scaled up for commercial concrete production.Carbonation curing sequesters CO2, reducing the environmental impact of cement production.Further research is needed to enhance reaction degrees and understand effect of limestone.