Review on CO2 curing of non-hydraulic calcium silicates cements: Mechanism, carbonation and performance

The manufacture of cement is associated with a large amount of CO2 emissions. Mineral carbonation technology (MCT) has been identified as one of the viable solutions to reduce the high environmental impacts of cement and concrete production via a long-term storage of atmospheric CO2 as stable forms of carbonates in cement-based products. This article reviews the status quo of hydration and carbonation activities of all calcium silicates system, especially three main non-hydraulic calcium-silicate-based binders (e.g. γ-C2S, C3S2 and CS). The influence of mineral structure on the types of carbonation products is examined to fundamentally explain the evolution of carbonation products and provide a solid theoretical basis for a wider application of carbonation technology in the future. Finally, effective measures to improve the carbonation performance are comprehensively discussed from the aspects of CO2 concentration, relative humidity, carbonation temperature, W/C ratio, etc., to highlight the potential of non-hydraulic calcium-silicate-based binders in reducing the global cement-associated CO2 emissions.