Experimental investigation and mathematical modelling of the carbon dioxide sequestration of cement pastes during pressurized

The mineral carbonation of concrete waste is a particularly attractive option to reduce the CO2 emissions of the construction industry. The aim of this study was to investigate the behaviour of CO2 capture by concrete wastes in response to various parameters, and to build a model for predicting the CO2 uptake of concrete wastes. A series of accelerated carbonation tests were performed under varying pressures of pure CO2 (0.1-1 bar), room temperature, 40% to 70% relative humidity, and carbonation times of 6, 12, 24, and 48 h. Cement paste samples with varying W/C ratios, conventional curing ages, and particle sizes were prepared and used as the concrete waste samples to emphasize its capability of CO2 sequestration. The amount of CO2 absorbed by the samples was assessed by thermogravimetric analysis (TGA). Various parameters affected CO2 uptake, and this information helped determine the optimal CO2 sequestration conditions for concrete waste. Over 40% of the CO2 emissions from cement production could be absorbed by the pressurized CO2 curing. A model was constructed by introducing the modification fraction based on experimental data, and this model could be used to evaluate the amount of CO2 uptake by concrete waste.