Enhanced carbonation curing of cement pastes with dolomite additive

Carbonation curing of cement-based materials has recently received increasing attention as a CO2 utilization technology. This study aimed at investigating the effects of carbonation curing on the performance of ordinary Portland cement (OPC) pastes with dolomite additive (DPC). The CO2 uptake capacity, after being normalized to carbonation active components, significantly increased with larger dolomite mixing ratios. For DPC-25% samples under 2.5 MPa curing pressure, the maximum CO2 uptake capacity reached 23.6 wt%, which was 23% higher than that of pure OPC samples under the same condition. Effects of water to solids (w/s) ratio and temperature on carbonation are two-sided. The optimum w/s ratio for CO2 uptake capacity of DPC-15% samples was approximately 0.20, while the optimum temperature was equal to 60celcius or higher than 60celcius. The CO2 uptake capacity increased with finer particle size and higher CO2 curing pressures. Compared to large particles, smaller particles are more likely to have a better dilution effect, providing more contact surface for carbonated precipitation. From the pore structure changes perspective, carbonation products filled the interface between the dolomite and amorphous particles. DPC-25% samples with higher dolomite mixing ratios provided more pores and pathways for gas diffusion, and exhibited a more uniform structure, thereby contributing to the highest compressive strength values of DPC-25% samples (63.8 MPa) among all the DPC samples. These findings imply the possible feasibility of dolomite as an additive in carbonation cured building materials. (c) 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.