Carbon sequestration in relation to cement variety: Mechanical properties, microstructural evolution and carbon footprint

The sustainable development of the cement industry not only alleviates the environmental burden associated with cement production but also highlights the excellent carbon sequestration capability from a full life cycle perspective. To this end, this study systematically evaluated the carbon sequestration capacity of calcium aluminate cement (CAC), calcium sulfoaluminate (CSA) cement, and high-belite CSA (HB-CSA) cement pastes under carbonation curing conditions using Portland cement (PC) as the control. Results indicate that the carbonation products in PC primarily exist in the form of calcite and aragonite, whereas those in the others are mainly aragonite. The effect of carbonation curing on the microstructure and the mechanical properties of different types of hardened cement pastes also varies. Especially, carbonation curing reduces the porosity of the HB-CSA cement pastes by 24.9 %, resulting in an increased compressive strength of 60 % at 3 days and by 56 % at 28 days. Although the CO2 absorption capacities of PC, CAC, CSA cement, and HB-CSA cement are 22.19 %, 6.34 %, 13.52 %, and 16.27 %, respectively, the total carbon emissions and net CO2 emissions of HB-CSA cement during production is the lowest.