Carbonated binder systems containing reactive MgO and Portland cement: Strength, chemical composition and pore structure

A sustainable binder system with a capacity to mineralize CO2 can be formulated by reactive MgO and Portland cement (PC). This research studies the properties of mortar specimens made with carbonated MgO-PC systems with a MgO substitution range of 0%-100% in order to evaluate and compare the compressive strength, chemical composition and pore structure. Key results indicate that the carbonation front of mortar subjected to the same curing regime is primarily controlled by the percentage of MgO. The carbonation depth together with the MgO substitution percentage impacts the type of the hydration and carbonation products and their quantity. This affects the mechanical properties and microstructure of the matrix. The compressive strength and pore volume are between of 27.5-84.7 MPa and 2.9%-8.7%, respectively. MgO substitution percentages of 60% and 70% were optimal to achieve both relatively high strength and low porosity. Carbonated MgO-PC binder with 60% MgO was found to possess 20% lower embodied CO2 than that of PC. (C) 2020 Elsevier Ltd. All rights reserved.