Mechanical strength and microstructure of mortars prepared with MgO-CaO-Fly ash-portland cement blends after accelerated carbonation

This paper was to investigate the effect of carbonation curing on the compressive strength and microstructure of mortars comprised of reactive MgO, CaO, fly ash and cement. The results show that the compressive strengths of mortars, after carbonation curing in 99% CO₂ at 0.55 MPa for 3-9 h, increased 1.1 to 4.6 times. The increase of temperature or carbonation curing time increases the compressive strengths of mortars. The treatment of CO₂ decreases the pH value, enhances the microstructures densification and decreases the amount of relatively coarse pores and total pore volume due to the formation of calcite (CaCO₃) and magnesium calcite (Ca_xMg_1-xCO₃).