Wet carbonating CaO-activated fly ash to improve CO 2 mineralization and supplementary cementitious material utilization

The low intrinsic reactivity of fly ash (FA) limits its efficient utilization as a supplementary cementitious material (SCM) and its potential for CO2 sequestration. To address this limitation, an integrated CaO activation-wet carbonation strategy utilizing the slaking behavior of quicklime was developed. The test results supported that carbonated CaO-activated FA (C-CAFA) with 15.00 wt.% CaO and 14 days of activation achieved net-negative carbon emissions (15.56 mg CO2 g−1 FA) and 62.29% carbonation efficiency. Mortar containing 25.00 wt.% C-CAFA exhibited compressive strengths of 26.0, 32.6, and 45.3 MPa at 3, 7, and 28 days, respectively, comparable to those of the reference PC mortar (25.1, 32.5, and 48.8 MPa). Therefore, this work offers a feasible and practical pathway to improve the double roles of FA in carbon reduction and carbon capture.