Carbonation curing of cement mortars incorporating carbonated fly ash for performance improvement and CO2 sequestration

Abstract

Carbonation treatment of fly ash (FA) is proposed as a promising method for stabilization of hazardous residues and CO2 sequestration. This paper aims to investigate the performance of cement mortar incorporating carbonated FA and the synergistic effect with carbonation curing. The results show that the content of free CaO and the hydration heat were reduced apparently by carbonation treatment. The synergy of carbonation treatment and carbonation curing compensated for the strength loss caused by FA incorporation, but can also delayed strength development brought by pozzolanic effect. CO32- on the surface of FA introduced by carbonation treatment competed with Cl− for binding AFm, consequently lead to decreased resistance of chloride ion penetration. Carbonation curing mitigated this degradation by improving the pore structure of cement mortar significantly. In summary, carbonation curing can be an appropriate complement to carbonation treatment of FA for performance improvement of cement-based materials and more efficient CO2 sequestration.