Effect of coal fly ash and CO2 curing on performance of magnesium potassium phosphate cement

Abstract

This study explores the combined effects of coal fly ash (FA) and CO₂ curing on the flexural strength, compressive strength, and water resistance of magnesium potassium phosphate cement (MKPC). Additionally, the hydration products and microstructure of MKPC and MKPC-FA blends are examined using X-ray diffraction (XRD), thermogravimetric analysis (TGA), mercury injection porosity (MIP), and scanning electron microscopy (SEM). The results demonstrate that carbonation curing effectively improves the mechanical strength and water resistance of MKPC-FA blends by refining the pore structure and reducing porosity. Incorporating fly ash into magnesium phosphate cement leads to a longer setting time and appropriate enhancement in the water resistance of MKPC-FA blends. It should be mentioned that the mechanical strength of MKPC-FA blends declines with increasing fly ash content, and carbonation curing can partially ameliorate these negative effects. Therefore, both incorporating fly ash and storing carbon dioxide have positive effects on the durability and environmental sustainability aspects associated with MKPC preparation.