Efficacy of carbonated petroleum coke fly ash as supplementary cementitious materials in cement mortars

In this study, an innovative valorization of petroleum coke fly ash as supplementary cementitious materials in blended cement mortars was investigated. To stabilize and upgrade the properties of fly ash, accelerated carbonation was performed to convert calcium oxide and other calcium-bearing species in fly ash into calcium carbonate. The results indicated the achievable carbonation conversion of fly ash was approximately 40%. The changes in physico-chemical properties of fly ash before and after carbonation also were examined by thermal analysis and Fourier-transform infrared spectroscopy. Several material function tests of blended cement mortars with carbonated fly ash, including workability, strength development and durability, were carried out. We found that the strength of cement mortars blended with carbonated fly ash was 20% higher than that of original Portland cement. A mathematical model on the strength development kinetics was developed to elucidate the relationship between mineral compositions and curing times. The carbonated fly ash could facilitate the hydration reaction in blended cement, as well as accelerating the strength development of blended cement by 28%. This study revealed the possibility of establishing a waste-to-resource supply chain by connecting CO2 mineralization with fly ash valorization as cementitious materials.