Carbonation behavior of lightweight foamed concrete using coal fly ash

Abstract

The purpose of this study was to prepare lightweight foamed concrete by mixing coal fly ash of circulating fluidized bed combustion(CFBC) with cement, and to develop uses for recycling by analyzing carbonation behavior resulting from a change in conditions for pressurized carbonation. For concrete, CFBC coal fly ash was mixed with Portland cement to the water-binder ratio of 0.5, and aging was applied at room temperature after 3 days of curing at 20°C, RH 60%. For carbonation, temperature was fixed at 60°C and time at 1 h in the use of autoclave. Pressures were controlled to be 5 kgf/cm2 and the supercritical condition of 80 kgf/cm2, and gas compositions were employed as CO2 100% and CO2 15%+N2 85%. In the characteristics of produced lightweight concrete, the characteristics of lightweight foamed concrete resulting from carbonation reaction were affirmed through rate of weight change, carbonation depth test, air permeability, and processing analysis for the day 28 specimen. Based on these results, it is concluded that the present approach could provide a viable method for mass production of eco-friendly lightweight foamed concrete from CFBC coal fly ash stabilized by carbonation.