Carbon dioxide sequestration in concrete in different curing environments

This paper summarizes the results of an investigation on carbon dioxide (CO2) sequestration in concrete. Concrete mixtures were not air entrained. Concrete mixtures were made containing Class C fly ash at 0%, 18%, and 35% of total cementitious materials. Effects of three different curing environments on properties of concrete were studied: (1) moist-curing room with 100% relative humidity (RH) and 0.15% CO2 concentration; (2) drying room with 50% RH and 0.15% CO2; and (3) CO2 chamber with 50% RH and 5% CO2. Concrete specimens were tested for compressive strength, splitting tensile strength, flexural strength, depth of carbonation, and abrasion resistance. Among the three curing environments, the rate of carbonation of concrete was the highest in the CO2 chamber. In spite of the lack of moist-curing due to the 50% RH environment in the CO2 chamber, the specimens carbonated in the CO2 chamber generally showed approximately the same strength as the specimens cured in the moist-curing room. The abrasion resistance of carbonated specimens was lower than that of moist-cured specimens. The specimens cured in the drying room without enough moisture or carbonation showed the lowest strength and abrasion resistance.