Carbonation of concrete containing mineral admixtures

This study deals with the carbonation of concrete incorporating ground granulated blast-furnace slag (GGBS), fly ash (FA), and silica fume (SF): It is observed that a decreased water-to-binder ratio and replacement level of GGBS, FA, or SF, or an increase in GGBS fineness and curing age in water, led to better carbonation resistance. However, compared to a plain concrete, the concrete incorporating mineral admixtures (except GGBS with higher fineness and SF) generally showed lower resistance to carbonation, possibly due to the dominating effect of the reduction in calcium hydroxide over pore refinement. Hence, adequate curing is recommended for enhancing the resistance of concrete containing GGBS, FA, and SF to carbonation. It is also found that both the carbonation coefficient and compressive strength served as good indicators for the carbonation rate of concrete with and without mineral admixtures.