Carbonation of concrete containing mineral admixture in normal indoor environment

The carbonation depth of concrete containing mineral admixture exposed in normal indoor environment after different moistly curing ages has been measured at different ages. The relationship among carbonation of concrete and several influencing factors, such as moistly curing ages before carbonation, water-binder ratio, kinds of mineral admixture, fly ash-slag mixing ratio and replacing proportions of mineral admixture have been discussed. The results showed that the carbonating depth of concrete increases along the prolongation of exposing time during the initial exposing period but decreases after six months. Moistly curing age obviously influenced carbonation of concrete at early age. The shorter the moist curing time is, the severer carbonation degree of concrete is, and the more the carbonating depth decreases in later age. The continuous hydration of binder in the carbonated concrete in suitable environment, which could increase the amount of Ca(OH)2 in it, may be the reason of carbonation degree decrease in later age.