Combining hydration and carbonation of cement using super-saturated aqueous CO2 solution

Abstract

Carbonation of cementitious materials is an attractive option to reduce the environmental costs of concrete production. Firstly, carbonation can strengthen cementitious materials and therefore reduce the use of cement. Secondly, carbonation can sequester carbon dioxide (CO2) economically on a large scale. However, the major obstacle to widespread implementation of the technique is that the hydration reaction of cement occurs much faster than the carbonation reaction in atmosphere. Therefore, novel mechanisms for the delivery of CO2 are required. In this study, water used for cement hydration was replaced by a super-saturated solution of CO2 to bypass the dissolution step in the carbonation reaction of cement, and increase the carbonation rate of young age cement. Cement made with saturated CO2 aqueous solution instead of regular water was observed to generate a 1-day strength 6% higher than a pure cement pastes and 26% higher than a cement with a 12% limestone replacement fraction.