REDUCTION OF THE ENVIRONMENTAL IMPACT USING CARBONATED CEMENTITIOUS MATERIALS WITH γ-2CaO・SiO₂

Abstract

γ-C₂S has the property of being hardened by reaction with CO₂ gases In this study, cement paste that substituted some part（30％, 50％, 70％）of γ-C₂S for Ordinary Portland Cement（OPC）was cured under high-temperature and highlγ-concentrated CO₂ conditions. Analyzing the cement paste after curing, it was found that compressive strength and porosity of cement paste which contains γ-C₂S becomes equivalent to that of OPC paste by carbonation curing. It was also found that carbonation depth of cement paste which contains γ-C₂S increased compared to OPC paste. It is because γ-C₂S can absorb a large amount of carbon dioxide compared to OPC. As a result of analysis, the amount of CO₂ absorption of the cement paste which is containing 70％ of γ-C₂S was 377kg/m³. In addition, we estimated the amount of CO₂ emission from the cement paste, which takes into account both the amount of CO₂ emission that lies manufactured of cement or γ-C₂S and the amount of CO₂ absorption of the cement paste by carbonation curing. The estimation results show that the amount of CO₂ emission of cement paste which contains 70％ of γ-C₂S was 47kg/m³, this value is 1/20 or less of OPC. From mentioned above, the environmental impacts could be considerably reduced by using γ-C₂S.