IMPACT OF CO₂ GAS ON CHEMICAL CHANGE OF C-S-H IN HIGH-TEMPERATURE ENVIRONMENT

Abstract

In this study, we investigated the impact of CO₂ in high-temperature environment on the chemical changes of C-S-H, and considered the mechanism of concrete carbonation due to fire damage. As a result of heating the synthetic C-S-H, difference of chemical change was not observed between CO₂ and N₂ flow, even in the different two types of Ca/Si molar ratio C-S-H. In the high-temperature CO₂ environment, a dramatic carbonation accompanied by structural change of C-S-H did not occur. The amount of CaCO₃ produced by heating hydrated ordinary Portland cement in CO₂ flow became the highest at around 600℃, which was almost the same as the amount of CaCO₃ calculated from the amount of Ca（OH）₂ before heating. The maximum value of CO₂ fixation due to high-temperature carbonation was almost dependent on the initial amount of Ca（OH）₂.