Application of Non-Isothermal Thermogravimetry to the Study of Activation Energy of Water in the Hardened Cement Paste

Abstract

　　　Thermal dehydration relating to the various water content conditions (including saturation) of hardened cement pastes was studied using non-isothermal thermogravimetry at three rates of linear increase of temperature from 30℃ to 420℃. The experimental data examined includes evaporation of free water in the pore spaces, dehydration of physically bonded water and decomposition of hydrated water. The influence of heating rates and water content gives to dehydration profiles were clarified. Ozawa method was used to determine activation energy. In the present work, activation energy changed depending on water content. Additionally, dehydration processes under constant temperature conditions were estimated.