Abstract: Hydration properties and hydration products of light magnesium oxide were investigated under different experimental conditions by means of TG-DSC and TG-FTIR. The results show that magnesium oxide calcinated at 900 ℃ tends to hydrate even at ambient temperature. Hydration can be significantly accelerated with increasing temperature. Under the atmospheric pressure and high humidity, hydration and carbonation were both exist when MgO was calcinated at 1300 ℃. The productions of reaction are hexagonally Mg(OH)_2 and amorphous carbonate. Production quantities of these two kinds of product increase obviously along with rising of curing temperature. Pyrolysis temperature of the carbonate generating in this experiment is within 300-450 ℃, which almost covering up the range of decomposition temperature of hexagonal Mg(OH)_2. After calcinated at higher than 1300 ℃, MgO has a great stability that it hardly react with H_2O or CO_2 at room temperature. But it still tends to hydrate and carbonate when curing temperature rises up to 40 ℃ or higher.

Key words: magnesium oxide;hydration reaction;carbonatation