火災熱や消火散水の影響を受けた石膏ボードの外観および化学組成の変化

抄録

To estimate the heated damage of gypsum board used as ceiling and wall in the investigation of building fire, the chemical composition and appearance of heated gypsum were examined. Three patterns of gypsum samples heated by cone calorimeter and electric furnace were prepared, and the chemical composition of the gypsum was analyzed by X-ray diffraction.

Calcium sulfate dihydrate in heated gypsum board was changed through two dehydrate reactions and finally turned into anhydrate via hemihydrate. The three layered structures with different colors appeared at the cross section of gypsum by watering after heating. The thicknesses of the three layers corresponded to the proportion of anhydrate, hemihydrate and dihydrate of calcium sulfate in gypsum board, respectively. Therefore, observation of three layers of gypsum after fire and fire extinction can help to estimate the degree of damage by fire.