EXPERIMENTAL STUDY ON HYDROSCOPICITY AND BOUND WATER OF GAOMIAOZI BENTONITE

Moisture in the air can be absorped by bentonite readily. This paper studies the hygroscopicity of Gaomiaozi Na-bentonite under different conditions including drying temperatures, drying time, environmental relative humidites, thickness, and surface area. The results show that the mass of bentonite is stable after it has been dried at 110℃for 8hours. The final absorped moisture content does not increase with the surface area. There is depth effect in bentonite that the absorped moisture content decreases as the depth increases. The relationship of the absorped moisture content with time is fitted well by Peleg model. First, 20g bentonite is dried at 110℃. Then the dried bentonite is exposed in air with 55% and 82% relative humidity, respectively. The strongly bound water is absorped in 2 minutes, which indicates that the adsorption of bound water is less affected by relative humidity. The contents of free water, weakly bound water and strongly bound water are 7.873%, 0.749% and 1.316%, and 9.408%, 1.128%, 1.412%, respectively. And their water film thickness is 5.56Å and 7.71Å, respectively.