Shigen-to-sozai, Vol.116, No.8, pp.656-662.
Behavior of Sandstone Subjected to Slow and
Uniform Temperature Changes
Haruyuki KITA1, Toshinori SATO2, Hiroshi TSUJIGAMI3, Youqing CHEN3, Takashi NISHIYAMA3 and Katsuhiko KANEKO4
| 1. Mitsui Construction Co., Ltd., Nagareyama-shi,
Chiba 270-0132 2. Tono Geoscience Center, Nuclear Cycle Development Institute 3. Graduate School of Energy Science, Kyoto University 4. Graduate School of Engineering, Hokkaido University |
| Changes in pore spaces and microcracks in
Shirahama sandstone subjected to slow and
uniform temperature changes up to 1,000℃
have been examined using a fluorescent technique.
A specimen heated up to a certain temperature
was kept at the constant for 24 hours, and
then cooled down to a room temperature. Texture
of the specimen was observed with a microscope. Above 500℃, new microcracks were observed along grain boundaries. The widening of grain boundary microcracks was recognized with increasing temperature. Thermal expansion caused by the α to β transition of quartz plays the dominant role in the development of grain boundary microcracks. Above 500℃, increase and enlargement of pore spaces in the matrix were also observed. The changes in matrix are caused by thermal reactions in the matrix constituent materials such as dehydration and formation of new minerals. At high temperatures, these reactions and the quartz expansion may occur simultaneously, so that microcracks and pore spaces significantly increase. Changes in physical properties such as porosity and elastic wave velocity show good agreement with the results obtained by microscopic observations. |
| KEY WORDS: Sandstone, High Temperature, Pore Space, Microcrack, Matrix |