The absorption factor of an Oya stone is very high, and it sexpands greatly when it absorb water. Moreover, the compressive strength in the wet condition quite falls less than in the dry condition. Furthernore, as compared with details of the stone, the specific gravity of rough-textured Oya stone is small, and its compressive strength is also low both in the dry and wet condition. The swelling pressure is hardly produced even if the Oya stone absorbs water for a long time, and then the internal structure is vulnerable. We are going to get behind the behavior of the Oya stone in this study.
