Changes in Rock Properties of Coarse Sandstone Due to Weathering

Abstract

Changes in rock properties and pore structure due to weathering were examined using Paleogene coarse sandstone in Amakusa Island, Kyushu, Japan. The results of the measurements are as follows：（1）according to observation of mineral texture in thin sections, matrix minerals such as calcite decrease with increasing weathering grade, while iron minerals have concentrated in matrix with increasing weathering grade,（2）effective porosity and pore volume increases with increasing weathering grade,（3）tensile strength and soil hardness decreases with increasing weathering grade.

These results suggest that increasing of pores in matrix of sandstone with increasing weathering grade is derived from leaching of calcite. Leaching of calcite and increasing pore volume plays a major role in the changes of rock texture of coarse sandstone due to weathering.