Basic properties and weathering process of strong weathered granite

Strong weathered granite is abundant in China and it is used extensively as a fill material. However, systematic research on this material is relatively less as compared to sedimentary type of soils like sand and clay. In this study, a series of laboratory tests were performed, including X-ray diffraction test, sieving test, liquid and plastic limit test, compaction test, and California bearing ratio (CBR) test, to study the basic characteristic of strong weathered granite. Specially, in order to evaluate the effects of clay content on the mechanical properties of the compacted weathered granite, the extra compaction test and CBR test were made by using samples with the five different clay contents of 4, 8, 10, and 12% by weight. Results of the laboratory tests indicated that the clay content of 8% could be a good indicator to determine the compaction characteristics of weathered granitic with different clay contents. Thus, clay content of about 8% would be advantageous to the compaction rate of subgrade and the stability of roads. However, The California bearing ratio of strong weathered granite with clay content of about 4% is largest, 95%. A preliminary relationship between weathering process parameters (m, r) and burying granite depth (h) was established to improve the understanding of weathering process and degree of this material. It is found in this research that as the depth h of weathered granite increases, the geological year's parameter m becomes smaller in a power function, but the geometric progression constants r becomes larger in a power function.