Weathered granite soil 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,California bearing ratio(CBR)test and large-scale triaxial test,to study the basic road performance of weathered granite soil.Specially,in order to evaluate the effects of clay content on the mechanical properties of the compacted weathered granite soil,the extra compaction test and CBR test were made by using samples with the four 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 soil with different clay contents.Thus,the 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 weathered granite soil with clay content of about 4%is largest,which is 95%.Though large-scale triaxial test,it is found that the particle breakage leads to the obvious characteristic of strength nonlinearity of the granite weathered soil.