Abstract: Disintegration test of compacted granite residual soil taken from Shenzhen was carried out in consideration of iron oxide content, water content, and dry density. Test results demonstrated that the compacted granite residual soil disintegrated quickly, during which the disintegrated materials gradually peeled off from the soil specimen from the form of small particles to debris and then to mud, until the soil sample completely disintegrated. The disintegration process of soil was mainly affected by the content of iron oxide rather than by the physical state of soil specimen. The disintegration rate of compacted granite residual soil changed with time in three modes: surged at first and then plummeted; surged at first and then stabilized; multiple peaks appeared. The maximum disintegration rate climbed with the expansion of iron oxide content but dropped with the increase of the water content and dry density. The degree of the impact of water content on complete disintegration time depended on dry density. In the presence of small dry density, the time required for complete disintegration changed within a small range; when dry density exceeded 1.50 g/cm³, the time required for complete disintegration elongated gently with the rise of water content. Given the same water content, the time required for complete disintegration gradually increased with the rising of dry density.

Key words: road engineering, granite residual soil, disintegration characteristics, iron oxide, dry density, water content