Abstract: To research the influence of water content (optimum water content, flow lower limit water content, flow upper limit water content) on basic properties of light weight soil, engineering properties of mixed soil are investigated by density test and unconfined compressive strength test. The results show liquidity of mixed soil can be controlled feasibly by liquidity indexes . When water content are on the points of flow lower limit water content and flow upper limit water content, unconfined stress-strain relation curves are almost coincident. So when water content is between flow lower limit water content and flow upper limit water content, engineering properties of mixed soil are approximative. Unconfined compressive strength decreases rapidly with increased water content, but there are no significant differences for the strength on the points of flow lower limit water content and flow upper limit water content. No matter how much the water content is, strength-age relation can be predicted by hyperbolic model. Empirical relations between strength of 7 d and 90 d and strength of 28 d are summarized. When water content is optimum water content, there is only a little shrinkage. When water content is between flow lower limit water content and flow upper limit water content, the range of line shrinkage ratio is [1.53%, 4.71%], and the range of volume shrinkage ratio is [4.53%, 13.46%]. Shrinkage property can be influenced by water content and cement dosage. Wet density of mixed soil can be predicted approximately by ideal density model, there is some error for predictive value, and error range is [3.834%, 8.231%].

Key words: light weight soil, water content, unconfined compressive strength, density, shrinkage ratio