According to the possible durability problem of high liguid limit clay as roadbed filling in rainy climate, a series of tests on water stability characteristics of pure high liquid limit soil and lime or cement improved soil were carried out.The pure soils was red clay which picked from under-construction Longquan-Pucheng Highway section. The tests focused on the unconfined compression strength and CBR under ordinary water immersion and drying-wetting cycle condition. Exprimetal results indicated that compacted high liquid limit clay with higher initial saturation had lower humidification speed , destructed slowlier, and had higher water stability. The unconfined compression strength and CBR of most pure high liquid limit clay and improved soils decreased with the increase of soaking duration. But CBR value of 4% lime-improved soils with water immersion increased within a porid. During drying-wetting cycles, the CBR value of the high liquid limit clay increased first and then decreased. The unconfined compression strength of improved high liquid limit soils improved with high dosage of lime or cement kept unchanged or decreased slightly and the soil still kept a high strength after multiple cycles.
