Laterite soil is one kind of high plastic clay being very sensitive to environmental heat and moisture variation

and mixing optimal ratio of lime into laterite soil is made when construction to improve pavement performance and prolong the life span. Engineering properties of subgrade are obviously affected by soil moisture state and its drying-wetting history during excavation and exertion of the expressway. Experimental investigations on strength and deformation properties of lime-treated laterite soil and laterite soil are carried out

considering two drying-wetting paths which are exactly accordant with practices. The results indicate that: with uniformity drying-wetting cycles

lime-treated soil

internal friction angle increase a little and cohesive strength decrease with shearing strength reducing and pavement performance has not improved greatly. With directional drying-wetting cycles

lime-treated soil have less drying-shrinking cracks with unconfined compression strength and deformation resistance decreasing a little and the long-term strength and deformation performance enhanced significantly.