STRENGTH AND STRESS-STRAIN CHARACTERISTICS OF A LIME-TREATED COHESIVE SOIL

Strength and stress-strain characteristics of a cohesive soil in natural and lime-treated states were investigated and compared. For this purpose, a cohesive soil from a semiarid region in Jordan was selected and subjected to various laboratory tests. The experimental program involved three levels of treatment (3, 6, and 9%) with hydrated lime and a range of curing times (0, 7, 14, 21, and 28 days). The experimental results indicated that increasing the percent lime increases grain size, calcium ions, and the pH value, whereas it decreases the plasticity index, sodium ions, and dispersion. The compaction characteristics of the soil studied were not significantly affected by lime. Furthermore, the unconfined compressive strength and the undrained angle of internal friction increased because of the addition of lime and curing time. The undrained cohesion decreased with lime treatment up to 3% and increased for lime content greater than 3%. The lime treatment strength ratio (LSR), defined as the ratio of the unconfined compressive strength of a treated specimen to an untreated one, was introduced. Greater values of LSR indicate that lime is more effective in stabilizing the soil as far as strength is concerned. For the soil studied, LSR increased both with lime percentage and curing time. In addition, the undrained modulus increased significantly for values of LSR between 1.0 and 2.0. For LSR greater than 2.0, the increment in undrained modulus was much smaller.