Comparison the resilient modulus behavior of untreated and treated soil by lime as base and subbase

Due to the sharp reduction in budget of civil projects and road construction, the need to use local soil as the base is felt as a way to reduce the final cost of projects. Therefore, this research examines the characteristics of untreated and treated base soil with 3% lime, including uniaxial compressive strengths and indirect tension (Brazilian) test and resilient modulus with different curing times, as well as after performing tests of wet -dry cycles and freezing- thawing. Uniaxial and Brazilian samples with a diameter of 10.1 cm and a height of 11 cm were made in 3 layers with the same thickness and dry density of 2.2 g/cm3 and initial moisture of 6% and 8%. The results show that the addition of lime significantly increases the CBR values and shear strength of the soil. Soil treatment with lime improves its resistance against wetting-drying cycles, but it is not suitable against freezing- thawing cycles. Also, based on the tests to determine the resilience modulus, a comparison was made to determine the relationship between CBR values of untreated and treated soil with lime under hot-dry weather conditions. The results showed that the modulus values of dry untreated soil and lime treated soil are equal. The CBR value (maximum value based on penetration of 2.5 mm or 5 mm) in untreated soil is equal to the same value for penetration of 1.25 mm in lime treated soil. Therefore, for design purposes, it is recommended to use correlation relations of resilience modulus and CBR values for penetration of 1.25 mm for soil treated by lime.