Effects of soil pulverization level on resilient modulus and freeze and thaw resistance of a lime stabilized clay

Abstract

In this study, effects of soil pulverization level on resilient modulus of lime stabilized soils were studied through extensive laboratory testing. Resilient modulus tests were carried on both non-freeze and thaw and freeze and thaw samples. California Bearing Ratio (CBR) tests were also carried out. The soil used was a high plasticity soil. The soil was pulverized in two different soil pulverization levels, both of which complied with the relevant soil pulverization criteria. Resilient modulus tests were carried out on unstabilized and 4%, 6% and 9% hydrated lime stabilized samples. Curing days were 7, 28 and 56 days respectively. One group of samples were tested for resilient modulus after curing duration was completed, while the other group of samples were measured for resilient modulus after freeze and thaw cycles were applied according to ASTM D. 560-03 (2015). For non-freeze and thaw conditions, resilient modulus and soaked CBR values showed that soil pulverization level affected the resilient modulus and CBR values significantly and fine soil pulverization revealed higher resilient modulus and CBR values compared to coarse pulverization. Resilient modulus values were stress state dependent. Freeze and thaw cycles decreased the resilient modulus for all samples, while lime stabilized samples retained at higher resilient modulus values compared to unstabilized samples. The tests showed the importance of using higher lime contents and extended curing as well as fine soil pulverization for increased freeze and thaw resistance. Under freeze and thaw conditions, coarse soil pulverization could only be partially compensated using higher lime contents, which means significant higher environmental and economic costs. The data showed that if severe freeze and thaw cycles are anticipated in the region, construction planning for lime stabilized pavements should be carried out so that minimum two months of curing can occur beforehand. P wave velocities were measured on some selected samples using an ultrasound equipment and it was shown that they were capable of reflecting the trend in mechanical properties and therefore there is a potential that they can be used as index properties for lime stabilized soils. The results of this study highlight that soil pulverization level in lime stabilized soils is as important as lime content and therefore should be given enough consideration in field construction. Otherwise targeted soil properties cannot be achieved in the field.