Soil behavior during freezing and thawing using variable and constant confining pressure triaxial tests

Abstract

Although variable confining pressure (VCP) triaxial tests are generally preferred to constant confining pressure (CCP) triaxial tests due to the more realistic stress application, VCP tests have never been utilized when investigating freeze–thaw effects on unbound road materials. In this study, three soils were investigated for resilient behavior during freezing and thawing utilizing both VCP and CCP triaxial testing. The soils were tested at selected temperatures between +20 and –10°C during one full freeze–thaw cycle. The results were analyzed in terms of the traditionally used resilient modulus and Poisson's ratio, as well as volumetric and shear components, and indicate a significant difference in moduli computed from CCP and VCP data. However, resilient moduli display compatible values when interpreted in terms of mean values of deviator stress and mean normal stress. With regard to freezevthaw effects on resilient moduli, the results are inconsistent with previous findings. However, this can be explained by the different test conditions applied.Key words: freeze–thaw, triaxial tests, unbound pavement materials, subgrade soils, resilient modulus.