Volume-Change Behavior of a Compacted Low-Plasticity Clay From Double-Odometer Tests

The compressibility of compacted soils is not only a function of soil type and density but also stress state, which is influenced by the existing matric suction and can be described using the fundamentals of unsaturated soil mechanics. This paper presents data from double-odometer tests on low-plasticity clay that demonstrates the effects of dry density and water content on volume-change behavior. Using the data set developed, the drained constrained modulus is determined using the stress-strain relations obtained from conventional odometer tests on soaked specimens, as well as specimens at their molding moisture content. The change of modulus with respect to degree of saturation is discussed and placed in context with the model used in the Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures [ARA, ERES Consultants Division, 2004, "Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures," Final Report NCHRP Project 1-37A, Transportation Research Board of the National Academies, Washington, D.C.]. A procedure for predicting the undrained modulus from the constitutive relation for drained loading and the predicted excess pore pressure caused by loading based on a modification of Hilf's equation [Hilf, J. W., 1948, " Estimating Construction Pore Pressures in Rolled Earth Dams," Proceedings of the 2nd International Conference on Soil Mechanics and Foundation Engineering, Vol. 3, International Society for Soil Mechanics and Foundation Engineering (ISSMGE), London, pp. 234-240] is also presented and discussed.