Volume 29, Issue 4 (July 2006)
A New Setup for Measuring Go during Laboratory Compaction
Soil stabilization by compaction plays an important role in foundation engineering, both for construction and maintenance. Compaction specifications often require achievement of an in situ dry density (ρd) of 90–95% of the maximum value obtained from laboratory standard or modified Proctor test. However, ρd is not a design parameter per se; it is rather used to infer other parameters such as strength and stiffness through some empirical relationships. This paper describes a setup and procedure by which the small-strain (dynamic) shear stiffness can be measured accurately by propagating elastic shear wave through the stabilized material during laboratory compaction. The method enables measurement of the shear modulus [Go(ij)] in both horizontal and vertical planes. The ratio between Go in these two orthogonal planes (i.e., Ghh and Ghv) is a measure of the degree of stiffness anisotropy, and this could be used as input parameter in deformation calculations. The setup is designed so that it can be readily incorporated into the familiar Proctor test.