ABSTRACT
In this paper some data about the Ko compression of a pumice sand a presented. Previous work obtained data on the one dimensional compression of pumice sand when tests were conducted at deformation rates of 20 mm/sec and 0.5 mm/min. Herein further tests are done in which controlled rate of deformation to investigate more clearly particle crushing effects, rate of deformation effects, and also relaxation of stress when the material is held at constant deformation after the completion of the controlled rate of deformation testing. The results indicate that the amount of particle crushing is a function both of the maximum vertical stress and the time for which the specimen is allowed to relax after the peak deformation is reached. Variations in specimen-to-specimen density were found to have a small but discernable effect on the results. The main conclusion of the paper is that particle crushing for this material has a time dependent aspect but that at very rapid rates of deformation the behaviour is different to that at slower rates.
