Characterization of a Cemented Sand with the Pulse‐Velocity Method

Abstract

The effect of variation in cement content, initial water content, void ratio, and curing time on wave velocity (low-strain property) and unconfined compressive strength (large-strain property) of a cemented sand is examined in this paper. The measured pulse velocity is compared with predictions made using empirical and analytical models, which are mostly based on the published results of resonant column tests. All specimens are made by mixing silica sand and gypsum cement (2.5 to 20 % by weight) and tested under atmospheric pressure. The wave velocity reaches a maximum at optimum water content, and it is mostly affected by the number of cemented contacts; whereas compressive strength is governed not only by the number of contacts but also by the strength of contacts. Wave velocities measured in small and large specimens are used to calculate the Poisson's ratio of the cemented sand. Experimental relationships are developed for compressional wave velocity and unconfined compressive strength as functions of cement content and void ratio. Available empirical models under-predict the wave velocity (90% on average), likely because of the effect of micro-fractures induced by confinement during the testing. Wave velocity is found to be a good indicator of cement content and unconfined compressive strength for the conditions of this study.