New density normalization approach for evaluation of the cyclic resistance of silts

This paper proposes a new normalization approach to replace relative density when evaluating the cyclic resistance of silty soils. Normalization of dry density is advantageous because it captures the combined effects of void ratio and fabric on strength for similar soil types. Relative density is commonly used to normalize the dry density or void ratio of sands with fines contents less than 15%, however there is currently no such standard for silts. The approach presented in this paper involves normalizing the dry density of a specimen by the maximum dry density obtained from a Modified Proctor test at a specific degree of saturation (or molding water content). Cyclic triaxial tests were performed on samples of four similar non-plastic silts from Rhode Island. Samples were prepared using a modified moist tamping approach at molding water contents corresponding to a degree of saturation of 55%. Previous work by the authors showed that samples prepared at this degree of saturation yielded the same cyclic resistance as samples prepared from a slurry and carved from an intact block. Samples of four different silts prepared to the same relative density had different cyclic strengths. Samples prepared to the same normalized density yielded the same cyclic strength suggesting that normalized density could be a useful approach for silty soils. © 2012 American Society of Civil Engineers