A practical method for estimating maximum shear modulus of cemented sands using unconfined compressive strength

The composition of naturally cemented deposits is very complicated; thus, estimating the maximum shear modulus (G_max, or shear modulus at very small strains) of cemented sands using the previous empirical formulas is very difficult. The purpose of this experimental investigation is to evaluate the effects of particle size and cement type on the G_max and unconfined compressive strength (q_ucs) of cemented sands, with the ultimate goal of estimating G_max of cemented sands using q_ucs. Two sands were artificially cemented using Portland cement or gypsum under varying cement contents (2%–9%) and relative densities (30%–80%). Unconfined compression tests and bender element tests were performed, and the results from previous studies of two cemented sands were incorporated in this study. The results of this study demonstrate that the effect of particle size on the q_ucs and G_max of four cemented sands is insignificant, and the variation of q_ucs and G_max can be captured by the ratio between volume of void and volume of cement. q_ucs and G_max of sand cemented with Portland cement are greater than those of sand cemented with gypsum. However, the relationship between q_ucs and G_max of the cemented sand is not affected by the void ratio, cement type and cement content, revealing that G_max of the complex naturally cemented soils with unknown in-situ void ratio, cement type and cement content can be estimated using q_ucs.