Dynamic Shear Modulus And Damping Of Cemented And Uncemented Lightweight Expanded Clay Aggregate (Leca) At Low Strains

Lightweight expanded clay aggregate (LECA) is a geomaterial that is low in density, porous, and has an enamel surface. A series of unconfined compression and resonant column tests were performed to understand the dynamic performance of LECA. Testing results show that the uncemented LECA is poorly graded but possesses a stable internal structure. The initial shear modulus, shear modulus reduction, and increase in damping with shear strain of uncemented LECA exhibits pressure-dependence. However, for cemented LECA, the increase in cement content and confining pressure leads to significant increases in the strength and stiffness, as well as greater nonlinearity in the dynamic shear modulus reduction. An empirical power law was recommended to describe the relationship between initial shear modulus and unconfined compressive strength. Cemented LECA exhibited larger damping characteristics than uncemented LECA for the range in strains investigated. The minimum damping ratio of LECA with a high cement content may exceed 5.0%, and generally increases with increasing confining pressure. Empirical equations were proposed to describe the modulus and damping ratio trends of LECA at low strains, and these relationships were compared to other geomaterials. The results were placed in the context of the application of LECA as an engineered backfill.