Strength of biocemented sand-EPS mixtures
Yang Xiao, Qingyun Fang, Xiang He, Hao Cui, Jiuhao Ge, Hanlong Liu
Abstract
Sand-expanded polystyrene (EPS) mixtures are widely used to address soil self-weight issues. This study investigates the shear behavior of biocemented sand-EPS mixtures through drained triaxial tests, focusing on the effects of three key variables, i.e. EPS dosage, biotreatment level, and confining pressure. The results demonstrate that biocementation can effectively enhance both the strength and the stiffness of sand-EPS mixtures. Specifically, biotreated specimens exhibited significant improvements in dilatancy angle, peak and residual deviatoric stress, and peak and residual mean effective stress compared to untreated ones at the same EPS dosage and confinement. Furthermore, the effectiveness of biocementation decreases with increasing EPS dosage or confining pressure. Notably, the stiffness of the mixtures increases with higher biotreatment levels, particularly when the calcium carbonate content exceeds 3%. In addition, an empirical approach was developed to establish strength equations for specimens with specific calcium carbonate contents or EPS dosages. These equations could accurately predict the strength and peak or residual-state mean effective stress. This study expands the potential applications of biocementation and provides new insights into the development of sand-EPS geomaterials with enhanced mechanical properties.