Resilient-modulus degradation of low-plasticity clays due to coal combustion residuals

Abstract

Coal combustion residuals (CCR) are waste products generated during the operation of coal-fired electric power stations, but the effect of CCR inclusions on the deterioration of road infrastructure at or near power plants remain uncertain. This study measured the resilient modulus (Mr) of low-plasticity clay (FS) mixtures with different proportions of CCR obtained from a coal-fired power station, without any additional cementitious substances or stabilizers. Resilient moduli were determined for both the raw materials (FS and CCR) and for mixtures ranging between 10% and 40% CCR by weight. All materials were characterized physically, chemically, and mineralogically. Resulting physical and mechanical-behavior parameters were compared across the CCR content range, specifically the change in index properties, USCS classification, maximum dry density, and resilient-modulus degradation. Results highlight the strong dependence of the soil’s resilient moduli on water content due to the inherent partially-saturated character of the material.