Mechanical behaviour of Hong Kong marine deposits stabilized with high content of coal fly ash

Dredged marine deposits are a major source of solid wastes in Hong Kong, which need suitable sites to dump. This study investigates the potential of using dredged marine deposits stabilized with coal fly ash as construction materials for reclamation to enhance sustainability. A series of unconfined compression tests were performed on sandy and clayey Hong Kong marine deposits stabilized with high content of coal fly ash, to reveal their stress–strain behaviour and failure modes, and to evaluate the factors affecting their unconfined compressive strength (q_u). Results show that the stress–strain behaviour of the stabilized soil shifts from ductile to brittle with increasing fly ash content, curing period and decreasing water content. The q_u increases marginally by further increasing the fly ash content from 30% to 40% and it attains much higher values (maximum 2.29 MPa) in the sandy samples than those (maximum 0.29 MPa) in the clayey ones. In general, brittle samples with higher strength fail in axial splitting mode while ductile samples with lower strength fail in shear or multiple shear fractures mode. The q_u is inversely proportional to the water to cementitious materials ratio (W/C). For a given W/C, the q_u increases with the soil to cementitious materials ratio (S/C). © 2023 Elsevier Ltd