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

Abstract

<p>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 (<em>q</em>_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 <em>q</em>_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 <em>q</em>_u is inversely proportional to the water to <a href="https://www.sciencedirect.com/topics/materials-science/cementitious-material" title="Learn more about cementitious materials from ScienceDirect's AI-generated Topic Pages">cementitious materials</a> ratio (W/C). For a given W/C, the <em>q</em>_u increases with the soil to cementitious materials ratio (S/C).<br></p>