Reusing dredged marine clay by solidification with steel slag: A study of Compressive strength

Construction of marine structures as well as maintenance of shipping channels produce large amount of dredged materials. The dredged soils, generally categorized as marine clays, consist of clay minerals, sand, pebbles and fragments of shells. As it is considered unfeasible from an environmental point of view to discard the material in open sea, the dredged soils need to be disposed off in man-made facilities, like bulkheads and landfill. Various efforts were directed at reusing the material by pre-treatment with chemicals or proprietary substances. While these endeavors have shown successes, the high incurred costs and potentially hazardous modification of the dredged soils to surrounding environment have prevented wider applications. This paper describes an exploratory study to solidify dredged marine clays with steel slag, a waste product of the steel manufacturing process. Cementing properties of the slag enabled the clay structure to be strengthened for possible reuse or stabilized containment. The study showed that while the steel slag can effectively solidify dredged materials, several key factors which affect the strength enhancement must be taken into account. These include slag dosage, mixing water content, pre-treatment of the slag and different clay minerals.