Recycling dredged sediment into fill materials, partition blocks, and paving blocks: Technical and economic assessment

Management of dredged sediment has been a worldwide challenge. Conventional off-site marine disposal of contaminated sediment incurs substantial cost implications and secondary pollution risks. This study developed value-added and time-effective approaches that transform contaminated sediment into construction materials to be used as fill materials, partition blocks, and paving blocks. The technical viability and economic feasibility of different binder/mixture designs and production methods were assessed. Thermogravimetric and X-ray diffraction analyses showed that contaminated sediment hindered hydrates formation and adversely influenced the properties of sediment-based products. Samples with 5 wt% binder could only fulfil strength requirements of fill materials. Tailored mixture designs with dry-mix/press method improved the precipitation reactions and densified the porous structure, which enhanced the performance and conformed to the requirements of partition blocks and even paving blocks. The leaching concentrations of potentially toxic elements and organic contaminants from the dredged sediment were substantially reduced by stabilization/solidification, which satisfied the leachability acceptance criteria for its on-site reuse. Moreover, cost and benefit assessment illustrated that the production of all three studied sediment-based products was potentially profitable, of which the scenario recycling sediment into paving blocks showed the highest profit. This novel solution can effectively mitigate burden of dredged sediment disposal and produce green construction materials in a sustainable way.