The roles of biochar as green admixture for sediment-based construction products

Routine navigational dredging generates huge quantities of marine sediment, posing significant environmental and economic burden. This research intended to explore the efficacy of wood waste biochar as a green admixture and assess the influence of different physico-chemical properties of dredged sediments on the mechanical performance of cement-based sediment products. X-ray diffraction and porosimetry analysis reflected that particle size distribution of sediments determined the pore structure formation and strength development. Thermal and calorimetry analyses showed that biochar incorporation slightly enhanced the cement hydration reaction, while its relatively large and brittle particles induced microcracks and weakened the strength of sediment products. Nevertheless, biochar addition enhanced immobilization of potentially toxic elements and organic contaminants, rendering the sediment products more environmentally acceptable. Hence, the innovative approach of this study can recycle dredged sediment and waste wood biochar to produce eco-friendly construction materials such as fill material and paving blocks. [Display omitted] •Dredged sediment could be recycled into value-added construction products.•Particle size distribution of sediments determined strength of sediment products.•Biochar incorporation had a beneficial effect on cement hydration reaction.•Yet biochar addition may incur micro-crack and reduce mechanical strength.•Biochar immobilized contaminants and promoted environmental acceptability.