title: Mixture design and treatment methods for recycling contaminated sediment.
abstract: Conventional marine disposal of contaminated sediment presents significant financial and environmental burden. This study aimed to recycle the contaminated sediment by assessing the roles and integration of binder formulation, sediment pretreatment, curing method, and waste inclusion in stabilization/solidification. The results demonstrated that the 28-d compressive strength of sediment blocks produced with coal fly ash and lime partially replacing cement at a binder-to-sediment ratio of 3:7 could be used as fill materials for construction. The X-ray diffraction analysis revealed that hydration products (calcium hydroxide) were difficult to form at high sediment content. Thermal pretreatment of sediment removed 90% of indigenous organic matter, significantly increased the compressive strength, and enabled reuse as non-load-bearing masonry units. Besides, 2-h CO2 curing accelerated early-stage carbonation inside the porous structure, sequestered 5.6% of CO2 (by weight) in the sediment blocks, and acquired strength comparable to 7-d curing. Thermogravimetric analysis indicated substantial weight loss corresponding to decomposition of poorly and well crystalline calcium carbonate. Moreover, partial replacement of contaminated sediment by various granular waste materials notably augmented the strength of sediment blocks. The metal leachability of sediment blocks was minimal and acceptable for reuse. These results suggest that contaminated sediment should be viewed as useful resources.
authors.affiliation: Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
authors.forename: June S H
authors.initials: JS
authors.lastname: Kwok
authors.affiliation: Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China. Electronic address: dan.tsang@polyu.edu.hk.
authors.forename: Daniel C W
authors.initials: DC
authors.lastname: Tsang
authors.affiliation: Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
authors.forename: Chi-Sun
authors.initials: CS
authors.lastname: Poon
mesh_terms: D002126:Calcium Hydroxide / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry; D060729:Coal Ash; D019245:Compressive Strength; D003252:Construction Materials / Q000191:economics; D019015:Geologic Sediments / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D059027:Recycling / Q000191:economics / Q000379:methods*; D014866:Waste Products; D014876:Water Pollution; D014961:X-Ray Diffraction
chemical_list: D002254:Carbonates; D060729:Coal Ash; D014866:Waste Products; D002245:Carbon Dioxide; D002126:Calcium Hydroxide
keywords: Carbon dioxide curing; Contaminated sediment; Stabilization/solidification; Thermal pretreatment; Waste recycling