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Novel synergy of Si-rich minerals and reactive MgO for stabilisation/solidification of contaminated sediment

2018; Elsevier BV; Volume: 365; Linguagem: Inglês

10.1016/j.jhazmat.2018.11.067

1873-3336

Lei Wang, Liang Chen, Dong-Wan Cho, Daniel C.W. Tsang, Jian Yang, Deyi Hou, Kitae Baek, Harn Wei Kua, Chi Sun Poon,

Recycling and utilization of industrial and municipal waste in materials production

Disposal of significant amounts of dredged contaminated sediment poses an economic and environmental problem worldwide. Transforming contaminated sediment into value-added construction materials using low-carbon MgO cement is a sustainable option; however, the weak mechanical strength and unreliable water-solubility of MgO cement restrict its practical engineering applications. This study elucidates the potential role of industrial Si-rich minerals in the performance enhancement of MgO-based products via the promotion of magnesium silicate hydrate (M-S-H) gel formation. Quantitative X-ray diffraction and 29Si nuclear magnetic resonance analyses indicated that compositions and crystallinities of the Si-rich minerals significantly influence the formation and polymerisation of the M-S-H gel. Pulverised fly ash was found to be a promising Si-rich mineral for generating polymeric M-S-H gel, whereas incinerated sewage sludge ash samples demonstrated a low degree of polymerisation, and the use of glass powder samples gave a low yield of M-S-H. The formation of M-S-H gel enhanced the compressive strength and water resistance (strength retention after water immersion). Further experiments demonstrated that Si-modified MgO cement can transform dredged sediment into fill materials with satisfactory mechanical properties and contaminant immobilisation. Therefore, the synergy between reactive MgO and Si-rich industrial waste is a novel option for sustainable remediation and environmental applications.