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

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

Research output: Journal article publicationJournal articleAcademic researchpeer-review

96 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)695-706
Number of pages12
JournalJournal of Hazardous Materials
Volume365
DOIs
Publication statusPublished - 5 Mar 2019

Keywords

  • Green/sustainable remediation
  • Metal immobilisation
  • Potentially toxic elements
  • Reactive magnesia cement
  • Waste valorisation/recycling

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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