Recycling contaminated sediment into eco-friendly paving blocks by a combination of binary cement and carbon dioxide curing

Lei Wang, Tiffany L.K. Yeung, Abbe Y.T. Lau, Chiu Wa Tsang, Chi Sun Poon

Research output: Journal article publicationJournal articleAcademic researchpeer-review

38 Citations (Scopus)

Abstract

This study demonstrated an innovative approach to transform contaminated sediment into eco-friendly sediment blocks by applying binary cement and CO2curing. The binary use of magnesium oxide cement (MOC) and ordinary Portland cement (OPC) with air curing improved the compatibility of heavy metals and cement by provision of sufficient magnesium hydrates for metal sequestration. However, an introduction of MOC weakened compressive strength and increased water absorption of sediment blocks. Therefore, 1-d CO2curing was employed to transform soluble magnesium hydrate into stable carbonates, and densify the microstructure and reduce the porosity from 18.5% to 16.9%, which enabled a substantial enhancement in strength (2.8 times) as well as carbon sequestration (3.98 wt%) in 40% MOC sample. A subsequent 7-d air curing with moisturizing facilitated continuous carbonation and rehydration of binary cement, resulting in a deeper carbonation and higher strength by the provision of additional nucleation sites of reactive magnesium oxide. Although accelerated carbonation had an adverse influence on metal immobilization in OPC sample due to pH decrease, it provided synergistic interaction with binary cement samples due to sufficient hydrates and pH buffering capacity. Therefore, binary cement with CO2curing presents a novel and green stabilization/solidification technology for recycling contaminated sediment as valuable and eco-friendly construction materials.
Original languageEnglish
Pages (from-to)1279-1288
Number of pages10
JournalJournal of Cleaner Production
Volume164
DOIs
Publication statusPublished - 15 Oct 2017

Keywords

  • Carbon sequestration
  • Contaminated sediment
  • Magnesium oxide cement
  • Paving blocks
  • Stabilization/solidification
  • Waste recycling

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Science(all)
  • Strategy and Management
  • Industrial and Manufacturing Engineering

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