Development of low-carbon alkali-activated materials solely activated by flue gas residues (FGR) waste from incineration plants

Muhammad Riaz Ahmad, Chandra Sekhar Das, Mehran Khan, Jian Guo Dai

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34 Citations (Scopus)


Flue gas residues (FGR), a waste from incineration plant was utilized as an alternative alkaline activator to energy intensive and costly commercial activators. Fly ash (FA) and slag were used as precursors materials along with the FGR to produce low-carbon and cost-effective alkali-activated materials (AAMs). Reaction products and micromechanical properties were investigated by advanced microstructure analysis techniques. Results from the infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and nanoindentation indicated that reaction products were comprised of N-A-S-H gel as a major reaction product along with the hybrid gel (C–N-A-S-H) and C-A-S-H gel. SEM-EDS and nanoindentation results showed that the formation of C-A-S-H gel was directly related to the content of FGR. The increase in volume of Ca-based reaction products (C–N-A-S-H and C-A-S-H) was associated with the activation of slag in presence of Na2SO4. Besides N-A-S-H gel, some new reaction products (zeolite, apatite and berlinite) were also observed from XRD analysis of pastes. The compressive strength of AAMs was in the range of 33.5–39.6 MPa and was in line with microstructure analysis results. Leaching concentrations of Ag, Ba, Cd, Cu and Zn heavy metals in FGR were 0.10, 0.40, 0.63, 0.26 and 1.65 mg/L respectively and below the regulatory limits and it was classified as a non-hazardous material.

Original languageEnglish
Article number136597
JournalJournal of Cleaner Production
Publication statusPublished - 15 Apr 2023


  • Alkali-activated gel
  • Alternative alkaline activator
  • Flue gas residues
  • Heavy metal leaching
  • Reaction products

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Building and Construction
  • General Environmental Science
  • Strategy and Management
  • Industrial and Manufacturing Engineering


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