The making of Class C fly ash as high-strength precast construction material through geopolymerization

Jinhong Zhang, Qingming Feng

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


A study has been carried out to apply fly ash as a high strength, water-resistant precast construction material through geopolymerization. Experiment results show that the working conditions such as water content, the concentration of NaOH, curing temperature, and curing time significantly affect the mechanical property of geopolymer matrix. Through optimization, an above-100 MPa compressive strength has been achieved with the geopolymerization products. The optimum working conditions involves 10 M NaOH concentration, 14–15% water content, and curing at 90 °C in an oven for 1 day or at ambient condition for 3 weeks. Adding Ca(OH)2 does not help to increase the compressive strength of the specimen. Water soaking tests show that the geopolymerization product has a very high water resistance without losing noticeable compressive strength, even after a 1-month soaking time. To elucidate the geopolymerization mechanism, microscopic techniques such as SEM/EDS (scanning electron microscopy and energy-dispersive X-ray spectroscopy), XRD (X-ray diffraction) and ATR-FTIR (attenuated total reflectance Fourier transform infrared) are also applied to investigate the microstructure, the elemental and phase composition of geopolymerization products. The findings of the present work provide a novel method for applying fly ash as a high-strength water-resistant precast construction material.

Original languageEnglish (US)
Pages (from-to)1603-1616
Number of pages14
JournalMining, Metallurgy and Exploration
Issue number5
StatePublished - Oct 1 2020


  • Alkali activation
  • Compressive strength
  • Fly ash
  • Geopolymerization
  • Water-resistant

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Chemistry(all)
  • Geotechnical Engineering and Engineering Geology
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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