Solidification of coal fly ash using hydrothermal processing method

Z. Jing, N. Matsuoka, Fangming Jin, N. Yamasaki, K. Suzuki, Toshiyuki Hashida

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27 Citations (Scopus)


Solidification of Coal Fly-ash (CFA) has been carried out using a hydrothermal processing method. In the hydrothermal processing, the CFA was first compacted in a mold at 20 - 50 MPa, and then hydrothermally cured in an autoclave. The hydrothermal curing was performed at 150 - 250°C for 15 - 60 h. The experimental results showed that NaOH solution, Ca(OH) 2 content, compaction pressure, autoclave curing temperature and time significantly affected the strength of solidified bodies. The most important strength-producing constituent in the solidified bodies produced with CFA was tobermorite, or tobermorite-like calcium silicate hydrate. When the CaO/SiO 2 ratio of the starting material was close to 0.83, tobermorite readily formed and the formed tobermorite enhanced the strength of solidified bodies. The tensile strength determined by the Brazilian test reached more than 10 MPa under the hydrothermal processing. As such, the hydrothermal processing method may provide a high potential for recycling CFA on a large scale.

Original languageEnglish
Pages (from-to)1579-1584
Number of pages6
JournalJournal of Materials Science
Issue number5
Publication statusPublished - 2006 Mar 1

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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