The conditions of ettringite formation by the reaction of a blast furnace slag with aqueous alkaline solutions

Aya Harashima, Kimihisa Ito*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Blast furnace (BF) slags have been utilized in cement, concrete aggregate, roadbed materials, and earth-work materials. If an appropriate control of the elution and compound formation is developed under severer environmental conditions, their usage would be more diverse. Because the chemical composition of BF slag is similar to that of Portland cement, the possibility of ettringite (3CaO·Al2O3·3CaSO4·32H2O) formation from BF slag following a mechanism similar to that of cement hydration might be possible under a wet alkaline environment. Therefore, the effect of an alkaline solution on ettringite formation from BF slags was investigated by slag-leaching experiments and thermodynamic calculations using PHREEQC. The formation of ettringite was observed only for the high pH solutions in the experiments, whereas its thermochemical possibility from the air-cooled BF slags was always expected by the calculation. The kinetic analysis showed that the dissolution of alumina from the slag may control the whole reaction rate. The mixing of granulated BF slag with air-cooled ones tended to enhance the ettringite formation. Furthermore, a technique for removing the ettringite formed in the slag was also developed.

Original languageEnglish
Pages (from-to)1738-1745
Number of pages8
Journalisij international
Issue number10
Publication statusPublished - 2016


  • Alkaline solution
  • Blast furnace slag
  • Ettringite formation
  • Reaction kinetics
  • Slag-leaching
  • Thermodynamic calculation

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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