TY - JOUR
T1 - The conditions of ettringite formation by the reaction of a blast furnace slag with aqueous alkaline solutions
AU - Harashima, Aya
AU - Ito, Kimihisa
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 2015
Y1 - 2015
N2 - Blast furnace (BF) slags have been utilized in cement, concrete aggregate, roadbed materials, and earthwork 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.
AB - Blast furnace (BF) slags have been utilized in cement, concrete aggregate, roadbed materials, and earthwork 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.
KW - Alkaline solution
KW - Blast furnace slag
KW - Ettringite formation
KW - PHREEQC
KW - Reaction kinetics
KW - Slag-leaching
KW - Thermodynamic calculation
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U2 - 10.2355/tetsutohagane.TETSU-2015-053
DO - 10.2355/tetsutohagane.TETSU-2015-053
M3 - Article
AN - SCOPUS:84946841754
VL - 101
SP - 566
EP - 573
JO - Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
JF - Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
SN - 0021-1575
IS - 11
ER -