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Activation of Ground Blast‐Furnace Slag by Alkali‐Metal and Alkaline‐Earth Hydroxides
Author(s) -
Roy Amitava,
Schilling Paul J.,
Eaton Harvill C.,
Malone Philip G.,
Brabston W. Newell,
Wakeley Lillian D.
Publication year - 1992
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1992.tb04416.x
Subject(s) - ground granulated blast furnace slag , thermogravimetry , alkali metal , chemistry , ionic radius , alkaline earth metal , inorganic chemistry , metal , ionic bonding , nuclear chemistry , mineralogy , ion , fly ash , organic chemistry
The effects of pH, time, valence, and radius of the activator cation on the reaction products and microstructure of ground granulated iron blast‐furnace slag were studied by thermogravimetry and derivative thermogravimetry, X‐ray diffractometry, scanning electron microscopy, and energy dispersive X‐ray microanalysis. Blast‐furnace slag was activated by alkali‐metal hydroxides of Li, Na, and K (12.34 pH 14.71) and alkaline‐earth hydroxides of Ca, Sr, and Ba(12.47 pH 13.53) using a water/slag ratio of 0.4 and curing for 1 day to 26 months. Reactivity of the slag was more strongly dependent on pH than on time. The reaction products were mainly varieties of C─S─H, (C,M) 4 AH 13 , and minor amounts of Ca(OH) 2 and C 2 ASH 8 (strätlingite). The nature of C─S─H was dependent on pH. A 1.2‐nm peak appeared in X‐ray diffractograms only when the activation pH was ⌣14.7. Water was present in the C─S─H in a way similar to water in tobermorite and synthetic C─S─H. Leached Ca from unreacted blast‐furnace slag was present around the glass particles as an amorphous layer which crystallized into Ca(OH) 2 with time; Mg behaved similarly. The effect of the charge or ionic radius of the activator cation was insignificant.