Copper and cobalt improve the acid resistance of alkali-activated cements

Experimental evidence of a new acid degradation mechanism in alkali-activated cements (AACs) micro-doped with copper (Cu) and cobalt (Co) is presented in this work. Cu and Co incorporation into binary metakaolin and basic oxygen furnace (BOF) slag-based AACs reduced bulk permeable porosity and acid...

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Bibliographic Details
Published in:Cement and concrete research 2019-01, Vol.115, p.327-338
Main Authors: Gevaudan, Juan Pablo, Caicedo-Ramirez, Alejandro, Hernandez, Mark T., Srubar, Wil V.
Format: Article
Language:English
Subjects:
Acid resistance
Alkalies
Basic converters
Calcium sulfate
Cement
Cements
Cobalt
Copper
Degradation
Electron probe microanalysis
Electron probes
Leaching
Magnesium
Metakaolin
Oxygen steel making
Porosity
Sulfuric acid
X-ray diffraction
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Summary:Experimental evidence of a new acid degradation mechanism in alkali-activated cements (AACs) micro-doped with copper (Cu) and cobalt (Co) is presented in this work. Cu and Co incorporation into binary metakaolin and basic oxygen furnace (BOF) slag-based AACs reduced bulk permeable porosity and acid penetration and retarded the formation of calcium sulfate phases upon exposure to acid. Analysis of microstructural evolution and elemental mobility using X-ray diffraction and electron microprobe analysis (EMPA) showed that Cu and Co doping was associated with major differences in AAC leaching patterns when exposed to sulfuric acid. Converging lines of evidence suggest that acid resistance is improved by the preferential mobilization of Cu and Co, along with other multivalent cations (i.e., magnesium), at the acid degradation front(s), stabilizing the AAC binder and inhibiting further deterioration.
ISSN:0008-8846
1873-3948
DOI:10.1016/j.cemconres.2018.08.002