Structure, Mechanisms of Reaction, and Strength of an Alkali-Activated Blast-Furnace Slag

This research examines the chemical activation of blast‐furnace slag pastes with alkaline solutions by means of various characterization techniques. Pastes were activated using sodium silicate solutions with modulus (Ms) of 0, 1, 1.5, 2, and Na2O at 5%, 10%, and 15%. Compressive strengths of up to 1...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2013-12, Vol.96 (12), p.3939-3948
Main Authors: Burciaga-Díaz, Oswaldo, Escalante-García, José Iván
Format: Article
Language:English
Subjects:
Activated
Alkalies
Chemical reactions
Diffraction
NMR
Nuclear magnetic resonance
Silica
Slag
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Summary:This research examines the chemical activation of blast‐furnace slag pastes with alkaline solutions by means of various characterization techniques. Pastes were activated using sodium silicate solutions with modulus (Ms) of 0, 1, 1.5, 2, and Na2O at 5%, 10%, and 15%. Compressive strengths of up to 108 MPa were achieved for Ms = 1–1.5 after 720 d of curing at 20°C. The addition of Na2O > 10% resulted in the formation of hydrotalcite and carbonated pastes with low compressive strength. X‐ray diffraction, microanalysis of outer products (OP), and nuclear magnetic resonance (NMR) results showed that the main reaction products in the activated cements with Ms = 1 and 5%Na2O had an average ratio Ca/Si = 0.71–0.9 and consisted of a mixture of two kinds of C–S–H; one similar to a 9 Å tobermorite‐type calcium silicate hydrate (Ca5Si6O16(OH)2 and other amorphous related to a cross‐linked structure of C–N–(A)–S–H gel. Both were intermixed with hydrotalcite and cross‐linked structures of silica gel.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.12620