TITLE:
Hydration of Portland Cement in the Presence of Highly Reactive Metakaolin
AUTHORS:
Alexey Brykov, Svetlana Krasnobaeva, Maxim Mokeev
KEYWORDS:
Metakaolin, Portland Cement, Hydration, MAS NMR, Pozzolanic Reaction
JOURNAL NAME:
Materials Sciences and Applications,
Vol.6 No.5,
May
15,
2015
ABSTRACT: The degree of conversion of highly reactive metakaolin in Portland cement metakaolin paste at
different ages as well as the influence of metakaolin on the degree of hydration of Portland cement
and composition of C-S-H is investigated by27Al- and 29Si-MAS NMR spectroscopy. At the age of 7
days, in the paste with 10% of metakaolin, the additive is completely consumed. In the 30% substituted
cement paste, the content of metakaolin remains quite high (about 40% of the initial
amount) even after 3 months of hydration. At the age of 1 - 3 months, the degree of Portland cement
hydration in the presence of metakaolin is of 15% - 20% less than without it, probably, due
to deficit of water or spatial restrictions. After 7 days of hydration, about half of C-S-H consists of
material derived from metakaolin. Metakaolin mainly contributes to Q2 and Q2 (1Al) species,
whereas PC does to Q1. After 1 day of hydration, an amount of ettringite in cement paste with high
dosage of metakaolin is higher than in pure PC paste.