Effect of Modified Metakaolin on Water Content of Hardened Cementitious Materials of Concrete

Abstract:

The effect of modified metakaolin (MMK) on the evaporable water and chemically bound water content of hardened cementitious materials have been investigated. Concrete specimens with 0%, 4%, 7% and 10% of MMK were included. Metakaolin was pre-modified in order to increase the dispersion and contact angle, which might further improve the workability of the concrete. The experimental results showed that both the evaporable water and bound water were increased with the increasing of the MMK content. MMK has a special layered structure. Water can get into the layers through this special layer during the mixing of concrete specimens. Part of MMK with water between the layers didn’t participate in the hydration reaction at the early stage of the hydration, which increased the evaporable water of the cementious materials. The water absorbed in MMK will be released to promote the formation of hydration products and thus the chemically bound water content will increase continuously at the later stages. It also reduced the autogenous shrinkage of the specimens which caused by the decrease of water in capillary pores at low water cement ratio (0.3).

• Periodical: Key Engineering Materials (Volume 599)
• Pages: 29-33
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.599.29
• Online since: February 2014
• Authors: Kang Wang*, Yu Ping Zhang, Ting Wei Cao, Jie Zhang, Zhong He Shui
• Keywords: Autogenous Shrinkage, Bound Water, Evaporable Water, Modified Metakaolin

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