Effectiveness of metakaolin in mitigating ASR with respect to bet surface and crystal water

Author(s): M. Sahmaran, G. Yildirim, H.E. Yucel
Paper category: Conference
Book title: 2nd International conference on Microstructural-related Durability of Cementitious Composites
Editor(s): Guang Ye, K. Van Breugel, Wei Sun, Changwen Miao
Print ISBN: 978-2-35158-129-2
e-ISBN: 978-2-35158-123-0
Publisher: RILEM Publications SARL
Pages: 1333- 1343
Total Pages: 10
Language: English

Abstract: The BET surface and crystal water of metakaolin influence the reduction of the pH value and K⁺/Na⁺ ion concentration in pore solutions and the increase of dense structure, which are two main reasons for the resistance in alkali silica reaction (ASR) of metakaolin products. In this investigation, the influence of three different metakaolin kinds on the resistance of ASR was studied. The first metakaolin kind (called a Mnw) has no crystal water, while the second kind has crystal water (called a Mw) and the highest BET surface. The third metakaolin kind has no crystal water, a finer particle size distribution but a lower BET surface (called M1f-nw and M2f-nw).

Pore solution compositions and pH value from blended pastes were investigated at 20°C and 70°C. Expansion tests were done for mortar bar tests according to the German Alkali-Guideline (2007) alternative method.

In this investigation, Mw showed the mitigation of ASR as good as other metakaolin like Mnw, M¹f-nw and M²f-nw. The achieved results showed that, it is not necessary for metakaolin to be a “real” metakaolin that has no crystal water content in the mineral structure, and a high thermal energy is not needed for the calcination.

Online publication: 2013
Publication Type: full_text
Public price (Euros): 0.00