The Effect of Metakaolin on Delayed Ettringite Formation of the Heat-Cured Mortars

Author(s): Van-Huong Nguyen, Nordine Leklou, and Pierre Mounanga
Paper category: Proceedings
Book title: Proceeding of the 71st RILEM Annual Week & ICACMS 2017
Editor(s): Manu Santhanam, Ravindra Gettu, Radhakrishna G. Pillai, Sunitha K. Nayar
ISBN:978-2-35158-195-7, 978-2-35158-190-2 (Set)
e-ISBN: 978-2-35158-191-9
Publisher: RILEM Publications SARL
Publication year: 2017
Pages: 343-352
Total Pages: 10
Language : English

Abstract: Delayed ettringite formation (DEF) is a type of internal sulfate attack caused by heat-induced decomposition and/or prevention of normal ettringite formed during the initial hydration of cement at elevated temperature (above about 70°C) and its re-crystallization in the hardened matrix. DEF is a physico-chemical phenomenon inducing an expansion of the cement paste that could lead to cracking of concrete. In this paper, the effect of metakaolin on DEF of the heat-cured mortars was investigated. To fulfil the aim of this study, a portion of cement was replaced by metakaolin, with three different dosages (10, 20 and 30%). The mortars were heat-cured at early-age, and the tests of expansion, strength, dynamic elastic modulus, mercury porosity and thermogravimetric analysis were carried on these mortars for a period of 650 days. Additionally, scanning electron microscopy (SEM) observations were realized. The test results obtained highlighted the mitigation effects of metakaolin on DEF. Keywords: Delayed ettringite formation, concrete, heat-cured mortar, metakaolin, expansion

Online publication :2017
Publication type :full_text
Public price (Euros) : 0.00