Acceleration of GGBS Cements by Chloride, New Insights on Early Hydration

Author(s): Steger L., Patapy C., Salesses B., Chaouche M. and Cyr M.
Paper category: Proceedings
Book title: Proceedings of International Conferences (ICACMS) Advances in Construction Materials and systems Vol 2
Editor(s): Manu Santhanam, Ravindra Gettu, Radhakrishna G. Pillai, Sunitha K. Nayar
ISBN: 978-2-35158-194-0
e-ISBN: 978-2-35158-191-9
Publisher: RILEM Publications SARL
Publication year: 2017
Pages: 126-133
Total Pages: 8
Language : English

Abstract: The substitution of ordinary Portland cement (OPC) by large proportions of ground granulated blast furnace slag (GGBS) reduces the early hydration kinetics, causing a slower development of mechanical strengths. Chlorides are well known for their accelerating effect on ordinary Portland based cements but are mostly used for specific applications such as non-reinforced concretes, due to their detrimental effects regarding the corrosion of steel bars. However GGBS based concretes are known for their ability to resist chloride ingress because of their refined porosity and their capacity to fix more chlorides in hydrates, reducing the free chlorides available for corrosion. Some studies have shown the positive effects of chloride products for early strength development of high-GGBS-content concretes, without an investigation of the microstructure development, and several works studied the effects of chlorides on OPC hydration during the 1980’s-90. From these studies, many hypotheses have been put forward, such as the impact of different anhydrous phases (C3S, C3A, GGBS, etc.) on dissolution kinetics and the nature of products, but the question has not been definitely settled. This experimental work brings new insights in to the interactions of chlorides/GGBS blends, including in-situ XRD monitoring of early age hydration for the crystalline phases (AFt, AFm, calcium sulphates, etc.). Scanning Electronic Microscope observations are used
at early age of hydration to observe dissolution/precipitation phenomena at the surface of GGBS grains and in the fluid filled areas.

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