Hydration of calcium sulfo-aluminate cement in presence of zinc chloride

Title: Hydration of calcium sulfo-aluminate cement in presence of zinc chloride
Author(s): S. Berger, C. Cau Dit Coumes, P. Le Bescop, D. Damidot
Paper category : conference
Book title: International Conference on Microstructure Related Durability of Cementitious Composites
Editor(s): W. Sun, K. van Breugel, C. Miao, G. Ye and H. Chen
Print-ISBN: 978-2-35158-065-3
e-ISBN: 978-2-35158-084-4
Publisher: RILEM Publications
Publication year: 2008
Pages: 67 - 76
Total Pages: 10
Nb references: 18
Language: English

Abstract: The structural flexibility of the two mains hydrates, ettringite and calcium monosulfoaluminate hydrate, produced by calcium sulfoaluminate cements (CSA cements) hydration may give rise to chemical entrapment of some heavy metals salts, such as ZnCl2.
The properties of mortars made with CSA cement (mechanical strength and length changes) and their hydration process were thus investigated (by calorimetric and XRD measurements) as a function of various parameters: the gypsum content of the CSA cement (from 0 to 35%), the composition of the mixing solution (either pure water, or a ZnCl2 solution with a variable concentration ranging from 0 to 0.5 mol/L) and the thermal evolution at early age, with a view to develop a cementitious material to stabilize Zn-rich waste. Increasing the gypsum content accelerates the hydration process but decreases the total heat of hydration. The precipitation of ettringite is promoted and the porosity increased. The influence of zinc chloride on hydration depends both on the zinc concentration in the mixing solution and on the gypsum content. The thermal history of the cement-based material is also a key parameter since it modifies the rate of hydration, the mineralogy of the cement paste and the macroscopic properties of mortar samples as mechanical strength.

Online publication: 2009-06-09
Publication type : full_text
Public price (Euros): 0.00