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Rapid determination of the oh- content in the aqueous phase of hardened cementitious materials by a leaching method: validation for different binders.



Title: Rapid determination of the oh- content in the aqueous phase of hardened cementitious materials by a leaching method: validation for different binders.
Author(s): M. Castellote
Paper category : conference
Book title: Third International RILEM Workshop on Testing and Modelling Chloride Ingress into Concrete
Editor(s): C. Andrade and J. Kropp
Print-ISBN: 2-912143-48-9
e-ISBN: 2912143578
Publisher: RILEM Publications SARL
Publication year: 2004
Pages: 193 - 203
Total Pages: 11
Nb references: 18
Language: English


Abstract: Chloride threshold is one of the key parameters needed for service life prediction of concrete structures. The most rigorous expression of this parameter seems to be in terms of the Cl-/OH- ratio due to the competitive action of both ions and to the fact that it also accounts for the different cement types and their evolution with time. However, the experimental determination of this parameter has not always been possible as squeezing of hardened cementitious materials at high pressures to extract their aqueous phase is not an available technique for most laboratories. Therefore, some methods have recently aroused to undertake this determination by leaching methods, mainly for chlorides. Recently, the authors developed an empirical leaching method for determining the concentration of hydroxyl ions in the aqueous phase of hardened cementitious materials considering different binders and phenomena (dilution + dissolution of solid phases) occurring during leaching. However, it had only been validated for OPC cements. In this paper, the method has been tested for different binders, including OPC, calcium aluminate cement, slag cement, and additions of fly ashes and silica fume. As a result, the empirical leaching method developed for determining the hydroxyl content in the pore phase of cementitious materials has been validated and the same empirical factor, for the different binders tested has been obtained. Therefore, it could be said that, in spite of the fact that fully understanding of the leaching mechanism is not achieved, the empirical method developed is of general application.


Online publication: 2002-12-15
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143578.012