Innovative study of non-steady-state tritiated water diffusion test

• Published in: Cement and concrete research 2007-08, Vol.37 (8), p.1145-1151
• Main Authors: Nugue, F., Yssorche-Cubaynes, M.-P., Ollivier, J.P.
• Format: Article
• Language: English
• Subjects: Applied sciences; Buildings. Public works; Characterization [B]; Concrete [E]; Concretes. Mortars. Grouts; Diffusion [C]; Exact sciences and technology; General (composition, classification, performance, standards, patents, etc.); Materials; Measurements. Technique of testing; Strength of materials (elasticity, plasticity, buckling, etc.); Structural analysis. Stresses; Transport properties [C]
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2007.02.012

The objective of this paper is to propose a new method for testing molecular diffusion in saturated cement materials. A saturated specimen of porous materials was placed between two compartments; the upstream compartment contained tritiated water (HTO) and the downstream compartment a solution without HTO. The activity gradient between the compartments induced a flux of tritiated water through the sample. Usually, the flux of HTO is repeatedly measured by analysing the content of the downstream cell in the steady state. In this work, a theoretical study based on Fick's laws is used to show that it is possible to determine the diffusion coefficient D Fick1 by considering only two measurements obtained in the non-steady state, in the downstream compartment of a diffusion cell. A significant saving of time (approximately half) can be obtained. An experimental study of this innovative method is presented.