IMPACT OF DRYING RATE ON DELAYED STRAINS IN CEMENT- BASED MATERIALS

Author(s): Justin Kinda (1,2), Laurent Charpin (1), Jean-Luc Adia (1), Farid Benboudjema (2), Sylvie Michel-Ponnelle (3), Paper category: Proceedings
Book title: SynerCrete’18 International Conference on Interdisciplinary Approaches for Cement-based Materials and Structural Concrete
Editor(s): Miguel Azenha, Dirk Schlicke, Farid Benboudjema, Agnieszka Jędrzejewska
ISBN: 978-2-35158-202-2
e-ISBN: 978-2-35158-203-9
Publisher: RILEM Publications SARL
Publication year: 2018
Pages: 719-723
Total Pages: 5
Language : English

Abstract: A part of the concrete containment buildings (CBB) in French nuclear power plants operated by EDF are double-walled CBBs. The concrete of the post-tensioned inner containment building plays a major role as a barrier against radiological release during a hypothetical accident. The leak-tightness of the inner CCB depends vastly on the pre-stress. If it is too low due to pre-stressing cable relaxation or concrete creep and shrinkage, some parts of the concrete might experience tension during the integrated leak rate test (performed every 10 years) or an accident, inducing cracking and an increased leakage.
Therefore, EDF builds simulation tools dedicated to the prediction of strains in CCBs, which
requires properly calibrated models. Most of the time models are calibrated on laboratory test on rather small samples, while CCBs are very large structures. These different concrete thicknesses induce vastly different drying kinetics. Thus, the concrete constitutive laws should be able to correctly take into account the effect of the rate of drying on the delayed strains (creep, shrinkage) of concrete.
As an introduction to this subject, it has been decided to work on the experimental data provided by literature.
The set of experimental data is first simulated with a delayed strains law used at EDF R&D [2]. Second, the microprestress-solidification law [3] (which was implemented for this purpose) is used.
It is shown that both these constitutive laws can reproduce the main features of the shrinkage and creep tests, but also that the experimental program lacks some information to be truly discriminant. This motivates further experimental developments which will be undergone in the future.

Online publication : 2018
Publication type : full_text
Public price (Euros) : 0.00