POST DOCTORAL POSITION - Steam-air permeability of cracks

1. Scientific Context

The proposed work will be done within the context of the extension of the French program MACENA whose purpose was to impulse significant progress in the modeling and numerical simulation of the safety of nuclear vessels under a potential accident. The MACENA program allows the community to better understand the effects of temperature and relative humidity on the instantaneous and delayed behavior of concrete [1]–[4], to make significant progress in the computation of the permeability to gas or water of concrete, even when cracked [5]–[8]. Unfortunately, this program wasn’t able to extend the problems of permeability to vapor. MACENA program is prolonged to MACENA-2 in the purpose of extending the knowledge of phenomena acting during an air vapor mixing through cracked concrete.

The MACENA-2 project puts in synergy 4 teams:

• EDF research is in charge of the numerical modelling in relation with the other teams. EDF will improve an existing finite element code during this project.
• University of Bordeaux whose purpose is to observe the phase changing during the flow at a small scale using a transparent porous.
• University of Pau & Pays Adour is will perform some experiment at the decimetric scale on perfect planes and real cracks on concrete at high temperature.
• University of Grenoble will do some neutron radiography of flow experiment through cracked concrete

II. Objectives

The objectives of the proposed work are :

• To perform scientific experiments of air-vapor flow through cracked concrete.
• To understand the coupling between thermal exchanges, phase changes and flow in this context
• To establish pertinent elements, parameters in order to model the observed phenomena and to do numerical simulations.
• To publish the results

III. Plan de travail / Work plan

An experimental setup with radial flux will be designed, the complexity of the crack walls will progress from a perfect plane to a real crack. The concrete parts will be heated at different temperatures in order to change the condensation conditions and study their effects. The flow will be measured at the input of the setup and the liquid flow will be collected and measured at the output.

IV. Literature References

[1] H. Kallel, H. Carré, C. La Borderie, B. Masson, et N. C. Tran, « Effects of the Hygrothermal Conditions on the Fracture Energy of the Concrete », in Key Engineering Materials, Milano, Italy, 2016, vol. 711, p. 397‑403.

[2] H. Kallel, H. Carré, C. La Borderie, B. Masson, et N. C. Tran, « Effect of temperature and moisture on the instantaneous behaviour of concrete », Cem. Concr. Compos., vol. 80, p. 326‑332, juill. 2017.

[3] H. Kallel, H. Carré, C. Laborderie, B. Masson, et N. Cuong Tran, « Evolution of mechanical properties of concrete with temperature and humidity at high temperatures », Cem. Concr. Compos., vol. 91, p. 59‑66, août 2018.

[4] F. Barre et al., Control of Cracking in Reinforced Concrete Structures: Research Project CEOS.fr. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016.

[5] M. Matallah et C. La Borderie, « 3D Numerical Modeling of the Crack-Permeability Interaction in Fractured Concrete », in Framcos’9, Berkeley, California, USA, 2016.

[6] G. Rastiello, C. Boulay, S. Dal Pont, J. L. Tailhan, et P. Rossi, « Real-time water permeability evolution of a localized crack in concrete under loading », Cem. Concr. Res., vol. 56, p. 20‑28, févr. 2014.

[7] G. Rastiello, S. Leclaire, R. Belarbi, et R. Bennacer, « Unstable two-phase flow rate in micro-channels and cracks under imposed pressure difference », Int. J. Multiph. Flow, vol. 77, p. 131‑141, déc. 2015.

[8] D. E.-M. Bouhjiti et al., « New continuous strain-based description of concrete’s damage-permeability coupling », Int. J. Numer. Anal. Methods Geomech., vol. 42, n^o 14, p. 1671‑1697, oct. 2018.