|Chemo-mechanical modelling of swelling concrete |
Conference: Upscaling for Strategic Materials (Montpellier, FR, 2019-09-02)
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In the context of lifetime extension of nuclear power plants, the french Institut de Radioprotection et deSûreté Nucléaire (IRSN) conducts researches to predict the aging of cementitious materials. The presentwork is focusing on the impact at the mesoscale of the chemical sulfate attacks on the overall materialproperties. The sulfate attacks are characterized by the ettringite precipitation that induces great pressurein the porous cement paste. The effect of the local swelling of cement paste on concrete, conducts somecracking by differential deformation. These cracks become preferred loci for ions diffusion and furtherettringite precipitations. These strongly coupled phenomena suggest a non-linear chemo-mechanicalmodelling where diffusion, precipitation, pressurization and crack process should be simultaneouslyinvolved:1. Species diffusion: diffusion is modeled by Fick’s law in a cracked porous medium  ;2. Chemical reactions: knowing species concentrations in solution, different types of reactions suchas aqueous, solid and sorption reactions  are modelled in order to estimate the amount of ettringitevolume;3. Mechanical: knowing the created solid volume, a local pressure is calculated in the poro-mechanicalmodel and in the cracks. The crack initiation, propagation and pressurization are based on a dedicatedCohesive Zone Model .The presented applications will focus on the impact of material properties, such as matrix composition,on strain kinetics. The impact of the clinker composition is estimated by a dedicated hydration computingwithin an analytical homogenization framework.REFERENCES J.M. Segura and I. Carol. On zero-thickness interface elements for diffusion problems. InternationalJournal for Numerical and Analytical Methods in Geomechanics, 28:947 – 962, 2004. L. Bichet. Taking into account the transport mechanisms in the fracture of heterogeneous materials:application to the nuclear power plant aging. PhD thesis, Univ. Montpellier II, 2017. C. de Dieuleveult, J. Erhel, and M. Kern. A global strategy for solving reactive transport equations.Journal of Computational Physics, 228:6395 – 6410, 2009. F. Perales, S. Bourgeois, A. Chrysochoos, and Y. Monerie. Two field multibody method for periodichomogenization in fracture mechanics of non linear heterogeneous materials. Engineering FractureMechanics, 75:3378 – 3398, 2008.