The French "Institut de Radioprotection et de
Sûreté Nucléaire" (IRSN) conducts researches on the impact of internal
swellings reactions on concrete, such as Sulfate Reactions. Such
reactions are characterized by the precipitation of ettringite which
induces swellings and cracks by differential strain. These cracks are
preferential location for ions diffusion and further ettringite
precipitations.
The
aim of the study is to model the degradation of a mature material by
ettringite pressure at the aggregate scale. A chemo-mechanical model
based on a coupling between reactive transport (species diffusion and
chemical reactions) and mechanics in cracked porous medium is developed
and is solved with a generic staggered approach. The initial
microstructure and poro-mechanical and diffusion parameters are
estimated by hydration computing and analytical homogenization. The
coupled chemo-mechanical model is validated and then applied to Sulfate
External and Internal Attack. The impact of the concrete composition and
the chemical environments on the swelling kinetics and crack path is
taken into account. Furthermore, our simulations highlight the
influences of inclusions and cracks on the inhomogeneous spatial
distribution of precipitation areas of ettringite and associated
swelling stress.