Coupling between mechanical and transfer properties and expansion due to DEF in a concrete of a nuclear power plant

•We model the thermal behavior of a nuclear vessel during its construction.•We follow the expansion of concrete samples that have followed a representative thermal history.•We examine the evolution of expansion and of the microstructure and mechanical properties of theses samples.•The permeability of these samples is strongly affected by expansion.

This paper focuses on studying the consequences of expansion due to delayed ettringite formation (DEF) on transfer and mechanical properties of concrete in the case of nuclear structures. It concerns a concrete representative of a containment vessel of a nuclear power plant where temperature variations at early age are very large. An experimental heat treatment, representative of the temperature history in the raft foundation of the containment vessel was reproduced after a modeling of its temperature rise. After this treatment, concrete exhibits swelling due to the development of DEF. The gas permeability is increased significantly after swelling, and the safety requirements expected by these structures are thus affected.