A bi-phase model for concrete subject to sulfate attack.

In the present paper we focus on the numerical simulation of degradation in concrete due to the development of secondary ettringite in the hardened material (delayed ettringite formation or DEF). This chemical reaction, causing expansion and microcracking of the material, can occur due to an external or internal sulfate attack. A chemical-diusion model allows for the computation of the amount of expansive products of the reaction. The concrete aected by DEF is then represented as a two-phase material made of a solid skeleton and an expanding phase, which exerts a pressure capable of damaging the concrete surrounding the reactive sites. The model is validated on the basis of experimental data on cement mortar specimens reported in the literature.