Finite-element modelling of alkali−aggregate reaction in a concrete hydraulic structure

Nowadays, Alkali-Aggregate Reaction (AAR) in concrete causes serious concerns for the operation and the integrity of many mass and reinforced concrete structures, basically for hydraulic structures (dams, powerhouses, etc.) and any other concrete structure that is exposed to moisture. It is recognized that the kinetic of AAR is greatly driven by the temperature and the moisture amongst other parameters and the induced strain is assumed to be oriented according to the stress state. Due to complexity of AAR and its multi-physical nature, the use of chemomechanical modelling is very helpful for making predictions in terms of displacements and concrete damage. Moreover, the macro modelling approaches are frequently preferred to perform engineering work for real structures. In this context, this paper presents the implementation of a chemomechanical model of AAR for concrete in Abaqus Explicit. With this approach, AAR effects are introduced via the VUEXPAN user-subroutine jointly with the Concrete Damage Plasticity (CDP) model of Abaqus. The Abaqus explicit solver is chosen as it deals effectively with very large finite element models simulating highly nonlinear deformation due to AAR. The verification of the proposed model is performed at the material level. Moreover, it is presented a case study regarding real hydraulic structure affected by AAR located in North America.