Engineering-based finite-element approach to appraise reinforced concrete structures affected by alkali–aggregate reaction

Modelling the expansion and damage generated by alkali–aggregate reaction (AAR) in reinforced concrete structures is quite complex, yet necessary to obtain accurate predictions of the structural response of distressed members. Several AAR models have been developed to predict expansion and damage at the material (microscopic) or the structural (macroscopic) scales. However, those models tend to either neglect or overemphasise the critical physicochemical parameters of the reaction, which limits their applicability. Therefore, a new simple yet reliable finite-element approach is proposed to fill this gap. It accounts for the most important parameters affecting AAR through an engineering approach, without the need for non-technical guesses or to ‘fit’ model parameters. The proposed model is validated through the computational simulation of reinforced concrete specimens cast and monitored in the laboratory. Results show that AAR expansion was accurately simulated by accounting for the anisotropic (stress state dependent) nature of the reaction, mechanical properties deterioration and an analytical equation capable of representing AAR's free expansion. Next steps include validating the approach by simulating real structures and incorporating phenomena like leaching and combined distress mechanisms.