Stress effect on degradation due to expansion in concrete
Résumé
Expansions in concrete are responsible for a wide range of structural degradations. They can have internal or external origins (alkali-aggregate reaction – AAR, delayed ettringite formation – DEF, external sulphate attack – ESA, freezing…). Expansions lead to cracking, abnormal displacements, and a decrease in mechanical properties. In structures, these mechanisms occur under stress due to loading or restrained expansion (caused by mechanical boundary conditions, presence of reinforcement, or expansion gradients due to chemical conditions). The impact of stress on the consequences of expansions in concrete is crucial for predicting the past and future behaviours of damaged structures: the orientation of induced cracks, the amplitude of displacements, and the anisotropy of mechanical properties. This paper reviews experimental work on AAR and DEF under stress and restraint, and their interpretation through numerical modelling. It highlights the relevance of this research for other expansive mechanisms and emphasizes the need to develop new experimental devices to better understand expansion in structures under specific loading conditions.