Long-term behaviour of concretes: pure water chemical damaging and coupling with mechanics

The durability of concrete structures represents an essential stake of the safety analysis of nuclear waste disposal centres (containers, sealing, casemates, surveillance galleries). The originality of this study is the coupling between the mechanical behaviour of the material (in particular the crack growth) and a damaging of chemical origin (dissolution of cement hydrates due to pure water trickling). A model has been developed to evaluate this coupling and introduced in a finite-elements calculation code. The calcium content of the interstitial solution is chosen as the status variable of the system. The elasticity modules changes as a function of this variable. The non-linear mechanical behaviour of the concrete is modeled according to the damaging theory. In parallel to this modeling approach, specific procedures and experiments were developed for industrial applications. (J.S.)