New continuous strain-based description of concrete's damage-permeability coupling

This contribution aims at improving the finite element modelling of concrete's damage-permeability coupling using continuous and elastic-based damage approaches. With this aim in view, a review of existing local and nonlocal damage formulations is performed showing how they differ in terms of damage estimation, crack propagation, and spatial discretization restrictions (when the energy-based Hillerborg criterion is applied). Another critical review of damage-based permeability laws is achieved to pinpoint their limitations. Indeed, the use of a bounded and strictly increasing damage variable does not allow (1) an accurate description of permeability in the presence of macrocracks that are physically unbounded and (2) a proper description of the permeability decrease as those macrocracks are closed. Accordingly, a new strain-based permeability law is suggested. Its analytical validation is based on the BIPEDE tensile test for one loading-unloading cycle. This new formulation intends to enhance the predictiveness of damage-permeability coupling models leading to a better assessment of large structure's durability and serviceability.