Experimental and Numerical FE² Study of Chloride Ions Ingress in Unsaturated Recycled Aggregates Concrete (Oral Presentation)

Chloride-induced corrosion poses a substantial risk to reinforced concrete structures. The use of Recycled Concrete Aggregates (RCA) as a substitute for Natural Aggregates (NA) exacerbates durability concerns. Indeed, the adherent mortar paste reduces the mechanical characteristics of concrete, whilst possibly altering its durability. However, Recycled Aggregates Concrete (RAC) presents a sustainable construction approach that reduces landfill waste and conserves natural resources.

A comprehensive experimental investigation was undertaken on concretes composed of NA and RCA within the laboratory. Their inherent properties in terms of water transport and chloride ion ingress were assessed, allowing a better understanding of the effects of replacing NA with RCA.

A multiscale chemo-hydraulic model was subsequently created using the Finite Element Squared (FE²) method, and then verified and calibrated. The model's constitutive equations use intrinsic properties obtained from experimental data.

The results demonstrate the model's accuracy in replicating experiments and providing additional insight into chloride ingress in both saturated and unsaturated concrete.

The research findings suggest that the durability of RAC may be comparable to that of NAC under specific mixture quality and environmental conditions. To evaluate this, a modelling application was carried out, which replicated actual circumstances on a maritime lock wall.