Hysteresis of the Water Retention Curve in Recycled Aggregates Concrete: Comparison of Experimental and Numerical Approaches

The effects of the water retention curve hysteresis on concrete made from Recycled Concrete Aggregates are investigated. A multiscale multiphase FE² model is developed and validated experimentally. Properties for the calibration of the hysteresis are also obtained experimentally. A coupled chemo-hydraulic multiscale model, able to represent the chloride ingress inside the porous structure of concrete, was developed with the Finite Element squared (FE²) method. The constitutive equations are based on properties that are measured in laboratory conditions, for concrete manufactured with 100% Natural Aggregates (NA) or Recycled Concrete Aggregates (RCA), respectively. The hysteresis of the water retention curve is implemented according to the Van Genuchten formulation. Results suggest that not accounting for the hysteresis of the water retention curve introduces a significative error in the saturation degree of concrete and, therefore, in the chloride content.