Application of a hysteresis model for the water retention curve in recycled aggregates concrete: experimental and numerical FE2 approaches

Water retention curves are used to describe the degree of water saturation in porous materials. These curves exhibit hysteresis, meaning that the relationship between water content and applied suction depends on the wetting and drying history of the material and environmental conditions. This study investigates the effect of hysteresis on the durability of concrete made from recycled concrete aggregates (RCA), demonstrating that the Van Genuchten model can be applied to such recycled materials. A chemo-hydraulic, multiscale finite element squared (FE
2
) model was developed and validated. This model represents chloride ingress within the unsaturated porous structure of concrete. The constitutive equations are formulated at the mortar scale based on experimentally measured intrinsic material properties. Through numerical homogenization, these properties are upscaled to simulate the macroscopic behavior of concrete made with 100% RCA. Hysteresis calibration properties were also obtained experimentally. Experimental validation confirms that the Van Genuchten model can be applied to recycled aggregate concrete. A sensitivity analysis of the hysteresis model parameters revealed that water content is significantly impacted. However, this influence is less pronounced when studying chloride ingress.