Mechanical behavior of concrete under high water pressure: Water penetration as a critical factor for mechanical properties

The combined effects of water pressure and water penetration on the mechanical behavior of concrete under hydraulic loading were investigated. When concrete is subjected to water pressure, a saturated zone forms near the surface and gradually progresses toward the interior over time, resulting in a non-homogeneous hybrid state with a saturated envelope and humid core (hybrid saturated state) during the initial stages of hydraulic loading. However, the mechanical behavior of concrete with a hybrid saturated state has hardly been investigated. This study performed the experiments on concretes with water pressures (~50 MPa). The results show that concrete with a hybrid saturated state exhibits higher peak mechanical stress than unconfined concrete. In contrast, the peak mechanical stress of fully saturated concrete remains comparable to that of unconfined concrete. This indicates that water penetration strongly influences the triaxial strength of concrete under water pressure, especially in the initial stages of hydraulic loading.