Experimental analysis of concrete behavior under high confinement: Effect of the saturation ratio

Abstract

a b s t r a c tThis study focuses on the identification of concrete behavior under severe triaxial loading in order to better evaluate the vulnerability of sensitive infrastructure to near-field detonations or ballistic impacts. For the purpose of reproducing high stress levels with well-controlled loading paths, static tests have been conducted on concrete samples using a triaxial press offering very high capacities (stress levels of around 1 GPa). It is a well-known fact that the concrete drying process is a slow phenomenon. Massive concrete structures, such as bridge piers, dams and nuclear reactors, could retain a quasi-saturated core throughout most of their lifetime, even though their facing dries very quickly. The objective of this article is to evaluate the effect of the saturation ratio on concrete behavior under high confinement; this article will present triaxial test results on concrete samples over a saturation ratio range extending from dried to quasi-saturated concretes. The subsequent analysis of results will show that the saturation ratio exerts a major influence on concrete behavior, particularly on both the concrete strength capacity and shape of the limit state curve for saturation ratios above 50%. This analysis also highlights that while the strength of dried concrete strongly increases with confining pressure, it remains constant over a given confining pressure range for either wet or saturated samples.

Deformation Mechanism of Hardened Cement Paste and Effect of Water

“…This result indicates that the HCP deformation is significantly affected by both confining pressure and water content. The effect of water on deformation has been reported for concrete (Vu et al 2009) and rocks (Krokosky and Husak 1968). The surface energy change for concrete has been supported as a moisture effect mechanism on strength (Hori 1962;Cook and Haque 1974;Matsushita and Onoue 2006).…”

“…Impact load has also been reported to induce a triaxial stress of more than 100 MPa (Gran and Frew 1997), followed by extensive studies on concrete behavior under high-pressure confinement. The effects of cement paste volume (Vu et al 2011), saturation degree (Vu et al 2009), and loading rate (Zeng et al 2013) have been studied. Results show that concrete deformation changes from brittle to ductile as the confining pressure (P c ) increases.…”

Dynamic testing of concrete under high confined pressure. Influence of saturation ratio and aggregate size

“…The aggregate distribution is similar to a standard concrete but at a lower scale. On the other hand, the R30A7 concrete is closer to a standard concrete with siliceous aggregates up to 8 mm diameter and a water to cement ratio of 0.64 resulting in a compressive strength of about 30 MPa [8,9]. Four levels of free-water saturation ratio are considered in the present study in the case of R30A7 concrete: dry, 60%, 80%, 100%.…”

“…3b). As explained by [7,9], the limited strength in saturated concrete is due to an increase of pore-pressure within the microstructure.…”

Experimental analysis of the shear behavior of concrete under high confinement

“…Under such conditions, shear deformation and high confining pressures can be observed. Extensive studies were carried out to study the behavior of concrete under high confinement [2,3] using a high-capacity hydraulic triaxial press called GIGA. But fracture of this material under mode II conditions remains largely unstudied.…”