Concrete behavior under very high stresses
Résumé
This communication concerns the concrete behavior under extreme loading situations (near field detonation or ballistic impacts). During such loadings, concrete material is subjected to very high-intensity triaxial stress states. The validation of concrete behavior models, which simultaneously take into account the phenomena of brittle damage and irreversible strain such as compaction, thus requires test results that enable reproducing complex loading paths. Since 2004, the University of Grenoble has launched in collaboration with the French Ministry of Defense (DGA, Centre d'Etudes de Gramat) a research program on the vulnerability of concrete infrastructures. This presentation is devoted to the results of this program. Triaxial tests on a low-strength plain concrete have been performed, using a large capacity triaxial press named "GIGA". Stress levels overpassing one GigaPascal with homogeneous, static and well controlled loading paths have been reached. The results show that contrary to what is observed in simple compression, when placed under high confinement, concrete behaves like a granular stacking. There is not any influence of the level of the cement matrix strength whereas the saturation ratio exerts a major influence. The concrete strength capacity can be divided by 5 if the concrete is saturated instead of dried. ©2009 Society for Experimental Mechanics Inc.