Compression triaxial behavior of concrete: the role of the mesostructure by analysis of X-ray tomographic images

This paper is intended to assess the mesostructural damage mechanisms of concrete under hydrostatic and triaxial loadings. Such a study is possible thanks to two state-of-the-art laboratory instruments: a high-pressure triaxial press, and an X-ray computed tomography instrument. The laboratory protocol consists of scanning the concrete prior to the initial loading and after each cycle. An analysis of the resulting images indicates that under high hydrostatic loading, significant damage is visible in cement paste at the mesoscopic scale. For two triaxial tests conducted at 50 and 650 MPa of confining pressure, results reveal major differences in both damage and failure mechanisms. At the lower pressure, shear loading creates a localised failure mechanism characterised by sliding on an inclined plane, whereas at the higher pressure, the strain and damage mode are much more homogeneous with a failure localisation after unloading. Cet article a pour objectif d’estimer les mecanismes d’endommagement du beton p...