In-situ 3D tomographic images of a wedge splitting test on a concrete specimen

The coupling of in-situ X-ray computed tomography (CT) with Digital Volume Correlation (DVC) is an appealing experimental procedure to study the effect of the mesostructure of heterogeneous materials on their fracture behavior [1-2]. In particular, it provides an unprecedented amount of data that can be used to formulate new models and/or to calibrate and validate existing ones under realistic three-dimensional loading conditions. This dataset contains a set of 3D images coming from the in-situ CT testing of specimens made of concrete [4]. To this end, we adopt as paradigmatic example the wedge splitting tests [5] performed with a custom-designed setup that permits to observe with a CT scanner the whole specimen, including the boundary surfaces where the loads or displacements are applied. Different tomographic images are taken both before and during the test at different load levels to enable DVC analysis allowing to track the changes in the specimen due to the applied loads and the resulting crack nucleation and propagation. The segmentation of the images is facilitated by the addition in the mixture of baryte sulphate as contrast enhancer [2]. The complete dataset obtained is used in [4] to propose a method to (i) obtain and analyze with DVC the data coming from in-situ CT testing of specimens made of a realistic concrete mix, (ii) calibrate a phase-field model based on experimental tests and (iii) validate the model by comparing 3D experimental and numerical results. References 1. S. Roux, F. Hild, P. Viot, D. Bernard, Three-dimensional image correlation from X-ray computed tomography of solid foam, Comp A: App Sci Man 39 (2008) 1253–1265. 2. P. Carrara, R. Kruse, D. P. Bentz, M. Lunardelli, T. Leusmann, P. A. Varady, L. De Lorenzis, Improved mesoscale segmentation of concrete from 3D X-ray images using contrast enhancers, Cem Concr Comp 93 (2018) 30–42. 3. B. Bourdin, G. A.Francfort, J-J.Marigo, Numerical experiments in revisited brittle fracture, J Mech Phys Solid 48 (2000) 797-826. 4. A. Mishra, P. Carrara, M. Griffa, L. De Lorenzis, Fracture in concrete: in-situ X-ray tomography tests, digital volume correlation and phase field modeling, (2023) In preparation. 5. E. Brühwiler, F. H. Wittmann, The wedge splitting test, a new method of performing stable fracture mechanics tests, Eng Fract Mech 35 (1990) 117-125.