Experimental and numerical investigations of concrete behaviour at meso-level during quasi-static splitting tension

The paper describes experimental and numerical results of quasi-static splitting tensile tests on concrete specimens at meso-scale level. The experiments were carried out on cylindrical specimens with the diameter of 0.15 m. The loading strip was made of plywood or steel. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: 3D X-ray micro-computed tomography, 2D scanning electron microscope and manual 2D digital microscope. The discrete element method was used to directly simulate experiments at the meso-scale. Concrete was modelled as a random heterogeneous 4-phase material composed of aggregate particles, cement matrix, interfacial transitional zones and macro-voids based on micro-tomographic images. Two-dimensional calculations with real concrete microstructure were carried out. The effect of the different loading/supporting strip type on the stress-strain curve and fracture process was studied. This effect proved to be significant. A satisfactory agreement between numerical and experimental results was achieved. The evolution of contact normal forces, coordination number, broken contacts, grain rotations and crack displacements was also investigated. In addition, each energy component was calculated and analyzed at a different stress-displacement stage.