Multifractality of fracture patterns under tensile and compressive stresses in cement-based materials

摘要

The scaling properties of the fracture surfaces generated by uniaxial tensile tests and of the crack networks induced by compressive loadings are investigated. In the case of the tensile tests, a laser profilometer was adopted to scan the fracture surfaces. In the case of the compression tests, after injection of a fusible alloy inside the specimen, scanning electron microscope was used to detect the stress-induced crack patterns. The highly localized energy dissipation in tensile fracture is shown to occur over a fractal domain with dimension larger than 2.0. Also, the microcracks network induced by compression loadings possesses fractal dimension much larger than 2.0 in the bulk. Fractality permits to explain some aspects of the fracture behaviour, like the stable crack growth encountered in the tests and the size-scale effect undergone by the toughness parameters.