Study of mode II fracture on fibre-reinforced gypsum notched specimens

Fracture on quasibrittle materials, such as concrete or gypsum, has been under study for decades. These studies have helped to understand what are the fracture mechanisms and the parameters that drive this phenomenon, giving rise to numerical models that can reproduce it using methods such as the finite element analysis. Nevertheless, mode I is clearly the best known fracture mode, since it has attracted much experimental work and has been used to define the formulation of some of the most successful numerical models. Nevertheless, in some occasions fracture results from a combination of modes I and II. In this regard, mode II fracture has been studied less often and not many examples can be found in the literature, partly because mode I fracture is more usual and partly because it is harder to experimentally induce fracture under mode II conditions. In this contribution, mode II fracture is studied on fibre-reinforced gypsum (FRG) specimens using two experimental setups; one defined by the Japanese standard JSCE-G 553-1999 1 and another one corresponding to a push-off test, recently used with success for analysing shear fracture in fibre-reinforced-concrete 2.