Modified push-off test for analysing the shear behaviour of concrete cracks

A detailed methodology to perform the so-called push-off test in precracked concrete specimens is presented. The test is performed with the specimen confined in 2 stages (precracking and push-off) to control crack width. Confinement is provided by a steel restraint frame, which includes a ball bearing to avoid shearing forces from being transmitted outside the shear plane. The real kinematic behaviour of a single-open crack can be assessed. This makes the experimental validation of crack dilatancy models possible. Therefore, the intention of this methodology is to take knowledge about direct shear behaviour on concrete cracks one step forward.