A new technique for studying the behaviour of concrete in shear

The direct determination of shear characteristics of concrete by universal tests is still a major concern for researchers. most available studies use a torque that is applied to a hollow cylinder with a thickness/radius ratio as small as possible. this serves to develop a test based on the behaviour of the material and not the structure. however, these tests may show dispersions due to problems of fragility or non-homogeneity of the material. for this, an original experimental device has been used by creating two stress free zones using two styrofoam pieces added to the cylindrical mold. new boundary conditions are created to transform the compression stress into shear on a limited area. the device ensures the perpendicularity of the cylinder and the good distribution and homogeneity of constraints. using this technique allows the determination of the influence of the failure surface inclination on the behaviour of concrete in shear