FRACTURE ENERGY AND THE COMPLETE TENSILE SOFTENING RESPONSE OF CONCRETE.

A simple test specimen for observing the post-peak uniaxial tensile response of concrete is introduced. The test was conducted using the closed-loop strain control and a simple self-interlocked grip. The complete load-displacement curve was monitored until the post-peak stress dropped to zero. The value of the maximum post-peak displacement, which is assumed to be the critical crack opening displacement (COD), is used for normalizing the post-peak stress-displacement relation. This normalized stress-displacement relationship was observed to be unique and may be considered as the materials property. In this study, three mix-proportions of mortar and one mix of concrete were studied. Three controlled grain sizes of sand were used to study the effect of aggregate grain size on the post-peak response of concrete. Fracture energy was also evaluated using different test specimens such as uniaxial tension specimen, notched beam and the compact tension specimen.