The effect of paste volume and concrete properties on size independent fracture energy

Post peak tensile behavior of concrete, softening, can be described using bi-linear curve. The area under this curve is the fracture energy GF which is necessary for the structural design. RILEM presented a recommendation for calculating GF but unfortunately the obtained value is size dependent. In this paper a large number of experimental Forces ? Crack Mouth Opening Displacement (F-CMOD) curves, obtained from three points bending tests, were analyzed through an inverse analysis procedure to obtain the size independent fracture parameters. The effect of compressive strength, aggregate size, and paste volume on the fracture behavior of concrete were studied and compared with the empirical formulas found in the literature. A new empirical relationship for the prediction of size independent fracture energy of concrete from compressive strength, aggregate size and paste volume was proposed. It is shown that the proposed model can predict the size independent fracture energy with a good accuracy.