Interpretation of aggregate volume fraction effects on fracture behavior of concrete

► We examined the effects of coarse aggregate volume on fracture energy of concrete. ► We applied 3-point bending tests on beams with single size but different notch sizes. ► The boundary effect model based fracture energies were calculated. ► We employed meso-mechanical relations to find the fracture energy of concrete. ► Two approaches were found in good agreement at low aggregate volume fractions. Fracture process zone has a strong effect on fracture energy particularly for concretes with coarse aggregates. In order to demonstrate this effect, four groups of concrete mixtures with various aggregate volume fractions were designed. Three point bending tests were applied on beam specimens with a single size but different notch size to obtain the boundary effect model based fracture energy. The results were evaluated to determine the effect of both aggregate volume fraction and notch size on fracture energy of concretes. In addition, meso-mechanical relations based on toughening mechanisms were employed in determining the fracture energy of concrete. The fracture energies obtained from the meso-mechanical approach and the boundary effect model were compared and found to be in good agreement.