Measurement of the fracture energy using three-point bend tests: Part 1—Influence of experimental procedures

Available measures of the fracture energy G_F obtained with the procedure proposed by RILEM TC-50 provide values that appear to change with sample size, calling into question the possibility of considering G_F as a material parameter. In this paper some possible sources of experimental errors, when the RILEM proposal is applied, are ascertained, namely the apparent energy dissipation from hysteresis in the testing equipment and energy dissipation in the lateral supports. It is concluded that either some other sources of energy dissipation are operative or that G_F cannot be considered a material property.