The effects of self-weight on the fracture energy of concrete are studied for 3-point bend tests on notched beams with the same thickness but different depth. Specimen sizes are varied from 100×100 ×400 mm to 100×500×2200 mm.
Two loading methods, vertical loading and horizontal loading, are used. In particular, the latter is to measure the net external load to bring about crack failure.
For the two cases the fracture energy of concrete is determined through size effect law which was recently derived for blunt fracture. And maximum load data from references are also used for regression analysis.
Test results according to the RILEM Recommendation show that larger values of $G_F$ are measured for larger specimen sizes. It may be seen that the effect of the self-weight of the beam in the calculations of $G_F$ by RILEM Recommendation is too large for larger beams.
Theoretical considerations and available experimental evidences suggest that the BKP approach is valid when very large beams are tested. For small beams it yields estimates lower than the directly measured $G_F$ value.
