Title:
True Fracture Energy of Concrete
Author(s):
Rajendra K. Navalurkar, Cheng-Tzu Thomas Hsu, Suk Ki Kim, and Methi Wecharatana
Publication:
Materials Journal
Volume:
96
Issue:
2
Appears on pages(s):
213-225
Keywords:
cracking; fracture properties; high-strength concrete; tension tests
DOI:
10.14359/448
Date:
3/1/1999
Abstract:
If fracture energy of concrete is to be considered as a material property, it must be a size- and geometry-independent parameter. At present, there are three different approaches for determination of fracture energy of concrete. Hillerborg’s work on fracture test, Bazant’s size effect model, and Shah’s two-parameter fracture model all yield varying values for fracture energy of concrete. In this study, comparison of fracture energies GF obtained from tension tests and notched beam tests (Hillerborg’s fracture test) reveals that fracture energy is a size and structural geometry-independent fracture parameter provided that the beam tests are carried out accurately. In the beam tests, the effect of notch-depth and span-depth ratios on fracture energy were considered. It is found that the method for determination of fracture energy from beam tests can be significantly affected if the load line measurements are not accurate. This is identified as the single most important factor that may have caused for researchers in the past to conclude that GF obtained from notch beam tests are size- dependent, and hence, invalid. A proposal is made herein that uses the crack mouth opening displacements (CMOD) instead of deflection measurements to calculate fracture energy of concrete.In this study, high-strength concrete (HSC) is studied. The conclusions formed in this study can easily be extended to all strengths of concrete.