Title: Crack Propagation and the Fracture of Concrete
Author(s): M. F. Kaplan
Publication: Journal Proceedings
Appears on pages(s): 591-610
The Griffith crack theory of fracture strength is discussed. Tests were performed on concrete beams with crack simulating notches, and two methods, which have been called the analytical and the direct experimental methods, were used to determine the critical strain-energy-release rate associated with the rapid extension of the crack. There was good agreement between Gc values for beams with different notch depths and which were loaded both by the third-point and center-point methods. However, 3 x 4 x 16 in. beams gave somewhat larger Cc values than did 6 x 6 x 20-in. beams. Although further research is necessary, the indications are that the Griffith concept of a critical strain-energy-release rate being a condition for rapid crack propagation and consequent fracture, i s applicable to concrete. The critical strain-energy-release rate may be ascertained by suitable analytical and experimental procedures and the fracture strength of concrete containing cracks can thereby be predicted.