International Concrete Abstracts Portal

Title: Fracture Energy of Concrete: Its Definition and Determination From Size Effect Test

Author(s): Z. P. Bazant and P. A. Pfeiffer

Publication: Special Publication

Volume: 100

Issue:

Appears on pages(s): 89-110

Keywords: concretes; cracking (fracturing); energy; failure; mortars (material); statistical analysis; Structural Research

Date: 4/1/1987

Abstract:
The previously derived size-effect law for concrete may be used to define the material fracture parameters in a less ambiguous, size-independent manner. By exploiting the size-effect law, the fracture characteristics can be defined for an extrapolated infinite specimen size, for which they must be independent of the specimen geometry. It is demonstrated experimentally that this definition yields less scattered results for the fracture energy than the existing methods. Three very different types of specimens, including three-point bent, edge-notched tension, and eccentric compression specimens, are found to yield approximately the same fracture energy values. Furthermore, the R-curves calculated from the size effect measured for various types of specimens are found to have approximately the same final asymptotic values for very long crack lengths, although they differ very much for short crack lengths. Finally, certain refinements of the size-effect law are discussed and their consequences pointed out, particularly with regard to the effect of aggregate size.