Fracture properties and brittleness of high-strength concrete

Ravindra Gettu*, Zdenek P. Bazant, Martha E. Karr

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

160 Scopus citations


The size-effect method for determining material fracture characteristics, as previously proposed by Bazant and extensively verified for normal strength concrete, is applied to typical high-strength concrete. Geometrically similar three-point bending specimens are tested and the measured peak load values are used to obtain the fracture energy, the fracture toughness, the effective length of the fracture process zone, and the effective critical crack-tip opening displacement. The brittleness of the material is shown to be objectively quantified through the size-effect method. Comparing the material fracture properties obtained with those of normal strength concrete shows that an increase of 160 percent in compressive strength causes: (1) an increase of fracture toughness by only about 25 percent, (2) a decrease of effective fracture process zone length by about 60 percent, and (3) more than doubling of the brittleness number, which may be an adverse feature that will need to be dealt with in design. The brittleness number, however, is still not high enough to permit the use of linear elastic fracture mechanics. The R-curves are demonstrated to derive according to the size-effect law exclusively from the maximum loads of specimens of various sizes and yield remarkably good predictions of the load-deflection curves.

Original languageEnglish (US)
Pages (from-to)608-618
Number of pages11
JournalACI Materials Journal
Issue number6
StatePublished - Nov 1990

ASJC Scopus subject areas

  • Building and Construction
  • General Materials Science
  • Civil and Structural Engineering


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