The authors describe modifications to a simple test using a circumferentially notched round bar under bending (cnrbb) making the loading of small specimens easier. In this test the concrete specimens are subjected to eccentric loading and need to be cut cleanly to provide a flat loading surface. Stress analysis is used to derive an expression for fracture toughness. The resulting equation, expressed in terms of the stress intensity factor k, is shown graphically. No special loading rig is required for the test, and the failure load is higher than the limits of sensitivity of some testing machines. Specimens as short as 3 cm may be used with the method. It is important that the circumferential notch is deep for small specimens to prevent shear failure occurring before crack propagation at the notch. Results given from fracture toughness tests on samples from a concrete beam show less variability compared with those of other traditional tests. /TRRL/

  • Availability:
  • Corporate Authors:

    Cement and Concrete Association

    Wexham Spring
    Slough SL3 6PL, Buckinghamshire,   England 
  • Authors:
    • Barr, B
    • Bear, T
  • Publication Date: 1977


  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 30-32
  • Serial:
    • Volume: 11
    • Issue Number: 4
    • ISSN: 0010-5317

Subject/Index Terms

Filing Info

  • Accession Number: 00163858
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: Dec 27 1977 12:00AM