The Toughness Index of Steel Fiber Reinforced Concrete
B. Barr and M. R. Mohamad Noor
Appears on pages(s):
compression tests; compressive strength; cracking (fracturing); fiber reinforced concretes; load-deflection curve; loads (forces); metal fibers; reinforced concrete; reinforcing materials; tension; tests.
An alternative definition of toughness index is proposed which has a number of advantages over the ACI definition. The toughness index is obtained from the load-deflection graph and is given by the ratio of the area under the graph (at the point of two times the deflection at first crack) divided by four times the area under the graph at the point of first crack. The proposed toughness index has the advantage that it can be used for both conventionally mixed and placed fiber reinforced concrete (FRC) materials and also sheet material such as glass fiber reinforced cement (GRC). The toughness index results presented were obtained from three notihed test-specimen geometries: compact compression, notched beam, and compact tension test specimens. The results for toughness were independent of both geometry and notch depth and showed that the toughness index of steel FRC increased by 100 percent as the fiber content was increased in the range of 0.03 to 0.9 percent by volume.