Fracture properties of steel fiber reinforced high strength concrete using work of fracture and size effect methods

- The effects of steel fiber volume fraction on fracture behavior of HSC were studied.
- The fracture energy obtained by work of fracture method and size effect method.
- The fracture energies measured by two methods were compared.
- Steel fibers significantly improve fracture behavior of HSC.

This paper deals with investigation of fracture behavior of steel fiber reinforced high strength concrete (SFRHSC) and compare it to plain high strength concrete (HSC). Based on an experimental program, a series of three point bending tests were carried out on 54 notched beams, as recommended by RILEM. The fracture parameters were measured by two methods: work of fracture method (WFM) and size effect method (SEM). Then the fracture parameters obtained from these two methods were compared. The results showed that with increase of steel fibers, fracture energy of GF in WFM and Gf in SEM increase but this increase in work of fracture method is more significant. The effective size of the process zone (cf) and the characteristic length (Lch) increase with increase of steel fibers, which indicates that the HSC becomes more ductile by introducing fibers. The accuracy of the fracture parameters obtained from the SEM for SFRHSC is acceptable for low steel fiber volume fractions. Also, GF/Gf ratio increased from about 2.5 for the HSC to around 10.5 for the SFRHSC.