Harmonized Test Procedures for Steel Fiber-Reinforced Concrete

A circular slab test method is described as an alternative to modulus of rupture and square slab tests for steel fiber-reinforced concrete. Results of 20 modulus of rupture, 12 square slab, and 24 circular slab tests are compared based on a general theoretical approach that accounts for the random fiber distribution and the successive softening by fiber pullout. Existing requirements for modulus of rupture and square slab tests are reviewed, and harmonized procedures for these as well as the circular slab tests are proposed. It is suggested that an effective flexural tensile strength and a fracture energy parameter be used to characterize the strength and toughness of steel fiber-reinforced concrete. Furthermore, an acceptance criterion is introduced, aimed at excluding materials with drastic softening.