Toughness enhancement and equivalent initial fracture toughness of cementitious composite reinforced with aligned steel fibres.

Based on theoretical analysis and numerical simulation, the impact of steel fibres on the stress intensity factor (SIF) at the crack tip for cementitious composite was studied. The enhanced toughness of steel fibre reinforced cementitious composite (SFRC) in resisting cracks was explained by the decrement of SIF caused by steel fibre inclusions at the crack tip of the composite. The equivalent initial fracture toughness Kme was used to characterize the crack initiation of SFRC. A simplified method for determining the Kme of SFRC was proposed based on a linear regression method. Fracture tests were conducted on three‐point bending notched beams with different steel fibre volume fractions and specimen sizes to study the crack initiation behaviour of aligned steel fibre reinforced cementitious composite (ASFRC). Kme of ASFRC was calculated, and the size effect of Kme was analysed. The results showed that Kme slightly increased with the steel fibre volume fraction and gradually became stable. For the tested specimens, whose heights varied between 40 and 100 mm, the specimen size had little impact on the Kme. [ABSTRACT FROM AUTHOR]