Fibre reinforced concrete with a combination of polyolefin and steel-hooked fibres

Self-compacting polyolefin fibre reinforced concrete has shown high performance in both fresh and hardened state. Post-cracking behaviour provides significant residual strengths especially for large deformations. For small deformations, flexural residual strength could be enhanced with a small amount of steel-hooked fibres, obtaining a hybrid fibre-reinforced concrete well suited for structural use. Four types of conventional fibre-reinforced concrete with steel and polyolefin fibres were produced on the basis of the same self-compacting concrete also manufactured as reference. These concrete mixtures were manufactured separately with the same fibre contents being subsequently used for two more hybrid mixtures. Flexural and uniaxial fracture tests were performed in addition to the assessment of fresh and mechanical properties. The research showed both synergies (with the two types of fibres working together in the fracture processes) and an improvement of the orientation and distribution of the fibres on the fracture surface.