Influence of matrix grade on the mechanical behaviour of fibre-reinforced concrete

Mechanical behaviour of fibre-reinforced concrete is influenced both by the properties of the fibres (geometry, aspect ratio, dosage) and the properties of the matrix (concrete grade, curing time, water-to-cement ratio). Many research studies have been published that focus on the influence of different kinds of fibres on the final properties of concrete. Against this the influence of the matrix grade on the mechanical properties of fibre-reinforced concrete is a topic that is almost unexplored. A mechanical characterisation of fibre-reinforced concrete in the hardened and fresh states is carried out, varying the concrete grade, the fibre dosage and the fibre type (steel and polyester). The results of the experimental research indicate the importance of the matrix grade on the bond between the steel fibre and the matrix and, consequently, on the mechanical performances of the composite material. Furthermore the concrete grade also influences the minimum volume fraction of polyester fibres affecting the matrix toughness.