ABSTRACT
Most modelling approaches start from the idealisation of a crack in fibre reinforced cements and concrete (FRC) into three distinct zones: the traction-free zone, the fibre-bridging zone and the ‘process zone’ at the crack tip, where both fibre and aggregate bridging have an effect. Careful consideration of fibre aspect ratio, strength and bond is required to design FRC with pull-out toughness. The nature of post-peak behaviour in secondary FRC is difficult to model using composite theory, but some key parameters can be identified. In theory, either a composite materials approach or the application of fracture mechanics can be used to quantify the mechanical behaviour of FRC. In practice, neither can fully describe all aspects of FRC behaviour and elements of both approaches are required. Post-peak toughness normally must be evaluated by experimentation and it is critically important that standard procedures are used to compare different secondary FRC materials.
