Concrete is an extraordinary material in compression but extremely weak in tension. Adding discontinuous fibres to the mix does not prevent the formation of the first crack, but radically alters its subsequent behaviour, avoiding brittle collapse.
The effectiveness of FRC is measured in terms of toughness, i.e. the energy the material absorbs as it deforms. When the cement matrix yields under tension, the fibres activate: they stretch like micro-ties, stitching together the edges of the crack (crack-bridging effect). This allows the conglomerate to retain significant residual strength even in the plastic phase, often completely replacing traditional welded wire mesh.
Steel fibres (with hooked ends for anchorage) are used for industrial floors and load-bearing structures. Synthetic macro-fibres (polypropylene or PVA) offer corrosion resistance (ideal in marine environments). AR (alkali-resistant) glass fibres are the standard for thin precast panels (GRC).
Standards
European and international references applicable.
Physical properties
Usage environment
The insertion of fibres reduces workability significantly. It is vital to calibrate the particle size curve and dose superplasticisers correctly to avoid fibre balling in the mixer. For structural FRC, always certify the residual strengths fR1 and fR3 through notched beam tests (EN 14651).