What is fibre-reinforced concrete?
Fibre-reinforced concrete is concrete to which short fibres have been added, distributed throughout the entire mass. In Dutch it is called vezelbeton. The fibres hold the concrete together when small cracks develop. As a result it cracks through less readily, cracks stay narrower and the material behaves in a tougher way than ordinary unreinforced concrete.
Types of fibre
- Steel fibres: short pieces of steel wire, often hooked at the ends. They can replace part of the traditional reinforcement, for example in industrial ground-bearing floors and in sprayed concrete for tunnels.
- Plastic fibres (usually polypropylene): thin microfibres mainly limit shrinkage cracks in the first hours after pouring. They are also used to limit spalling of concrete in a fire.
- Glass fibres: in glass-fibre reinforced concrete (GRC) for thin facade panels, ornaments and precast elements. Special alkali-resistant glass fibres are needed for this.
In practice
- Fibres are not an automatic substitute for reinforcement. In structural members such as beams, lintels and suspended floors, ordinary reinforcement remains necessary unless a structural engineer has done the calculations for the fibre-reinforced concrete.
- For a ground-bearing floor or a driveway, steel fibre concrete can replace the reinforcement mesh. That saves labour, but the dosage and fibre type must be matched to the design. Have this determined by the concrete plant or structural engineer.
- Microfibres do not prevent shrinkage caused by poor curing. Covering and keeping moist remain necessary.
- Finish: with steel fibres, fibres can protrude at the surface and cause small rust spots. For exposed floors a dry-shake wearing layer is therefore often applied or a different fibre type is chosen.
- Compare the total costs: fibre-reinforced concrete is more expensive per m³ than ordinary concrete, but you save on reinforcement and labour. Ask for several quotes with and without fibres.
Related terms
- Concrete
- Reinforcement
- Shrinkage crack
- Concrete floor
- Sprayed concrete
- Curing of poured concrete
Want to learn more about construction terms? Visit our knowledge base at fredsdiyplans.com.