Fibre reinforced concrete: frequently asked questions

An overview of the most frequently asked questions about fibre reinforced concrete — handy as a reference or to quickly find an answer.

What exactly is fibre reinforced concrete?

Fibre reinforced concrete (FRC) is concrete to which small fibres of steel, synthetic material, glass or basalt have been added during mixing to improve tensile strength, crack resistance and wear resistance.

Does fibre reinforcement always fully replace traditional reinforcement?

No. For non-structural or lightly loaded applications (yard pavements, industrial floors, light foundations), fibre reinforcement can often replace traditional reinforcement entirely. For heavily loaded, primarily structural elements such as bridges or multi-storey buildings, traditional reinforcement generally remains (partly) necessary. Always seek advice from your structural engineer for this.

Which fibre type is best?

There is no universal “best” fibre type — it depends on the application. Steel fibre offers the highest structural strength, synthetic fibre is non-corrosive and effective against shrinkage cracks, and basalt fibre combines high strength with low density and excellent heat resistance.

Does steel fibre rust as quickly as traditional reinforcing bars?

Steel fibre that is fully embedded in the concrete is protected against corrosion in a similar way to traditional reinforcement. Fibres that become exposed at the surface through wear can show light, localised rust spots — usually a cosmetic issue, rarely a structural problem.

Is fibre reinforced concrete more expensive than traditionally reinforced concrete?

The direct material costs of fibres can be similar to, slightly higher than, or slightly lower than the cost of reinforcement mesh, depending on fibre type and dosage. The biggest saving usually lies in reduced labour hours, since no separate operation is needed to place reinforcement.

Can fibre reinforced concrete be worked with a pump?

Yes, at the correct dosage the concrete mix remains readily pumpable. At higher dosages, an adjusted (wetter) consistency may be needed to safeguard workability.

Is fibre reinforced concrete suitable for outdoor applications?

Yes, and for some outdoor applications (such as damp or chloride-exposed environments), synthetic or basalt fibre is actually a better choice than steel fibre, because of the absence of corrosion risk.

Can I have fibres added to an existing concrete order?

Yes, fibres are added during the mixing process at the concrete plant. When ordering, clearly state the desired fibre type and dosage.

Do I need a reinforcement calculation for fibre reinforcement?

For non-structural applications, usually not. For structural applications — where fibres (partly) take over the role of traditional reinforcement — a calculation based on the reinforcement plan is generally required, carried out by the structural engineer together with the fibre supplier.

What happens if I add too many fibres?

Too high a dosage can lead to blockage of the dosing equipment, reduced workability and fibre balling during mixing, which can actually cause weak spots in the concrete. Always stick to the dosage recommended by your supplier.

Can fibre reinforced concrete be identified or checked after the fact?

With steel fibre, the fibres are sometimes visible at the surface, particularly after wear. With synthetic fibre this is less the case. For structural applications, dosage and distribution are generally checked by sampling during production, in line with applicable quality standards (such as ATG certification).

In conclusion

Have a question that isn't answered here? Feel free to get in touch — Dutch Fiber Trading provides free advice on fibre type, dosage and application for your specific project.