Fibre-reinforced concrete in practice

Our constructive synthetic fibres are used in precast concrete elements, cycle paths, roundabouts and concrete floors. The static calculation provided by us shows which type of fibre is suitable and the required dosage of fibres per m3 of concrete. There are a number of things to take into account when choosing fibre reinforced concrete.

Concrete mixture

The minimum concrete strength for a static calculation is C25/30. In agreement with the client, the prescribed concrete strength is used in the static calculation. The fibres do not absorb water, but by adding the constructive synthetic fibres, the specific surface area is increased, resulting in a more thixotropic concrete. This can be solved by adding (super) plasticiser or water, provided the water cement factor allows this.



Fibrofor® High Grade and Fibrofor® Diamond can be dosed with the aggregates before entering the mixer. In addition, both types of fibres can be dosed during the unloading of the concrete into the concrete mixer truck. Please note! The packaging of both fibres is not water-soluble. Please watch our dosing instruction videos for the Fibrofor® High Grade and the Fibrofor® Diamond.

Concrix® fibres are supplied in bundles with a water-soluble foil, which must never be removed in order to prevent clumping. The Concrix® fibres should always be dosed with the aggregates before entering the mixer. Watch our dosing instruction video.


With Fibrofor® High Grade and Fibrofor® Diamond the mixing time does not have to be adjusted. In the case of earth-moist concrete, the required mixing time must be determined in consultation with Convez.

With the Concrix® fibres, the dry mixing time (sand and gravel) is at least 30 seconds. The wet mixing time (cement, water, additives, sand and gravel) is between 120 and 240 seconds, depending on the type of concrete and the type of mixer. The required mixing time must be agreed with Convez.


If the fibre concrete has to be pumped, we recommend using a higher consistency class of concrete than was initially planned. Also take into account the diameter of the hose (pipe). If in doubt, you can always contact the Convez team.

Depending on the type of fibre, fibres may be visible on the surface after processing the fibre concrete. These will largely disappear during the finishing process. Otherwise, they will fade away during use.

Caution! The use of fibre concrete is strongly discouraged with residential concrete floors.


The quality of concrete depends to a large extent on the way in which newly-poured concrete is post-treated in the first period after pouring. The aim of post-treatment is to retain the water in the hardening concrete immediately after pouring and not to allow it to evaporate.

For more information on the post-treatment we refer you to the website of Betonhuis  


More information about fibre-reinforced concrete in practice? Contact us.