Reinforcing Fibres

KOREFIB^® MacroFibers G40

Composite macro fibres made of glass fibres for dispersed concrete reinforcement as an alternative to steel fibres and polymer fibres. They do not corrode and are dosed directly into the concrete mix.

Suitable for concrete and industrial floors, screeds, precast production and technical concrete elements. Manufactured in the Czech Republic, with a Building Technical Assessment and certification.

Dispersed reinforcement for concrete

KOREFIB^® MacroFibers G40 are composite fibres based on ECR glass fibres and an epoxy polymer matrix. They are used as dispersed reinforcement for concrete, screeds, floor slabs, precast elements and concrete components.

The fibres are dosed directly into the concrete mix. After mixing, they form a spatial reinforcement throughout the entire volume of the concrete and help limit the formation and development of cracks.

40 mmfibre length for concrete mixes

20,000 pcs/kghigh number of fibres per dose

1–7 kg/m³indicative dosage depending on application

KOREFIB MacroFibers G40 composite fibers for concrete

Concrete that doesn't fail once a crack appears

Ordinary concrete has high compressive strength but is brittle in tension. As soon as a crack forms, tensile load-bearing capacity is lost rapidly.

KOREFIB^® MacroFibers G40 help to limit this problem. After a crack forms, the fibres bridge its opening, transfer tensile stresses and improve the residual load-bearing capacity of the concrete.

help limit crack propagation,
increase the toughness of the concrete,
improve the behaviour of the element after failure,
act throughout the entire volume of the concrete mix,
are not dependent on one specific position like a conventional mesh.

KOREFIB MacroFibers G40 dispersed reinforcement for concrete

How the fibres work in concrete

After being added to the mix, the fibres disperse evenly among the aggregate and cement matrix. Once the concrete hardens, they form a spatial network of randomly oriented reinforcing elements.

This network helps the concrete respond to tensile stresses arising from shrinkage, bending, point loading, impact or service loading.

The fibres do not automatically replace every type of steel reinforcement. For structurally significant structures, their use must be verified by calculation or by a designer's specification.

KOREFIB MacroFibers G40 fiber packaging for concrete

Where MacroFibers G40 make sense

The fibres are suitable wherever there is a need to limit cracking, improve concrete toughness and reduce the risk of problems associated with the corrosion of conventional reinforcement.

concretes, screeds and precast elements,
floor slabs on ground subgrade,
screeds over underfloor heating,
garages and technical spaces,
industrial floors with higher loading,
warehouses and operations with forklift traffic,
structures exposed to moisture, salts or chemical loading.

Use of KOREFIB MacroFibers G40 in a concrete mix

Main advantages of KOREFIB^® MacroFibers G40

Crack controlThe fibres help limit the formation and development of shrinkage and service cracks.

Residual strengthAfter a crack forms, they help transfer tensile stresses and improve the behaviour of the concrete.

Non-corrosiveThe composite material is also suitable for moist, alkaline or chemically loaded environments.

Easy dosingThe fibres are added directly to the concrete mix without laying mesh or tying reinforcement.

Indicative dosage of KOREFIB^® G40

Dosage	Typical use	Purpose of use
1–3 kg/m³	Concretes, screeds, precast elements	Increased toughness, reduction of shrinkage cracks and improved overall behaviour of the mix.
3–4 kg/m³	Floor slabs on ground subgrade, screeds over underfloor heating, garages, precast elements	Higher crack control, better distribution of tensile stresses and increased durability of normally loaded structures.
4–7 kg/m³	Floor slabs, industrial floors with high loading, warehouses, operations with forklift traffic	Higher residual strength after a crack forms and improved behaviour of the concrete under service loading.

The dosage given is indicative. The exact amount must be determined according to the specific structure, concrete formulation, loading and the required function of the fibres.

Behaviour of fibre-reinforced concrete under load

The graph shows the course of the loading force in relation to deformation for concretes with KOREFIB^® G40 fibres. What matters is not only the maximum force before a crack forms, but above all the behaviour of the concrete after failure. It is precisely in this phase that the fibres help bridge the crack and improve the residual load-bearing capacity of the concrete.

Graph of loading force and deformation of concrete with KOREFIB G40 fibers

The graph is taken from the test documentation for concrete with G40 fibres. For design use, the specific concrete formulation, fibre dosage and the required residual strength values are decisive.

Dosage and design

The correct fibre dosage depends on the type of structure, the concrete class, the required function of the reinforcement, the loading and the required residual strength after a crack forms.

A different dosage is used to limit shrinkage cracks, another to increase toughness, and yet another for structures where the fibres are to fulfill a design or structural function.

to limit shrinkage cracks,
to increase the toughness of the concrete,
to improve behaviour after a crack forms,
to partially replace conventional reinforcement,
for design use according to calculation.

For structurally significant structures, the use of the fibres must be verified by calculation, testing or a designer's assessment. The manufacturer bears no responsibility for the method of use or the results of the application.

Processing in the concrete mix

For the fibres to function correctly, their even dispersion in the concrete mix is important. It is advisable to add the fibres gradually and to ensure a sufficient mixing time.

For higher dosages, it is advisable to verify the workability of the mix with a trial batch and, if necessary, adjust the concrete formulation.

add the fibres gradually,
do not add the entire amount at once in one place,
ensure a sufficient mixing time,
check the consistency and workability of the mix,
for higher dosages, adjust the concrete formulation,
carry out a trial batch before series production.

Technical documents and tools

Detailed instructions, documentation and calculation tools for the composite fibres can be found in the technical section.

Fibre-reinforced concrete calculator Indicative design of an industrial fibre-reinforced concrete floor according to TR 34 and the recommended G40 dose. Launch calculator › Composites in practice Practical guides on composite reinforcement in concrete — how reinforcement behaves, dosing and processing, and designing correctly. Open the guides › Documentation for download Technical data sheets, certificate, Building Technical Assessment and catalogue to download. View documents › Questions and answers Frequently asked questions about dosing, fibre function, certification and the behaviour of fibre-reinforced concrete. View answers ›

Need a recommendation for the right dosage?

Send us the type of structure, the concrete thickness, the loading and the required function of the fibres. We will recommend a suitable procedure or prepare documents for assessment.

info@korefib.cz | +420 605 833 755

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KOREFIB® MacroFibers G40 Composite fibres for concrete

In stock

from 210 Kč / pcs

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Reinforcing Fibres

KOREFIB® MacroFibers G40