Our extensive knowledge of the use of synthetic fibres goes back to the 1970s, when the company Arnheiter AG (Forta Seilwerke), which later became part of the Brugg Group, was granted a patent for «Fibrous reinforcement for cement-bound building components and coverings».
While the fibre invented and patented by Arnheiter AG was initially only used for reducing shrinkage cracks, the technology has been developed further and further over the years, resulting in the synthetic high-performance fibres available today. These are able to either reduce or completely replace conventional steel reinforcement, always on the basis of static calculations according to currently valid regulations and standards.
In 2010, the fibre know-how was transferred to the newly founded company Brugg Contec, which is responsible for developing and producing new high-performance fibres and marketing them worldwide.
Through the change in ownership in 2017 and the associated relocation of the company headquarters to Domat/Ems, the name was changed to Contec Fiber AG at the start of 2018. The company’s tried and tested services will continue to be offered to all partners and open-minded interested parties.
What’s the dosage of Contec Fiber fibres?
Fibrofor High Grade and Fibrofor Standard: 1 kg/m³ Fibrofor Diamond: 2 – 3 kg/m³ Concrix: 2 – 7.5 kg/m³ Fibrofor Multi: 900 g/m³ Fibrofor Green: 600 g/m³
Which characteristics of the concrete are improved by adding Contec Fiber fibres?
Flexural strength, shrinkage characteristics, frost-thaw-salt resistance, sulphate resistance, impact resistance, wear resistance, water absorption, fire resistance.
Does the addition of fibres influence the consistency of the concrete?
Yes, it does; the consistency of the concrete is reduced. This means the concrete becomes stiffer and, depending on its use, has to be optimised with concrete plasticiser or liquefier (avoid the addition of more water).
Is any post- treatment of the concrete necessary?
An accurate finishing according to national standards and regulations is a must despite the use of Contec Fiber fibres. This process is crucial for a satisfying result and is not influenced by adding fibres.
What is the difference between synthetic micro and macro fibres?
According to EN 14889-2 the difference between micro and macro fibres lies in their diameter. The defined limiting diameter is given as 0.3 mm. Furthermore the addition of micro fibres has a positive effect in particular on the shrinkage behavior of concrete, and depending on the construction and composition of the fibres, also on its flexural strength. On the other hand the addition of macro fibres leads to a significant increase in the post-cracking tensile strength and can thus be regarded and used as a fully adequate substitution for steel fibres.
What is fibre concrete with Concrix?
Fibre concretes are manufactured according to EN 206 specification and contain a specified quantity of synthetic macro fibres in order to obtain a post-cracking tensile strength. The interaction results in a ductile and macroscopically isotropic composite building material in which the technical properties are enhanced. Concrix-Macrofibres are mixed in quantities of 2 to 9 kg/m³, without adversely affecting the processability. Synthetic fibres affect the shrinkage behavior of concrete in a positive way. The fibres control and bridge cracks in concrete and result in a specific level of post-cracking tensile strength. In addition the fibres prevent macro cracks from occurring.
Is the fibre distribution with Concrix in concrete uniform?
The very high number of fibres per kg (100,000 /kg) ensure a dense network of Concrix-Macrofibres. MRI pictures of test samples have this confirmed. Provided that the mixing have been done well, areas without fibres (which can happen by using steel fibres with low dosage) can be avoided.
Can Concrix-Macrofibres also be added to a self-compacting concrete (SCC)?
Yes! Concrix-Macrofibres can be added without any problem to self-compacting concrete. Thanks to the specific surface structure, the processability is still possible even after addition of large quantities, by controlling the fine materials and the liquefier content.
Does the addition of Concrix-Macrofibres affect the processability of the concrete?
Yes! The addition of Concrix, particularly if larger amounts are added, will make the concrete stiffer. At additions of 3-4.5 kg/m³ the consistency of the concrete must be reduced by a class. This is adjusted by controlling the liquefier content. The addition of more water is fundamentally prohibited!
Can Concrix fibre concrete also be pumped?
Yes! Concrix fibre concrete can be pumped even at high addition levels. The flow properties of the concrete are only marginally affected. The protection of the equipment should also be emphasized here. The flexible Concrix fibres cause significantly less wear and tear on pumps and hoses than with steel fibre concrete. This lengthens the lifetime of the hoses and pumps considerably and results in cost benefits for the company involved.
What is balling and how can it be prevented?
In concrete technology balling is referred to as the appearance of aggregated fibres that have interlocked into the shape of a ball. These balls can block the concrete pump and lead to its damage. Incorporated balls can also lead to the formation of individual cracks in the concrete due to the defects. Usually a similar picture is found when cutting open such balls. The fibres become solidified due to penetration of fine concrete particles and can no longer be separated. This effect can only be prevented by observing the correct procedure when adding the fibres or by ensuring the basic consistency of the concrete. A faulty procedure can be largely excluded if the appropriate leaflets for adding Concrix in the concrete factory and the truck mixer are taken into consideration.
How can the fibre content be measured in fresh or hardened concrete?
The macro fibre content can practically only be determined in fresh concrete. At least 10 liters of concrete are necessary for washing out the macro fibres. The low specific weight of the synthetic fibres allows them to be skimmed off the surface of the water, then after drying they are weighed and thus the added quantity approximately determined. In hardened concrete it is practically impossible to determine to amount of fibre metered, since breaking and crushing the concrete sample also damage the fibres and thus they can no longer be reliably measured. The absence of the reflecting property in the synthetic material means that X-ray techniques also cannot be used. Optical testing can only be carried out using an expensive MRI instrument and subsequent data analysis.
Can synthetic macro fibres replace traditional reinforcement in all applications and if not why not?
When cracks form there is a partial loss of load capacity which can be compensated by Concrix fibres for non load-bearing applications and temporary construction measures and thus they can replace the use of traditional reinforcement. However for operation in load-bearing applications, the required full ductility of concrete cannot be attained by fibres. Depending on the application, the combination of synthetic fibres with reduced conventional reinforcement can considerably reduce costs.
Can Concrix fibre concrete also be used in outside areas?
Of course Concrix fibre concrete can also be used in outside areas. The utilization of synthetic fibre concrete is a straightforward choice for this area of application, since the unpleasant property of corrosion can be excluded for synthetic fibres, which in the case of steel fibre concrete can be found regularly in outside areas. Besides the optical defect from corroded steel fibres close to the surface, the risk of injury and/or damage arising from protruding fibres in connection with increasing abrasion of worked-out steel fibres can be excluded when using synthetic fibre concrete.
What information is necessary in order to compile a structural analysis for an industrial floor?
In order to compile a structural analysis for an industrial floor, information is required concerning the base, the intended loads, the exposure of the floor and geometric information about the concrete slab. Support is available from our data acquisition sheet. The base can be characterized in different ways. There is a choice of the following procedures: Westergaard modulus, Ev1- and Ev2- values, and the k-value stiffness modulus method. The most common information concerning the foundation soil comes from the Ev1- and Ev2- values, which consist of measurement results from the first and second loading.be regarded and used as a fully adequate substitution for steel fibres.
How important are the subsurface conditions for the preparation of a durable industrial floor?
The degree of compaction of the foundations is of crucial importance for the final result of an industrial floor. It must be ensured that the compaction is not too variable, in order to exclude differential settling. Subsequent settling or major deformations in the substrate inevitably lead to the formation of cracks due to incalculable additional stresses in the concrete floor. Visible grooves in the flat surface are clear indications of an inadequately compacted substrate. Indications for such deficiencies are longitudinal cracks in the driving lanes and crack formation in the middle of the area between joints.
What special attention has to be paid to jointless industrial floors?
In the case of jointless floors, attention must be paid to edge stresses occurring due to increased shrinkage stresses. Steel joint profiles along the outermost edges and partial edge reinforcement should be included. A further decisive factor is the concrete formulation, which must consist of a suitable type of cement, an appropriate cement dosage and a tailored water-binder ratio. The addition of monofilament micro fibres (type Fibrofor Multi or Fibrofor Green) can be used to effectively assist optimal shrinkage behavior. The joint pattern should be reasonable and concreting sections should be taken into consideration. Finally, however, the standardized after-treatment of the surface also contributes to the success of the construction.
When is the right time for sawing the dummy joints?
Contraction or dummy joints should take place as soon as possible after the concrete has hardened. This moment is directly dependent on the construction temperature and the construction consistency of the concrete. In the summer the waiting period tends to be shorter than in winter. As a rule this period is between 12 and 24 hours following construction. Experienced contractors can reliably recognize the right time.
How important is the after-treatment of concrete in industrial floors?
Due to the large surface area in 2-dimensional slabs such as industrial floors, there is an enormous potential for evaporation of water at the concrete surface. Thus it is absolutely necessary to limit the evaporation to a minimum. Spraying on of evaporation protection or covering with plastic sheeting or a moist textile, which has to be kept constantly damp, is required for this purpose. Loss of surface concrete mixing water leads to the formation of cracks and to curling of the slab edges. Another result of inadequate after-treatment is the so-called spider-web cracks, which give rise to cracks on the surface, as the name suggests, in the form of spider webs.
Other documents desired?
Safety data sheets
Declaration of performance
- Declaration of Performance Concrix DM
- Declaration of Performance Concrix ES
- Declaration of Performance Concrix HS35
- Declaration of Performance Concrix M507
- Declaration of Performance Concrix SA
- Declaration of Performance Fibrofor Multi 127
- Declaration of Performance Fibrofor Multi 63
- Declaration of performance Fibrofor Standard
- Outside paving Logistic area Westfields, Oirschot (NL)
- Outside slab - American Football Field, Monterrey (MX)
- Industrial slab - Production hall and warehouse Alois Müller, Ungerhausen (DE)
- Industrial slab - Productionhall Gematec, Wittnau (CH)
- Excavation / Shotcrete Excavation - shotcrete infill, Biology Centre University Vienna (AT)
- Precast element - Retrofitted balconies for apartments, Dornbirn (AT)
- Excavation - Shotcrete infill Red Cross and building authority, Vaduz (FL)
Press reports and presentations