Use of steel fibres to reinforce concrete is continually increasing in quantity and applications. Metal fibres were initially used in two fundamental fields:
Projected concrete for temporary tunnel lining and clearing concrete in industrial paving works, airports, ports, etc.
This structural reinforcement technology is being used with excellent results in new applications, such as segmens or rings for final lining of tunnels, prefabricated units and other concrete structures.
Our fibre FF3 is present in engineering works, such as the AVE high speed railway lines, and on Line 9 of the Barcelona Metro, with 42 km of tunnel.
There are now national and international Standards and Draft Standards, both for steel fibres as well as polypropylene fibres.
Fibres with an adequate mechanical resistance to traction, distributed homogeneously in the concrete matrix, form a highly resistant three-dimensional reinforcement, able to bear appreciable deformations, maintaining a good resistance – DUCTILITY – and avoiding propagation of the fissure forming phenomenon, dissipating deformation energy – TENACITY -.
Wirand® fibres to reinforce concrete are produced from steel wire with a low carbon content. They act as a three-dimensional reinforcement, absorbing the tensions applied in the structural element, thus increasing its resistance.
The use of Wirand® steel fibres in the concrete provides a better behaviour of the structure, as it reduces fissure formation, providing greater quality and durability of the works. Other advantages of using Wirand® Fibres are elimination of conventional reinforcement in some applications, thus reducing time and labour costs. It also prevents waste of materials and simplifies the tasks of transport, stocking, handling and placement.
The most usual applications are tunnel construction, paving and prefabricated concrete elements.
The main objective that must be fulfilled by any system to provide concrete passive protection against fire is to achieve that, if a fire breaks out, the mechanical characteristics of the structural elements of the concrete remain stable during the evacuation process and action by the fire brigade (in a tunnel for example), avoiding loss of human life. Thus, the protection system must act during the first moments of the fire.
The SPALLING effect
When concrete is exposed to fire, the surface temperature begins to increase and the water vapour generated inside gravitates toward the core of the matrix where the temperatures are lower. This phenomenon causes an increase in the internal temperature that eventually exceeds the actual resistance of the concrete, causing a series of violent explosions during the first 20 minutes of the fire (depending on the nature of the material that is burning). The result is flaking of the surface face of the concrete, more commonly known as the SPALLING effect.
Recent research and testing concludes that addition of polypropylene microfibres of diametres under 32 µm significantly reduces the SPALLING phenomenon in concrete during a fire and there is a relation between the number of fibres included in the matrix and the improved behaviour of the concrete in the event of fire.
FibroMac® polypropylene fibres are manufactured from extremely fine filaments, produced by an extrusion process.
FibroMac® fibres are designed to protect the integrity of the concrete when it is subjected to high temperatures and direct fire. They also reduce the fissure formation phenomenon caused by retraction or plastic settling and increase control over exudation and segregation phenomena.
SOLUCIONES-Refuerzo del hormigón-1
SOLUCIONES-Refuerzo del hormigón-2