In the early ages of concrete (from the time of pouring to 24 hours later), the strength gained by concrete is negligible and the slightest stress can lead to cracking. Cracks are caused by the binding of concrete and its tendency to shrink, temperature changes (cooling of concrete after the temperature of concrete rises due to cement hydration), or evaporation of water from the surface of concrete. The very high tensile strength of the fibers at this time prevents cracking of concrete.
Using fibers to prevent cracking of concrete at early ages (plastic shrinkage) seems more suitable than other existing solutions. The very large number of fibers per cubic meter of concrete (more than one hundred million strands in the usual amount of consumption, which is not comparable to other types of fibers) means that a very large surface area of ​​fibers is connected to the concrete, and the small fiber distances prevent cracking.
Fibers prevent concrete from sagging and prevent water from transferring to the concrete surface, which results in homogenization of the concrete and equalization of the water-cement ratio throughout the concrete and continuation of the hydration process.
These fibers reduce the permeability of the concrete surface and increase the life of the concrete and increase the abrasion resistance of the concrete, so the concrete surface does not crumble and peel.
Reducing cracking in the early ages of concrete and preventing its sagging means preventing the formation of weak sections in the concrete and after the concrete hardens, it greatly prevents its shrinkage and the formation of thermal cracks.
Fibers significantly increase the resistance of concrete to impact loads (more than 15% increase in resistance in the usual amount of consumption, which increases the impact resistance even more than this amount with increasing consumption), which is important in dynamic loading such as gusts of wind, earthquakes, vibration of heavy machinery and impacts caused by missiles, explosions, etc.
The use of these fibers significantly reduces the brittleness of concrete and fiber concrete exhibits ductile behavior under various loads, which is important during earthquakes or any sudden loading.
The use of these fibers increases the tensile, flexural, and shear strength of concrete, and the concrete remains integral after failure (even under bending moment).
Increased resistance to melting and freezing cycles, which is caused by reduced permeability of concrete, and increased resistance to fatigue, abrasion, and cavitation, are other advantages of using fibers. It is worth noting that these fibers do not cause any harm to human health and do not have any health or environmental complications.