In foam concrete products, we always add fibers in many products. Some manufacturers who have just contacted foam concrete do not know why to add fibers and how to choose fibers for concrete.
Foam concrete is a hydration reaction between cement and water during the hardening process, which causes the shrinkage of the concrete volume. In the later stage, the dry decrease is caused by the free water evaporation in the concrete. These shrinkage stresses will exceed the tensile strength of the cement matrix and will be inside the concrete. About 70% of the micro crack development is completed in the 3-7d gel period, at which time the tensile strength of the concrete is less than 1MPa. After adding PVA fibers for concrete in the concrete, the fibers can be easily and quickly dispersed uniformly in the concrete to form a chaotic support system, which disperses the directional stress of the concrete, prevents the occurrence and development of the original cracks in the concrete, and eliminates or reduces the initial micro cracks. The quantity and size of the concrete significantly improve the ability of concrete to prevent cracks and seepage, enhance the toughness of concrete, and thereby extend the service life of the concrete. Besides, because the fiber itself has an individual strength, fibers for concrete are evenly dispersed in the concrete and form an anchoring effect, which can absorb a certain amount of damage energy in an instant.
Luoyang Tongrun is a PVA fiber supplier. PVA fiber has undergone special anti-static and anti-ultraviolet treatment to make fibers for concrete dispersed evenly in concrete and can exert its effect for a long time. The "Y" section of PVA fiber increases the surface area of the tissue, which significantly improves the binding force between the texture and the cement-based aggregate, and does not have any conflicts and chemical reactions with the foam concrete aggregate, admixtures, and cement, so have good adaptability.
At present, we have three main choices in foam concrete: glass fiber, PP fiber, and PVA fiber. Glass fiber has excellent corrosion resistance and high mechanical strength, but its disadvantages are brittleness and weak wear resistance. Due to its characteristics, it cannot be effectively and uniformly distributed in concrete. Because it is relatively brittle and cannot play an excellent tensile effect, it can not achieve the result of crack resistance and increase flexural strength. Polypropylene fibers and polyvinyl alcohol fibers have good strength and excellent toughness. PP fiber and PVA fiber have become the mainstream fibers used in foam concrete.