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Polyvinyl alcohol (PVA) fibers themselves possess excellent properties such as high strength and modulus, alkali resistance, corrosion resistance, good adhesion to cement matrix, and uniform and stable dispersion. Relying on their outstanding mechanical characteristics, excellent substrate affinity, and stable and reliable chemical stability, they can form a fine and flexible “nano network” within concrete, optimizing the internal structural stress state and comprehensively enhancing the practical performance of concrete.

Enhance crack resistance

Inhibit early shrinkage cracks: PVA fibers are randomly and uniformly distributed in concrete. When concrete experiences tensile stress due to plastic shrinkage or temperature changes, these fibers can effectively disperse and transfer internal stress, preventing the formation and development of micro-cracks from the source.

Transform wide cracks into micro-cracks: Once concrete develops fine cracks, PVA fibers will play a powerful “bridging” role, holding the materials on both sides of the crack and restricting further opening of the crack. It can transform a potentially wide crack into multiple micro-cracks that are barely detectable by the naked eye (with a width controlled within 100 microns), significantly improving the waterproofing and impermeability of concrete.

 Enhance the ability to resist bending

Enhance flexural strength and deformation capacity: Ordinary concrete is a brittle material when subjected to bending, breaking immediately upon cracking. After the addition of PVA fibers, the concrete exhibits excellent toughness. During the bending process, the fibers can span across cracks to transfer tensile forces, enabling the material to maintain a certain load-bearing capacity even after cracking, demonstrating the characteristic of “strain hardening” (i.e., the greater the force applied, the stronger the resistance to deformation).

Significantly increase fracture energy: Experimental studies have shown that with a reasonable increase in the dosage of PVA fibers, the flexural tensile strength, flexural elastic modulus, and fracture energy of concrete all increase significantly. This means that the concrete can absorb more energy and undergo greater deformation before bending failure.

 Enhance impact resistance

Efficiently absorb impact energy: When subjected to sudden impact forces such as earthquakes, explosions, or heavy object drops, PVA fibers can consume and absorb the huge energy brought by shock waves through their own tensile deformation and frictional sliding with the matrix.

Prevent brittle collapse: This energy dissipation mechanism significantly delays the damage process of concrete, transforming its failure mode from instantaneous brittle fragmentation to a ductile and slow damage, thereby significantly improving the seismic, blast, and fatigue resistance of the structure.

Engineering Application Tips:

The improvement effect of PVA fibers on the performance of concrete is closely related to the volume fraction of the fibers. Generally speaking, within the reasonable range of 0.5% to 2%, the toughening and crack-resisting effect will increase with the increase of the dosage; exceeding the critical value, they tend to agglomerate and disperse unevenly, affecting the application effect. In actual engineering, the optimal proportion should be determined according to the demand.