PVA (polyvinyl alcohol) fibers are very high-performance reinforcement fibers for concrete and mortar.
PVA fibers are well-suited for a wide variety of applications because of their superior crack-fighting properties, high modulus of elasticity, excellent tensile and molecular bond strength, and high resistance to alkali, UV, chemicals, fatigue and abrasion.
PVA fibers are unique in their ability to create a molecular bond with mortar and concrete that is 300% greater than other fibers.

Crack Reduction

PVA fibers are also used to reduce many types of concrete cracks. To restrain shrinkage cracking, the fiber should be stiffer than the concrete it is reinforcing. PVA fibers reduce normal cracks to micro-cracks that restrict water penetration and protect steel reinforcement. Because they are less “stretchy” with a higher modulus of elasticity, PVA fibers are more effective than other fibers in reducing long-term drying cracking. Relatively low dosages of PVA fibers can effectively reduce many types of cracking, including drying shrinkage, settlement and fatigue-related crack.

PVA vs. Steel & AR Glass Fiber Reinforcement

Like steel and alkali-resistant glass, they are stiffer than the concrete matrix and have high tensile strength. Steel fibers, however, have relatively low bond strength with concrete and mortar, causing the fibers to pull out under strain before reaching their tensile strength.

PVA, on the other hand, is unique in that it forms a molecular bond with cement during hydration. This high bond strength of PVA results in a mortar or concrete with significantly increased tensile, flexural and impact strength.

The tensile stress-strain behavior of PVA is more like steel than concrete. It can be used in many applications to provide structural reinforcement for concrete, often eliminating the need for rebar or wire mesh. Optionally, it can be used together with steel to reduce the concrete cover or to increase its strength and durability.

Compared to glass fiber reinforcement, PVA-ECC (Engineered Cementitious Composite) reinforcement is stronger, much less expensive, and significantly more durable in a high alkali environment. Alternatively, glass and PVA can be used together as a highly effective hybrid for fiber-reinforced cementitious composites. PVA fiber also offers substantial weight advantages over steel and glass: PVA is half the weight of glass fiber and one-sixth the weight of steel.

PVA 15
15 denier (8mm) PVA for concrete slabs, thin overlays, countertops, all precast products with low dose applications.
PVA 4000
4400 denier (30mm) PVA super-macro structural for shotcrete, slopes, all precast, floor slabs.Use in back coat for GFRC and Precast Countertops.

Properties

Benefits of PVA Fibers

NyconPVA fibers are a more efficient reinforcement system than other conventional synthetic and steel systems:

• In low dosages, they provide superior short and long-term crack control.
• In higher dosages, they replace or reduce the need for steel and/or wire mesh, providing a rust-free solution that streamlines the construction process, reduces wear and tear on equipment, labor, time and material costs.
• They are a preferred alternative to steel fibers with superior properties: higher ductility, no sharp fiber protrusions and no rust staining.
• They reduce the amount of water penetration in concrete and results in decreased spalling and premature deterioration of the concrete in a freeze-thaw environment.

Usage Levels:

For a batch mix that does not employ the facecoat/backcoat technique use 120-200 grams per cu.ft. of the PVA 15 fibers. One can use the PVA 4000 however these will show when grinding and polishing. The PVA 4000 can provide an interesting decorative look when polished.

For a facecoat/backcoat mix:
30-50 grams of PVA 15 in the facecoat
250 grams of PVA 15 / PVA 4000 in a 60/40 ratio. 150 grams of PVA 14 and 100 grams of PVA 4000.

Add the fibers at the end of the mix cycle.