Synthetic Fibers for Concrete

Synthetic fibers engineered for use in concrete can withstand the long-term alkaline environment of concrete. These fibers are manufactured polymer-based materials such as polypropylene, nylon, or polyethylene. Synthetic fibers are added to concrete before or during the mixing operation. The use of synthetic fibers at typical addition rates of 1 to 2 lbs per cubic yard does not require any modification to concrete mixtures. At higher addition rates, workability may be reduced and water reducing admixtures may be required to retain slump.

Synthetic fibers benefit the concrete in both the plastic and hardened state. Benefits include:

• Reduced plastic settlement cracks
• Reduced plastic shrinkage cracks
• Increased toughness and impact resistance
• Provides energy absorption

Use Synthetic Fibers For:

• Reduction of concrete cracking as a result of plastic shrinkage
• An alternate system of nonstructural shrinkage/temperature reinforcement (with documentation)
• Greater toughness and resistance to impact
• Internal support and cohesiveness; concrete for steep inclines, shotcrete, and slip­formed placements
• Reduction of concrete cracking as a result of plastic settlement
• Applications where nonmetallic materials are required

Do Not Use Synthetic Fibers For:

• Control of cracking as a result of external forces
• Higher structural compressive or flexural strength development
• Replacement of any moment-resisting or structural steel reinforcement
• Decreasing the thickness of slabs on grade
• The elimination or reduction of curling and/or creep
• Increasing control joint spacing
• Reduction in the size of the support columns
• Reducing the thickness of bonded or unbonded overlay sections