WHAT are Synthetic Fibers?

Synthetic fibers specifically engineered for concrete are manufactured from man-made materials that can withstand the long-term alkaline environment of concrete. Synthetic fibers are added to concrete before or during the mixing operation. The use of synthetic fibers at typical addition rates does not require any mix design changes.

WHY use Synthetic Fibers?

Synthetic fibers benefit concrete in both the plastic and hardened states. Some of the benefits include:

  ® Reduced plastic settlement cracks

  ® Reduced plastic shrinkage cracks

  ® Lowered permeability

  ® Increased impact and abrasion resistance

  ® Increased shatter resistance

Some synthetic fibers may be used as secondary reinforcement (Hardened Concrete Performance Documentation required).

HOW do Synthetic Fibers Work in Early-Age Concrete?

Volume changes in early-age concrete cause weakened planes and cracks to form, because a stress exists which exceeds the strength of the concrete at a specific time. The growth of these micro shrinkage cracks is inhibited by mechanical blocking action of the synthetic fibers. The internal support system of the synthetic fibers inhibits the formation of plastic settlement cracks. The uniform distribution of fibers throughout the concrete discourages the development of large capillaries caused by bleed water migration to the surface. Synthetic fibers lower permeability through the combination of plastic crack reduction and reduced bleeding characteristics.

HOW do Synthetic Fibers Work in Hardened Concrete?

The early-age concrete benefits of using synthetic fibers continue to contribute to the hardened concrete. Hardened concrete attributes provided by synthetic fibers are lowered permeability and the resistance to shattering, abrasion, and impact forces.

The ability to resist shattering forces is greatly enhanced with the introduction of synthetic fibers to the concrete. When plain concrete is compressed, it will shatter and fail at first crack. Synthetic fibers manufactured specifically for concrete prevent the effect of shattering forces by tightly holding the concrete together.

Abrasion resistance is provided when synthetic fibers are used, because the water-cement ratio at the surface is not lowered by variable bleed water. The water-cement ratio is more constant at the concrete surface. This improvement is assisted by the internal settlement support value of the synthetic fibers contributing to uniform bleeding.