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Fibrous Concrete Reinforcement
Synthetic-fiber reinforcement to reinforce concrete in nonstructural applications
Reinforcing concrete to keep it from cracking is nothing new -- even the earliest civilizations used natural fibers to inhibit cracking in structures. Today, synthetic-fiber reinforcement is available to reinforce non-structural concrete applications with superior results, according to manufacturers. Currently, the most widely accepted form of reinforcement is welded-wire fabric (WWF), a mesh of thick steel wires that is placed in concrete. However, synthetic-fiber reinforcement avoids the increased labor costs and difficulty in placement that are associated with WWF.
Synthetic-fiber reinforcement prevents cracks in concrete, unlike WWF, which controls crack width -- cracks actually need to occur before the WWF goes to work. Small-diameter synthetic fibers (nylon and polypropylene) are now being added to concrete to reduce shrinkage cracking by more than 80% according to independent lab tests. Reducing cracks lowers concrete permeability, increases its toughness and long-term weatherability, and can reduce callbacks in concrete slab floors, decks, driveways, and walks. According to fiber manufacturers, the placement, curing, or finish characteristics of the concrete are not affected by the addition of fibrous reinforcement.
Larger-diameter synthetic fibers (steel and polyolefin), added at higher content by volume (0.5% to 1.5% respectively), also enhance hardened flexural strength, but at increased cost.
Fibrous reinforcement is primarily used to reduce cracking in nonstructural concrete applications. Steel fibers rust and can cause surface discoloration. Although higher fiber content by volume improves performance, it costs more and has a greater potential for creating dense concentrations of fibers in the concrete which can lead to problems.
Article courtesy of:
NAHB Research Center
http://www.nahbrc.org
and
http://www.toolbase.org
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