What is Fiber Reinforced Concrete?

Conventional fiber reinforced concrete, sometimes called FRC, is concrete that has been strengthened by adding shreds of other materials to the wet concrete mix. Concrete is quite brittle; it has very good compressive strength but comparatively little tensile strength, which makes it likely to crack under many conditions. Cracking leads to further damage. Fiber reinforced concrete is less likely to crack than standard concrete.

Using fibers to reinforce other materials is not a new idea. In fact, it has been practiced for thousands of years, with straw mixed into mud bricks and horsehair included in mortar. In the early years of the 20th century, asbestos fibers were added to concrete. By the 1960s a variety of materials, such as polypropylene, glass, and steel fibers, were used in fiber reinforced concrete.

Current research suggests that microfibers, rather than long fibers, best increase tensile strength. However, adding fibers causes relatively little improvement in impact resistance. Polypropylene fibers reduce damage from freeze-thaw cycles and reduce the chances of spalling or explosion if there is a fire. Cellulose fibers from genetically modified pine trees have also shown promise in testing.

Glass fiber reinforced concrete, which contains alkali-resistant glass fibers, is especially resistant to ordinary deterioration caused by environmental conditions. It is also an ecologically friend kind of fiber reinforced concrete because the glass fibers are made from natural materials and take comparatively little energy to produce.

December 8, 2011

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