Glass Fiber Reinforced Concrete
How to use GFRC for better decorative panels and countertops
When someone says fiberglass, we think of insulation or boats or Corvettes, but maybe we should think of concrete. Technically, fiberglass is simply very fine glass fibers. The material used to make boats or other products, although called fiberglass, is really glass fiber reinforced plastic-glass fibers in a polymer matrix. If, instead of the polymer, we use portland cement and sand, the resulting material is glass fiber reinforced concrete--GFRC or sometimes GRC (the Brits call it glassfibre reinforced concrete).
The problem with using glass fibers as reinforcement for concrete is that glass breaks down in an alkaline environment--and there's almost nothing more alkaline than concrete. You may have heard of concrete being damaged by alkali-silica reactivity (ASR) when there is reactive silica in the aggregate. Glass is primarily silica. The original GFRC in the 1940s rapidly lost strength as the glass was destroyed by the alkaline environment. In the 1970s alkali-resistant (AR) glass fibers were perfected by Owens-Corning and by Nippon Electric Glass (NEG) leading to a rapid increase in applications.
GFRC has been used for the past 30 years to produce many concrete products, especially thin architectural cladding panels, but also for ornamental concrete such as domes, statues, planters, and fountains. Recently, decorative concrete artisans have discovered the benefits of GFRC for decorative panels (such as fireplace surrounds), concrete countertops, and artificial rock work.
Author Bill Palmer, ConcreteNetwork.com Columnist