Glass fiber reinforced concrete

Glass fiber reinforced concrete or GFRC is a type of fiber-reinforced concrete. The product is also known as glassfibre reinforced concrete or GRC in British English. Glass fiber concretes are mainly used in exterior building façade panels and as architectural precast concrete. Somewhat similar materials are fiber cement siding and cement boards.

Glass fiber-reinforced concrete consists of high-strength, alkali-resistant glass fiber embedded in a concrete . In this form, both fibers and matrix retain their physical and chemical identities, while offering a synergistic combination of properties that cannot be achieved with either of the components acting alone. In general, fibers are the principal load-carrying members, while the surrounding matrix keeps them in the desired locations and orientation, acting as a load transfer medium between the fibers and protecting them from environmental damage. The fibers provide reinforcement for the matrix and other useful functions in fiber-reinforced composite materials. Glass fibers can be incorporated into a matrix either in continuous or discontinuous (chopped) lengths.

Durability was poor with the original type of glass fibers since the alkalinity of cement reacts with its silica. In the 1970s alkali-resistant glass fibers were commercialized. Alkali resistance is achieved by adding zirconia to the glass. The higher the zirconia content the better the resistance to alkali attack. The best fibers have zirconia contents of 19% or higher.

A widely used application for fiber-reinforced concrete is structural laminate, obtained by adhering and consolidating thin layers of fibers and matrix into the desired thickness. The fiber orientation in each layer as well as the stacking sequence of various layers can be controlled to generate a wide range of physical and mechanical properties for the composite laminate. GFRC cast without steel framing is commonly used for purely decorative applications such as window trims, decorative columns, exterior friezes, or limestone-like wall panels.

The design of glass-fiber-reinforced concrete panels uses a knowledge of its basic properties under tensile, compressive, bending and shear forces, coupled with estimates of behavior under secondary loading effects such as creep, thermal response and moisture movement.

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