What is GFRC?

Glass Fibre Reinforced Concrete ( GFRC ) is a proven engineered composite building material consisting of Portland cement, aggregate, water, glass fibre reinforcement and additives. The glass fibres reinforce the concrete, much as steel reinforcing bars do in conventional construction. The glass fibre reinforcement results in a product with much higher flexural strength than normal concrete, allowing its use in thin-wall casting applications.

For building panel construction, GFRC castings are manufactured by spraying a series of layers of polymer-concrete material with glass fibre reinforcement in a female mold. A steel frame is bonded to the casting, allowing the panels to be installed by bolting or welding the frame to the building's structural steel. The flex-anchors, which connect the skin to the frame, allow movement of the skin relative to the supporting structure.

In the late 1960s, GFRC was first successfully produced in England. The key to success was the development of alkali-resistant glass fibres, capable of resisting the alkali attack that occurs when the fibres are mixed with normal hydrating Portland cement.

In 1980 the product began to be used in the USA. During the 1980s and 1990s, GFRC became widely accepted, and the industry has grown dramatically.

GFRC has made a major contribution to historical restoration because of its fine texture, allowing almost perfect replication of building ornaments and terra-cotta. Its very low shrinkage allows molds to be made from existing structural ornamentation, then cast in GFRC to replicate the original designs.

Specification

MANUFACTURER QUALIFICATIONS:

Manufacturer shall have a minimum of five years successful experience in the fabrication of GFRC units of the application and type specified. Fabricator must demonstrate that it has sufficient production capacity to produce the units specified within the time required, so as not to delay other work.

CASTINGS

Castings shall be produced in accordance with the standards set by the Prestressed Concrete Institute (PCI) as published in the manual "Recommended Practice for GFRC Panels", and shall conform to the colour and surface appearance of the samples provided. All anchorage attachments shall be supplied by the GFRC fabricator. Castings produced by the alternate pre-mix method using approved AR-Glass fibres shall also be deemed acceptable.

MATERIALS

3.1 Portland Cement: ASTM C 150 Type I 3.2 Aggregate: ASTM C 33 manufactured sand unless otherwise specified. 3.3 Fibreglass Reinforcement: Alkali-resistant (AR) fibreglass filaments shall be continuously introduced by a premix process into the GFRC mix for all backing coats in a manner to produce a continuously dispersed fibreglass mat reinforcement. Insertion of fibreglass mats or scrims shall not be acceptable.