Glass fibre reinforced concrete is a cement and sand matrix reinforced with alkali-resistant glass fibre instead of steel. It is called GFRC and spelled “fiber” in the United States, and GRC across the United Kingdom, the Gulf, Australia and Asia. Same material, different vocabulary, and the difference matters when you are reading a specification written in another market.
Why there is no steel in it. Steel reinforcement needs concrete cover to protect it from corrosion, which sets a minimum panel thickness. Glass fibre needs no cover, so the panel can be 15 to 25 mm instead of 100 mm or more. That single fact is where every other property of the material comes from: the low weight, the thin section, the ability to follow curves.
The naming, market by market
A specification written in Houston will say GFRC. The same detail written in London, Dubai, Kuala Lumpur or Sydney will say GRC. Neither is more correct. European standards documentation tends to use “glass fibre reinforced concrete” in full, and the International Glassfibre Reinforced Concrete Association, of which ShapeShift Technologies is a Full Member, uses “glassfibre” as one word.
Two related acronyms are not the same material and are worth separating early. GFRG, also written GRG, is glass reinforced gypsum, an interior material. GFRP is glass fibre reinforced polymer, a composite with a resin matrix rather than cement. ShapeShift makes all three, as ShapeShell-RC, RG and RT respectively.
How it is made
Three processes cover almost all architectural work. Sprayed GRC delivers the matrix and chopped fibre into the mould at the same time through a concentric gun, giving the highest fibre volume and the highest strength. Premix GRC blends fibre into the mix before it is cast or vibrated into place, and suits small, intricate or heavily detailed sections. Stud frame GRC bonds a sprayed skin onto a steel stud frame with flex and gravity anchors, which is how large panels are built.
The fibre itself must be alkali-resistant glass with a zirconia content of 16 percent or more. Cement is strongly alkaline and ordinary E-glass loses strength in it over time. This is not a minor specification detail, it is the difference between a facade that lasts and one that does not.
Standards that apply, by market
The material and test standards a project quotes depend on where it is. In Australia and New Zealand, AS 1530.1 covers non-combustibility, AS 1530.3 covers early fire hazard indices and AS 5113 is the large-scale facade test. In Europe, EN 13501-1 sets the Euroclass reaction-to-fire classification. In the United States, NFPA 285 is the full-scale wall assembly test the IBC calls up, with ASTM E84 for surface burning. In the United Kingdom, BS 8414 with the BR 135 criteria performs the equivalent role to AS 5113.
Results do not transfer between these regimes. A panel classified under EN 13501-1 has not thereby passed NFPA 285. The facade fire standards atlas sets the nine main jurisdictions side by side so you can see which test does what, and the fire test evidence page sets out what ShapeShell holds.
Typical properties
Figures below are for ShapeShell-RC. Properties vary with process, mix and fibre volume, so always work from the panel schedule and the engineering for a specific project rather than from a generic table.
ShapeShell-RC properties
| Property | Value |
|---|---|
| Panel thickness, typical | 15 to 25 mm |
| Reinforcement | Alkali-resistant glass fibre, 16 percent or more zirconia |
| Stiffness | 50 percent higher than standard GFRC |
| Matrix | Cement and sand, polymer modified |
| Geometry | Single and double curvature, freeform, perforated |
| Fire, Australia and New Zealand | AS/NZS 1530.1 non-combustibility result from Ignis Labs |
| Manufacturing | Batam Island, Indonesia |
| Warranty | Up to 50 years |
To size a panel and check crane class for your own project, use the facade panel weight calculator. For the product page see ShapeShell-RC, and for the supply and geometry side see GFRC panels.
Terms explained
Short definitions of the terms on this page, in our facade materials encyclopedia.
Common questions
Is GFRC the same as GRC?
Yes. GFRC is the American term and spelling, GRC is used in the UK, the Gulf, Australia and Asia. The material is identical.
Why is glass fibre used instead of steel?
Steel needs concrete cover to stop it corroding, which forces a thick panel. Glass fibre needs no cover, so the panel can be 15 to 25 mm. Everything else follows from that.
What is alkali-resistant glass fibre?
Glass fibre containing 16 percent or more zirconia, which allows it to survive in the alkaline environment of cement. Ordinary E-glass loses strength over time in concrete and is not suitable.
Is GFRC the same as GFRG or GFRP?
No. GFRG is glass reinforced gypsum, an interior material. GFRP is glass fibre reinforced polymer, which has a resin matrix rather than cement. ShapeShift makes all three but they are different products for different jobs.
Which fire standard applies to my project?
It depends on the jurisdiction. AS 1530.1 and AS 5113 in Australia, EN 13501-1 in Europe, NFPA 285 in the United States, BS 8414 in the United Kingdom. Results do not transfer between them, and the pathway for any building is set by its fire engineer and approving authority.
How heavy is a GFRC panel?
A fraction of the weight of a precast panel of the same face area. Exact weight depends on thickness, any stud frame and the finish, so use the panel weight calculator or ask for the engineering on a specific panel schedule.
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies.