Glassfibre reinforced concrete manufacture
GRC components can be manufactured by various methods but the two most common are Simultaneous Spray-up and Cast Premix.
In the Spray-up method, the continuous glassfibre strand is fed into a chopping gun, cut to 25 to 37mm and simultaneously sprayed out with the cement mortar. The cement mortar is fed to the spray gun by a pump, and is atomised by the spray gun using compressed air. The glassfibres and cement mortar are sprayed together onto a prepared mould where they are compacted to produce the composite using rollers. Normally the glassfibre content is in the range 3.5 to 5% the product thickness is in the range 10 to15mm. The process is suitable for products of relatively large area such as cladding panels and many other thin-section components.
In the Premix method, pre-chopped strands typically 12-40 mm in length are blended into the mortar mix at low speed, and the resulting mix is cast with vibration into moulds. Glassfibre content in this process is in the range 2-3.5% and product thickness is greater than in spray-up, depending on the component requirements. As a variation on this method, the premix of fibres and mortar can be delivered by a pump and spray gun system onto the mould (Sprayed Premix). Premix GRC is used for smaller architectural components, drainage items, decorative sunscreens and many others.