Month: July 2016

Manufacturing in GRC (Part 4) Spray Lay-up

So we’ve looked at the mould-making process. Now we move on to making products in GRC.

GRC stands for glassfibre reinforced concrete which means it is a composite material made up primarily of sand and cement plus glassfibres for structural reinforcement. At Quatro Design we use equipment specifically designed for GRC manufacture. The first piece of equipment is a shear mixer which mixes fine sand, cement, water and additives at high speed. This results in a render with a consistency a bit like soft-serve ice cream. This render mix is then transferred into the GRC spray pump which then pumps the render to a spray gun that incorporates a fibreglass roving chopper. The spray gun does two things at the same time – it atomises the render and chops the fibreglass roving into strands around 25-35mm long. It then simultaneously shoots both the render and the chopped fibres at the mould causing them to mix together as they exit the gun.

In the video here you can see a bowl being laid up in GRC. See how Anthony moves the gun around the mould applying an even layer of render mixed with glassfibres. When he’s finished spraying, the GRC will be hand-compacted using special rollers. With this bowl, a rim will be laid up separately in a matching rim mould and later joined on to the bowl mould. The next morning the completed bowl will be lifted out of the mould ready for detailing.