GRC manufacturing process

A hand sprayed craft

The GRC production process

Our glassfibre reinforced concrete (GRC or GFRC) elements are manufactured using the hand spray-up method, which is the most conventional method for architectural GRC cladding. This method allows for thinner sections and larger elements. The GRC mixture is sprayed onto casting moulds and between coats, it is compacted by hand using rollers to remove air pockets and to ensure an even distribution.

The casting moulds are custom-made for each project and is carefully produced in our mould shop. Intelligent mould design makes it possible for us to make adjustment to single moulds to they can be used for several variants, if the project calls for a multitude of varying element types.

The GRC manufacturing process requires great craftsmanship and the many steps makes it crucial to adhere to strict quality controls. BB fiberbeton is a Full Member of GRCA, which verifies that we have sufficient resources in our plant, equipment, and labour to consistently design and manufacture high quality GRC. We also have quality management systems and production controls in place to comply with the requirements of the GRCA Specification, Method of Testing and Practical Design Guide.

A specialised craft

Hand spray cast GRC

All GRC elements from BB fiberbeton are manufactured by hand spraying the GRC into a mould. This is the traditional method and requires experienced workers and extensive equipment.

For this spaying technique, we use a concentric chopper spray gun, which is fed by a spool of glass fiber threads and the chopped strands are blended at the nozzle.

This method allows for a low water/cement-ratio and the GRC mix has a higher fiber content than can be achieved with premix. It also makes it possible for us to manufacture larger and more complex GRC elements. Compared to the Premix method, which has pre-chopped glassfibre strands blended into the mix, the spray-up technique produces thinner elements.

A coloured & textured finish

Producing a unique GRC surface

GRC elements can be decorated with an almost endless array of colours, textures, and finishes.
As part of the GRC production process, we can create patterns and textures as part of the actual mould design, a CNC milling, or with patterns from Reckli. With these methods even the smallest details are shown.
Another way to decorative the surface with texture and depth, is to expose aggregates in the surface. Many types and sizes of aggregates are available to achieve a multitude of colour and texture combinations. When manufacturing a surface with exposed aggregates we generally differentiate between fine and coarse aggregates, each giving a very different expression.

With finer aggregates you achieve an even and smooth surface with smaller visible grains of sand. This will leave the elements with a still polished expression while also still achieving a textured and dynamic expression.

For a coarser textured surface, we use larger stones and pebbles. These coarse aggregates create more depth, contrast, and roughness to the expression. A great example of this finish is the GRC facade of NH Collection Hotel.

Our GRC is naturally white as we use white cement in our mixture. By adding coloured iron oxides and other aggregates we can achieve various colours, nuances, and tone. Our use of white cement is significant, since it helps to render clearer colours. The addition of iron oxides will result in cement-based colours that are very coloured and will not fade over time.

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