Why GRC?

GFRC is a composite material made from hydraulic cement, silica sand, alkali-resistant (AR) glass fibres, and water. The inclusion of glass fibres significantly enhances the mortar mix, improving its tensile and flexural characteristics.

Key Advantages of GFRC:

• Lightweight & Strong: GFRC panels offer substantial weight savings compared to traditional precast concrete alternatives. This translates to significant cost reductions in transportation, handling, and erection, and can lead to substantial economies in the design of foundations and superstructures for high-rise buildings.

• Design Flexibility: GFRC can be moulded into a wide variety of complex shapes and profiles, making it ideally suited for modern building exteriors that utilize lightweight, prefabricated cladding panels. This includes the creation of intricate 3-dimensional forms, curves, and diverse textures and patterns.

• Durability & Performance: GFRC boasts excellent durability, chemical resistance, non-combustibility, and good sound/heat insulation properties6. It also exhibits impact resistance.

• Sustainability: By significantly reducing weight, GFRC contributes to lower embodied carbon in construction compared to heavier concrete solutions.

• Cost & Program Benefits: The lightweight nature and ease of prefabrication lead to lower overall project costs and faster installation times

What is GRC?

Constituent materials

Glass Fibre reinforced concrete (GRC) is a composite material made up of various constituent materials including; Binders (cement, pozzolans), Aggregates (silica sands), Fibre (Alkali resistant glass fibre), Admixtures (e.g. plasticisers, polymers, titanium dioxide, oxides etc) and water.

production

GRC is typically made in one of two methods, either ‘spray-up’ or ‘premix’. The method selected is largely dependant on the product being made (e.g. large flat panels vs complex 3D forms respectively) with each having their own advantages for the desired performance characteristics. With premix the fibre is pre-cut, mixed with the other ingredients and then hand pressed or trowelled into a mould. With the continuous spray method a glass fibre ‘roving’ is fed into a compressed air spray gun, where the fibres are cut to length and mixed simultaneously with a sand/cement slurry. Both methods require careful hand compaction into the mould using a spring roller.

For both methods Liquidstone first lay down a fine ‘mist’ coat which has no fibre onto the mould and this forms the decorative or face layer. Using this technique achieves a superior quality finish and often times means no additional post-production is required e.g. repairs, fairing, filling, painting etc.

Moulds and formwork

Moulds can typically be made from a variety of materials such as MDF, Plywood, Steel, Fibreglass and Polyurethane rubber etc or a combination of one or all of these materials.

Careful consideration must be taken to select the most appropriate material or combination of materials for each mould or application e.g. a single use one-off product will likely have a mould made using low cost material such as MDF whereas a mass produced product may benefit from a more expensive mould made from fibreglass with a PUR rubber liner that can be used many 100’s of times.

Surface finishes and treatments

There are almost limitless possibilities for colour and texture that can be applied post-production

• Off-form - smooth or textured surfaces, intricate patterns

• Exposed / fine aggregate including ‘Graphic concrete’ and Sand-blasting

• Mechanical abrasion - honing / polishing

• Painting / Staining - a wide range of colours and effects are achievable

• Hydrophobic coating and sealers

Properties of GRC

Permeability, water absorption and apparent porosity

Well compacted GRC has inherently low water permeability and can be used as for drains, culverts, pits and water tanks.

Acoustic performance

Well designed GRC can be effectively used as sound attenuating barriers alongside motorways and railways lines etc. For example a 10mm thick GRC panel will provide 20kg of mass per square meter which when combined with relief patterns and perforations designed to diffract sound the GRC panel will provide excellent sound / acoustic barriers.

Toughness and impact resistance

GRC is inherently tougher and more impact resistant than standard concrete and many other fibre reinforced composites.

Fire resistance

The basic constituents of GRC are inorganic and non-combustible. The fire performance classification according to standard test procedure is “A1”.

Recycling of GRC

GRC products are suitable for recycling in a similar way to standard concrete and in fact due to the relative high percentage of cement can contribute to the development of additional strength in concrete made from recycled aggregates.