GRC GUIDE
What is Glass Reinforced Concrete?
Glass Reinforced Concrete is a composite material composed of a cementitious matrix reinforced with fine Alkali-Resistant Glass Fibres. These fibres act as the principal load-carrying component of the composite whilst the surrounding matrix keeps them in position and transfers the load between the fibres, forming homogenous dispersed reinforcement throughout the material’s composition.
Combining the strength and durability with the flexibility and lightweight properties of glass fibres offers architects and engineers a versatile solution for creating architectural elements, facades and structural components with exceptional strength and aesthetic appeal.
The material is known by many names around the world such as Glassfibre Reinforced Concrete, GRC, GFRC, Composite Ciment Verre, CCV, Fiber Beton, Fiber Takviyeli Beton and Glasfaserbeton but, for the sake of clarity, we’ll refer to it as Glass Reinforced Concrete (GRC) in this article.
Worldwide Appeal
What can Glass Reinforced Concrete be used for? Since the material’s emergence in the 1970s, it has been used in some of the most world’s most spectacular architectural designs – just take a look at the One Thousand Museum in Miami or the Masdar Institute in Abu Dhabi as examples.
We have an extensive collection of Glass Reinforced Concrete project case studies available on our website so, if you’re your interested in learning more about the material’s potential, click the button below:
Variable Properties & Performance
GRC’s performance can differ greatly on several factors such as the production method, the mix design and, notably, the type and quantity of Alkali Resistant Glass Fibre used.
The two most popular methods of GRC production (Traditional Hand Spray and Sprayed Premix) offer varying mechanical properties so it is important to consider which production method is best suited for your project.
The table below demonstrates the differing properties between these two methods:
| Property | Units | Hand Spray | Premix |
|---|---|---|---|
| Fibre Content | Wt.% | 4 – 5 | 1.5 – 3.5 |
| Density (Dry) | g/cm³ | 1.8 – 2.1 | 1.8 – 2.1 |
| Flexural Strength LOP | N/mm² | 6 – 10 | 5 – 10 |
| Flexural Strength MOR | N/mm² | 18 – 30 | 5 – 15 |
| Compressive Strength | N/mm² | 40-70 | 50 – 80 |
| Tensile Strength UTS | N/mm² | 8 – 12 | 3 – 6 |
| Tensile Strength BOP | N/mm² | 4 – 6 | 3 – 5 |
| Thermal Conductivity | w/m°C | 0.9 – 1.5 | 0.9 – 1.5 |
| Thermal Expansion Coefficient | x10-6/°C | 7 – 12 | 7 – 12 |
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Traditional Hand Spray vs Sprayed Premix
The Traditional Hand Spray method is known to achieve the highest strengths due to a synergistic mix of high AR Glass Fibre content, made possible by simultaneously spraying chopped fibre and cementitious slurry through a specially designed spray gun. Additionally, this method benefits from low water-to-cement ratios, lengthy fibre strands and a planar orientation of the fibres.
In comparison with the Traditional Hand Spray method, strengths attained through the Sprayed Premix method are generally lower, mainly due to reduced AR Glass Fibre content (generally around 3% by weight), shorter fibre lengths and a multi-dimensional fibre orientation. However, Sprayed Premix stands out by delivering mechanical properties that are more consistent and, in some cases, superior to those produced by the Vibration Cast Premix method by ensuring uniform distribution of fibres throughout the mix, thus forming products that exhibit exceptional integrity and durability.
For a more detailed comparison of Traditional Hand Spray and Spray Premix, click here.
The Future of GRC
GRC’s diverse qualities provide benefits that span a wide range of sectors, from small-scale kitchen worktop production to the manufacture of large-scale architectural cladding, the GRC industries encompasses a vast range of unique and innovative applications.
More specialists are adopting the material – notably in modular construction, restoration work, cladding and formwork – utilising GRC’s practical advantages of lightweight, durability and versatility to meet the complex and varied demands of construction.
Development of GRC is ongoing, as it has been since its’ emergence in the 70s, with new standards continually being developed and advancements being made in production techniques and material formulations, further solidifying the material’s position in the construction industry.
You can stay up-to-date with the latest developments in the GRC industry and find helpful information and advice in our GRC Journal, updated regularly.
