GRC GUIDE
Is GRC a Sustainable Building Material?
Looking at the figures, it should be no surprise that sustainability has become such a major concern in construction. Studies have shown that the buildings and construction sector alone are responsible for nearly 40% of annual global carbon emissions, 28% of which is embodied in materials used. If the industry is to align with a more sustainable future, more environmentally-friendly building techniques and materials need to be urgently adopted.
Glassfibre Reinforced Concrete (GRC/GFRC) is a particularly versatile material for sustainable applications; embodying a unique blend of practical and green attributes that can be leveraged to meet both performance and sustainability goals. In fact, a study carried out by the UK Government’s DETR/Concrete Alliance ‘Partners in Technology’ project found that, when compared to its precast concrete equivalent, GRC has a far lower environmental impact by a factor of as high as 60% (Ferry & Parrott, 1999).
What key factors underpin GRC’s credibility as a sustainable building material? Here are five of its most important attributes…
The 5 Sustainable Attributes of GRC
1. Resource Efficiency
Traditionally, steel rebar has been used to reinforce concrete structures – a resource-inefficient method with a high environmental impact associated with material extraction, processing and transportation. Steel reinforced products also tend to require a minimum concrete cover to protect the reinforcement from corrosion, resulting in further resource expenditure and thicker products.
By comparison, GRC uses Alkali-Resistant Glass Fibre as a reinforcing agent, which acts as three-dimensional, homogenous reinforcement throughout the product’s matrix. This translates into an incredibly strong material; in fact, in some cases, AR Glass Fibres can yield results of up to 30% greater tensile strength than steel. As this fibre is also corrosion-resistant, no minimum concrete cover is required, thus allowing for the creation of thinner profile products that require less resources to produce.
Further, GRC products are traditionally manufactured off-site in a controlled factory environment, ensuring that fewer product defects occur, facilitating reduced material wastage.
2. Weather Resistance
Resilience to the elements is a key factor in a material’s validity as a sustainable building material. If one is to be labelled ‘green’ it should maintain structural integrity and visual quality when faced with adverse weather conditions, ensuring that frequent repairs and replacements are not required.
GRC is well-known for its weather-resistant attributes; engineered to withstand extreme temperatures, humidity fluctuations and harsh climatic elements, GRC products remain reliable over the long-term.
Notably, the material’s resilience excels in three areas:
3. Durability & Longevity
More than just weather-resistant, GRC demonstrates remarkable overall durability and resultant enhanced product lifespan. Whereas traditional concrete products are prone to cracking and deterioration, properly designed, manufactured and installed GRC products exhibit far superior resilience, attaining a service life well in excess of 80 years. This augmented operational lifespan reduces the carbon footprint of GRC as the need for product replacements and repairs are mitigated.
More than just resistant to cracking, GRC products exhibit slow carbonation and low permeability which ensures resistance against de-icing salts and other corrosive agents, further enhancing product longevity.
Outstanding longevity is also present in the supporting frameworks of buildings utilising GRC. The thinner profiles and general lightweight nature of GRC products reduces structural stress and minimises wear and tear, enhancing the overall structural lifespan of buildings.
Pictured: Masdar Institute, Geelong Library & Heritage Centre (Photo Credit: “EHB_6331” by yesperhapsno, CC BY 2.0), Elizabeth Line
4. Reduced Energy Consumption
The low density and thin profiles of GRC products also results in lower energy consumption during production. By reducing the thickness of the products, significant savings can be made in weight which facilitates easier installation and faster overall construction times. In certain cases, these lightweight products can even be manually handled and installed, negating the requirement for heavy machinery and associated energy consumption.
These energy-efficient characteristics have led Glassfibre Reinforced Concrete to become highly rated in the LEED (Leadership in Energy and Environmental Design) certification process. LEED certification has set the framework for what is truly green in construction and many sustainable building projects have incorporated GRC into their specifications to achieve such status; the Masdar Institute in UAE being one such example of this.
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5. Insulation Enhancement
Another aspect of GRC that facilitates reduced energy consumption and further validates the composite as a sustainable building material is its insulative properties which can enhance the thermal insulation and energy efficiency of buildings.
Thermal conductivities in GRC panels vary but can achieve levels as low as 0.9-1.5w°C. The thinness of these panels leaves room for insulating materials to the incorporated into the building envelope, effectively minimising heat transfer. This low thermal conductivity enables reduced usage of artificial heating and cooling, resulting in lower carbon emissions over the building’s lifecycle.
Whilst GRC embodies a number of sustainable characteristics, a key component of its composition weakens the composite’s position as a definitive ‘green’ material. The key component in question is of course cement, which accounts for a significant proportion of the world’s CO₂ emissions.
Yet, despite this, GRC still exhibits resource efficiency, weather resistance, durability, longevity, reduced energy consumption and insulation enhancement: all factors that contribute to GRC’s credibility as a sustainable alternative to the majority of modern construction materials. This is highlighted by the growing number of projects utilising the material in meeting their sustainable building objectives, the Masdar Institute and Geelong Library & Heritage Centre being notable examples.
For a more comprehensive and technical analysis on GRC as a ‘green’ material, click here to read a paper on the topic written for the GRCA 2011 Congress in Istanbul.
Read more in our GRC Guide:
What is Glassfibre Reinforced Concrete?
GRC, Traditional Hand Spray, AR Glass Fibre, LOP & MOR – what does it all mean? Read our comprehensive introduction to Glassfibre Reinforced Concrete.
