What is Glass-fibre Reinforced Concrete?

  • GRC is a cement-based composite reinforced with special alkali-resistant glass fibres, which are blended throughout the concrete matrix. The resulting material has highly usable tensile, flexural and impact resisting properties, the precise level being a function of mix design and, most importantly, glass-fibre content.
  • Glass-fibre Reinforced Concrete (GRC) was first developed in the UK in the late 1960s. Although experiments to reinforced concrete with glass fibre strands had been conducted since the 1940s these had been in the main unsuccessful due to the alkaline nature of the cementitous matrix reducing the effectiveness of the fibres.
  • This problem was eventually overcome after collaboration between the British Research Establishment and Pilkington Glass resulted in the introduction of alkali resistant glass fibres which maximized the long term performance of the material.

Glass-fibre Reinforced Concrete Durability & Weathering

  • Over the last 40 years more research has been done into the durability of the GRC than virtually any other façade cladding material.
  • As GRC contains no steel reinforcement there need be no concerns regarding concrete cover. Equally because the reinforcement is spread throughout the matrix and not just in the tensile stress area, elastic and ultimate bending strengths are significantly increased. These properties allow items to be manufactured using thin skin profiles thus reducing component weight.
  • Although it has long been understood that there is some loss in ultimate bending strength or ductility over time equally elastic strength increases as hydration of the cement continues.
  • Properties of GRC is a favoured material in areas at risk from seismic activity. In these areas full scale testing has shown very high resistance to cracking.

GRC Appearance

  • GRC is a versatile material, which is used on some of the world’s largest and most prestigious building projects and is gaining popularity with architects, contractors and house builders as a lightweight and durable alternative to more traditional architectural cast stone dressings.
  • GRC is an excellent material and can be made in many different forms and formulations. Of equal importance to many is the ability of the material to retain it’s supplied appearance.
  • GRC is a dense concrete and although it demonstrates similar water absorption to most other concretes, the water permeability is significantly lower. For this reason GRC is extensively used to manufacture water channels and ducting.
  • The rate of carbonation is also significantly lower in GRC than other forms of pre-cast concrete with independent tests showing a 90% decrease over a given period. As a result of the above GRC will retain its supplied appearance longer than most other forms of pre cast concrete such as cast stone.
Long term analysis of installed GRC indicates that the application of surface sealants assist in the preservation of both physical and visual attributes of newly produced GRC. Such coating, applied after the initial curing but before dispatch, effectively seal the surface of the GRC reducing even further permeability.
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