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Glassfiber reinforced plastics (GRP)
A sustainable material challenging the traditional market

Today’s life without glassfiber reinforced plastics would be difficult to imagine. Discovered for industrial purposes around the beginning of the 20th century, the material has initially been used for insulating houses. Further applications quickly evolved, and today the material is commonly used in the aerospace, automotive, marine, and construction industries.


What it’s made of

Glass(fiber) Reinforced Plastic (GRP) is a composite material that consists of a polymer matrix and glass fibers. The polymer matrix is usually an epoxy, vinylester, or polyester thermosetting resin. The resin brings the environmental and chemical resistance to the product, is the binder for the fibers in the structural laminate and defines the form of a GRP part. The glass fibers add strength to the composite. They may be randomly arranged, or conveniently oriented. The most common type of glass fiber used for GRP is E-glass, which is alumino-borosilicate glass. E-CR-glass (Electrical/Chemical Resistance) is also commonly used in applications that require particularly high protection against acidic corrosion.


Why it’s so strong

As with many other composite materials, the two materials supplement each other to form a stronger compound. Plastic resins are strong in compressive loading; the glass fibers are very strong in tension. By combining the two materials, GRP becomes a material that resists both compressive and tensile forces very well. Production methods of GRP include filament winding, centrifugal casting, hand lay-up and spray lay-up, and pultrusion.


What the superior advantages are

GRP features many beneficial characteristics. It comes with low weight at high mechanical strength, resistance against chemicals and corrosion (thanks to its non-conductive properties also electrolytic corrosion), UV radiation and temperature stability, and environmental friendliness. GRP is waterproof, making it ideal for all outdoor applications. It can be customized to be fire-retardant by using non-flammable resins. GRP is a highly durable material with a very long lifetime expectancy, ideally suited for a wide range of applications in various industries.

GRP in pipeline construction


Since the 1950s, GRP has gained a firm foothold in the construction of pipelines. The range of applications covered by GRP piping solution today is broad: from sewer systems and potable water lines to storage tanks, drainage pipes, hydropower penstocks, industrial pipe systems, as well as rehabilitation solutions with special non-circular pipe profiles, to name just a few. The methods by which the pipes can be installed are just as manifold and include open trench, above ground, on suspensions, underwater, and by means of trenchless technologies such as relining and microtunneling.


GRP pipes by Amiblu are primarily produced by filament winding (Flowtite technology) or centrifugal casting (Hobas technology). In both methods, sand and fillers are added to the fiber-resin composite to build a sufficient wall thickness and thereby increase the strength and stiffness of the pipe. The filament winding process employs continuous and chopped glass fiber reinforcements, that are applied onto a rotating, advancing mandrel in circumferential direction. The pipe is thereby formed from the inside outwards. In centrifugal casting, the pipe wall is built from the outside inwards in a rotating mold. The raw materials, including chopped glass fibers, are subsequently fed into the mold by means of a feeder arm moving forward and backwards. Either process results in a GRP pipe with defined characteristics, which prevail over other pipe materials in various aspects.

Advantages of Amiblu GRP pipes:


  • Reliable operational service life of over 150 years
  • Global use and acceptance by major water and sewage authorities all around the world
  • Fully automated production process, allowing for each pipe to be manufactured with the specific properties required for its application and operation demands
  • High stiffness classes available (e.g. for areas with weaker soils)
  • Light weight and convenient length. GRP pipes weigh only 1/4 of ductile iron pipes and 1/10 of concrete pipes. This leads to considerable savings through reduced transport, nesting, handling, and installation costs
  • Lower surge and water hammer pressure due to low surge wave celerity
  • Corrosion resistance over a wide pH range
  • No electrolytic corrosion. GRP pipes require no cathodic or other type of protection
  • Ability to withstand high longitudinal compressive loads (2-3 times higher than concrete) that occur during pipe jacking
  • Low coefficient of thermal expansion
  • Excellent hydraulic flow characteristics. Smooth internal pipe surface, resulting in significantly lower friction than with other materials

What is sustainability?


The World Commission on Environment and Development defines sustainable development as “development which meets the needs of current generations without compromising the ability of future generations to meet their own needs”.


For complete sustainability, society, environment, and economy must work together. All three factors overlap, they interact, and if any of them is weak, a system cannot be sustainable. We therefore need to look at the many different forces, processes, and actors that shape a system in a holistic way and understand how they influence each other. Compared to other materials, the production of GRP is exceptionally benign and sustainable. This is because the production of base resins and fiber rovings have a much smaller environmental impact than metals like steel. Thanks to the material’s very long lifetime expectancy, supreme quality, and environmental friendliness, GRP products are solutions for generations and contribute to each of the three pillars of sustainability.

Environmental sustainability

Environmental sustainability

Environmental sustainability is the ability to keep renewable resource use, pollution, and non-renewable resource depletion at levels that don’t harm the future of our planet. This pillar of sustainable development is needed to be given top priority: It’s a prerequisite for both social and economic sustainability.


Economic sustainability

Economic sustainability

Economic sustainability is the ability to support a defined level of economic production indefinitely. It is, in other words, the process of allocating and protecting scarce resources, while ensuring positive social and environmental outcomes.


Social sustainability

Social sustainability

Social sustainability is the ability of a social system, such as a country, to maintain a defined level of social wellbeing indefinitely. Future generations should have the same or greater access to social resources as the current generation. Furthermore, there should be equal access to social resources within a generation.


Pipes designed for generations