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The composites which revolutionised the construction sector

The composites or compositess of polymer matrix have revealed one of the biggest revolutions for the construction sector. Designers and architects have seen how thanks to them, virtually any barrier that until now prevented them from executing their most futuristic creations has disappeared.

Advantages of composite materials

One of the main advantages of matrix polymer composite (formed by two or more components that act in synergy) is that they are materials that offer a higher mechanical resistance with respect to their density, in comparison with conventional materials. Thanks to this, the composites play with a series of advantages very significant for a wide range of applications. For example, they allow to obtain complicated ways with great precision, also they have an excellent resistance to degradation, and they are highly resistant to corrosion. The composite materials advanced and have been used in the last 50 years in a variety of applications with high performances: military vehicles, luxury yachts, large wind turbine blades, aircraft, sports and leisure equipment such as skis, snowboards and surfboards. Also, they are starting to be used more increasingly in the world of architecture where they offer a significant saving in weight and the ability to create complex shapes that gives architects more freedom to design. Precisely, the design with composite materials opens an enormous range of possibilities in the application of the construction sector, such as how to optimise the performance structure by the means of simple changes in some of the components of the of the composite material (type of resin, types, and configuration of support materials).

Design freedom and futuristic constructions

If during the last 100 years, architects had limited the utilisation of common construction materials in their designs (wood, stone, steel, concrete), today the composite materials would not be revolutionising architecture. Its application in the environment of construction has allowed the substitution of progressive reform of traditional materials and with those, it has eliminated many barriers that designers have found in the face of their projects with futuristic designs. Until now, composites have been more commonly used in secondary structures or big self-supporting structures such as domes. But recently, some architects and engineers are developing more complex solutions in order to satisfy the creativity of some designers and their desire to challenge established norms for the design of buildings and singular work. These applications are only possible with composite materials because they have an approved combination of low weight of these materials with its capacity to be moulded into complex shapes. Between these main advantages, the composite materials offer in comparison to the traditional materials some of the things we have highlighted below:

  • Higher mechanical resistance: the composite materials are more efficient in the job as elements that proportionate a higher resistance. They can be designed for supplying specific interval mechanical properties, like resistance to traction, inflection and resistance and compression. In addition, the pieces of the composite can be manufactured with reinforcement with a determined orientation that can provide an additional resistance where the design requires it.
  • Aesthetic: they provide new aesthetic possibilities thanks to its capacity to mould complex, fluid, and creative shapes, as well as the capacity to integrate special surface finishing touches and an increased variety of effects, including the simulation of traditional materials
  • Corrosion resistance: The composite materials that do not oxidise, do not corrode. They are a multitude of polymer matrix systems that exist to provide resistance for the main part to the majority of environment temperatures and chemical environments. The pieces of composite material are correctly designed to have a long useful life and a minimal management in comparison to traditional construction materials.
  • Lightness: The composites have a specific high resistance to the majority of materials used in similar applications. These can offer more strength for weight than the majority of metal alloys
  • Durability: How much time do composites take? There are references to duration of more than 50 years and counting. The composites of the polymer matrix are relatively recent materials in comparison to the materials that are often substituted, concrete, steel, wood, so their life expectancy has not yet been reached in many of the components in use.
  • Design flexibility: The composite materials can be obtained in any form: they can be complex in their formation, big or small. Structural, decorative, or a combination of all these things. The composites free the minds of architects and designers in order to try new concepts, from prototype to production. Due to this flexibility, individual composite parts can replace complex unit assemblies that require multiple fixation elements when they are manufactured with traditional materials like wood, steel, and aluminium.
  • Dimensional stability: The composite materials of FRP maintain its form and functionality including low mechanical tensions and strict environments.
  • Dielectric behaviour: The composite materials of the polymer matrix have excellent electric isolation properties.
  • High service temperature: The manufactured pieces with the polymer matrix and correct loads can behave extremely well in the applying of high temperatures.

Advanced composites for high-performance applications

A composite material or a composite is formed from the combination of two or three different natural materials that combine to offer superior properties to the original components. The polymeric composites, as the name indicates, have a polymeric or material phase that performs the matrix functions. In this matrix, they bring together other materials that perform reinforcement functions (typically glass, carbon, or aramid fibres) and when it is possible, other reduced-cost materials, also known as loads.

These composite materials have come to be used in construction since the ambiguity: mixed clay with straw, plaster with horsehair etc. However, the natural polymeric composites started to appear at the beginning of the 20th century when they discovered thermostable resins.

Of these, war applications first and then aerospace after with industrialisation and costs reductions, the use of composites in other areas of the industry, and today, the composite thermostable matrix materials present excellent characteristics applicable in construction, for example:

  • They have low density, that can be translated to equal volume weight compared to traditional materials (steel, concrete etc)
  • They will not be affected by corrosion nor the attack of environmental agents. They do not oxidise
  • They present excellent mechanic properties
  • They offer a great freedom of shape and design
  • Some are transparent to electromagnetic waves
  • They present a great variety of finishing touches due to the great range of existing coatings (”gel-coats”)
  • They can act as isolated electrics
  • They have a competitive cost production

However, the use of composite materials, although it is accepted without reservation in sectors such as wind, the treatment of residual water, nautical (boat helmets, deck accessories, etc.) or the automotive (interior, body, etc.) among others; it doesn’t have the same growth in construction. This is fundamentally due to the low grade of normalisation that currently exists in composite materials. On the other hand, traditional materials (concrete, metals, ceramics etc) exercise strong competitiveness because their benefits are well-known to people with projects, contractors and including their own clients.

Reinforced material composites using fibres

The main implementations in buildings are reinforced compound materials using fibres (FRPs) with different natures including, the growing order of structural demand, window frames and doors, moulds used in architecture, secondary structures such as wall panels, roofs and floors, bars, and primary structures for modular buildings.

In reference to the structures mentioned, we can find implementations such as enfolding bridges, pedestrian bridges, vehicular bridges, aerodynamic fairings, concrete reinforcements, columns, pressure tanks, insulating and enfolding floors, etc.

The implementations of FRP´s in the architectural sector were initially developed in America, where today there is a large market. At the European level, although the market is still reduced, the introduction of the first FRP domestic doors approximately 15 or 20 years ago started the upwards trend of these types of material. The different FRP compositions allow the production of articles with properties custom-made to satisfy the market requirements such as new buildings and refurbishment of the former in both the public and private sectors. One very important advantage of composites in construction is the possibility of satisfying the strict requirements against fire and acoustic insulators that the current regulations imply. This is following the most efficient way when the composites combine with other materials (generally nucleus) so that steel, thermoplastics, or recycled plastics can fulfil the cost requirements. Furthermore, in this area, FRP´s have benefits of the social type such as better thermal efficiency in the home and more durability, increased reconstruction intervals.

Composite material implementations 

Another trend that day to day is gaining importance is the implementation of composites in the construction of bridges. Bridges are one of the most demanding infrastructures of civil engineering. Little structures present the same combination of functionality and visual impact. In vehicular bridges, the use of concrete and steel enjoys almost absolute supremacy. However, composite materials can be executed (and in fact, they already do have) a fundamental role in the replacement of boards that form the floor of bridges, where resistance to corrosion and rapid installation are important. In a similar way, the enfolding bridges also are carrying out these types of composite materials. Special mention should be made of pedestrian bridges, usually installed in hard-to-reach areas, the lightness of composite materials allowing their installation without the use of heavy vehicles such as cranes.

The use of composite material as coverings is a good method to supply added value to buildings, both new ones and the restoration of existing ones. The implementations in the appearance, structure, towers, vaults, domes etc, create a new alternative to stone, bricks, wood, tiles, etc., compared to those that present advantages such as low maintenance, UV resistance, low weight, and ease of creating replicas of parts for replacement.

The installation of fences is another important application. In the domestic plan, it is still being used for its low weight and maintenance and excellent resistance to the outdoors. On the other hand, this application highlights the fencing of airports due to the composite materials being inherently transparent to the radar waves, so, it eliminates the risk of interference with these landing and take-off teams. An additional motive in its fragility, that although they are highly rigid and resistant materials, they can break easily in the case of a collision with an aeroplane, minimising the consequences of an accident.

Modular structures are a series of pultruding panels that weave together in order to give a place to constructions with structural integrity for themselves, this is, without the necessity of additional frames. The most highlighted advantage in this application is the possibility of the same premanufacturing, its facility to transport and its sensitive installation. Its applications are varied: cold towers, warehouses, and tunnel washers.

The possibility of designing composite materials with structural requirements “measures” thanks to the preferential orientation of fibres, making them very suitable for applications with high structural requirements, such as masts, towers, and poles. The benefits of these products are, above all, electric and telecommunications companies, that can carry out the distribution through positioned lines that are between them, because it eliminates the risk of electric arc, thanks to dielectrics of these materials, which also find room as utility poles, solar panel supports, marine pillars, etc.

The facility of processing polymeric matrix composites makes them ideal to reinforce structures. In the case of beams and bridges, carbon fibre is applied (that can be conventionally good or good pre-tenses) in its inferior part, that is subjected to traction. Also, it is used in the repairing and reinforcing of appearances, roofs, roads etc. The most significant advantage is the job of reinforcing carbon fibre resin composites over steel is the weight reduction of its own structure. The carbon fibres have a much higher resistance to traction than steel and furthermore, they are much lighter and do not present corrosion. The reinforcements of fibreglass are one of the more economical alternatives. Whatever may be the option, the unity between covering and structure is of great importance for the recovering to fulfil its function, In order to prevent the breaking of the same they have developed methods of non-destructive analysis for the determination of holes between the reinforced and covered structure, as a represented term of transitory ultrasonic firmness.

The composites materials have been considering many innovative structural applications due to flexibility: it is possible to combine them with traditional materials to obtain synergetic effects at competitive prices. Its main durability, resistance to corrosion, facilitating of transport and possibility of premanufacturing open a new door to the professionals of construction.

Other sectors of applying composites

Another sector where composites are collecting big importance is in wind. The fundamental enforceable requirements to the blades of wind turbines, they are an excellent resistor to wear out, and corrosion (especially for the turbines installed on the coast), have minimal maintenance, a life expectancy of fewer than 30 years and light. Composite materials suppose and ideal answer to this necessity and have totally disregarded steel and aluminium.

There is a new trend with wood plastic composites (WPC). These are a combination of wood (in diverse forms) with a thermoplastic or a thermostable. Generally, it’s based on wood flour or sawdust, and although priori wood is a composite that in addition to absorbing moisture, it doesn’t present a high resistance, this composite material has been found for application in interior design, the manufacturing of gardens products etc. because in addition to presenting a high aesthetic value, it allows the recycling of excess industrial wood, contributing to the sustainable development and environment.

New thermoplastic composites

One of the major areas of demand in the market is for high performance materials which are more flexible in terms of processing options (reprocessability) and are also more environmentally friendly (recyclability and reparability).

This demand is largely met by using continuous fibre thermoplastic composite materials. Sectors including the construction, automotive and aeronautics industries have begun to use these products, mainly due to their processing/cycle time, reprocessability and recyclability advantages.

Adapting processes designed for composites with thermosetting resins to continuous fibre thermoplastic composite materials is an enormous challenge for companies which can be met with the help of AIMPLAS.

The advantages of continuous fibre thermoplastic composite parts are:

  • Recyclability.
  • Good fire retardant and mechanical properties.
  • Reduced cycle times.
  • Low production cost as well as being safe and versatile.
  • More ecological process and product (depending on the type of polymer) with lower energy use and based on renewable and/or recyclable material.
  • Reduction in the part’s weight.
  • Easy transport and assembly.