Magical mystery materials tour

This Issue This is a part of the The future is now feature

By - , Build 165

Scientific advances are enabling building materials that are lighter and stronger than traditional materials. While some are only possibilities, others are already in use.

WE CAN BECOME somewhat complacent in our work. Sticking with the familiar keeps the stress levels lower and in essence makes our life easier. This can be particularly so in the building industry where designers commonly work with a known or familiar type of detail and palette of materials and finishes.

This can mean that new options, materials or systems may not get the consideration they deserve as they are perceived as being too hard to research and ultimately get through the consent process. This is a pity considering a performance-based Building Code designed to allow innovation has been in place for over 25 years.

What’s in the pipeline?

What might we consider in the not too distant future? An internet search has turned up some potentially significant developments, with some already in use.

There are a range of different materials and composites:

  • Graphene – a material extracted from graphite that occurs as sheets or flakes and is stronger and stiffer than both steel and carbon fibre although much lighter. The difficulty in producing it has been overcome by the US Oak Ridge National Laboratory, opening possibilities for its use in buildings.
  • Carbon-fibre balsa – a cellular composite material of unprecedented light weight and stiffness developed as a replacement for real balsa wood, which is hard to produce and expensive.
  • Carbon-fibre rope – an extremely strong fibre that could have the ability to permit lifts to rise to twice the current limits, allowing taller buildings.
  • Thermoplastic carbon-fibre composites – for seismic reinforcement. The carbonfibre inner material is covered with an outer layer of synthetic fibre and inorganic fibre that is then impregnated with thermoplastic resin.
  • Spray-on strengthening – consists of a ductile cementitious composite that is applied in a 10 mm thick coating to walls or existing structures. The material comprises polymer-based fibres, fly ash that replaces 70% of the cement and other industrial additives.

Variations on traditional concrete and bricks:

  • Cement-less concretes – these use organic renewable materials like rice hull ash, bones, shells and sea sponges to bind the aggregate rather than cement.
  • Concrete alternative that use recycled materials including waste steel dust to create a concrete-like building material said to be stronger than concrete.
  • Green-mix concrete – an economical and eco-friendly substitute for traditional concrete using conventional ingredients mixed with suitable waste and recycled materials such as fly ash, recycled concrete aggregates and aluminium can fibres.
  • Smart bricks – moulded from concrete that fit together like Lego but they have an adhesive applied to contacting surfaces. Holes formed in the bricks allow for the installation of reinforcing and services.

Some different energy sources for lighting, heating and cooling:

  • Beer power – this occurred when waste biogas from a brewery was used as an alternative energy source for a hospital.
  • Hydroceramics – a manufactured tile component combining the thermal mass and humidity control properties of clay and fabric with the liquid absorption and evaporation properties of hydrogel bubbles or spheres. They can absorb liquid, and on hot days, the contents evaporate and cool the space. Hydroceramic wall finishes could replace conventional air conditioning.
  • Solar concentrators – use mirrors or lenses with tracking systems to focus a large area of sunlight onto a small area. The concentrated light is then used as heat or as a heat source for a conventional power plant in a process called solar thermoelectricity.
  • Mechanoluminescence – occurs when a specific material is put under stress and lights up as a result. In South Korea, it has been moulded into plastic tubes infused with coloured phosphors made from copper-doped zinc sulphide. When subject to wind, the tubes deflect and illuminate with a white light.

Further innovations

Other innovations include:

  • silicon living glass with embedded wires that provide an electrical stimulus allowing material cells to open and close in response to CO2 levels in the air, thereby regulating air quality
  • applying the way organisms can maintain equilibrium for everything from sugar content levels to temperature to mimic in buildings what we do naturally – selfregulate based on environment
  • bricks made from plastic residues
  • pollution-absorbing bricks
  • cement that can generate light and also absorb and irradiate light energy
  • optically transparent wood
  • break-sensing conductive paint – a break in the paint film indicates a crack
  • boards made from compressed chicken feathers bound in cement
  • bioplastics, cellulose and other materials created by combining certain materials with specific varieties of bacteria — the resulting metabolic process produces solid, surprisingly durable byproducts
  • bioplastics made from discarded shrimp shells utilising the tough yet flexible natural chitin or insect cuticle
  • fungal mycelium from mushrooms for use as insulation
  • synthetic spider silk.

Ready for use

Already available, although not necessarily in New Zealand, are:

  • translucent concrete with optical fibres in a fine concrete matrix that is supplied as tiles
  • hempcrete, a biocomposite, thermal wall material made of hemp, lime and water
  • bendable self-healing concrete with up to 5% tensile strain
  • carbon-absorbing magnesium silicate cement substitutes
  • food waste used to manufacture construction products, including:
    • panel products made from compressed wheat, corn cobs, a blend of seeds, stalks, leaves and sunflower crop waste
    • fabrics and textiles from banana plants, pineapples and citrus peel fibres
    • cork substitute from potato peelings
  • wood made from newspapers, nappy roofing, blood bricks and asphalt that uses recycled plastic instead of sand as a filler.

These are innovations in the early stages of development that could result in products to aid building and construction in the future.

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