Construction’s brave new world of materials

Science keeps pushing the boundaries of what’s possible with building materials, from flexible concrete to transparent wood, so what might tomorrow’s builders use to shape the future? Tim Clark reports

They can self heal, alert occupants to danger, or help the world reach its sustainability targets; the ever increasing array of wonder materials looks set to revolutionise the world of construction.

But how likely are we to utilise such materials, and just what is available? Build In Digital has taken a look to see which materials are being used on what projects now in the UK, and what is being invested around the globe.

Research conducted by McKinsey Global Institute found that the rise of innovative materials may help solve construction’s chronic productivity problem.

According to the institute, global labour productivity growth in the sector averaged around 1% over the past 20 years, falling way behind the average growth of 2.8% of economies as a whole, and even further behind other sectors such as manufacturing, which has a 3.6% growth rate over the same period.

The report stated that: “Construction lags significantly behind other sectors in its use of digital tools, and is slow to adopt new materials, methods, and technology. Significant advances being deployed or prototyped today can transform the effectiveness and efficiency of construction in three areas: Digital technologies, advanced materials, and construction automation.

“Emerging disruptions, including industrialisation and new materials, the digitalisation of products and processes, and new entrants, will shape future dynamics in the industry.”

Getting to know your ABMs from your ABCs

The new materials mentioned by McKinsey are known as Advanced Building Materials, or ABMs. They are at the frontline in a new generation of materials that have exceptional properties, such as light-weight steel frames, transparent materials, and those which have a memory of shape or can be bent without losing structural strength.

The aim of such materials is to cut costs and increase productivity, cut carbon from the construction sector, and make buildings more resilient as well as smarter.

They include new forms of concrete which is lower carbon, innovations within wooden building typologies, and enhanced glass.

Innovations also include transparent wood, transparent aluminium, super-strong plastics, and 3D printed building elements made from a type of fungus.

According to Market Research Future, the advanced building materials market was valued at $54.2bn in 2021, and rose to $57.47bn in 2022. By the end of the decade it is expected to reach $91.7bn.

Structural healing

Cement and concrete lay at the heart of the construction sector’s carbon emissions. Cement production accounts for around 10% of carbon emissions, and even though the sector has strived to decarbonise in recent years, particularly in the UK, it still has a long way to go to be anywhere near sustainable.

Researchers have also begun experimenting on what is known as bendable concrete – or engineered cementitious composite (ECC) – that can self-heal without human intervention. All types of concrete are able to self heal to a certain extent – which means that when they are cracked those cracks can close up due to new bonds forming within the material. ECCs however take this concept even further.

The University of Michigan’s centre for low carbon built environment is one institution which has been researching the properties of ECCs to create materials that have a higher stress level without failing structurally.

Traditional concrete can crack or break suddenly if it is put under stress that reaches its breaking level. ECCs can effectively bend to absorb this load better without any lasting cracks or damage.

“This is what we call plastic behaviour,” says Victor Li, professor in the department of civil and environmental engineering at the University of Michigan. “The material provides a give under extreme loading, instead of fracturing and still holding [the load].

“Structural safety under extreme loading such as an earthquake or man-made disasters such as bomb blasts, we would like, to keep the occupants safe.”

Cost and productivity are two areas where material innovation is pressing forward; a third area is reducing the carbon count of the industry.

Squaring the circle

In January Build in Digital highlighted how many firms are looking to ‘square the circle’ when it comes to their own carbon emission conundrums.

One major source of emissions is the traditional clay brick, which need high temperatures to be baked. UK firm Kenoteq has launched a new product, the K-Briq which aims to change all that.

Using up to 95% recycled material, the firm claims that the patented brick uses only 20 grams of CO2 to produce, and 1 kg of CO2 per m2 of bricks, which is 95% less than a traditional clay brick.

The key to the brick’s low-carbon count is the fact it requires no firing and very little water to make, the recycled content, that can include mortar, old plasterboard or rubble, is instead glued together.

Kenoteq states that it has saved 87,600 kg of CO2 and over 440,000 kg of water from its products compared to the equivalent traditional materials, stating that there is a “distinct lack of low carbon materials to meet net zero carbon targets, and a fundamental need for sustainable building materials”.

It adds: “Our vision for 2024 is to deliver 3m certified bricks for exemplar projects, blazing a trail in the circular economy revolution and bringing a scalable manufacturing and sustainable product solution, together with waste management partners, into an international marketplace.”

Utilising waste to make bricks is one area where material innovation is pressing ahead. The construction world is also beginning to look beyond concrete and bricks or steel for its structural solutions.

According to the American Society of Civil Engineers, the US will need to invest $2.6trillion into repairing and maintaining its infrastructure. Reinforced concrete forms a key material for this sector, and research is underway to see what materials can replace the traditional steel rebar and concrete mix.

The Rensselaer Polytechnic Institute in Brooklyn, New York has developed a method of using hemp to produce a natural, non-corroding natural fibre-reinforced thermoplastic (NFRT) that can be used as an alternative to concrete and rebar in the construction industry.

The research project began in 2021 and according to the institute, the goal is to provide a technology that is more cost-effective, easier to install, and utilises less embodied energy compared to current materials, and use NFRTs to match the mechanical and durability performance by weight of stainless steel or FRP, but at a cheaper cost to both manufacturers and construction firms.

The project is still in its research phase, and a viability study on the material was undertaken in 2022 for its use in cementitious materials, however it is hoped the material can be used on structures in the near future.

What’s shaping the advanced materials market?

Self-healing materials

In essence these materials can suffer from minor cracks and have the ability to repair without any human intervention. This can allow for two things: More intricate designs can be used on materials such as concrete, and also less overall material can be used. The pros are that they are light-weight, use less CO2 and need less maintenance.

The negatives are whether how long-term they prove to last, or have the same fate as Reinforced Autoclaved Aerated Concrete (RAAC), which has suffered from safety and structural problems.

Smart materials

From helping to earthquake-proof structures to materials which have a “memory” of a previous shape – and so can be deformed and return to original state – smart materials could become more widely used in coming years. The materials can change their properties when exposed to a magnetic field, and are used in bridges and skyscrapers.

Mushroom printing

An even more dynamic material which has been developed in recent years is the 3D-printed mycelium. Mycelium is the root-like part of a fungus which consists of thread-like hyphae. It isn’t normally what would be considered a suitable building material, however combining the threads with other substances has come up with some interesting materials. A mycelium composite can be made from coffee cup waste, for instance, which is boiled and mixed with mycelium to create the material – with colours added by pigments. Mycelium tissue can trap more heat than fibreglass insulation, is fireproof and non-toxic. In terms of comparable strength it is stronger than concrete.

Transparent wood

In early 2021 researchers at the University of Maryland announced that they had created a type of transparent wood using techniques that are more akin to the manufacture of nanomaterials. The researchers managed to replace the Lignin in the tree’s cells with a transparent epoxy.

The slices of wood can be less than 1 millimetre thick or up to a centimetre, but have similar qualities and can perform better than plastic or glass under testing conditions such as how easily they break or fracture under pressure.

In terms of advantages, transparent wood is a better insulator than glass, and as such may be better for use in helping buildings retain heat. The university launched a spin-off company called InventWood to take the project further.

Read next: Holyrood ditches carbon emissions targets

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