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A Biomason biologically grown brick

Five innovative materials that could change construction

Image credit: Biomason

Many of today’s most widely used building materials have limitations, especially with regard to their impact on the environment. In response, innovative engineers around the world have developed new building materials that could provide an alternative.

What’s the most widely used manmade material in the world? It surrounds you day and night – when you work, when you’re entertained and when you sleep.

The answer is cement.

Cement, along with other common construction materials such as bricks, wood, steel and glass, is used almost universally in construction. These popular building materials have become so ubiquitous in large part thanks to their versatility, low cost and practicality. Nonetheless, they have their limits.

For instance, the worldwide production of cement amounts to about 5 per cent of human-generated CO2 emissions every year, according to a 2017 study. Brick production is also blamed for a range of ills – including soil degradation from the sourcing of raw materials. And, of course, wood burns, steel rusts, and glass breaks.

In response to these drawbacks, engineers, scientists and start-ups are proposing alternative materials, which they say could help improve on our existing building staples. Here we look at five of the more intriguing ones.

1. 3D-printed bioplastics

Waste is a major problem in the construction industry. Various studies put the quantity of building materials that end up in a skip at anywhere between 20 per cent and 30 per cent – representing an enormous environmental and economic cost.

This is where Dutch firm Aectual believes its bioplastic constructions can make a real difference. The firm uses large 3D printers to build complex and sophisticated designs, from floors to façades, stairs and even entire buildings. Besides using 3D printers to build the buildings, it’s the use of bioplastics which is especially innovative in terms of sustainability and waste reduction.

The firm says the bioplastics used by its 3D printers are made from 100 per cent renewable plant-based polymers, and can also deploy recycled plastics (it should be noted that producing bio-plastics still requires large-scale production of plants such as corn). What’s more, should the printer make a mistake, the plastic can simply be shredded and returned to the mix, resulting in building projects with no waste at all – in theory, at least.

2. ‘Programmable’ cement

When cement (an aggregate made of various materials) is mixed with water, sand and stone and left to dry, it forms concrete – the basis of the vast majority of modern buildings. But concrete is porous, allowing water and chemicals through. This degrades the concrete itself and can lead to rust in any steel supports encased within it. The problem is that on a molecular level, concrete particles form randomly, allowing space for liquid and other compounds to pass through.

Scientists at Rice University, Texas, have discovered a method for ‘programming’ the molecular structure of concrete as it sets, meaning builders could ‘tell’ the cement to form into more tightly packed cubes, spheres or diamond-shaped structures, for instance. The team discovered that by adding negatively and positively charged surfactants (compounds that lower surface tension) to the cement mix they could control the form that the cement particles took as the cement set.

In practical terms, this would mean concrete that sets harder, is significantly less porous, and stronger. What’s more, the scientists suggest this means less concrete would be needed to form strong structures.

3. Hydroceramics

Imagine a hot summer day in a stuffy office. The solution: turn on the air conditioning. Particularly in warmer climates, air-conditioning systems contribute enormously to energy bills. So, what if buildings could be designed using materials that manage these temperatures instead?

This was the goal of a recent project at Barcelona’s IAAC architecture school. Researchers developed a prototype material – a product they call hydroceramics – that passively cools buildings and can reduce the internal temperature by as much as 5°C compared to the outside level.

Essentially, the material is a kind of façade made of ceramic panels imbued with hydrogel, an insoluble polymer that can absorb up to 500 times its weight in water. When applied to buildings, this has rather intriguing possibilities. Since the hydrogel  is built into the ceramic façade of a building, it is able to absorb humidity from the air. During hot days, the water held in the polymer begins to evaporate, which has a cooling effect on the building – the IAAC describes it as the building ‘breathing’ through evaporation and perspiration. The researchers suggest that buildings clad with this material would be 5°C to 6°C cooler than the outside temperature and could reduce air-conditioning bills by 28 per cent.

4. bioMASON bricks

Trillions of bricks are made every year, and the majority are heated to extremely high temperatures in kilns as part of the process – all of which requires large amounts of energy. And this is where North Carolina business bioMASON hopes to make a difference.

The start-up has discovered a way of growing concrete bricks in ambient temperatures – which eliminates the need for firing them. Inspired by the formation of coral – a natural yet hard substance – the firm has created a method of ‘growing’ cement bricks. The company places sand in rectangular moulds and then injects bacteria that wrap around the grains of sand. They then ‘feed’ this mix with nutrient-rich water over the course of a few days.

The result is calcium carbonate crystals that ‘grow’ around each grain of sand and form a hard, stone-like substance in just a few days. BioMASON says its products are equal to standard bricks, yet require significantly less energy to create, meaning they’re much more environmentally friendly.

5. Alusion panels

The variety of materials used for ceilings, floors and cladding is often limited to brick, sheet metal, concrete or painted plaster. ALUSION, a product of Canadian firm Cymat Technologies, aims to provide architects and designers with something more.

The material is claimed to be uniquely versatile, and suitable for covering buildings, doors, floors and more. The Toronto-based business discovered a way of injecting air into molten aluminium which forms bubbles thanks to the dispersion of ceramic particles in the mix – not unlike how air bubbles form in a chocolate bar.

Besides making for a striking design material, ALUSION offers noise reduction benefits, is 100 per cent recyclable and is strong and non-combustible.

While it’s certain that many of today’s leading building materials will continue being used for decades – if not centuries – to come, the development of alternatives is certainly promising.

If nothing else, having access to a wider variety of source materials will ensure the construction sector is built on solid foundations.

History

The Roman concrete that gets stronger

It’s long been a mystery of ancient engineering: how did the Romans build concrete structures that have lasted thousands of years, while today’s concrete rarely lasts more than a few decades? The Romans invested heavily in designing a concrete that could withstand earthquakes, remained resilient to corrosive seawater and held its form even without steel support. Now scientists say they have cracked the recipe.

A 2017 study of Roman concrete found that it was made of volcanic ash, seawater, lime and lumps of volcanic rock. When first laid, chemical reactions would occur between these ingredients and form new substances, including a rare mineral called tobermorite. Intriguingly, whenever a crack appeared in the cement, more tobermorite crystals seem to form and patch the crack.

The Roman concrete depended on rare volcanic ash, making widespread replication difficult. Even so, the finding offers us a new way of looking at concrete: whereas the modern stuff is designed to harden and never change, the Roman approach would produce concrete that effectively heals itself. By finding a material that imitates the Roman ash, we could build structures that would withstand the test of time.

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