Tag Archives: Brick

Bacteria-laden materials point the way to living, growing, healing buildings

New research at the University of Colorado Boulder (UCB) aims to pave the way to living, breathing buildings by mixing concrete with bacteria.

One of the shapes the team used to test their material.
Image credits UCB College of Engineering & Applied Science.

Walls that heal, scrub the air clean, or even glow on demand — that’s what the team envisions for the future. Led by engineer Wil Srubar from the UCB, they’re trying to make it happen by mixing living bacteria with sand and gelatin and then having them produce concrete on the spot, out of thin air. In addition, such an approach would help scrub CO2 out of the atmosphere.

Tiny building blocks

“We already use biological materials in our buildings, like wood, but those materials are no longer alive” said Srubar, an assistant professor in the Department of Civil, Environmental and Architectural Engineering at the UCB.

“We’re asking: Why can’t we keep them alive and have that biology do something beneficial, too?”

The bacteria-laden material isn’t commercially available just yet. However, the little bugs have survived in the hardened mixture for several weeks, suggesting that the approach is viable.

Mineralization comparison of the gelatin scaffold for the experimental (A, B) and bacteria-free control (C, D) bricks.
Image credits Chelsea M. Heveran et al., (2020), Matter.

Srubar and colleagues experimented with cyanobacteria belonging to the genus Synechococcus. Under the right conditions, these green microbes absorb carbon dioxide gas to help them grow and make calcium carbonate—the main ingredient in limestone and, it turns out, cement. The researchers bred colonies of these cyanobacteria and injected them into the sand and gelatin matrix, which serves to provide the shape and other materials required for the desired piece of concrete.

With the right tweaks, the calcium carbonate mineralizes with the gelatin that binds the grains of sand together, producing a brick.

“It’s a lot like making rice crispy treats where you toughen the marshmallow by adding little bits of hard particles,” Srubar said.

The material effectively acts as carbon storage, because it scrubs the gas from the air and chemically binds it into a stable compound. Because the bacteria don’t die off after crystallization, they could be used to repair any cracks or similar damage sustained by the brick (or a whole building), much like the living cells in our bones. The team managed to keep around 9-14% of the bacterial colonies in their material alive for 30 days, having spent three different generations in brick form.

“We know that bacteria grow at an exponential rate,” Srubar said. “That’s different than how we, say, 3-D-print a block or cast a brick. If we can grow our materials biologically, then we can manufacture at an exponential scale.”

But are they any good as far as bricks go? It seems so — the team found that the bacteria-laden bricks have similar strength to Portland cement-based mortars humidity conditions. In the future, they see their material as being delivered in bags on-site, where it would just be mixed with water and shaped, then allowed to develop.

 Cyanobacteria growing and mineralizing in the sand-hydrogel framework.
Image credits UCB College of Engineering & Applied Science.

The team also hopes to help slash emissions and energy use related to construction material manufacturing. Cement and concrete production for roads, bridges, skyscrapers and other structures generates nearly 6% of the world’s annual emissions of carbon dioxide, they explain.

However, there is still a lot of work to be done before such material becomes commercially available. One of the team’s goals right now is to grow cyanobacteria that is more resistant to dry conditions (the team’s bacteria currently need humid conditions to survive) so that they can be employed in hotter, drier areas.

The paper “Biomineralization and Successive Regeneration of Engineered Living Building Materials” has been published in the journal Matter.

Urine Brick.

Bricks grown from your urine make for greener houses, plumper crops

University of Cape Town (UCT) researchers want to make cheaper fertilizers and greener buildings — using your toilet.

Urine Brick.

(From the left) UCT’s Department of Civil Engineering’s Dr Dyllon Randall and his students, Vukheta Mukhari and Suzanne Lambert, holding the newly-unveiled bio-brick.
Image credits University of Cape Town.

Building materials like concrete, steel, or bricks are quite energy-intensive to produce. Since most of this energy is produced in fossil-fuel plants, it has a sizeable carbon footprint. Emissions associated with fuel use and those released by certain chemical processes during manufacture add to these products’ overall carbon footprint.

But, if you’re looking for a more eco-friendly alternative for all your masonry pursuits…

Urine luck

A team led by Suzanne Lambert, a civil engineering master’s student at the UCT, unveiled the first bio-brick developed from human urine. The material is created through microbial carbonate precipitation, a process similar to that used by marine creatures to build their shells.

It largely involves strengthening sand with chemicals derived from urine. The sand is colonized with bacteria that produce urease (an enzyme that breaks down urea in urine. The resulting calcium carbonate binds the grains of sand together, creating a very solid object in virtually any shape. It has to be mentioned, however, that sand is becoming an increasingly scarce material.

The concept of using urea for bricks isn’t exactly new — it was first tested in the U.S. a few years ago. However, Lambert’s team is the first one to use human urine, not synthetic solutions, for the process. This isn’t the first bio-brick to be developed, nor the first solid brick based on simple materials — but they do come with a wide range of bonuses that make them stand out.

One of the best parts of the new bricks is that they’re fabricated in molds at room temperature. This drastically reduces their emission levels compared to regular bricks. The fabrication process can also be tweaked to address particular needs — lower production times (and thus, costs), or higher-strength.

“If a client wanted a brick stronger than a 40 percent limestone brick, you would allow the bacteria to make the solid stronger by ‘growing’ it for longer,” said Dr. Dyllon Randall, a senior lecturer at UCT and Lambert’s supervisor. “The longer you allow the little bacteria to make the cement, the stronger the product is going to be. We can optimise that process.”

Brick the houses, sow the fields

Bio-bricks could also, surprisingly, help us grow plumper crops. Urine is rich in several chemical compounds that are key ingredients in fertilizers: nitrogen, potassium, and phosphorus (we’re running low on virtually every one of those compounds). Chemically speaking, Dr Randall adds, urine is liquid gold. Although it accounts for under 1% of domestic wastewater by volume, it provides 80% of the nitrogen, 63% of the potassium, and 56% of the phosphorus in wastewater. Nitrogen is particularly important from an agricultural point of view.

Most of these compounds can be harvested from wastewater, the team adds. Some 97% of the phosphorus present in urine, for example, can be recovered and used for fertilizers.

Virtually nothing is wasted when producing these bio-bricks, the team writes. The process starts with urine collected from novel fertilizer-producing urinals. Here, it’s used to create a solid fraction (which is basically a fertilizer mix). The liquid fraction is then used to grow the brick themselves.

“In that process, we’re only after two components: carbonate ions and the calcium. What we do last is take the remaining liquid product from the bio-brick process and make a second fertiliser,” Dr Randall explains.

The main hurdle the team has to overcome is logistics — namely the collection and transport of urine to processing facilities. How society reacts to the idea is another hotbed for discussion. Right now, the team is only dealing with urine collection from male urinals “because that’s socially accepted,” says Dr Randall. However, that leaves “half of the population” out of the process, which is a shame.

Still, Dr Randall hopes that their work will help people reconsider their relationship with waste — of any kind.

“In this example you take something that is considered a waste and make multiple products from it. You can use the same process for any waste stream. It’s about rethinking things,” he said.

The Mars brick.

Turns out you can make harder-than-concrete bricks on Mars simply by compressing soil

Mars colonizers might use the planet itself to make their homes — a new technique has been developed which can turn Mars’ reddish soil into bricks without the need for ovens or any extra ingredients. All you need to do is press hard enough on it.

The Mars brick.

Made from compacted Martian soil, without the need for additional ingredients or baking, this simple brick could one day house our first colonists on the red planet.
Image credits Jacobs School of Engineering / UC San Diego.

We’ll need to design a new range of materials if we’re to colonize space. Not only because they need to resist the vicissitudes of whatever planet or body we’re aiming to settle on, but also to save on cash — shuttling things through space is really expensive. Mars is the likely candidate for our first colony.

The idea of using its soil to build the first homes up there isn’t new. But previous technologies were reminiscent of traditional brick-making back on Earth, requiring brick kilns (nuclear-powered, of course), or involved mixing the material with chemical mixes to turn in-situ organic components into binding polymers.

It seems that we don’t have to do any of those things — making bricks on Mars is as easy as compacting soil. The surprising technology was developed by a team of engineers at the University of California San Diego, who initially started work with Mars soil simulant to try and reduce the amount of polymers required in brick-making.

To their surprise, they found out that only two steps are needed to turn the red dirt into a resilient building material. First, you have to place the soil in a flexible container (the team used a rubber tube). Then, you press it really hard — for a small sample, roughly the same pressure generated by a 10-lb hammer droped from a height of one meter is enough, said Yu Qiao, a professor of structural engineering at UC San Diego and the study’s lead author.

“The people who will go to Mars will be incredibly brave. They will be pioneers. And I would be honored to be their brick maker,” Qiao, added.

Their process results in small, round soil pallets that are about one inch tall that can later be cut into individual bricks. It likely all comes down to the iron oxide in the soil, the team says. Qiao and his team studied the simulant’s structure with various methods and found that the iron oxide particles coat the larger basalt bits in the martian soil. This is the same substance that lends Mars its shade of red and forms flat particles with clean facets which readily binding together under pressure, basically performing the same task as any added polymers would.

When testing the bricks’ strength, the team was surprised to find that they were stronger and more resilient than steel-reinforced concrete even without any kind of rebar. Which is a lot. Quao’s team says their method may be compatible to additive manufacturing, meaning astronauts wanting to build a structure would simply have to lay down a layer of dirt, compact it, lay another layer and so on until they’re done.

Next on the list, they say, is to tailor the production method to create bigger bricks.