Thomas Edison had a thing for concrete. In 1899, the renowned inventor developed his own brand of cement, and later supplied the concrete for the original Yankee Stadium. He even hoped to revolutionise housebuilding, and in 1906 created a design for concrete homes that would be cast in one piece – complete with concrete bathtubs and beds integral to the design.
Edison’s cast homes failed to take off – although there are some still standing in New Jersey – but concrete went on to build the modern world. Made from cement mixed with water, sand and aggregate, such as gravel, concrete is the world’s second-most consumed material, after water. In 2017, an estimated 4.65bn tonnes of Portland cement (the most popular cement used in concrete) was manufactured worldwide, over half of that in China. But the environmental cost is huge. Hillsides are gouged away to extract limestone to make the cement and more quarries are dug to get aggregate for concrete. Portland cement manufacture accounts for about 8% of global carbon emissions – partly through the chemical process of making cement and partly because of the energy needed to heat the kilns.
“Portland cement has been around for over 200 years, and bricks for thousands. Not much has changed in our supply chains and our dependencies upon limited resources,” says Ginger Krieg Dosier, who is determined to change that. Her company, bioMASON, is pioneering a way to grow bricks, tiles and a trade-marked biocement at room temperature using bacteria.
Dosier trained as an architect but found inspiration in the natural world – in particular, from corals, shells and also the way that some sandstones are formed by bacteria cementing sand particles together. “Nature already exhibits the ability to grow strong and durable cements without harming the surrounding environment, and this was the early inspiration to grow cement materials,” she says.
For two years, toiling away in her spare bedroom, Dosier experimented with various mixes of non-pathogenic bacteria, sand, nutrients, a nitrogen source, a calcium source and water, attempting to mimic what nature does when forming sandstone over millennia. Most of her results failed but, finally, one day she had a strong, enduring “baby brick”. The biological cement forms when the bacteria induce calcium carbonate crystal formation, stitching aggregate particles together as a structural lattice.
Dosier founded bioMASON in 2012, spurred on by having earlier won a design award run by the architecture and design magazine Metropolis. Today, her North Carolina-based company has 29 employees researching and developing bacterial biocement that can glue together grains of sand – or even demolition waste – to make bricks and tiles with the appearance of natural stone.
In 2013, bioMASON won the Postcode Lotteries Green Challenge, taking home €500,000 to help realise its business plan. Dosier has credited the win with putting the company on the map and introducing it to its first licensees.
R&D still comprises most of bioMASON’s work, although a production plant making tiles suitable for floors and exterior facades is on the cards. Maybe in the future we will live in homes built with the help of trillions of microscopic organisms? “It has been said that the 19th and 20th centuries were the ages of chemistry and physics, but the 21st century is the age of biology,” says Dosier.
Another startup addressing the need for more eco-friendly building materials is EarthEnable, a social enterprise focused on a specific issue thrown up by the rapid modernisation of parts of the developing world – the need for viable alternatives to concrete floors.
As homeowners in parts of rural Africa replace houses made of sustainably harvested materials with more durable concrete and steel, one of the first things they attend to are dirt floors, which can harbour insects, parasites and pathogens, and can turn into mud. While concrete floors made with Portland cement are the obvious solution, an innovative alternative developed by EarthEnable has been gaining ground.
EarthEnable began in 2013 as the project of four students from the US’s Stanford University on a “Design for extreme affordability” class hosted in Rwanda by nonprofit architectural practice MASS Design Group. MBA student Gayatri Datar, a graduate in international development, consulted with villagers on how best their lives could be improved. “The root cause of most problems turned out to be having a dirt floor,” she says.
The students’ solution was a specially sealed earthen floor. Tamped local gravel, sand and laterite (clay-like soil used for road-making) is sealed to a hard polish with linseed oil. The team developed a proprietary recipe of environmentally sound, non-toxic linseed oil varnish, free from the usual additives of drying and anti-skinning agents. The trade-off is a longer curing time: one week compared with three days. Sealed-earth floors are 75% cheaper than concrete ones.
After graduation, Datar settled in Rwanda and is now CEO of the company she co-founded with biochemist, Rick Zuzow. EarthEnable has more than 80 employees that, to date, have installed sealed-earth floors in more than 2,500 homes. In 2017, they won Postcode Lotteries Green Challenge, and they are now expanding into Uganda.
Such simple but effective alternatives to concrete not only improve quality of life, but also help to mitigate carbon emissions. “Billions of people live in substandard housing,” says Datar. “We are determined to address this issue, retrofitting with sustainable materials, to transform lives.”
Are you working on an idea with the potential to contribute to a sustainable planet? The Postcode Lotteries Green Challenge is one of the world’s largest sustainable entrepreneurship competitions. This year’s contest is now open and looking for innovations with a viable business plan and the potential to scale. Find out more at greenchallenge.info. Deadline for entries: 1 May 2019.
