An Amazing Wee Machine for Construction

An Amazing Wee Machine for Construction

30th November 2015

Over the past few months we’ve published a series of articles on concrete. We’ve told you all about the history of concrete, the different types of concrete available and even taken a look at some of the latest developments like microbial concrete that heals itself and concrete that glows in the dark. During our research on concrete we came across all sorts of fascinating facts – we brought you a story about concrete being used as an art medium .

We then came across an amazing story about a new type of material that could present a challenge to concrete in the future. An artist turned mycologist (mushroom expert) in San Francisco has been experimenting with growing mushrooms that can be used to produce chairs, stools and even building blocks! In a similar vein, we’ve found a sort of parallel development to this – a student who’s discovered a way of making solid pieces of sandstone by mixing urine, bacteria and sand – and, no, we’re not taking the p***.

It seems that an art student at Edinburgh College of Art has built a machine called Dupe that converts, sand, urine and bacteria into a new type of biomaterial that’s similar to concrete. Peter Trimble who holds a BA (Hons) in Product Design has come up with a process that forms mineral composites at biological temperatures to produce a biomaterial that is structurally comparable to concrete but the process produces no greenhouse gases. With concrete being so widely used for all types of construction projects, it’s responsible for 5% of the planet’s manmade CO2 emissions. You can watch a video about it here.

As part of his thesis project, Peter was interested in how bacteria combined with the urea in urine could be converted into a reusable material that requires fewer resources than conventional concrete. He built a portable machine called Dupe that injects a liquid solution into a mould full of sand that bonds together the grains creating a type of biostone.

In true Maker style, Dupe was created from an old coffee machine, a mixer from an old blender, a mould and a tank to hold the liquid. The mould is filled with sand and sealed while the tank contains a nutrient broth that grows the bacteria bacillus pasteurii. Bacillus pasteurii is commonly found in soil, so there’s no shortage of it. The nutrient broth from the tank is pumped into the sand and left overnight to permeate the sand particles. The next day, urea and calcium chloride and more of the nutrient broth are added. The urea encourages the growth of the bacteria before it combines with calcium chloride to form calcite which is the glue that holds the grains of sand together.

The whole process takes just two days to complete and at the moment, Dupe is busy producing stools that can support over 90 kg. However, this process could also be used to produce eco-bricks that can then be used in building projects, especially in areas where sand is widely available.

One of the main advantages to this process is that the biostone is produced in an eco-friendly manner and once the object it has been used to produce is no longer needed, it can be used as a fertiliser, returning to the earth and nurturing plant growth.