Biocement From Bacteria, Urine, and Calcium Is A Greener, More Sustainable Alternative to Current Cement in the Market, Study Claims

Scientists from Nanyang Technological University (NTU) in Singapore have turned bacteria, urine, and other waste materials into renewable cement that makes a great alternative to regular ones. They call it the biocement and it is greener and more sustainable than the current ones in the market.

Biocement typically uses bacteria to form a hardening reaction that binds the solid into a solid block, while the urea and calcium form a hard solid. Together, the three materials result in a sturdy and less permeable solid block of biocement.

Biocement-Making Process

According to TechXplore, the process of making the biocement only needs less energy and generates fewer carbon emissions compared to regular cement. The NTU scientists have created it using two types of waste, which include urea from urine and the waste material industrial carbide sludge from the production of acetylene gas.

The first step in making biocement is treating carbide sludge with an acid to produce soluble calcium. After that, they added urea to it to form a cementation solution before adding the bacterial culture. The bacteria can break down the urea to form carbonate ions that react with the soluble calcium and generate strong bonds to soil or sand particles.

As their bonds strengthen, it limits the pores between them and reduces water seepage through the material. It now has a reinforced compression strength of up to 1.7 megapascals (MPa) higher than the same soil treated with regular cement.

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Biocement Uses

With the incredible strength and reduced water seepage of biocement, NTU said in a news release that the new product could potentially become a sustainable and cost-effective method for soil improvement.

It reduces dust or wind erosion, and makes building freshwater reservoirs in beaches and deserts possible. The biocement is suitable for solid improvement projects, like strengthening the ground and reducing water seepage.

The team noted that the process can also be used on rock joints to repair rock carvings since the biocement solution is colorless, so the original color of the sand, soil, or rock will be preserved when applied.

The formula will allow the restoration of old rock monuments and artifacts easily while preserving their color. Today, biocement is being used to restore broken-off pieces, like Buddha's fingers from the UNESCO World Heritage Site in China, the Dazu Rock Carvings.

Greener and More Sustainable Cement

Unlike the traditional cement-making process, NTU Center for Urban Solutions director Profesor Chu Jian said that the biocement generates fewer carbon emissions.

The Straits Times reported that traditional cement-making burns raw materials at very high temperatures of more than 1,000 degrees Celsius, producing lots of carbon dioxide. On the other hand, the production of biocement can be done at room temperature, which makes it less energy demanding and carbon-neutral.

Carbide sludge is a waste material in Singapore and can now be used to create biocement. By extracting the calcium from carbide sludge, they produce a more sustainable material than using limestones mined from a mountain.

The team discussed in full their biocement in the study, titled "Utilization of Carbide Sludge and Urine for Sustainable Biocement Production," published in the Journal of Environmental Chemical Engineering.