Biocement developed from mud and urine

Nanyang Technology University (NTU) scientists announced that they have succeeded in converting urine and industrial waste into a renewable cement type with a new method they have developed. The new method will make it possible to create a greener and more sustainable alternative to traditional cement.

The developed biocement, which can be used in the restoration of ancient monuments

, has two main ingredients. The first is industrial carbide sludge, a by-product of acetylene gas production, while the other consists of urea derived from the urine of mammals such as humans, cows or pigs.

Calcium was first obtained by treating carbide sludge with an acid. The cementation solution was formed by adding urea to this calcium. Adding special bacteria to this created solution allowed it to break down the urea to form carbonate ions. Afterwards, in a process called ‘microbically induced calcite precipitation’, these carbonate ions dissolved and reacted with calcium ions, resulting in a hard, solid calcium carbonate product.

While the reaction was taking place, when the mixture combined with sand or soil, calcium carbonate bound the sand or soil particles together and filled the spaces between them. With the realization of all these processes at room temperature, a much easier and more environmentally friendly method will be offered compared to the traditional cement production processes.

It is stated that the developed biocement can be used to strengthen the ground at construction sites and to build fresh water tanks. The material can also be used to fill cracks and rebuild parts of damaged stone monuments.

NTU researchers said the biocement was used to restore broken pieces in the fingers of a Buddha from the Dazu Rock Carvings, a UNESCO World Heritage Site in China.