Wu Shifan, Senior Research Fellow, Centre for Urban Solutions, School of Civil and Environmental Engineering, NTU and Chu Jian, Chair of the School of Civil and Environmental Engineering, NTU holding up blocks of biocement made from urea and carbide sludge. Credit: Nanyang Technological University, Singapore
Scientists from Nanyang Technological University, Singapore (NTU Singapore) have devised a way to combine two common waste materials—industrial carbide sludge and urea from the urine of mammals—to create biocement.
They developed a process in which the reaction of urea with calcium ions in industrial carbide sludge forms a hard solid, or precipitate. When this reaction takes place in soil, the precipitate bonds soil particles together and fills the gaps between them, creating a compact mass of soil. This results in a strong, sturdy and less permeable block of biocement.
The team, led by professor Chu Jian, chair of the School of Civil and Environmental Engineering, showed in a proof-of-concept paper published in the Journal of Environmental Chemical Engineering that their biocement could potentially become a sustainable and cost-effective method for soil improvement, such as strengthening the ground for use in construction or excavation, controlling beach erosion, reducing dust or wind erosion in the desert, or building freshwater reservoirs on beaches or in the desert.
The researchers say it can also be used as biogrout to seal cracks in rock for seepage control and even to touch up and repair monuments, like rock carvings and statues.
“Biocement is a sustainable and renewable alternative to traditional cement and has great potential to be used for construction projects that require the ground to be treated,” said Chu, who is also the Director of NTU’s Centre for Urban Solutions. “Our research makes biocement even more sustainable by using two types of waste material as its raw materials. In the long run, it will not only make it cheaper to manufacture biocement, but also reduce the cost involved for waste disposal.”
Photo: Wu Shifan, Senior Research Fellow, Centre for Urban Solutions, School of Civil and Environmental Engineering, NTU and Chu Jian, Chair of the School of Civil and Environmental Engineering, NTU holding up blocks of biocement made from urea and carbide sludge. Credit: Nanyang Technological University, Singapore