Chementator briefs

Biocement Scientists from Nanyang Technological University, Singapore (www.ntu.edu.sg) have found a way to create biocement from two common waste materials — industrial carbide sludge (a waste product of acetylene production) and urea (from urine). To make the biocement, carbide sludge is first treated with an acid to produce soluble calcium. Urea is then added to the soluble calcium to form a cementation solution. A bacterial culture is then added and the bacteria break down the urea into carbonate ions, which react with the soluble calcium ions in a process called microbially induced calcite precipitation (MICP). When this reaction occurs in soil or sand, the resulting calcium carbonate generated bonds soil or sand particles together to increase their strength, and fills the pores between them to reduce water seepage through the material. The same process can also be used on rock joints, which allows for the repair of rock carvings and statues. The soil reinforced with biocement has an unconfined compression strength of up to 1.7 MPa, which is higher than that of the same soil treated using an equivalent amount of cement. The proof-of-concept research was described in a recent issue of the Journal of Environmental Chemical…