b'mixture of partially dissolvedlimestone and urea. Thesewe?re alsolooking into more commercial applications of bacteria produce an enzyme that splits theurea, whichthe material that willreduce production costs?, says causes the pH to increase again. Under such conditions, Balzer Le. ?The most realistic scenariowill be to make calcium is formed together with calcium carbonatecommercially-manufactured bricks that can be crystals, and it isthese crystals that act as the bindingtransporteddirectly from a factory to a construction agent in bacteria-basedconcrete?, she explains. site?, she says.After drying, the material in the mold becomes solid. InPractical and recyclableessence,this method is an extension of the well-known biogeochemical processknown as Microbially-InducedIt is too early to say how this biological cement will Calcite Precipitation (MICP). Calciumcarbonateperform in terms of quality.precipitates as result of the interaction between natural ?It will not be as strong as conventional concretes, but minerals and bacterial metabolism. MICP is used, amongthere areapplications where its material strength will other things, bythe American company bioMASONprobably be more thanadequate?, says Balzer Le, adding to manufacture and stabilize subsoils. that there are many potential ways ofmaking BioZEment concretes stronger.These include a variety of typesof reinforcement using either aluminum or cellulose fibers derived fromtimber, both of which will make the material practical for a number ofdifferent applications.The researchers also recognize the potential to recycle BioZEment.?This will result in less use of raw materials, making this a very exciting field of research for us?, says Balzer Le.The mixture of bacteria and sand in the mould is fed with finelyground limestone that is partially dissolved by another bacteria and asolution containing urea.Interaction of the two bacteria causescalcium carbonate crystals to precipitate, and these bind the sandgrains together. After drying, a small brick of concrete is removed fromthe mould. Photo: Hvard Egge.?The advantage of our approach is that both the calcium and thecarbonate are derived from the limestone, whichADVERTISE IN THE enables us to reduce theuse of urea compared with another commonly applied form of MICP thatobtains itsOMA /TMI NEWSLETTER!carbonate solely from urea?, says Balzer Le.Start by making bricksThe researchers have been looking into a number ofContact Rachel Pinkus at different ways ofapplying this technology. The most937-278-0308 or straightforward approach will mostlikely be to manufacture bacteria-based bricks, which will probablyrpinkus@assnsoffice.comcostonly about ten percent more to make than standard bricks.?Making bricks will enable us to develop the process, but 5'