Different treated methods of microbiologically deposited caco3 layer on hardened cement paste surface

Some bacteria in nature can mineralize its surrounding medium to form an inorganic layer on the surface of stone material continuously and precisely by its life activity. Some accelerated experimental simulations of the microbiologically precipitation process were conducted after selecting a carbonate-mineralization microbe. The bio-deposited layer was about 100 μm and bound tightly with the surface of cement pastes after treated for 7 d. The treatment methods such as immersing, spraying and brushing immobilized media were chosen to carry on microbiologically deposited layer through the contrast of scanning electron microscope analysis, layer thickness measurement, and coefficient of capillary suction of the specimens. The results show that the treatments can be simplified with micro-environment supply and optimization, especially when odium alginate and agar are used as the media brushing layer immobilized bacteria to cling to the specimen surface, which keep urease in the cells active in long term compared with the spraying method. According to the experiment results, the coefficient of capillary suction of the treated hardened cement paste is reduced by 90% and reveals an outstanding protective effect.