7. Biocementation and Biocements

Cement is an energy-consuming construction material with environmentally unfriendly production. Due to the high viscosity of cement paste it cannot be used for the grouting. New construction material, microbial biocement can be produced either from limestone or dolomite or from calcium salt chloride solution at ambient temperature. Dry biocement can be dissolved and as solution of low viscosity can be sprayed over, injected in, or percolated through the porous soil for its strengthening. This strengthening is applicable to enhance stability of the slopes and dams, for road construction, prevention of soil erosion, for the construction of the channels, aquaculture ponds, reservoirs, landfills in sandy soil, to reinforce sand in near-shore areas, for the remediation of cracks in concrete and the self-remediation of concrete, consolidation of porous stone and fractured rocks, the bioremediation of weathered-building stone surfaces, the fractured rock permeability reduction, the mitigation of earth quake-caused soil liquefaction, the encapsulation of soft soil, the coating of surfaces with calcite for protection of concrete from corrosion and for enhanced marine epibiota colonization. The concept of bacterial self-healing is under question because only 30 % of the concrete cracks volume can be filled by calcite produced from 5 % (v/v) of introduced into concrete capsules.