Experimental Study On The Sand Soil Solidification Using Carbonic Anhydrase Induced Precipitation

With the speeding up of the modernization and the growth of the population,The land reached the requirements for the construction is on the decrease,and the soil strengthening methods used commonly often could waste more mechanical energy consumption or use of chemical pulp material may do harm to the environment,so a more environmental and friendly way of curing emerges at the right moment-Microbial Induced calcium Carbonate Precipitation?MICP,Microbially Induced Carbonate Precipitation?,its mechanism is simple and quick.The application of MICP technology by domestic and foreign scholars mainly focuses on the solidification of sand soil,cracks of concrete surface and the restoration of stone relics surface.etcThis paper is conducted by carbonic anhydrase?CA?microorganism produced CO₂ reversible hydration reaction catalyzed by calcium carbonate effect and influencing factors of reinforced sand,providing the reference,for subsequent application of carbonic anhydrase microbial solidified soil research.The main research contents and research results are as follows:?1?selection of test strains and optimal growth conditions was done.Species4 was selected to be the best test strain,bacillus of the optimum culture conditions of the tested soil to cultivate at 30°C,medium pH=6 to7.?2?study on the influence factors of carbonic anhydrase catalyzed carbon dioxide reversible hydration reaction MICP process was done.In calcium source sedimentary system,Calcium chloride and calcium nitrate are suitable for the deposition of calcium carbonate,calcium chloride in temperature sedimentary system,30°C is optimum to deposit,sedimentary system in concentration,concentration of 1.5M the most suitable carbonic anhydrase induce deposition of calcium carbonate.With the participation of carbonic anhydrase mineralized bacteria,calcium carbonate not only has calcite crystal type,but also induces vaterite crystal type.?3?study on the influence factors of MICP solidification of carbonic anhydrase mineralized bacteria was done.The mixed grouting method has the highest strength.When calcium nitrate was used as calcium source,the shear strength of the solidified specimen was the highest.The shearing strength of the solidified specimen with increase with the rising of temperature,the strength of the curing temperature of 50°C specimen maximum increase,curing effect is best.Using different cementing fluid concentration to do curing experiments,found that calcium carbonate content increases with the increase of concentration,cementing fluid concentration within the scope of 0.5 to 1.5M,the shear strength of the specimens with cementing fluid concentration is linearly related to the cementing fluid concentration 1.5M has the highest strength of solidified specimen,curing effect is best.The solidifying effect of particle size range of 0.28mm?d<0.85mm specimen is best.It was found that the more calcium carbonate crystals existed in the sample,the cementation effect was significant and the strength increased.