Experimental Study Of Microbial Perfusion Slurry Vertical Cracks In The Concrete Block

Concrete, as the current most widely materials used for building, has problems causing leakage after it has been plagued by crack engineering. Currently, there are many methods of concrete repairing leaks, but mostly there are poor adhesion and durability, environmental pollution and other shortcomings. In recent years, microbial-induced calcium deposition repairing techniques have become the focus of scientific research personnel for its good results of repairing, environmental protection, etc. The technique utilizes the metabolic activities of microorganisms produce urease urea decomposition of carbonate ions, and then combined with the environment to produce calcium carbonate crystals of calcium deposition in the cracking of the site, in order to achieve concrete crack repairing. However, when using the microbial grouting methods to repair cracks in concrete vertical, the liquid grout filled cracks easily due to the weight. Therefore, how to block vertical cracks has become an obstacle to the application of this technology to promote the bottleneck.Increasing the yield of early precipitation of calcium carbonate is a key technology to block cracks in concrete, this paper describes the experimental optimization to improve the yield of calcium carbonate. Through multiple sets of comparative test shows that:the concentration of urea which take 3mol/L, the concentration of calcium sources:Calcium chloride take 2.5mol/L, the concentration of calcium nitrate take 2mol/L, can produce the highest yield of calcium carbonate. The urea which is added to broth in advance can effectively improve the yield of early precipitation reactions and help Grouting concrete cracks, most more importantly, having little effect on the final amount of precipitation. Therefore, adding to the broth in the mixed broth with calcium source solution before 60min ahead of urea.Carried out repair cracks in concrete vertical orthogonal experiment with using the bacteria, urea, calcium source solution method of vertical cracks drip concrete block. Tests have set crack interface for four different factors such as crack depth, calcium source types, the presence or absence of oxygen. remove the glass tank seepage tests and visual analysis and cutting observations to test the appearance of crack repair effect. The results show that:the greatest one of four factors impacting on the interface crack is sealing effect, and cracking depth is the secondary factor, and the minimal ones are calcium source type and whether the oxygen. In the several factors and interface cracks, splitting crack interface is most likely to be blocked. This is mainly because the splitting crack interface is rougher and more conducive to the adhesion and accumulation of calcium carbonate. In fact, splitting crack interface is closer to the actual splitting crack. Through observation shows that calcium Vertical concrete cracks within the lower are denser than the upper; Similarly, the lower are stronger than the upper. The lower part of the crack depth direction along the crack, the crack density of less calcium carbonate in the depth direction, the upper crack crack depth direction along both sides not dense, there are more holes in the middle denser.