Application And Optimization Of Bactericide In Concrete Under Sewage Environment

With the acceleration of urbanization in China,the matching of municipal sewage project matures gradually.At the same time,the concrete pipe for transporting sewage has been seriously damaged.Therefore,it is urgent on the corrosion prevention of concrete sewage.In the prevention measures,concrete modification and surface coating protection can not solve the problem of sewage corrosion fundamentally.Thus,microorganism killing technology is used in the paper,the bactericide are mixed in concrete,which is a active measure for concrete anti-corrosion work.Firstly,for a comprehensive evaluation for adaptability,five different types of bactericides are selected in this paper,the methods of high-throughput sequencing,inductively coupled plasma mass spectrometry(ICP),confocal laser scanning microscope(CLSM)and so on were employed,and their bactericidal ability,dissolving property,effective content as well as the influence on the fluidity and strength of concrete are studied.Secondly,the effective content of five bactericides are unified to research the effect of different bactericide on concrete anti-sewage corrosion performance.In order to accelerate the corrosion of concrete,the artificially intensified sewage with high concentration is prepared.The strength,mass loss rate,surface pH of concrete without and with different bactericides are tested in sewage,and the bactericidal mechanism of each bactericide in concrete are further explored.Finally,based on gray correlation analysis and fuzzy comprehensive evaluation,the primary and secondary factors affecting anti-sewage corrosion performance of concrete with bactericide and a special bactericide suitable for the use of concrete in sewage environment is optimized.The results show: copper phthalocyanine has the best effect on the anti-sewage corrosion of concrete.After three months of sewage corrosion,the mass loss and corrosion resistance coefficient of concrete with copper phthalocyanine is about 150% and 80% of that of blank concrete,respectively,and the surface pH is still as high as 10.6,whereas that of blank concrete is almost close to neutral.This is not only due to the high sterilizing rate(82.59%)and retention rate(99.77%)for copper phthalocyanine under sewage environment,moreover,the increase of concrete strength after adding it also makes some contribution to its high corrosion resistance.The anti-sewage corrosion behaviors of concrete with sodium tungstate and zinc oxide are only inferior to that of concrete with copper phthalocyanine,and the mass loss rate is 5.40% and 6.04% respectively,which is 50% higher than concrete without bactericide.However,the bactericidal effect of sodium tungstate on microbes in sewage is poor,the bactericidal rate is only 21.95%.The addition of zinc oxide reduces the fluidity of the fresh concrete,and the strength of the hardened concrete is smaller than concrete without bactericide.The anti-sewage corrosion effects of concrete with sodium bromide and dodecyl dimethyl benzyl ammonium chloride have no obvious improvement comparing to concrete without bactericide.Based on grey correlation analysis,the main factor affecting anti-sewage corrosion performance of concrete with bactericide is the effect of bactericide on concrete performance and the bactericidal rate of bactericide on microorganisms in sewage,whose correlation is more than 0.9;secondly the dissolution rate of bactericide on concrete under sewage environment and the effect of bactericide on microbial acid production,whose correlation is between 0.7~0.8;Based on fuzzy comprehensive evaluation method,copper phthalocyanine is selected as a bactericide of being suitable for concrete with good effect,less content,low cost,little pollution,followed by zinc oxide and sodium tungstate,however sodium bromide and dodecyl dimethyl benzyl ammonium chloride have worst effect,which is not suitable for concrete to sewage corrosion prevention.The results can provide a theoretical basis for the bactericide used in concrete under sewage environment.