Mechanism And Prevention Of Microorganism Corrosion Of Aluminate Cementitious Materials In Seawater Environment

In addition to the damage caused by physical and chemical erosion,the offshore oil production platform and the submarine pipeline also suffer serious microbial corrosion.To clarify the mechanism of corrosion resistance of aluminate cementitious materials,carrying out the properties of aluminate cement modified by ordinary Portland cement and dihydrate gypsum at different curing temperatures,the growth and propagation of microorganism and the effect of microorganism on the properties of aluminate cementitious materials in seawater environment.On the basis of the above corrosion laws and mechanisms,the effect of the protective materials of bactericidal dosage forms on the biocorrosion resistance of aluminate cementitious materials were also discussed.Conclusions are drawn as follows:?1?The quality ratio of the aluminate cement,ordinary Portland cement and dihydrate gypsum in cementitious system is 85%:4%:11%,through the analysis of the effect of ordinary Portland cement and dihydrate gypsum admixture on the properties of aluminate cementitious mortar under the curing conditions at 20?and 50?.?2?The growth curve of microorganisms in seawater environment including lag phase,fast split phase and stable phase and decline phase.It is determined that seawater corrosion medium is oscillating culture for 4 days,the 12 days is a replacement period,and the concentration of sodium thiosulfate is 10 g·L^-1.?3?The corrosion of the aluminate cementitious materials in full immersion environment is more obvious than that in the semi dipping environment.It is known from the mass change and the corrosion coefficient that the microorganism has an obvious corrosion effect on the aluminate cementitious materials under the age of 120days in full immersion environment.XRD and SEM analysis results show that the corrosion medium of microbiological corrosion of aluminate cementitious materials,resulting in ettringite growth and number increased,and changed the shape of ettringite,reducing the cementitious gel or C-S-H gel.?4?Comparative study on the sterilization effect of three kinds of bactericidal protective materials:sodium tungstate,sodium bromide and potassium bromide.The concentrations of three bactericides are 100 mg·L^-1,200 mg·L^-1 and 250 mg·L^-1,respectively.It is found that the best sterilization effect is sodium bromide with concentration of 200 mg·L^-1,and the period of drug addition is 6 days.On the basis of above research,studying on appearance change of aluminate cementitious mortars in corrosive medium with and without bactericides.It is found that the addition of bactericides can reduce the concentration of bacteria in the solution and reduce the formation of the corrosion material on the surface of aluminate cementitious mortars.