Experiment On Steel Reinforcement Anti-corrosion In Magnesium Oxychloride Cement Concrete And Comprehensive Evaluation

The durability of reinforced concrete in the salt lake area is one of the basic theoretical research problems needed to be solved urgently in the strategic implementation of "The Belt and Road " Initiative,which is of great practical significance.In the salt lake area,the requirement of brine corrosion resistance quality of reinforced concrete is higher,and the ordinary portland cement concrete can be destroyed due to severe salt brine corrosion in 3~5 ages,while magnesium oxychloride cement concrete has better brine corrosion resistance.At present,magnesium oxychloride cement concrete cannot be used as load-bearing structural materials in building because of its high corrosive to steel reinforcement.If the corrosion problem of steel reinforcement in magnesium oxychloride cement concrete could be solved,new applications in the field of structural materials could be opened,application scope of magnesium cement could be expended and the destruction of "magnesium damage" in salt lake area could be reduced.In this paper,based on the National Natural Science Foundation of China(Basic research of magnesium oxychloride cement reinforced concrete based on saline lake " magnesium harm" problem in western area,No.51468039),study on reinforcement protection in magnesium oxychloride cement concrete and comprehensive evaluation of magnesium oxychloride cement reinforced concrete were made.The main contents of this paper:(1)According to the actual environment in saline lake area,rapid corrosion test scheme of magnesium oxychloride cement coated reinforcement concrete was designed—there are six kind of coated reinforcement under different protective layer thickness—bare steel reinforcement and five kinds of coated steel reinforcement.And all the test blocks were putted in four simulation test environmrnt—indoor natural dry environment,wet environment,sulfate and chloride immersion environment.At last the corrosion of(coating)steel reinforcement in magnesium oxychloride cement concrete under four simulation test environment was studied.The results show that although the anti-corrosion effect of the coating is different,they are effective in the protection of steel reinforcement.(2)Based on the four kinds of simulation test environment s,the SEM,EDS and XRD experiments of magnesium oxychloride cement were carried out,and the corrosion of magnesium oxychloride cement(coating)reinforcement concrete was studied as well.At last microstructure and composition of bare steel reinforcement,coated steel reinforcement and magnesium oxychloride cement concrete were identified.The results show that with the increase of corrosion,the corrosion products are in transition from flake structure or needle structure to lumphy structure.(3)According to the corrosion condotion of in magnesium oxychloride cement(coating)reinforcement concrete,the evaluation parameters ?0 of coating anticorrosion effect,comprehensive evaluation parameters ?b of(coating)steel reinforcement corrosion resistance and evaluation parameters ?c of magnesium oxychloride cement concrete were put forward,and the classification criteria of coating corrosion resistance effect,of(coating)steel reinforcement corrosion resistance and of magnesium oxychloride cement concrete were worked out respectively.Combining the durability evaluation parameters of magnesium oxychloride cement concrete under four kinds of simulation test environment,the durability comprehensive evaluation parameters ?3 of magnesium oxychloride cement concrete was designed.Through a variety of evaluation parameters putted forward,performance evaluation system of magnesium oxychloride cement(coating)reinforced concrete was established to predict the service life of magnesium oxychloride cement(coating)reinforced concrete.