| Concrete infrastructure construction in Saline soil and salt lake area is one inevitable problem in"The Belt and Road"strategy of China.As saline soil and salt lake area contain a lot of chloride,sulfate and bicarbonate that the working life of ordinary concrete building is greatly affected.So that ordinary cement concrete infrastructure failed to meet the durability requirements in these region and broke in the prescribed time-limit.Magnesium oxychloride cement has a good performance of bittern-resistance without modification,which makes its application in saline soil area possible.As a kind of magnesia cementitious material that composed of MgO-MgCl2-H2O system.However,its corrosion to steel bar is the main reason to limit its popularization and application.If the corrosion problem of steel bar in magnesium oxychloride cement concrete can be solved then the infrastructure construction problem in saline soil and salt lake area will be solved.The application of magnesium oxychloride cement concrete will be greatly improved and reducing the"magnesium Harm"problem.Under the supported of National Natural Science Foundation?Basic research of magnesium oxychloride cement reinforced concrete based on saline lake"magnesium harm"problem in western area,No.51468039?,this paper carried out a three-year electrochemical study on magnesium oxychloride cement?coated?reinforcement concrete.Studied the anticorrosion mechanism of coated steel bar in magnesium oxychloride cement concrete.And competitive failure analysis of magnesium oxychloride cement coating-steel bar concrete.The main contents of this paper:?1?Rapid corrosion test of magnesium oxychloride cement coated reinforcement concrete of nature environment,moist environment,magnesium chloride solution environment,sulfate solution environment were designed according to simulation the actual condition of Saline soil and salt lake area?the coatings in magnesium oxychloride cement concrete were divied into five types,and the bare steel bar was used control group?.By analyzing the high frequency impedance arc radius and the low frequency impedance characteristics of-Nyquist,the time parameters of Bode arc,the occurrence of the Weber effect in the unit test cycle,the size of the polarization impedance,and the medium involved in the corrosion.The result show that,the coating has a protective effect on steel and the protectiveeffectlevelisGH>GMT>MGL>BNC>DKL?natureenvironment?,GH>MGL>GMT>DKL>BNC?moist environment?,GH>GMT>MGL>DKL>BNC?sulfate and chloride environment?.?2?The nondestructive testing was carried out on magnesium oxychloride coating reinforced cement concrete by HC-U83 Multifunctional Concrete Ultrasonic Detector,then can obtained the relative dynamic elastic modulus evaluation parameters of different period.The electronic balance is used to test the quality of magnesium oxychloride cement concrete to determine the period of specimen quality loss.The results show that the corrosion products of the coating have not produced large cracks in the magnesium oxychloride cement coated steel bar concrete during the coating serves as sacrificial anode in the process of providing cathodic protection.The quality loss of magnesium oxychloride cement?coated?reinforced concrete during the accelerated experiment is relatively small.?3?The?coated?steel bar corrosion current density,polarization resistance,relative dynamic elastic modulus evaluation parameters and relative quality evaluation parameters were analyzed by regression analysis to study competition failure.The results show that the corrosion current density,polarization resistance and relative dynamic elastic modulus evaluation parameters of the steel bar can be expressed by the two terms exponential function.Coated steel corrosion current density,polarization impedance can be expressed by five terms Fourier function.The failure time of magnesium oxychloride coated steel bar cement concrete is 40000d under magnesium chloride solution environment. |
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