The Research On Evaluation Of Steel Corrosion And Technology Of Anti-corrosion For Reinforced Concrete

Reinforced concrete is the preferred form in the design of building structural engineering For its high tension of steel bars and good compressive properties of concrete,and the cost is low.In highway engineering,Corrosion problems of the steel bars are becoming more serious because of deicing salt and the external environment,which will affect the service life of structures.Nowadays evaluation methods of reinforced concrete corrosion and anti-corrosion technologies have become research hotspots.At present,the structural concrete corrosion evaluation method still has problems such as long measuring period,complicated operation and single corrosive environment.Based on these problems above,the research,relying on the key scientific and technological project of Gansu Provincial Transportation Department “Research on anti-corrosion technical performance index and construction technology of highway concrete bridge”,study the typical distribution range of sulfate ion and chloride ion concentration in the soil of Hexi region of Gansu Province by statistical method.The environmental corrosion grade of the saline soil in Hexi was divided and the corrosion experimental conditions were determined.The reliability of the electrochemical evaluation method was analyzed by the electrochemical evaluation method and the traditional weight loss method.The influence of corrosive ion concentration on the passivated steel bar and the steel bar rust inhibitor and cathodic protection system were studied based on the electrochemical evaluation method.The main research results are as follows:(1)Based on the normal distribution analysis of chloride ion and sulfate ion concentration in saline soil in Hexi area,the typical distribution range of chloride ion is [1233-2276mg/L],and the typical distribution range of sulfate ion concentration is [1925-4078 mg /L],referring to the existing domestic standards,the environmental corrosion level of the area is classified as severe corrosion of Level D.(2)Accelerating the corrosion of the steel bar by the dry-wet cycle and electromigration accelerated test,and after linearly fitting the corrosion current density and the weight loss rate of the steel bar after corrosion,the steel bar is accelerated after the dry-wet cycle of the chloride salt,sulfate salt and composite salt The correlations are 0.8059,0.9433,0.8912,respectively,and the correlation is better with the decreasing of corrosion current density.The electromigration acceleration experiment of steel in real concrete shows that the current corrosion density and weight loss rate change in the same way,so the current Corrosion density can be used to quickly evaluate corrosion of steel bars.(3)Based on the electrochemical evaluation method,the threshold value of corrosion of the passivated steel in the concrete simulated liquid was studied.And the corrosion value of the steel bar was 0.07mol/L.Even in the absence of chloride ions,some sulfate ion concentration can make the steel bars in the concrete simulation liquid start to corrode,and it can be concluded by the current corrosion density that the sulfate ion concentration makes the corrosion threshold lower than the chloride ion concentration.In the composite salt ion,the sulfate has a certain inhibitory effect on the corrosion of the chloride salt.(4)The effects of steel bar rust inhibitor and cathodic protection anti-corrosion measures were studied by the electrochemical evaluation method,The research shows that adding steel bar rust inhibitor can significantly improve the corrosion resistance of steel bars,reduce the corrosion current density of steel bars and reduce the current efficiency and the value is about 70%;in the electric acceleration experiment,the protective effect of cathodic protection is obvious.