Experimental Research On The Corrosion Of Forced Steel Wire In Chlorine Salt Environment

In this paper,through a series of experiments simulating the stressed steel wire in the pore solution,the changes of the steel wire rusting and rust rate and their influencing factors and micro-mechanism were studied in order to obtain the common understanding of the actual concrete structure stress steel rust.The main research work and results are as follows:(1)Based on the review and analysis of the domestic and foreign research status of steel wire and steel bar corrosion,two mechanical rust breaking devices relying on bow and box are proposed,and the steel wire is monitored individually or jointly by electrochemical,microscopic visual inspection and mechanical rust breaking method.The overall research plan of the time-varying corrosion process focuses on the changes in the rusting and corrosion rate of the steel wire under the influence of the chloride ion concentration and p H value of the simulated pore solution,the passivation state of the steel wire,the tension level and the corrosion state;(2)Based on the electrochemical monitoring of corroded steel wire,visual observation with high-precision digital microscope and identification of mechanical rust breakage,the differences and correlations of the three types of rust formation of steel wire "depassivation rust","floating rust" and "mechanical rust break" Sexual analysis."Depassivation rust" and "floating rust" are not always monitorable.At this time,the electrochemical monitoring and microscope visual inspection methods fail,but mechanical rust breakage will always prompt;if the three rusting states occur,they will occur in sequence and follow the wire tension The level increase will tend to be consistent."Mechanical rust break" has better stability and practicality for identifying and characterizing steel wire rust.(3)The rust formation forms of uniform corrosion and local corrosion are different,and the direction of rust development is also different.Among them,uniform corrosion extends radially from a single rust point,and local rust develops from multiple rust points in the depth direction.This leads to that in the electrochemical image,the pitting corrosion in the early stage is greater than the uniform corrosion,but in the long run,the corrosion degree of the uniform corrosion is greater than the pitting corrosion.(4)In general,the higher the chloride ion concentration and the lower the p H value of the simulated pore solution,the faster the steel wire will rust and the greater the corrosion rate,but there is a phenomenon that the steel wire will rust faster at a larger p H value.This unconventional phenomenon is related to the behavior of steel wire corrosion-pitting corrosion leads to cross-sectional damage faster than uniform corrosion.(5)Passivated and non-passivated steel wire rust also has anti-intuitive understanding.The faster rusting of the passivated steel wire can also be explained by the rusting behavior of the steel wire tending to pit or even corrosion: passivation often leads to pitting of the steel wire and thus rusts faster.(6)Different from the surface damage of the steel wire or steel bar identified by the electrochemical method,the mechanical rusting method directly identifies the damage of the section;when the corrosion of the test piece is close to the uniform corrosion behavior,the identification results of the two have good consistency.