Method for predicting initial corrosion time of steel bars in concrete

Abstract

The invention relates to the field of corrosion of steel bars in concrete and particularly relates to a method for predicting initial corrosion time of steel bars in concrete. The method comprises thefollowing steps: taking chloride ion diffusion coefficients as a random variables, determining a group of chloride ion diffusion coefficient data according to experiment, combining with a migration model of chloride ions in the concrete to obtain time data reaching critical concentration of the chloride ions when reaching a certain depth, and building a response surface of the chloride ion diffusion coefficient and the time reaching critical concentration of the chloride ions; actually measuring a group of time reaching the critical concentration of the chloride ions and obtaining a group ofnew chloride ion diffusion coefficients by using the response surface; combining the group of new chloride ion diffusion coefficients with the migration model of chloride ions in the concrete to obtain a group of initial corrosion time data of the steel bars in the steel bar depth, and counting to obtain the probability distribution of the initial corrosion time of the steel bars.

Description

technical field [0001] The invention relates to the field of health monitoring of civil engineering structures, in particular to a method for predicting the initial corrosion time of steel bars in concrete. Background technique [0002] The monitoring and prediction of the initial corrosion time of steel bars is a difficult problem in evaluating the durability of concrete. Chloride ion erosion in sea corrosion environment is the main cause of steel bar corrosion in concrete. At present, steel bar corrosion monitoring is mainly divided into physical and electrochemical methods. It is used to characterize the electrochemical state, physical state of steel or concrete, and various corrosion-inducing factors in the surrounding environment. The main methods used are: (1) Electrochemical monitoring method: Since the corrosion of steel bars in concrete is an electrochemical process, electrochemical measurement is an important means to reflect its essential process. The existing ele...

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Problems solved by technology

Its disadvantage is that the physical method of measuring the corrosion of steel bars is easily disturbed by other damage factors in concrete, such as micro cracks, etc., and it is difficult to establish the corresponding relationship between physical measurement indicators and steel bar corrosion, so the method of physical testing is not suitable for steel bars. Generally, the degree of corrosion can only provide qualitative conclusions, but it is difficult to provide quantitative analysis.

(3) The monitoring method of corrosion influencing factors. The existing methods mainly focus on the monitoring of chloride ion concentration and pH value. When it is used for embedded on-line monitoring, it is often difficult to avoid its own long-term durability problems. The peeling off of concrete will cause the sensor to fail; in addition, the impact parameters have the same problem as electrochemical methods such as resistivity testing in that the measured data can only evaluate the possibility of corrosion of steel bars, but cannot quantitatively judge the specific corrosion of steel bars. low reliability

(4) Corrosion monitoring based on the stress concentration of the plane stress state is a newly emerging steel corrosion monitoring method. This method is based on the structural monitoring of the sensitive components in the plane stress state, and corrosion leads to local stress concentration in the plane stress state to monitor corrosion. This method is relatively It is novel, but it is still in the stage of principle exploration, especially the corrosion monitoring data processing method based on the stress concentration of the plane stress state is not perfect, which limits the wide application of this method

Existing methods are difficult to achieve quantitative analysis and prediction from time series at different depths, and the use of a single index or data from a single depth for analysis will lead to insufficient reliability of monitoring results; Corrosion is directly related, but the existing chloride ion sensor is difficult to realize long-term in-situ monitoring in the concrete environment due to the limitation of the preparation process and the materials used, and it is difficult to directly characterize the position of the critical concentration front through numerical values. It is difficult to predict and quantitatively analyze; the initial corrosion time of steel bars is affected by the environment, concrete materials and exposed areas. Traditional deterministic analysis methods cannot give the possibility of steel bar corrosion at any time, and cannot judge the probability of steel bar corrosion at a certain time

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