An in-situ monitoring method for steel bar corrosion and stress state in concrete

Abstract

The invention is a method for in-situ monitoring of steel bar corrosion and stress state in a reinforced concrete structure. The method is to construct a prestressed self-balancing system, apply initial prestress to a steel bar sheet made of the same material as the steel bar in the concrete, and embed it in the concrete structure. Middle; set continuous strain measuring points at different heights on the steel bar sheet to monitor the stress state in this area; the steel bar sheet forms a plane stress state, and stress concentration occurs after local corrosion, and the strain changes at the continuous measuring points at different heights of the section reflect the initial corrosion of the steel bar Time, corrosion rate and degree of corrosion. The invention can be buried at different depths from the concrete surface, so as to realize the monitoring and corrosion risk assessment of the corrosion degree of steel bars at different depths and the stress state of the buried area. It is not affected by environmental factors such as various ions, temperature and humidity in concrete, and is especially suitable for the evaluation of the corrosion risk and corrosion degree of reinforced concrete structural steel bars in splash areas and tidal range areas in marine corrosion environments.

Description

technical field [0001] The invention belongs to the health monitoring technology of civil engineering structures, in particular relates to the durability of reinforced concrete structures, and is applied to the corrosion monitoring and durability evaluation of reinforced concrete structures. Background technique [0002] Existing technology: Steel bar corrosion is the main reason for the durability damage of reinforced concrete structures. At present, the steel bar corrosion monitoring technology is mainly divided into two methods: physical and electrochemical. Electrochemical means are widely used, mainly around the measurement of the corrosion current generated during the steel corrosion process or the potential difference between electrodes to characterize the possibility of corrosion. The specific methods are: (1) trapezoidal anode method, by arranging several anodes at different depths of the concrete layer, and monitoring the current between each anode and the same cat...

AI Technical Summary

Problems solved by technology

The specific methods are: (1) trapezoidal anode method, by arranging several anodes at different depths of the concrete layer, and monitoring the current between each anode and the same cathode to characterize the intrusion of chloride ions or the development of corrosion, thereby indirectly predicting the corrosion of steel bars, This kind of method has been applied in some engineering and laboratories, but the public test data is less, and the effectiveness needs to be confirmed

(2) The monitoring and detection methods represented by the half-cell potential method and the linear polarization method measure the potential or polarization resistance of each part of the steel bar on site to judge the possibility of corrosion everywhere, but these methods are not easy to implement for a long time Embedded online monitoring, and because the polarization resistance and potential are easily disturbed by various factors, the exact corrosion state of the steel bar cannot be judged

Polarization resistance measurement cannot determine the steel bar area affected by the disturbance signal, and often gives an overestimation of the actual corrosion degree. Another problem is that it is impossible to determine the appropriate excitation time, so that the current response measured during this time only contains Electrochemical information about the corrosion interface, independent of the electrochemical information of the concrete itself

The current physical methods mainly focus on the monitoring of the strain and stress generated by the expansion of corrosion products after corrosion of steel bars. Since these two parameters are less affected by humidity, temperature, electromagnetic field, stray current and pore solution concentration, solid physical methods Difficulties mainly focus on the design of the method. Due to the complex interaction force between concrete and steel bars, the relative displacement between steel bars and concrete will be limited, making it difficult to monitor the rust expansion stress caused by the expansion of steel corrosion products. The surrounding concrete strain is also difficult to collect due to the mutual constraints of concrete. At the same time, the stress and deformation of the structure itself also produce strain, and the strain caused by the expansion of corrosion products is buried in it, making it difficult to distinguish

Therefore, the sensors designed based on the corrosion and expansion mechanism of steel bars will be seriously affected.

At the same time, the existing steel corrosion monitoring methods often destroy the microenvironment of the steel surface, making the corrosion-inducing factors such as the diffusion of chloride ions different from the actual situation. Larger, the actual usage has yet to be verified

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