In-situ monitoring method for rusting and stress state of reinforcing steel bar in concrete

Abstract

The invention relates to an in-situ monitoring method for rusting and a stress state of a reinforcing steel bar in concrete. The method comprises the following steps of establishing an automatic prestress balance system, applying initial prestress to a reinforcing steel bar sheet which is made of a same material with that of the reinforcing steel bar in the concrete, and embedding the reinforcing steel bar sheet into a concrete structure; arranging continuous strain measuring points on different heights of the reinforcing steel bar sheet, and monitoring the stress state of the area in which the strain measuring points are arranged; and forming a plane stress state on the reinforcing steel bar sheet, generating stress concentration after the reinforcing steel bar sheet is locally corroded, and reflecting the initial rusting time, rusting rate and rusting degree of the reinforcing steel bar according to the strain variation of the continuous measuring points on the different heights of the cross section. The reinforcing steel bar sheet can be embedded in different depths from the surface of the concrete, and the monitoring and rusting risk evaluation on the rusting degree of the reinforcing steel bar and the stress state of the embedded area in the different depths can be realized. The method is not subjected to the influence of ambient factors such as different ions, temperature and humidity in the concrete and is particularly suitable for evaluating the rusting risk and the rusting degree of the reinforcing steel bar in the reinforced concrete structure in a wave erosion environment wave splashing area and a tidal range zone.

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...

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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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