Fabry-Perot cavity type optical fiber sensor for monitoring concentration of chloride ions in concrete

Abstract

The invention belongs to the technical field of structural health monitoring, and discloses a Fabry-Perot cavity type optical fiber sensor for monitoring the concentration of chloride ions in concrete. The sensor comprises an optical fiber sensing unit, a copper support and an optical fiber protective sleeve. The sensor is based on the principle of a Fabry-Perot interferometer, and indirectly monitors the chloride ion concentration and diffusion condition of a concrete protection layer in the depth direction by monitoring the change of interference spectrum signals of optical fiber sensing units with different burying depths in an optical fiber sensing unit array. The sensor can realize long-term, lossless and real-time monitoring of the chloride ion concentration in concrete, has high measurement precision, has the advantages of simple structure, small size, high strength, high sensitivity and the like, has a wide application prospect, and is easy to popularize.

Description

technical field [0001] The invention relates to a Fab cavity-type optical fiber sensor for monitoring the concentration of chloride ions in concrete, which belongs to the technical field of structural health monitoring, and is especially used for monitoring the concentration of chloride ions in reinforced concrete structures in seawater environments. Background technique [0002] Reinforcement corrosion caused by chloride ion attack is the main cause of rust swelling and cracking of reinforced concrete structures, which will seriously endanger the safety performance of reinforced concrete structures in service. Chloride ions are not directly involved in the generation of rust, but act as a catalyst. Chloride ions invade the concrete and gather on the surface of the steel bar. After the chloride ion reaches the critical concentration, it destroys the passivation film of the steel bar; the iron matrix exposed by the destruction of the passivation film serves as the anode, and ...

AI Technical Summary

Problems solved by technology

This kind of analysis is very destructive to the tested material, the operation is very complicated, and often consumes a lot of manpower and time, and it is impossible to realize the real-time monitoring of the expansion and concentration distribution of chloride ions in concrete

Although the chloride ion selective electrode method can detect the concentration of chloride ions in concrete in a short period of time, the long-term reliability of the currently disclosed electrode method for monitoring the diffusion of chloride ions in concrete is insufficient, and the accuracy of the monitoring results is low and the volume is large. , has a certain degree of damage to the concrete structure

Existing wireless sensors for monitoring chloride ion concentration in concrete generally have the problems of low radio frequency power and radio frequency utilization, large equipment volume, and low sensitivity. In addition, this wireless sensor cannot realize the detection of chloride ion diffusion along the depth monitor

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