Durability tests of a fiber optic corrosion sensor

Area of Science:

• Materials Science
• Civil Engineering
• Sensor Technology

Background:

• Steel corrosion significantly degrades reinforced concrete structures.
• Effective, cost-efficient detection methods for corrosion initiation are crucial.
• Existing methods may lack practicality or cost-effectiveness for widespread application.

Purpose of the Study:

• To present a novel, low-cost, and user-friendly fiber optic corrosion sensor for practical use.
• To demonstrate the multiplexing capability of these sensors using optical time domain reflectometry (OTDR).
• To validate the sensor's performance and durability in real-world conditions.

Main Methods:

• Fabrication of a fiber optic sensor by sputtering a thin iron film onto an optical fiber end.
• Utilizing changes in reflected light intensity to detect film corrosion.
• Implementing multiplexing of multiple sensors using OTDR and optical splitters.
• Conducting a three-year field trial in a marine environment and performing accelerated life and freeze-thaw tests.

Main Results:

• The sensing principle relies on the significant drop in reflected signal intensity as the iron film corrodes.
• Multiplexing several sensors via OTDR allows for distributed corrosion monitoring.
• The three-year field trial demonstrated practical applicability in an aggressive marine setting.
• Accelerated tests confirmed the sensor's durability against chemical and physical degradation.

Conclusions:

• The proposed fiber optic sensor offers a cost-effective and practical solution for early corrosion detection in concrete structures.
• Multiplexing capabilities enhance its utility for monitoring larger infrastructures.
• The sensor exhibits sufficient durability for long-term deployment in challenging environments.