IIT Researchers Tackle Rebar Corrosion Detection Issue

Brief 

A team led by researchers at the Indian Institute of Technology Bombay used a pulsed eddy current method to measure the extent of corrosion in concrete buildings. It is usually difficult to use that specific nondestructive testing method to detect rebar corrosion, but the researchers have solved that problem with a low-cost, high-performance probe with an anisotropic magnetoresistive sensor that relies on a novel signal processing method.

Insight

Concrete structures such as bridges, buildings, and roads use steel reinforcement bars—called rebars—to increase the strength of the concrete and make the structure durable.

Despite using preventive measures such as anticorrosive coatings, these rebars are prone to rust, leading to corrosion. Several factors such as water seepage, exposure to chemicals and incorrect salinity and acidity of concrete can cause corrosion. Timely corrosion detection can warn about structural degradation and significantly lower repair and maintenance costs.

Today, the most commonly used methods to examine corrosion do not accurately estimate the extent of corrosion and, therefore, the remaining service life of the structure.

A team led by Prof Siddharth Tallur and Prof Sauvik Banerjee of the Indian Institute of Technology Bombay (IIT Bombay) has developed a probe to measure the extent of corrosion in rebars embedded in concrete. The probe can be placed on the surface of a concrete structure to make the measurement.

Probe and sensor design improvements and novel signal processing techniques make it more sensitive and accurate than conventional measurement techniques. The research was partially funded by the Department of Science and Technology, Government of India, and Sanrachana Structural Strengthening Pvt. Ltd. A study based on this work was published in IEEE Sensors Journal.

One of the currently used methods, the half-cell potential measurement, involves drilling a hole in the structure to expose a portion of the rebar. This portion is connected to the measuring instrument. The method uses the voltage difference created due to different electrochemical properties of corroded and non-corroded regions.