How To Assess Corrosion in Concrete with an NDT Method

Have you ever been driving over a bridge and wondered who is in charge of making sure it is safe? Or how they test for rust and corrosion? Or maybe you have some knowledge of testing methods for corrosion, but you still aren’t sure of the best way to assess concrete structures, or what concrete NDT methods are all about. No matter where you are at, this blog will explain why corrosion assessment is important, the different ways to do it, and the differences between destructive and non-destructive testing (NDT).

Why Corrosion Assessment is Important

Rusty chain

ASTM International defines corrosion as “a chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties.” Or, in simpler words, they summarize with this: “corrosion is the deterioration of a metal and is caused by the reaction of the metal with the environment.” Corrosion is a natural process and is visible in everyday life (like on a cast iron pan). However, there are many types of corrosion. When large concrete structures with steel rebar begin to corrode it can create serious hazards for the bridges, highways, and buildings we use every day. This type of corrosion can often go unnoticed for a long time, which is one of the reasons regular testing is important. By the time you see corrosion of the rebar coming through a concrete structure, it may be too late to repair.

Click here to read more about the process of corrosion in reinforced concrete.

How to Test Concrete for Corrosion

There are so many ways to test for corrosion. Some common methods for testing damage and deterioration on rebar include:

  • Visual Inspection
  • Infrared/Thermal Imaging Inspection
  • Coring and chipping
  • Ground-Penetrating Radar (GPR)
  • Half-cell potential test

Each of these methods have their own pros and cons. Some are destructive methods, which we will explain in the next paragraph. Others are very difficult to implement, like the Ground-Penetrating Radar (GPR) technique, which requires an expert for data interpretation. Finally, some of these methods can be ineffective or inaccurate. In particular, the visual inspection method is only a starting point to determine immediate repair needs but cannot provide a proper assessment.
Read more about these methods here.

Non-Destructive vs Destructive Testing Corrosion Testing Method

As the name suggests, destructive testing – such as coring and chipping – damage the concrete in such a way where it needs repair after testing. The idea is that by breaking off or destroying a piece of concrete, you can easily examine it using a variety of methods. However, this has obvious side effects. If the results reveal that the rate of corrosion is not of concern, you have damaged the structure for no reason.

On the other hand, non-destructive methods, such as Infrared/Thermal Imaging Inspection allow an engineer to test a concrete structure safely, without damaging it. These methods allow you to gather results quickly, and if the concrete is performing well you can leave it as is. These methods are often simple, and there is no need to worry about performing them too frequently, as your concrete structure will not be negatively affected by using the device. However, it is important to note that some of these methods are more accurate than others.

An Award-Winning NDT Device for Concrete Corrosion Monitoring

iCOR corrosion detection device

If are considering using an NDT device to monitor corrosion and are deciding which method is best for you, we highly recommend our iCOR® device. ICOR is a unique, wireless option for NDT corrosion detection in reinforced concrete structures. iCOR uses patented CEPRA technology which allows the device to estimate the corrosion rate of rebar without requiring a physical connection to the rebar (as most other devices do). This makes iCOR the most convenient and only wireless corrosion rate measurement device that may be used in the field or the laboratory. For further details, check out our iCOR FAQ page.

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