Reinforcement destruction is critical trouble for huge damage in RC or reinforcement construction. In any construction, reinforcement bars play an important role because it is the only thing that can protect the whole structure from any kind of carbon dioxide related issue.
So, it is crucial to go for a quality check process for all RC construction. Through the quality check, it will be easier to find out the thickness and diameter of all reinforcement bars. But the only thing to keep in mind is the process of quality check should be non-destructive in nature. There are a lot of non-destructive testing processes which are known as NDT.
Widely used NDTs are rebound hammers, cover metres, impact echo, linear polarisation resistance, ultrasonic pulse velocity, etc. Among all of these various systems, the cover metre is the most demanding and widely known one.
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Cover metre: Description of cover metre
Cover metre is basically an instrument which is used for locating and finding all rebars. Along with locating those rebars, the cover metre is also helpful for gauging appropriate concrete cover. The concrete cover is the minimum distance between the surface of the entrenched reinforcement and the exterior surface of the concrete.
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Previously, these measurements were taken with the help of rebar locators but somehow it was not such an effective device. So, to make the whole process more efficient, the cover metre is used.
Cover metre: How to use it?
The working system of the cover metre is dependent on electromagnetic pulse induction technology. This process makes work the technique to locate all bars. Usually, in this device, coils are charged by current pulses but it happens with a time gap. When the coils are completely charged, a magnetic field is formed.
When there is a bar, it means there is an electrically conductive material. These bars produce magnetic field-based Eddy current. But this current flows in the opposite direction of the magnetic field.
Also, there can be field-based changes in voltage. This is also helpful in finding bars properly. The whole process remains unaffected by all kinds of wooden pieces, plastic materials, concrete structures, etc.
Cover metre: Advantages of the cover metre pulse induction method
The cover metre pulse induction method is used widely because it has a few effective advantages. These are
- Higher rate of accuracy
- Unaffected by moisture
- Unaffected by wooden pieces, plastic materials, concrete structures, etc
- Unaffected by natural influences like rain, heat, cold, etc
- Cost-effective
Cover metre: Disadvantages
- The detection range is not broader. It can cover only a limited place at a time.
- Cover depth is responsible for minimum spaces between all bars.
Cover metre: What are the standards of the cover metre?
The cover metre is dependent on various standards which are implemented in reinforcement constructions. These standards are as follows:
- BS 1881:204
- DGZfP: B2
- DIN 1045
- ACI Concrete Practices Non Destructive testing 228.2R-2.51
Cover metre: Application
In the field, there are various real-time applications of cover metres. Those are as follows.
- With the help of a cover metre, it is easy to find out all the details about an old building which is demanding maintenance immediately. It helps to find out the worst sides of a building.
- With the help of a cover metre, reinforcement constructions are tested on-site.
- It also helps to find out where bars are located. So, if there is any requirement for drilling or such a process, it will be easier to go for it.
- Cover metre also helps to check the conformity of any new building.
- A cover metre is responsible for corrosion analysis which is a major part of all kinds of reinforcement constructions.
Precautions for making use of a cover metre
Using a cover metre includes a few precautions which must be followed always.
- Accuracy of a cover metre can be reduced if there is a higher concrete cover.
- If there is no sufficient space between bars, it can not detect the measurement properly. So, it is always suggested to choose a place of structure, where proper space between rebars is present. It will help to get the diameter of the bar prominently.
- In case, there are two different steel structures in one reinforced structure, it is mandatory to pick the first one for the cover metre.
FAQs
What is the role of a cover metre in RC or reinforcement construction?
The cover metre is used for a non-destructive measurement of reinforcement concrete covers to understand the quality of the structure.
What does the cover metre test define?
The cover metre test defines where and how a reinforcement bar is situated in concrete.
Mention at least one thing that can affect cover metre measurement?
Cover metre results can be dependent on neighbouring bars that are close parallel bars situated nearby.
Is chloride harmful to concrete?
Yes, chloride is harmful to concrete because it reacts with the steel and other materials and the whole process creates hydrochloric acid; this hydrochloric acid causes issues like concrete cracking, spalling, weight failure, etc.
