Benefits of Ground Penetrating Radar

Ground penetrating radar is equipment that penetrates beneath the surface of the ground or concrete and provides images that can be used to determine the embedment’s such as reinforcing in concrete. This is particularly useful when wanting to dig or drill in a particular location in order to prevent hitting a buried object.

The ground penetrating radar works on the principle of using radio waves penetrating the ground or concrete and reflecting from the buried objects. The radio waves are completely safe and also have very high penetrating power. This means that it has become very popular as a method by which risk can be mitigated on building sites.

This non-destructive testing equipment comes with various benefits. Some of the primary ones are:

• The equipment has applications in the high speed mapping of cracks and voids in a newly laid pavement. This can help in the rectification process and also aid in increasing the safety quotient of the pavement.
• The results are obtainedinstantly and are can be highly accurate. New GPR equipment lowers the processing and testing time tremendously. The instant results may be utilized on a more productive basis, when intime is of the essence.
• GPR is useful in testing the thickness of a concrete as well as the location of rebar, through continuous measurements. So, one can check their uniformity.
• The radio waves are highly powered to enter concrete of thicknesses up to around half a meter.
• Also, the portability of the equipment allows one to handle it efficiently on a range of elements.

The machine comes with certain drawbacks such as sensitivity of this equipment to water in the concrete and also itslack of penetration where the concrete is dense with rebar.

However, the GPR is one of the fastest growing test methods in the construction industry, due to its large number of applications and its ever improving image quality and data processing.

Applications of Ultrasonic Pulse Velocity Testers

Half-cell potential method is highly popular in the concrete repair and concrete investigation industries in Australia. Specialised half potential meter make it easy to measure potential difference of the reinforcing steel inside concrete against a standard reference electrode. This potential difference give the user and understanding of the corrosion risk of the steel reinforcing. It does not however give any information about whether the rebar is actually corroding or the corrosion rate.

Corrosion is one of the principaldeteriotationthat a concrete structure faces. Half cell potential measurement is a quick and easy method by which the corrosion risk of the rebar in a structure can be mapped out. Once mapped the engineer can use external clues such as cracking and spalling to interpret the results. Alternatively other devices such as resistivity meters or Corrosion rate meters can be used.

Corrosion is an electrochemical reaction, which involves the formation of iron oxide in the corroding areas and other reagents in the cathodic zones (passive). Half cell potential meters allow the early onset of corrosion can be determined by locating these anodic corroding areas.

Half-cell potential is mostly non-destructive. Being electrochemical it requires a connection to the rebar to be made, however as long as the reinforcing is electrically continuous no other damage is required. The half cell is then placed in a grid manner over the concrete surface with the readings recorded in the meter and then graphed on the screen or later on PC.

Historically Half-cell potential measurements were made usinga high impedance voltmeter and a half cell (such as coper/copper sulfate). The reading were then manually recorded for adata entry and graphing on leaving site. This process was very time consuming and would mean surveys took manner hours, if not days to complete. The introduction of half cell potentials meter has allows the data to be stored automatically and the graphing of results to occur instantaneously.

The half-cell potential measurements thus, are an extremely important tool to investigate corrosion of structures in the construction industry.