Concrete Scanning / X-Ray using Ground Penetrating Radar (GPR)

CMD implement non-destructive testing systems to scan concrete structures to verify steel reinforcing placement and possible services within concrete. CMD's Ground Penetrating Radar (GPR) scanning division is based in Melbourne yet operates throughout Victoria and South Australia where we can assist with simply scanning to identify a safe location to core through to complete reinforcing surveys to verify As-Built plans.   Need to identify: Post-Tension Cables Steel Reinforcing Live Electrical Conduits Voiding Concrete Cover Under Ground Storage Tank (UST's) Pipes Structural Beams and Footings

No survey is to large or to small so contact us today to discuss the requirements of your next project.

CMD Standard Ground Penetrating Radar Survey Procedure CMD Civil operate trained and experienced ground penetrating radar (GPR) technicians and advanced Ground Penetrating Radar (GPR) systems; we conduct a comprehensive and time proven process for all our concrete imaging and inspection surveys performed, with strict adherence to the following process: Consult: As-Builts or other information regarding building design where available. Project manager / Site Manager with CMD technician to determine scope of project and boundaries of survey area. GPR Survey: Calibration is performed to make certain the GPR system is reading an accurate distance. Test scans are performed by making scans in both the north-south and east-west directions. Dielectric value is determined by scanning over an object of known depth or by performing a test dielectric. The survey area is scanned by making a series of evenly spaced parallel scans (at progressive greater distances from the initial scan) in both the north-south and east-west directions. Identify & Mark: Rebar, post tension cables, mesh, conduits, pipes, deteriorated areas or voids are marked on concrete with coloured paint, chalk, tape, permanent marker or wax pencil. In the case of power conduits we also operate a live cable locator in conjunction with the ground penetrating radar system allowing for greater accuracy of detection. Report: Standard For every project we undertake a standard “GPR Survey Report” is issued which incorporates images from the GPR system, photographs of the survey location and a detailed breakdown of all services, reinforcing or other anomalies identified within the survey area. This is presented in a digital format for ease of distribution.             Comprehensive For consultants, designers or engineers we can offer a more comprehensive report output incorporating CAD drawings and marked up plans of any location surveyed.   CMD regularly liaise with geophysicists and testing consultants, keeping our technicians well informed and up to date for the ever increasing demands in non-destructive testing and the latest technology being made available.

Frequently Asked Questions:

What is Ground Penetrating Radar (GPR) ???

GPR is a non-destructive testing (NDT) service that can be used to help gather information on subsurface elements in roads, bridges, sports grounds, golf courses, cemeteries and all reinforced concrete structures.

How does it work ???

The ground penetrating radar equipment is made up of an antenna and a processor. The antenna has a transmitter and a receiver. The transmitter sends out a radio frequency that reflects off objects under the surface of the medium you are scanning back to the receiver. The speed of the speed of the signal is adjusted to match the dielectric constant of the medium you are scanning.

What is a dielectric constant ???

The dielectric constant is a measure of the resistivity of the medium you are scanning.

How deep can you scan ???

The depth of the scan depends of the frequency of the antenna you are using. The lower the frequency the deeper the penetration of the signal, this produces a lower resolution of the detected objects. Higher frequency antennas produce much higher resolution scans but with shallower depths.

What are the applications for GPR equipment ???

• Clearing areas safe to drill, cut or core in concrete, by locating power cables, post-tensioned cables and other critical structural reinforcing.

• Measuring the thickness of:

- Pavement layers

- Asphalt layers

- Backfill layers

- Concrete slabs and walls

- Concrete cover over reinforcing

See Also: Subsurface surveying using Ground Penetrating Radar

• Mapping of pavement and fill layers on roads for use in asset management modelling software. This information can be combined with a geographic positioning system (GPS) and the produced layer in Google earth.

• Mapping of asphalt layer thickness on bridge decks to maximise recycling of the existing asphalt layer without cutting into the concrete deck.

• Mapping of backfill layers in trenches to confirm bedding depths etc…

• Mapping of concrete slabs and walls where it is inaccessible to measure conventionally.

• Mapping of concrete cover over reinforcing to be used in conjunction with concrete inspections for asset management deterioration modelling.

• As-Built certification, mapping of reinforcing and services in concrete structures to verify As-Builts.

• Void location behind concrete retaining structures such as bridge abutments, tunnel linings, void location in road pavements.

What are the benefits of using GPR ???

The main advantage of this service is it is a non-destructive method for gathering data and information on subsurface elements that you otherwise wouldn't be able to view /access.

GPR can provide benefits at all stages of the project life cycle. In the early stages of a project our GPR service can be used as a tool to gather information for project feasibility studies and design. During construction it can be used as a risk reduction tool as well as a quality assurance tool. At the commissioning stage our GPR service can be used to verify As-Builts, this is particularly useful for both the client and the contractor as it is an independent third party verification.

During the maintenance period our GPR service can be used to help gather information for deterioration modelling and maintenance programming.