GIE Technologies adheres to the practice of effective and strong project management for our client’s projects.  Our policy is to make responsiveness, submission timeliness, and budget management second to none in the engineering community.

  GeoRadar

A ground penetrating Georadar system (Georadar for short) makes use of high frequency electromagnetic impulses which are directed by a transceiver towards the bridge/road surface. Waves are then reflected back to a receiver and monitored using sophisticated electronic equipment.

The waves which are received and recorded are indicative of the composition of the deck/road. As a Georadar wave propagates through a deck/road foundation and encounters an interface between two materials with different dielectric constants, a portion of the energy is reflected back while the remaining energy continues through the deck/foundation. The travel time of the wave between two interfaces can be used to compute the thickness of that layer, such as asphalt thickness, granular thickness and cover over the reinforcing steel.  

Examples of radar data extracted from the profile collected

45 mm                         55                              75                               100                        145

Color MAP showing the distribution of pavement thicknesses

Color MAP showing the distribution ( Low, Medium, High) of probability of reinforcement corrosion

On asphalt covered bridge decks, Georadar can be used to identity the areas of high probability of reinforcement corrosion. This is accomplished by monitoring the amplitude of the Georadar reflection at the asphalt overlay/concrete deck boundary compared to that at the surface of the deck. There is a high correlation between the presence of humidity and chloride ions (usually responsible for reinforcement corrosion) and the amplitude of the Georadar reflection.

For bridge deck survey, GIE uses a 1,5GHz ground coupled Georadar antenna. For road thickness layer GIE uses a combination of Georadar antennas allowing to measure thickness at depths up to 1.5 meters.

   System Characteristics

	Can be used on soft pavements/roadways as well as rigid and mixed.
	Allows for the collection of precise, non destructive sub-surface information.
	Collects information at traffic's speed, minimizing the impact on users.
	References information acquired according to the vehicle's position (DMI).

  Equipment

GIE Technologies uses the most up-to-date Georadar system conceived by Geophysical Survey System Inc.  The ground penetrating Georadar equipment is comprised of the control unit SIR-10H and different types of Georadar antennas installed on the vehicles used to acquire data. The data acquired is interpreted and analyzed by means of a software package developed specifically for this type of application by GSSI.  The results presented on various formats are geared and conceived to answer to the needs of the engineers responsible for the roadways systems.

    Specifications:

	Maximum number of layers: unlimited
	Measurement precision: ± 5 to 10% (Asphalt Thickness) and ± 10 to 15% (Granular Thickness)

Investigation depth / antennas and minimal thickness

Survey speed:  varies from 5 to 75 km/h, according to the acquisition and the foreseen application.

   Survey

With the exception of the ground coupled 1.5 GHz and 400 mHz antennas which are directly dragged on the inspected surface, the Georadar antennas (2.5 GHz, 1.0 GHz,) are mounted on a fixed mast attached to the front of the inspection vehicle and raised to approximately 300 mm above ground. 

Once the measuring device is zeroed at a reference point, the van proceeds with the survey. Survey Speed is governed by the type of survey performed (Bridge Deck,  versus Road Layers Thickness).

A bridge deck evaluation with the ground coupled 1.5 GHz antenna is relatively slow compared to the Road Layers Thickness Survey since the antenna is directly in contact with the surface. Road Layers Thickness Survey with the antennas raised to approximately 300 mm above ground carried out at traffic speed. Once the survey is completed, a number of cores to be sampled are localized with paint marks on the bridge deck/road surface.

    Processing

As stated before the data acquired is interpreted and analyzed by means of a software package developed specifically for application by GSSI.  Results are generated on various formats according to the specific needs of the road network management engineers.

The most popular format is the table presenting the thickness of each layer at the intervals specified by the client and can include statistics such as:  the average thickness, linear reference, minimum and maximum values. The presentation on the form of a graph is also appreciated:  it allows to graphically visualize the results.  It may consist of a continuous profile of layers, allowing to illustrate for example the depths of various interfaces.

All plans are presented using Excel, Surfer or the AutoCAD software and can be superimposed on existing drawings.

  Latest news

 See our latest tool!  Our New Geographical Visualization Interface.  Visualize through the use of a single application an unlimited quantity  of infrastructure data elements including pavement and right-of-way imaging. Read more

  Quality Control on Cracking Data. 
How do we do that?  Once the cracking data is extracted from the  Data Collection System the results are verified against pavement digital images  Read more

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