RIS Hi-BrigHT Bridge-Deck GPR

Condition assessment represents a unique problem in asset maintenance. A combination of traffic loading, marine or semi marine environments and the compromises that must be made during construction and maintenance lead to fast deterioration and make surveying or maintenance difficult and expensive.

Traditional visual surveying only catches advanced degradation and coring, while providing excellent information, only provides information about the point of the core and is destructive and expensive. Conventional GPR systems can provide some useful information, but are limited by processing designed for other tasks and difficult envrionments such as combined concrete and road base structures.

The IDS RIS Hi-BrigHT has been designed specifically for quality assurance survey and is a complete package with a 16 channel high frequency antenna array, scanning cart, data logger, and HD3 Bridge analysis software.

Data can be collected quickly on site, reviewed on the datalogging PC to support current work or processed in HD3 to reveal damage, at risk areas or other vital information.

Applications

Slabs on Grade

Where there is a distinct difference in the emmisivity of the ground and concrete the radar will show the slab thickness to within 25mm for slabs up to 300mm thick. This is sufficient to check a common problem with slabs; inadequate thickness of the slab and correct thickening at joints. The scan will clearly show the reinforcement layout and the cover. This enables checking the reinforcement has been included and is at the correct depth. At joints it will show if the dowels are located in the correct locations and at the correct depth.

Suspended Slabs

In suspended slabs the reinforcement's correct location is particularly critical and scans will quickly confirm correct rebar spacing and depth. The air to concrete interface also provides an excellent image of the slabsbase. High frequency dual polarity antennae make top and bottom mats detectable.

Bridge Decks

Bridge deck survey is one of the tasks the Hi-BrigHT was specifically designed for. Surveys can detect all the problems already described and provide information on the road base and any deterioration of the concrete due to marine environments or de-icing salts.

Road Pavements

These are essentially a subset of slabs on grade but the scan will also identify if voids have developed under the slab. This can be an issue at leaking pipes and where there is 'pumping' at edges.

Precast Panels

Where panels are cast on a flat bed the scan can be used to provide a very rapid means of quality assurance. It provides a picture of all inserts, reinforcement and defects.

Sample Analysis

Damage Survey - The image below is sample of data processed to show internal damage suchas delamination.

This image was created with HD3 software and red shows areas of greatest damage, green undamaged areas.

On Site Tomography - Data collected on site can be reviewed by depth; the first image shows a slice of data at 50mm the second at 100mm, the data has been collected over renewal work covering an area of deterioration.

50mm Scan – The section highlighted displays a rectangular section of renewed concrete; this is obvious due to the difference in material properties of the old and new concrete.

100mm Scan – Located underneath the renewed section the deteriorated concrete is visible in black, in darker grey the reinforcing grid at the same level is visible .

Thickness Scanning - Processing can alternately be used to examine the thickness of the concrete cover which is the first and best protection against corrosion initiators.

The colour code on the right shows that red or black sections are perilously thin, yellow or white is a more reasonable cover depth.

3D CAD Recreation - An experienced operator can lay out a detailed model of the reinforcing grid with annotations for damage and repair using only the collected scan data.

The Image above is created from the data previous shown for on site tomography.

System Configuration

Due to the extremely high antenna count the Hi-BrigHT can gather 3D data from an area up to 1.5m wide in a single pass at a moderate walking pace. The high frequency 2GHz antennas offer superior resolution and their arrangement in cross polarised pairs offers the best visibility of a second layer of reinforcing possible.

Additional Information

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