Before any core drill or saw cutter touches a concrete element, there is a critical step that should never be skipped: scanning. Ground penetrating radar (GPR) and electromagnetic cover meters are used to locate reinforcement, post-tension cables, conduits and other embedded services within the concrete, allowing coring and cutting to proceed safely and without damage to the structure.
What is GPR scanning?
Ground penetrating radar sends electromagnetic pulses into the concrete and records the reflected signals. Different materials, including steel reinforcement, post-tension cables, plastic conduits and voids, produce distinct reflections that a trained operator can interpret. The result is a map of what lies within the concrete element before any penetration occurs.
GPR is a non-destructive testing method. It does not damage the concrete, does not require access from both sides, and provides real-time results on site.
The risks of coring without scanning
Coring or cutting into a concrete element without first scanning carries significant risks. Striking a post-tension cable can result in catastrophic structural failure and serious injury. Cutting through live electrical conduits creates electrical safety hazards. Damaging reinforcement reduces the load-carrying capacity of the element.
These are not theoretical risks. Cable strikes on post-tensioned structures have resulted in fatalities on Australian construction sites. Safe work regulations require that embedded services be identified and marked before any penetration of concrete elements.
When should GPR scanning be used?
GPR scanning should be performed before every core hole, saw cut, and chase in concrete. This includes service penetrations for plumbing, electrical and mechanical trades, investigation holes for condition assessment, joint cutting and panel removal, and any breakout for repair works on post-tensioned structures.
GPR vs cover meters
Cover meters use electromagnetic induction to detect ferrous metals (steel reinforcement) and measure concrete cover depth. They are effective for identifying rebar location and spacing but cannot detect non-ferrous items such as plastic conduits, copper pipes, or fibre optic cables.
GPR detects both ferrous and non-ferrous targets, as well as voids and changes in material density. For post-tensioned structures or elements with complex embedded services, GPR provides a more complete picture.
Scanning as part of coordinated delivery
When concrete scanning, coring and repair works are coordinated through a single subcontractor, the process becomes more efficient and less prone to miscommunication. The scan results inform the coring plan, the coring supports the repair scope, and each stage feeds into the next with clear documentation.
CARE delivers GPR scanning as part of its integrated service capability. Every scan is documented, every core location is confirmed against the scan results, and all penetration work is recorded in the project ITP.