South-East Scanning recently completed a critical Ground Penetrating Radar (GPR) survey at the UnityWater water tank in Tanawah, Sunshine Coast. The project involved locating post-tension cable "onions" in a tilt-panel slab and ensuring that at least 50mm of concrete cover met the stringent engineering specifications. The high precision required for this project was crucial for securing engineering approval and avoiding costly design rework. This case study highlights the benefits of using GPR technology for such detailed investigations and showcases the success of our efforts.
Project Overview
Client:Â Advanced Concrete Engineering
Site Location:Â Tanawah Reservoir, 180 Tanawah Road, Tanawah, QLD
Objective:Â Locate post-tension cable “onions” in a tilt-panel slab and confirm at least 50mm of concrete cover.
Equipment Used:Â Proceq GP8000
The Proceq GP8000 is a state-of-the-art GPR unit renowned for its high resolution and advanced 3D modelling capabilities. This equipment was pivotal in achieving the detailed subsurface imaging required for this project. The GP8000’s ability to create precise three-dimensional representations of subsurface structures allowed us to visualise the exact positions and depths of reinforcement bars and post-tension “onions.”
Calibration Process
On-site calibration was performed and observed by a third-party observer to ensure the accuracy of the GPR scans. The calibration process involved:
- Physical Measurement:Â The concrete cover in the reservoir floor was physically measured using a tape measure.
- GPR Scan:Â A GPR scan was conducted over the same reinforcement to verify the accuracy of the Proceq GP8000.
- Comparison:Â The results of the physical measurements were compared to the GPR scan results to ensure they matched.
This calibration confirmed that the GP8000 accurately detected the concrete cover, ensuring reliable data for the subsequent scans.
Survey Findings
Our site technician conducted multiple GPR scans across the tilt-panel slab to ensure comprehensive coverage and verification of the concrete cover. The results were as follows:
- Concrete Cover:Â The scans confirmed that at least 50mm of concrete cover was present from the reinforcement bars and the PT onions throughout the tilt-panel slab, meeting the engineering specifications provided by Advanced Concrete Engineering.
- Post-Tension “Onions”:Â The Proceq GP8000 detected the post-tension “onions” within the slab. The 3D modelling capabilities detailed these features, confirming their positions and ensuring adequate concrete cover.
Benefits of GPR Technology
High Precision and Accuracy:Â The Proceq GP8000’s high-resolution scans and 3D modelling capabilities allow for precisely identifying subsurface features, ensuring that critical structural components like post-tension cable “onions” are accurately located and assessed.
Non-Invasive Method:Â GPR is a non-invasive technique that does not damage the concrete structure. This makes GPR ideal for detailed investigations in sensitive areas where structural integrity must be maintained.
Cost-Effective:Â By providing accurate data, GPR helps avoid costly rework and potential structural failures, saving time and money.
Comprehensive Reporting:Â The ability to generate detailed reports with visual representations of subsurface features ensures clear communication with clients and stakeholders, facilitating informed decision-making.
Outcomes for the Client
The GPR survey conducted at Tanawah Reservoir demonstrated the effectiveness of the Proceq GP8000 in locating and verifying subsurface features, ensuring the structural integrity of the tilt-panel slab met the required engineering specifications. The successful identification of post-tension cable “onions” and confirmation of concrete cover thickness were crucial in securing engineering approval and avoiding costly redesigns.
South-East Scanning’s use of advanced GPR technology and rigorous calibration processes highlights our commitment to delivering high-quality outcomes for our clients. Whether working with Queensland Government agencies or private clients, our expertise in GPR surveys ensures precise and reliable results, making us a trusted partner in concrete scanning and structural analysis.
For more information about our GPR services and how we can assist with your next project, please visit South-East Scanning or contact us directly.
