At South-East Scanning, we’re accustomed to tackling tough jobs — but this one in Aldoga, just outside Gladstone, presented us with a real challenge (and we love a challenge).
Our client needed to determine whether any voids or air pockets were present within a 350 mm thick post-tensioned concrete panel stitch. The stitch panel was installed on a 5-million-liter water tank for the Fitzroy-Gladstone pipeline. The concern was that, due to the discovery of small voids at the bottom of the 12m stitch, those voids may have been present throughout the entire 12m height of the stitch, rather than being localised at the bottom. This is, unfortunately, a common issue when concrete is not vibrated properly.
Given the scale and reinforcement inside the wall, this wasn’t a job for a GPR scanner. We brought out the Proceq PD8050, our go-to ultrasonic pulse-echo unit for gaining deeper insights into congested concrete.
The Job
– Location: Aldoga, Gladstone Region, QLD
– Structure: Post-tensioned panel stitch – 350 mm thick
– Tools Used: Proceq PD8050 ultrasonic pulse echo scanner
– Goal: Detect any internal voids, gaps, or defects in the concrete
The Challenge
This wasn’t just any slab. It was packed with:
– Reinforcement at 200 mm centres
– Large post-tensioning ducts
– Another layer of steel on the far side
To top it off, the wall stood 12 metres high, with access to only one side, and surface obstructions, such as exposed bars and metal caps, made scanning trickier than usual.
Normally, we’d perform a stripe scan (which covers wider areas), but in this case, the physical obstructions required us to switch to line scans in the clear areas to ensure high-quality data collection.
What We Found
Despite the challenges, our scan revealed a few interesting features:
– No significant voids were detected, which is great news for the client.
However, we always inform our clients that small voids (under 10–20 mm), especially around post-tension ducts, are quite common and can be challenging to detect due to the steel congestion.
One part of the scan showed a powerful vertical reflection, which we believe is likely a steel plate or an anchor group, rather than a void.
– Another area showed an unusual hyperbolic-shaped echo. While it might appear to be a void at first glance, we interpreted it as a point reflector — possibly a dowel or a duct end cap.
What We Recommended
Since the slab was so congested, and our results were inconclusive for smaller voids, we recommended the client consider:
– Impact-echo testing is another excellent non-destructive method that works well in reinforced concrete.
– Or, for complete peace of mind, a targeted core sample to visually confirm the internal condition.
Final Thoughts
This job in Aldoga is a great example of how we adapt to site conditions, select the right technology, and clearly explain the findings. Whether it’s a factory slab, bridge deck, or post-tensioned panel, South-East Scanning brings the confidence and clarity you need to make informed decisions.
Seeking expert void detection or ultrasonic scanning services in the Gladstone region?
Contact our team — we’ll help you see what’s going on inside your concrete.
