Concrete Scanning Services

No. We cannot eliminate risk. Utility locating is a risk-mitigation measure, not a risk-elimination measure. However, the more information that we have available, i.e., private site plans, civil construction plans, and complete site access, the greater the likelihood of success.

That depends. Conductive utilities, such as electrical and copper telecommunications services, are relatively easy to trace. For polyethene water or gas lines, we rely on ground-penetrating radar, which does not guarantee successful location every time and is highly dependent on the work area, surface, and soil type. Sometimes these utilities are laid with tracer wires, which make them easy to locate. For sewer and stormwater lines, we generally need access to a manhole or inspection opening to insert a trace rod.

We locate fibre-optic cables using a trace rod inserted into the cable duct, as fibre-optic lines are non-conductive.

That depends on the quality of the signal that our transmitter generates. If we have a strong, consistent, round signal, we are confident of the utility's position. If, however, the area is heavily congested with utilities, overhead power lines, temporary fencing, and other signal impediments, our signal and accuracy can be affected. We outline the level of risk and confidence in our site reports.

AS5488, the Australian Standard that governs subsurface utilities information, provides a 300mm width tolerance and a 500mm depth tolerance on site markings. We can generally locate utilities to within a far more accurate degree; however, it is worth noting these tolerances before excavating.

Quality levels (QL) range from A (most accurate) to D (least accurate). We can think of them as degrees of confidence, rather than accuracy.

• QL-A — the utility has been potholed and physically verified.
• QL-B — a strong, consistent EMF reading with a verified depth.
• QL-C — visual surface features confirming a utility's location, but no EMF or GPR readings (e.g., a sewer line running from pit to pit, where the sewer pits are inaccessible).
• QL-D — no information beyond the site or BYDA plans.

We receive this question quite a lot. Dial-before-you-dig is now BYDA (Before You Dig Australia). BYDA provides free utility plans to the public; however, these are QL-D (quality level D) and require a skilled locator to inspect the site and physically locate the utilities.

It really depends on the site context. We generally rely on ground-penetrating radar to find water pipes; however, the site context and depth matter. If we are looking for a 20mm polyethene water line in a front garden, we can likely find it. Is it under reinforced concrete? The likelihood of successfully locating it is slim to none. The pipe's diameter matters too. 100mm polyethylene pipes are commonly used in shopping and retail centres for their fire services. When buried at depths of 700mm to 1m, these can be exceptionally difficult to spot, even for a highly skilled operator.

We often recommend potholing water utilities when an accurate location is required and conventional methods such as EMF and GPR have been unsuccessful.

Generally, yes. If you are building near public infrastructure that traverses your property (which is very common in Brisbane), you need a utility location report from a certified locating organisation to the QL-B standard, confirming depth, orientation, and distance from the property boundary. You will need to do this to submit a build-over application (BOA). We need to confirm access to a manhole before attempting to trace the utility. If you have a sewer manhole on your property, great. If not, you may need to chat to your neighbours about organising access.

This is a very common question. Our handheld GPR systems can scan most concrete slabs and provide information on the reinforcement bar configuration, slab depth, concrete cover (the depth of concrete to the first layer of reinforcing steel), and the presence of post-tensioned cables, embedded conduits, and anomalies such as voids or honeycombing. They're quite a useful piece of equipment!

In terms of their maximum depth, it depends on the contents of the slab. As a rule, we can achieve a depth of around 500mm; however, the GPR signal attenuates (weakens) the deeper it scans and the more heavily the slab is congested. For example, scanning a podium slab with 4 layers of reinforcing steel, including large-diameter dowels, is rarely feasible, so we must rely on alternative testing methods, such as UPE.

UPE stands for 'Ultrasonic Pulse Echo' testing. It is a non-destructive testing (NDT) method that uses high-frequency sound waves to inspect the internal structure of materials, most commonly concrete, by emitting pulses and analysing echoes from defects or boundaries. It enables scanning from one side to identify subsurface voids, cracks, and thickness. It's a very useful tool for detecting voids and anomalies at depths beyond the reach of GPR.

Identifying reinforcement bar diameter using NDT is a common question we receive, especially from structural engineers. Unfortunately, there is no defensible way to determine the reinforcement bar diameter using NDT, aside from taking a core sample or breaking out the concrete.

We use a Proceq PM8000 Profometer, or cover meter reader, to obtain reinforcement bar diameter estimates; however, these estimates are subject to several limitations, including a maximum concrete cover depth of 63mm and the presence of non-bonded reinforcement bars. If you require a specific diameter, you must take a core sample or break out a section of concrete.

Yes, we can. Using a combination of GPR and UPE testing methods, we can easily identify voids. A common request we receive is to check Besser-block walls for voids due to insufficient concrete vibration or concerns about the concrete mixture, or to check slabs for voids or cold joints where the concrete pour was staged.

Yes, absolutely. Our investigations can provide engineers with critical information about reinforcement layout, internal defects, and anomalies such as voids and delamination. Our detailed reports can assist in structural assessments, remediation planning, and asset management strategies.

Yes. We have conducted many asphalt thickness assessments for major clients and are well-versed in the methodology. We use high-frequency radar and specialised data analysis to determine accurate asphalt thicknesses as part of road or deck-wearing-surface assessments.

We have two methodologies for testing concrete hardness. We use a Proceq Silver Schmidt Rebound Hammer to test for surface hardness. This tool is a spring-loaded hammer tool that analyses rebound responses. Where a definitive MPa value is required for an engineering assessment, we scan the slab, identify suitable coring locations, remove 3–4 core holes and send them to a lab for testing. This destructive method is the most accurate way to measure concrete's MPa.

There are multiple reasons why your concrete might be cracking. The size and path of cracks often indicate whether the cracking is geotechnical (i.e., soil-related), curing- or expansion-related, or related to reinforcement bar placement. Our scanning assessments can help narrow down the cause by providing key insights, including concrete cover depth, whether the mesh was correctly placed, or whether there is a moisture or groundwater issue.

There are many reasons why moisture may leak through a slab. Water intrusion through concrete floors may result from hydrostatic pressure, slab cracks, rising damp, poor waterproofing, or leaking services beneath the structure. Subsurface investigations can help determine whether moisture is coming from beneath the slab or from within the concrete structure.

Typically, a sagging slab results from a loss of support. Possible causes include soil erosion, leaking pipes (commonly stormwater pipes), poor soil compaction, and voids beneath the slab caused by soil washout or an incorrect concrete mixture. Our subsurface diagnostic strategies can help to identify the exact cause of the sag.