GPR detects metallic and non-metallic features that create a contrast with the surrounding material. In concrete: rebar, post-tension cables, conduits, pipes, voids and layer boundaries. In the ground: buried pipes, cables, ducts, voids, geological layers and obstructions. The depth of detection depends on the material and the antenna frequency used.

How deep can GPR scan?

In concrete, GPR typically penetrates 300–500 mm in normal-density concrete. In the ground, penetration depth depends on soil type and moisture content — typically 1–3 metres in most soils, and up to 5–10 metres in dry sandy soils. We will advise on expected penetration depth for your specific site conditions.

Does GPR work through reinforced concrete?

Yes. GPR is specifically designed for use in reinforced concrete. The radar images the full depth of the slab, detecting rebar, post-tension cables and other embedded features simultaneously. Heavily reinforced concrete can reduce signal penetration, but in practice GPR reliably images the reinforcement layout in the vast majority of slabs encountered on construction projects.

How long does a GPR survey take?

Survey duration depends on the area to be scanned and the level of detail required. A typical pre-coring survey of a few proposed core locations takes 1–2 hours. A full floor plate scan of a large commercial building may take a full day. We will advise on expected survey duration when you enquire.

Do you need access to both sides of the slab?

No. GPR scans from one surface only — the antenna is placed on the top or accessible face of the element. No access to the underside or the ground below is required.

What areas do you cover?

We cover London, Kent, Surrey, Essex, Hertfordshire, Berkshire and the wider South East as standard. We also carry out surveys UK-wide for the right project. Call 07340 549892 to discuss your location.

GPR survey equipment — antenna array with tablet display showing live scan data

Non-Destructive Survey

GPR Surveys

Ground penetrating radar surveys for concrete scanning, void detection and buried utility mapping. London, Kent, the South East and UK-wide.

Call 07340 549892 Get a Quote

What is GPR

Ground Penetrating Radar Surveys

Ground penetrating radar (GPR) is a non-destructive survey method that uses high-frequency radar pulses to image the interior of structures and the ground below the surface. The radar antenna transmits pulses that reflect off buried features — reinforcement, voids, pipes, cables, layer boundaries — and the reflected signals are recorded and processed to produce a cross-section image of what lies beneath.

GPR is fast, non-invasive and requires no excavation or drilling. It can be used on concrete structures, tarmac, paved surfaces, grass and bare ground. Results are available immediately on site, with a written report typically issued within 24–48 hours.

ACUO uses the Proceq GP8000 and GS8000 GPR systems — among the most capable instruments available for construction and civil engineering surveys. All surveys are carried out by Gary Stringer, a GPR NDT Civil Engineer with over 20 years of experience.

Get a GPR survey quote

Tell us the element or area to be surveyed, the location and what works are planned. We'll provide a fixed-price quotation, typically within 24 hours.

07340 549892 [email protected]

Send an enquiry

Two applications

Concrete GPR vs Ground GPR — What's the Difference?

GPR is used in two distinct contexts on construction and civil engineering projects. The physics is the same; the target, the equipment configuration and the interpretation are different.

Concrete GPR

Scanning inside concrete structures

Concrete GPR scans the interior of slabs, walls, columns and beams. The antenna is placed directly on the concrete surface and moved across it in a systematic grid. The radar images the full depth of the element, detecting reinforcement, post-tension cables, conduits, voids and slab thickness.

Concrete GPR is used before coring, drilling, cutting, fixing and structural alteration — any intrusive work where hitting reinforcement or a post-tension tendon would cause damage, delay or a safety incident.

Typical applications

Locating rebar and post-tension cables before coring or drilling
Mapping embedded conduits and services before cutting
Measuring slab thickness and cover depth
Detecting voids and delamination within concrete elements
3D scanning of complex reinforcement layouts

Concrete scanning service

Ground GPR

Scanning below the ground surface

Ground GPR surveys the sub-surface below tarmac, paving, grass or bare earth. The antenna is moved across the ground surface and the radar images the layers and features below — buried pipes, cables, ducts, voids, geological layers and obstructions.

Ground GPR is used for utility mapping before excavation, void detection beneath slabs and paved surfaces, and sub-surface investigation for engineering and geotechnical purposes.

Typical applications

Utility mapping — locating buried pipes, cables and ducts before excavation
Void detection beneath slabs, tarmac and paved surfaces
Sub-surface investigation for engineering and geotechnical surveys
Layer thickness measurement — tarmac, sub-base, concrete
Locating buried obstructions before piling or foundation works

Void detection service PAS 128 utility survey

GPR equipment

Equipment We Use

ACUO uses Proceq GPR systems — the same instruments used by leading structural engineering and NDT contractors across the UK.

Proceq GP8000

Concrete & ground surveys

High-resolution single-channel GPR for detailed B-scan imaging. Used for concrete scanning, void detection and ground surveys where precise depth and position data is required. Frequency range 200 MHz–4 GHz.

Best for: Pre-coring surveys, post-tension slab scanning, targeted void investigation

Proceq GS8000

Large-area 3D scanning

Multi-channel GPR array for rapid 3D scanning of large floor plates and ground areas. Captures multiple parallel scan lines simultaneously, producing depth-slice images that show the complete sub-surface layout at each depth level.

Best for: Large commercial floors, car parks, wide-area void surveys, complex reinforcement mapping

GPR scan data showing subsurface features

3D GPR depth-slice image showing buried features

GPR survey services

Our GPR Survey Services

Concrete Scanning

GPR scanning of concrete slabs, walls and columns to locate rebar, post-tension cables, conduits and voids before intrusive works.

Rebar Scanning & Reinforcement Detection

Locate reinforcement, measure cover depth and estimate bar size with GPR and covermeter surveys.

Post-Tension Cable Detection

Locate post-tension tendons and ducts with GPR before coring, cutting or fixing in post-tensioned slabs.

Void Detection

GPR void detection beneath slabs, tarmac and paved surfaces. Locate voids before they become a safety risk.

PAS 128 Utility Survey

PAS 128 compliant utility mapping using GPR and electromagnetic detection to locate buried services before excavation.

Concrete Scanning London

GPR concrete scanning across all London boroughs. Fast mobilisation, fixed-price quotations.

Survey deliverables

What You Receive

On-site mark-up of detected features using spray paint or chalk
Annotated site photographs showing the marked-up findings
Written survey report with B-scan and 3D depth-slice images
Depth data for all detected features
Safe zone recommendations for proposed intrusive works
CAD or PDF plan showing feature positions where required

Reports issued within 24–48 hours of survey as standard.

Common questions

Frequently Asked Questions

What can GPR detect?: GPR detects metallic and non-metallic features that create a contrast with the surrounding material. In concrete: rebar, post-tension cables, conduits, pipes, voids and layer boundaries. In the ground: buried pipes, cables, ducts, voids, geological layers and obstructions. The depth of detection depends on the material and the antenna frequency used.
How deep can GPR scan?: In concrete, GPR typically penetrates 300–500 mm in normal-density concrete. In the ground, penetration depth depends on soil type and moisture content — typically 1–3 metres in most soils, and up to 5–10 metres in dry sandy soils. We will advise on expected penetration depth for your specific site conditions.
Does GPR work through reinforced concrete?: Yes. GPR is specifically designed for use in reinforced concrete. The radar images the full depth of the slab, detecting rebar, post-tension cables and other embedded features simultaneously. Heavily reinforced concrete can reduce signal penetration, but in practice GPR reliably images the reinforcement layout in the vast majority of slabs encountered on construction projects.
How long does a GPR survey take?: Survey duration depends on the area to be scanned and the level of detail required. A typical pre-coring survey of a few proposed core locations takes 1–2 hours. A full floor plate scan of a large commercial building may take a full day. We will advise on expected survey duration when you enquire.
Do you need access to both sides of the slab?: No. GPR scans from one surface only — the antenna is placed on the top or accessible face of the element. No access to the underside or the ground below is required.
What areas do you cover?: We cover London, Kent, Surrey, Essex, Hertfordshire, Berkshire and the wider South East as standard. We also carry out surveys UK-wide for the right project. Call 07340 549892 to discuss your location.

Related Insights

What Can GPR Actually See in Concrete?

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How Much Does GPR Concrete Scanning Cost?

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Scanning Before Coring: Why Post-Tensioned Slabs Need Extra Care

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PAS 128 Explained: What the Quality Levels Mean for Your Project

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Case Studies

3D GPR Concrete Scanning

Basement Plant Room GPR Scanning, London

3D GPR survey of a basement plant room slab to locate reinforcement, screed layers and possible pile positions — delivered without any surface markings.

1 m × 1 m

3D grid size

Marks made

Read case study