Our GPR surveys provide a fast and efficient NDT means of surveying large or small areas of concrete floor slab. They can determine construction detail and help identify possible defects. Suitable for warehouses, offices, car parks, etc.

Floor slab survey

A GPR floor slab survey may be used to:

  • Determine construction details.
  • Verify construction drawings.
  • Identify the reason for slab failure.

The GPR survey involves scanning the required area of the floor slab with a series of scan lines. These are usually on a regular orthogonal grid, but this can be flexible to accommodate obstructions.

GPR surveyor scanning a large warehouse floor slab
Scanning large warehouse floor slab using Ground Penetrating Radar

For offices, warehouses, or any other floor slab survey, we use a GSSI SIR-3000/4000, dual-frequency, or multi-channel GPR system. Dual-frequency scans provide a greater depth range with better resolution than a single-frequency antenna. Multi-channel systems use an array of antennas, providing rapid scanning of large open areas.

Antenna central frequency is typically in the range of 1600 MHz to 900 MHz. We frequently scan using several different frequencies to obtain a range of penetration depths and resolutions. The 1600 MHz antenna would typically penetrate to a depth of 400 mm in concrete and is best for detecting shallow features such as layers of reinforcement. The 900 MHz antenna can penetrate to a depth of 0.9 m or more (conditions permitting), thus resolving deeper features, albeit with a loss in resolution in the data.

We save the site survey data electronically and process it at our offices using specialist Radan software. This has two main advantages. Firstly, it means data collection on site is quick and efficient, keeping any disruption of occupied premises to a minimum. Secondly, the results are more accurate because data processing, such as surface position correction, gain adjustment, and migration, make interpretation easier.

Survey deliverables

Our results and interpretation are presented in a clear report. They include CAD drawings, sketches, photographs and annotated radargrams as required.

GPR depth slice of floor slab showing top reinforcement layer
GPR depth slice image showing top layer reinforcement

Why undertake a GPR floor slab survey?

We typically undertake GPR floor slab surveys to determine or confirm the following:

  • Floor slab construction detail (e.g. reinforced concrete, mass concrete, clay-pot, precast planks, etc.).
  • Slab thickness.
  • Reinforcement distribution.
  • Adequate mesh overlap.
  • Detect variations in floor slab construction detail.
  • Determine the position of any ground beams and pile caps.

Advantages of a GPR floor slab survey

GPR offers several clear advantages over more traditional survey methods. Notably, as it detects changes in the sub-surface, it will detect not only reinforcement but also any voiding beneath the slab, the slab thickness, construction layers, variations in construction, services (including plastic), etc.

GPR is non-intrusive and can be carried out in occupied premises with minimal disruption. It is suitable for scanning large or small areas. Furthermore, on-site scanning is quick and efficient. This is because typically, we save the data electronically and undertake processing and interpretation off-site. Consequently, this keeps the time spent on-site to a minimum.

Need more information?

Contact us

Contact us to find out more about GPR concrete floor slab surveys and how we can help you:

Tel: 0207 565 7056
Email: gpr@sandberg.co.uk

Information sheets

Download the following information sheets relevant to concrete floor slab surveys:

Are you wondering what else GPR can be used for? GPR surveys can investigate the subsurface and detect unseen features. Learn more about our most popular GPR surveys.