Wall and slab thickness measurement surveys

Our non-intrusive GPR surveys can provide thickness readings for concrete slabs, screeds, walls, road construction, etc. Variations in thickness and construction detail can also be detected. Typically, only one-sided access is required.

Traditionally, the thickness is determined by direct measurement; however, this requires access to both sides. One solution would be to drill through and then measure the thickness, but this is not always possible (listed building, party wall or you simply don’t want to damage cosmetic finishes).

Ground Penetrating Radar (GPR) offers a solution to this problem. It is suitable for most (non-metallic) materials and can even determine the thickness of several layers of construction simultaneously e.g. asphalt layers in road construction, the thickness of screed and underlying concrete slab, etc. GPR is particularly useful for the following:

• Concrete slab thickness (reinforced or mass concrete)
• Screed thickness
• Wall thickness
• Swimming pool walls
• Asphalt layers in road construction

GPR scans continuously record thickness information along a scan line; therefore, effectively providing a cross-section through the substrate. This makes the GPR especially suitable for detecting variations in thickness.

An additional benefit of using GPR is that other information can be collected at the same time, such as reinforcement distribution, depth of cover to rebar, delamination between layers, voids, etc.

Advantages of GPR thickness surveys

Sandberg offer GPR surveys to determine the thickness of construction. Our experienced surveyors can undertake anything from simple spot readings to extensive and comprehensive surveys of large areas to determine the thickness of construction and variations in thickness. Advantages of using GPR include:

• Access to one side only required
• Non-intrusive
• Suitable for most non-metallic materials
• Minimal disruption so can be carried out in occupied premises
• Quick
• Suitable for large or small areas
• Clean and no noise

Screed and concrete slab thickness surveys

GPR can be used for screed and concrete slab thickness surveys. It is very quick and efficient and suitable for small or large areas, e.g. offices, warehouses and car parks. It can be used to confirm if thicknesses are within specified tolerances, or determine the minimum/maximum thickness of a concrete slab for structural analysis.

Small areas can be scanned with individual scan lines as required, while larger areas are typically scanned on a regular orthogonal grid.

Wall Thickness

The physical measurement of wall thicknesses can often be very difficult if not impossible. Party walls are a good example of this.

GPR offers a quick and effective non-intrusive survey method of determining the thickness of walls. It is suitable for both concrete and solid masonry. GPR will also detect any wall protrusions, columns and chimney breasts on the other side of the wall. Results can be marked onto CAD drawings or annotated on radargrams showing a pseudo section view of the surveyed wall.

Deliverables

Results can be marked onto CAD drawings as spot readings, contour plots or colour coded thickness zones along scan-lines.