When extending, renovating or modifying an existing property it is essential that the construction details of the building are known. From simple things like are the beams reinforced concrete or concrete encased steel. To complex information like exactly how many bars are in a column, shear rail information or the details of the hogging reinforcement over a beam.
Ideally, this information would be found in the design or as-built drawings for the buildings. However, these drawings often don’t exist or have been lost or destroyed.
Radar offers a great tool to nondestructively recreate as-built drawings. Gathering information to allow structural engineers to be able to calculate load capacities and determine what needs to be done to get a project underway.
Radar can be used to scan the majority of structural elements of buildings to ascertain the thickness of materials, reinforcement layout and other information.
Scans can be conducted on beams and columns to resolve the number of main bars and the spacing of the links. GPR can even determine if the beams are prestressed or map the number, position and path of cranking bars.
The layout of slab reinforcement, including mapping area of additional reinforcement, variations in the reinforcement layout or shear rails, can be determined by GPR being conducted on a grid pattern.
As GPR can typically penetrate to a depth of 500mm in reinforced concrete scans can be conducted from one side only. This allows GPR to determine both layers of reinforcement in ground bearing slabs or party walls; something that other methods cannot do.
Our experienced surveyors will process the data collect on site and provide a detailed written report, with figures and CAD drawings, to clearly set out how a structure has been built.
GPR and Ferroscan surveys
Radar and the Hilti Ferroscan are both techniques to be able to map and locate reinforcement. The Ferroscan is a system that has the advantage over the GPR in that in can provide estimations of bar sizes, however, this is within ±1 standard bar size and only to a depth of 60mm. While GPR cannot determine the bar sizes it has a much greater depth penetration and a higher resolution. GPR can resolve two or three layers of reinforcement to a depth of approximately 500mm.
The two techniques combined allow for an in-depth analysis of the reinforcement in concrete.