Measurement of concrete clear cover in tunnel construction, bridges and retaining walls

Whether it’s tunnels, bridges or retaining walls – concrete clear cover surveys are an important quality assurance measure with numerous steel reinforced building elements.

With railway and motorway tunnels which, using the blast excavation method, are built as a twin-shell vaulted construction with an inner shell of vaulted concrete, a concrete clear cover survey must take place for reasons of quality assurance. Even with retaining walls and bridges, the concrete clear cover is being more precisely checked by an increasing number of construction clients – for example in the case of flood water protection measures, new construction of railway and motorway tunnels or the rerouting of urban bypasses. The retaining walls assume an important traffic safety function here which is why the quality assurance of the concrete clear cover plays a particularly large role.

We implement the concrete clear cover survey using the Hilti Ferroscan PS 200 measuring equipment. We currently deploy six of these high-quality-units. Thanks to our in-house developed, innovative scanner extension, we are in a position to carry out surveys particularly quickly and efficiently. The big advantage of this to you means that up to a height of 5 metres, we do not require any scaffolding.

The concrete clear cover surveys in tunnels, however, constitute only one part of the work we do; the more crucial part is the evaluation and documentation of the measured results. Based on our long years of experience, we have developed a completely new type of documentation which gives our customers a more rapid overview of the measured results. To this end, all measurements for each block are illustrated in a coloured overview so that the customer can recognise all potential weak spots at a glance.