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Structure condition surveys

James Fisher Testing Services hold a wealth of experience in providing structure condition surveys for a range of buildings and concrete structures as part of their regular maintenance plans.

Structure condition surveys by JFTS can identify poor materials, environmental contamination from road salts, sulphates and carbon dioxide to offer valuable information to engineers for determining refurbishment costs and future life predictions.

We provide a full service from sending our professional site testing and sampling team to conducting the relevant laboratory tests on materials to producing comprehensive reports with recommendations for any remedial work that may be required.

The range of laboratory tests provided include:

  • Chloride ion content
  • Sulphate content
  • Cement content
  • Comprehensive strength tests
  • Petrographic examinations
  • HAC - presence and condition
  • ASR - presence
  • Thaumasite reaction identification
  • Steel - identification of type and yield strength

There are occasions when it becomes necessary to verify the condition of concrete pavement or floor slabs. Voiding can occur beneath the slab due to washout, slab movement or subsidence and this can lead to rapid degradation of the slab. This becomes an important issue in heavily congested areas such as airfield aprons and warehouse floors or concrete roadways, where safety is a concern.

JFTS has developed several non-destructive techniques to check for voiding in concrete slabs which can be applied singularly or in conjunction with each other.

The mechanical impulse test or impedance test was originally developed for the non-destructive testing of deep foundations, and it is now increasingly being applied to testing concrete structures to locate voiding, poor support, delamination and poor quality concrete.

The method is based on measuring the dynamic impedance and mobility of a structure. It is often applied to factory and warehouse floors, tunnel and sewer linings as well as concrete highways and runway slabs to detect problems associated with slab movement either side of the transverse joints. This also extends to monitoring slabs repaired by grouting to improve their seating.

Impedance testing was used extensively on the Channel Tunnel to assess the effectiveness of the grouting operations behind the linings.

Impulse radar can be used for checking the thickness of concrete slabs as well as detecting reinforcing steel and voiding both within and beneath the slab.

Results can be confirmed by drilling a small diameter hole through the slab and examining the suspected void with a flexible endoscope at discrete intervals.

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