Rebar Surveys

Locating steel reinforcement bars and metal pipes is essential in the construction and maintenance of structures. Damage caused when a drill or a fastener makes contact with a pipe is costly. A drill making contact with re-bars or tendon ducts however, not only destroys the drill bit, but can lead to serious structural damage.

Before carrying out any maintenance work, it is vital to identify the location, orientation and depth of sub-surface metalwork. This was traditionally carried out by intrusive works, e.g. breaking out. However, there is a non-intrusive way.

Using Elcometer concrete inspection equipment we can quickly and accurately measure the orientation and the depth of cover over reinforcement bars. The size of the re-bar can also be calculated.

For design work, the location and orientation can provide useful information regarding the make-up of the floor / bridge / decking / wall and therefore possible 'loading' values or characteristics can be accounted for.

The presence of reinforcement in the concrete is detected by the influence that reinforcing steel has upon an electromagnetic field generated by the covermeter. The position and direction of the steel reinforcement is determined by moving the covermeter over the surface of the concrete slabs, walls, bridge deck. etc.

Results are data-logged in the equipments internal memory for later downloading analysis and statistical reporting. All data is backed-up for quality control purposes and historical value. These can be output as a series of graphs in a report. Alternatively a drawing can be produced to show the position or section of the re-bar.

If used in conjunction with Ground Penetrating Radar more information regarding the make-up of the surface may be determined.

Our Covermeter is also capable of assessing the severity of corrosion in the re-bar using an electrochemical technique commonly known as half-cell potential. To perform this service the re-bar has to be firstly located and then exposed in one location by intrusive methods. Thus allowing maintenance work to be scheduled accordingly.

Effectiveness

Estimation of bar size, spacing, orientation and depth is influenced by neighbouring bars and surface conditions.

It is hoped to achieve accuracy of results to BS4408:Part1:1969 rewritten as BS1881:Part204:1988 between Levels L2 and L3 although the notes above can affect the level of accuracy on site as opposed to laboratory testing.

Penetration

Up to 200mm, but this depends upon surface / site conditions and the reasons above

If you would like more information on Rebar Surveys then contact Steve Hawkins at london@lasersurveys.com or on telephone 01708 438408.