ABSTRACT
There are a variety of methods and techniques available for the non-destructive testing of structural concrete, which can be broadly divided into those that assess the concrete itself, and those which are concerned with locating and determining the condition of the steel embedded in it. An estimation of the strength of concrete is often required, and therefore the degree of correlation of the non-destructive test measurement(s) with strength is important, and will be discussed in each case. It will be apparent that a single non-destructive test rarely gives a single definitive answer, and engineering judgement is required in interpreting the results. Less energy is absorbed by a harder surface, and so the rebound number is higher. A smooth concrete surface is required, but even then there is considerable local variation due to the presence of coarse aggregate particles or a void just below the surface, and therefore a number of readings must be taken and averaged.
