Prefabricated power support structure foundations are made in prefabrication plants where concrete is laid in layers in moulds. The quality of the prefabricated units depends mainly on proper concrete mixture compaction, which is usually effected by means of immersion vibrators. It happens that when the vibrator is withdrawn too quickly, defects, in the form of, e.g., air voids and zones of insufficiently vibrated concrete, appear. Modern non-destructive acoustic techniques, which in recent years have been increasingly commonly used in the construction industry, are highly suitable for testing concrete elements, particularly prefabricated concrete units. The non-destructive impact-echo technique is particularly useful for determining defect location depth and for locating defective areas.
Hydro-acoustic Techniques in Hydraulics Engineering
