Acoustic waves spread through different media at different speeds. These waves are reflected at the boundary surfaces between two materials â€“ for example at the interface between concrete and air.
The ultrasonic measurement process is based on analysis of the reflected acoustic waves. Special sensors capture the oscillations which the reflected waves produce at the surface.
The ultrasonic process is used for thickness measurement of steel reinforced concrete elements. Structural examinations on steel and prestressed concrete are also possible using ultrasonic testing.