Ultrasonics or UPV

Ultrasonics

Like Dynamic Impedance, Ultrasonic Pulse Velocity measurements of a material are used to assess the mechanical properties such as strength, integrity and crack depth of materials.

Piezoelectric cells are used to pass pulses of acoustic energy into the material of the wall, and the response recorded in the time domain to analyse the form and mechanical properties of the materials. The velocity of the ultrasonic pulse is proportional to the density and elastic modulus of the material, but may be altered by passing round a crack.

The relationship between strength and velocity is not linear, and ranges between values that are comparable with loose aggregate, and dense hardened concrete. As a relative measure for intermediate concretes and weathered stone it is however invaluable.

The range is typically limited to c.300mm, and can only operate between attachment points, thus 'sounding' to the far face from one side only is rarely possible.

Used in parallel with the radar, which may locate the arrangement of an object, this technique allows the strength of stone and concrete to be evaluated at critical points within the overall arrangement.