Ultrasonic tests

Ultrasonic tests estimate the strength of hardened concrete elements through the determination of the propagation speed of ultrasonic waves. The speed, obtained by measuring the time of flight of ultrasonic mechanical pulses in the concrete between one or more pairs of survey points, is closely correlated with the elastic modulus of concrete, which is in turn correlated with the compression strength. The ultrasonic test can also propose information about the homogeneity of the concrete tested in different areas or elements. The equipment includes a pulse generator, a pair of transducers, an amplifier and an electronic timing device to measure the time interval between the start of the pulse generated by the transmitter and its arrival at the receiver. The speed measurements of the pulse can be performed by placing two transducers on opposite faces (direct transmission), or on adjacent faces (semi-direct transmission), or on the same face (indirect transmission) of a concrete structure. Test points are selected with a covermeter that identifies any presence of rebar, to avoid carrying out the test in proximity to superficial reinforcement bars.

Reference standards: UNI EN 12504-4:2021.