This tests consists in establishing the propagation time of the wave’s impulses of high frequency vibrations (>20 Khz) in the concrete. The equipment employed in this kind of measurements is composed of two probes: one for the emission of the mechanical vibrations impulses and the other one for the reception of such vibrations. It includes also a device for the amplification and and the emitted sign treatment, while another electric device is designed for the measurement of the interval between emission and reception.
The propagation speed values of the ultrasound impulses, established in this way, depend on the elastic features and on the density of the concrete where they are propagated; they also provide good informations about the homogeneity of the examined conglomerate (if there are or not gaps, degraded areas, cavities, etc.).
The test is standardised by the rule UNI 9524 providing the execution of three typologies of test:
- Direct Transmission
- Indirect Transmission
- Semi-direct Transmission
- Establishing the consistency state of the concrete and identifying possible internal anomalies
- Establishing the theoretic length of lesions in the concrete
- Establishing a dynamic elastic module in the concrete
- Non-invasive technique
- Establishing test values immediately and performing rapidity