ASTM
ASTM C597
Standard Test Method for Ultrasonic Pulse Velocity Through Concrete
The UPV method, which measures the transit time of a compression wave between two transducers to infer concrete quality. Velocity falls as cracking, honeycombing and deterioration increase, so the test is used comparatively — element against element, or an element against itself over time — rather than as an absolute strength measurement. Direct transmission with transducers on opposite faces gives the most reliable result; indirect and semi-direct arrangements are used where only one face is accessible, and read lower.
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