Which non-destructive method measures the speed of ultrasonic waves through concrete?

• A. Rebound Hammer
• B. Ultrasonic Pulse Velocity
• C. Tap test
• D. Mass per volume

Answer: (B)

Measuring the speed of ultrasonic waves through concrete is done with Ultrasonic Pulse Velocity. This non-destructive test uses a transmitter and a receiver to send a short ultrasonic pulse through the concrete and records the time it takes to travel a known distance. The velocity is then calculated as distance divided by travel time. This speed reveals how uniform and crack-free the concrete is and helps gauge quality, potential defects, and relate to properties like strength or modulus of elasticity. The method can be used in different path configurations, such as direct through the member or through-transmission from one side to the opposite side.

Rebound Hammer, Tap test, and Mass per volume assess other properties: the rebound hammer estimates surface hardness and, loosely, strength; the tap test relies on listening for changes in sound to spot voids or honeycombing; and mass per volume (density) measures weight per unit volume, not ultrasonic wave speed.