Ultrasonic Pulse Velocity (UPV) testing is a non-destructive method widely employed to assess the quality of concrete directly on-site. This evaluation revolves around measuring the speed of electronic pulses traveling through concrete, from a transmitting transducer to a receiver transducer.
The UPV test operates on the principle that the speed of sound in a solid material correlates with the square root of the ratio of its elasticity to density. Density reflects material quality, while elasticity relates to strength.
The equipment for UPV testing includes a transmitter and receiver applied to two faces of concrete. The transmitter emits ultrasonic pulses through the concrete, received by the opposite face’s receiver. The travel time of these pulses is recorded, and the average velocity of wave propagation is determined.
| Pulse Velocity (Km/s) | Quality of Concrete |
|---|---|
| Below 3.0 | Doubtful |
| 3.0 to 3.5 | Medium |
| 3.5 to 4.5 | Good |
| Above 4.5 | Excellent |
The measurement of electronic pulse velocity can be conducted in three ways:
Direct Transmission – Opposite Faces
Semi–Direct Transmission – Adjacent Faces
Indirect Transmission – Same Face
1. Smoothness of Contact Surface : Surface should be even; use coupling medium like jelly or oil.
2. Length of Path : Longer path provides more accurate results with fewer errors.
3. Moisture Content of Concrete : Pulse velocity increases with higher moisture content.
4. Temperature of Concrete : Optimal range for accurate readings: 5°C to 30°C. Pulse velocity increases below 5°C; decreases above 30°C.
5. Presence of Steel Reinforcement : Pulse velocity in RCC is 1.2 to 2 times higher than PCC.
