Select the correct option regarding the Ultrasonic Pulse Velocity (UPV) test: 1. Used to measure strength of wet concrete. 2. Used to estimate strength of finished concrete elements. 3. It is a non-destructive test.
Correct Answer: B. 2 and 3
📚 Detailed Explanation: UPV Test — Statements 2 and 3 Are Correct
Why B (2 and 3) is correct: The UPV (Ultrasonic Pulse Velocity) test is an established NDT (non-destructive testing) method governed by IS 13311 Part 1: 1992. It sends an ultrasonic pulse through hardened concrete and measures transit time to assess quality, detect cracks, and estimate compressive strength. Statement 1 is false because the test is not applicable to wet/fresh concrete.
Analysis of Each Statement
| Statement | Correct? | Explanation |
|---|---|---|
| 1. Measures strength of WET concrete | ✗ FALSE | UPV requires a solid, homogeneous medium. Fresh/wet concrete is a slurry; there is no defined solid matrix for the pulse to travel through. Only applicable to hardened concrete. |
| 2. Estimates strength of finished elements | ✓ TRUE | In-situ UPV measurements on hardened structures correlate with compressive strength via established curves. Widely used for assessing existing structures without sampling. |
| 3. Non-destructive test | ✓ TRUE | No drilling, coring, or sampling needed. Transducers placed on the surface; concrete is undamaged. Classified as NDT per IS 13311. |
UPV Quality Classification (IS 13311 Part 1: 1992)
| Pulse Velocity (km/s or m/s) | Concrete Quality |
|---|---|
| >4.5 km/s (>4500 m/s) | Excellent |
| 3.5–4.5 km/s | Good |
| 3.0–3.5 km/s | Medium / Questionable |
| <3.0 km/s (<3000 m/s) | Poor (investigate further) |
UPV Test Procedure
| Step | Detail |
|---|---|
| Equipment | UPV meter; transmitter and receiver transducers (54 kHz); couplant gel |
| Transmission modes | Direct (opposite faces); semi-direct (adjacent faces); indirect/surface (same face) |
| Measurement | Transit time T (µs); path length L (mm); UPV (m/s) = L/T × 1000 |
| Higher velocity means | Denser, more homogeneous, better-quality concrete |
- UPV test: non-destructive; used on hardened concrete only; NOT applicable to wet/fresh concrete.
- IS 13311 Part 1: 1992 governs; often combined with Rebound Hammer test for better accuracy.
- UPV > 4.5 km/s = Excellent; 3.5–4.5 = Good; 3.0–3.5 = Medium; <3.0 = Poor.