Select the correct option regarding the Ultrasonic Pulse Velocity (UPV) test: Statement 1: Used to measure strength of wet concrete. Statement 2: Used to estimate strength of finished concrete elements. Statement 3: It is a non-destructive test.
Correct Answer: B. Statements 2 and 3 are correct
📚 Detailed Explanation: UPV Test — Non-Destructive Test for Hardened Concrete
Why B (Statements 2 and 3) is correct: The Ultrasonic Pulse Velocity (UPV) test is a non-destructive testing (NDT) method (Statement 3 is true) used to assess the quality and estimate the compressive strength of hardened (finished) concrete elements (Statement 2 is true). Statement 1 is false because UPV cannot be used on wet/fresh concrete — the test requires a solid, hardened medium for the pulse to travel through.
Analysis of Each Statement
| Statement | Correct? | Explanation |
|---|---|---|
| 1. Used to measure strength of WET concrete | ✗ FALSE | UPV requires a solid medium; fresh/wet concrete is a slurry with no defined solid matrix; the test is only applicable to hardened concrete (>24 hours minimum, typically 28-day samples) |
| 2. Used to estimate strength of finished concrete elements | ✓ TRUE | UPV is used in-situ on hardened concrete structures to estimate compressive strength via correlation curves; IS 13311 Part 1 governs this |
| 3. It is a non-destructive test (NDT) | ✓ TRUE | UPV is classified as an NDT; no samples are removed, no damage is done to the structure; the transducers are simply placed on the concrete surface |
UPV Test Procedure
| Step | Action |
|---|---|
| 1. Equipment | UPV meter with transmitter and receiver transducers (54 kHz); couplant gel applied to transducer faces |
| 2. Placement | Transducers placed on opposite faces (direct transmission), adjacent faces (semi-direct), or same face (indirect/surface) |
| 3. Measurement | Pulse travel time (T) measured in microseconds; path length (L) measured |
| 4. Calculation | UPV (m/s) = L(mm) / T(µs) × 1000 |
| 5. Interpretation | Higher UPV = denser, higher-quality, higher-strength concrete |
UPV Quality Assessment (IS 13311 Part 1: 1992)
| Pulse Velocity (m/s) | Concrete Quality |
|---|---|
| >4500 | Excellent |
| 3500–4500 | Good |
| 3000–3500 | Medium / Questionable |
| 2000–3000 | Poor |
| <2000 | Very poor |
- UPV test: non-destructive (NDT); used on hardened concrete only; NOT applicable to wet/fresh concrete.
- IS 13311 Part 1: 1992 governs UPV test for assessment of concrete quality.
- UPV is often used alongside the Rebound Hammer test (IS 13311 Part 2) for more reliable in-situ strength estimation.