As per IS 13311 (Part 1), in the ultrasonic test for hardened concrete, good quality of concrete is indicated if the pulse velocity is:
Try it first: pick an option, then read the explanation.
Correct answer: C. Between 3.5 km/s to 4.5 km/s
Detailed Explanation: IS 13311 Ultrasonic Pulse Velocity Test
Why C (3.5–4.5 km/s) is correct: IS 13311 Part 1 (Method of Non-Destructive Testing of Concrete — Ultrasonic Pulse Velocity) classifies concrete quality by the speed of ultrasonic pulses (P-waves) travelling through it. Denser, stronger, more uniform concrete transmits sound faster. Cracks, voids, and weak zones slow the pulse.The classification is: >4.5 km/s = Excellent; 3.5–4.5 km/s = Good; 3.0–3.5 km/s = Medium; <3.0 km/s = Doubtful quality.
IS 13311 Part 1 — UPV Quality Classification
| Pulse Velocity (km/s) | Concrete Quality |
|---|---|
| >4.5 | Excellent |
| 3.5–4.5 | Good |
| 3.0–3.5 | Medium / Questionable |
| <3.0 | Doubtful / Poor |
- Good quality concrete: UPV = 3.5–4.5 km/s per IS 13311 Part 1.
- UPV test is non-destructive — no cores needed; widely used for in-situ assessment of existing structures.