Question

An Ultrasonic Pulse Velocity (UPV) test was done on a hardened concrete element using direct transmission method as per IS 516 (Part 5/Section 1): 2018. The distance between the transducer and receiver is 600 mm. The time taken for the induced wave to travel this distance is 0.18 milliseconds. Based on the following Table, the concrete quality grading is \(\underline{\hspace{2cm}}\).
\[\begin{array}{|c|c|} \hline \textbf{Velocity (km/s) – cross probing} & \textbf{Concrete quality grading} \\ \hline \text{Above 4.4} & \text{Excellent} \\ \hline \hline \text{3.75 – 4.4} & \text{Good} \\ \hline \hline \text{3.0 – 3.75} & \text{Doubtful} \\ \hline \hline \text{Less than 3.0} & \text{Poor} \\ \hline \end{array}\]

• A. Excellent
• B. Good
• C. Doubtful
• D. Poor

Hint:

UPV increases with better concrete quality—higher velocity indicates a denser, stronger concrete matrix.

Answer 1

The Correct Option is C

The distance between the transducer and receiver is 600 mm = 0.6 m.
The time taken for the wave to travel is 0.18 milliseconds = 0.00018 seconds.
Velocity is computed as:
\[ V = \frac{\text{Distance}}{\text{Time}} = \frac{0.6}{0.00018} = 3333 \text{ m/s} = 3.33 \text{ km/s} \] From the table, 3.0–3.75 km/s corresponds to Doubtful quality.