As per Indian Standard (IS 383 : 2016), the grading of fine aggregates is divided into how many zones?
Correct Answer: A. Four
📚 Detailed Explanation: Fine Aggregate Zones in IS 383:2016
IS 383:2016 is the updated revision of the 1970 standard for natural aggregates used in concrete. While the 2016 edition introduced several changes (additional aggregate types, revised limits for deleterious materials, inclusion of manufactured sand), the fundamental four-zone grading classification for fine aggregates was retained without change.
Why A (Four) is correct: The 2016 revision deliberately kept the four-zone system (Zone I — coarsest, to Zone IV — finest) because it was already well-established in Indian practice and aligned with mix design procedures in IS 10262. Changing the number of zones would have required wholesale revision of mix-design tables and site practices, so the four-zone framework was preserved.
IS 383:1970 vs. IS 383:2016 Key Differences
| Feature | IS 383:1970 | IS 383:2016 |
|---|---|---|
| Grading zones for FA | 4 (I to IV) | 4 (I to IV) — unchanged |
| Manufactured sand (M-sand) | Not covered | Included with specific limits |
| Deleterious material limits | Basic | Revised and expanded |
Key Concepts for Students
- Both IS 383:1970 and IS 383:2016 specify four grading zones for fine aggregate — the answer is the same whichever edition is cited.
- IS 383:2016 also introduced grading limits for manufactured sand (M-sand), widely used where natural river sand is scarce.
- When an exam question specifies IS 383:2016, the answer for the number of fine aggregate zones is still four.