Sieve-by-sieve grading limits for natural sand (4 zones) and coarse aggregate (10, 20, 40 mm nominal sizes) per IS 383:2016. Coarser sand = lower zone number. Use Zone II for general concrete; Zone III/IV need higher cement content. For pumped concrete, prefer well-graded mixes with FM 2.6–3.0.
Fine Aggregate — Sand Zone Limits (% passing)
Choose zone such that >95% of samples fall within range
| Sieve | Zone I | Zone II | Zone III | Zone IV | Note |
|---|
| 10 mm | 100 | 100 | 100 | 100 | All zones must pass 100% |
| 4.75 mm | 90–100 | 90–100 | 90–100 | 95–100 | Coarse particles |
| 2.36 mm | 60–95 | 75–100 | 85–100 | 95–100 | Medium coarse |
| 1.18 mm | 30–70 | 55–90 | 75–100 | 90–100 | Medium fine |
| 600 µ | 15–34 | 35–59 | 60–79 | 80–100 | Fine — most discriminating sieve |
| 300 µ | 5–20 | 8–30 | 12–40 | 15–50 | Very fine |
| 150 µ | 0–10 | 0–10 | 0–10 | 0–15 | Dust limit |
Sand Zone — Quick Use Guide
| Sieve | Zone I | Zone II | Zone III | Zone IV | Note |
|---|
| Zone I (coarsest) | — | — | — | — | FM 2.7–3.5; high cement, harsh mix; reduce sand by 10% |
| Zone II (most common) | — | — | — | — | FM 2.4–3.1; default for general RCC; M20 to M40 |
| Zone III | — | — | — | — | FM 2.0–2.7; finer; increase sand by 10%, more water demand |
| Zone IV (finest) | — | — | — | — | FM 1.5–2.4; not for RCC unless blended; plaster work only |
Coarse Aggregate — Single Size (% passing)
| Sieve | Zone I | Zone II | Zone III | Zone IV | Note |
|---|
| 80 mm | — | — | 100 | — | 40 mm aggregate |
| 63 mm | — | — | 85–100 | — | 40 mm aggregate |
| 40 mm | — | 100 | 0–30 | — | 20 mm/40 mm aggregate |
| 20 mm | 100 | 85–100 | 0–5 | — | 10 mm/20 mm/40 mm |
| 16 mm | 85–100 | — | — | — | 10 mm aggregate |
| 12.5 mm | — | — | — | — | — |
| 10 mm | 0–20 | 0–20 | — | — | 10/20 mm |
| 4.75 mm | 0–5 | 0–5 | 0–5 | — | All sizes |
Aggregate Properties — Permissible Limits (IS 383)
| Sieve | Zone I | Zone II | Zone III | Zone IV | Note |
|---|
| Specific gravity (typical) | 2.60–2.80 | — | — | — | Higher for granite/basalt |
| Bulk density (loose) | 1450–1650 kg/m³ | — | — | — | DLBD test |
| Water absorption | ≤ 2.0% | — | — | — | 24-hr soak (≤0.5% preferred) |
| Aggregate Crushing Value | ≤ 30% (general) | ≤ 45% (light duty) | — | — | IS 2386 Part IV |
| Aggregate Impact Value | ≤ 30% | ≤ 45% | — | — | Wear resistance |
| Los Angeles Abrasion | ≤ 30% (wearing) | ≤ 50% (others) | — | — | Roads, runways |
| Flakiness Index | ≤ 35% | — | — | — | Particle shape |
| Elongation Index | ≤ 35% | — | — | — | Particle shape |
| Silt content (sand) | ≤ 3% (natural) | ≤ 15% (M-sand) | — | — | Wash test |
| Material < 75 µ (coarse) | ≤ 1% | — | — | — | Crushed: ≤ 3% |
Notes
• Fineness Modulus (FM) = Σ (cumulative % retained) / 100 — for sand, FM 2.6–2.9 is ideal for RCC
• Maximum nominal aggregate size ≤ ¼ × least dimension of member, ≤ ¾ × min cover, ≤ min spacing of bars
• 20 mm is the default for slabs and beams; 12.5 mm for thin members and congested reinforcement
• Manufactured sand (M-sand) per IS 383:2016 Cl 6.4 — silt limit relaxed to 15% (vs 3% for natural)
• Always do a wash test (IS 2386 Pt 2) on incoming sand — high silt → low strength + crack
• Reject aggregate with organic impurities darker than IS 2386 reference colour
• Bulk and absorbed water must be accounted for when batching by weight
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