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.
Related 📐 IS 383 ✏️ Max Aggregate Size By Member 📘 Concrete cover 📖 Min cover for RCC 🔧 RCC design
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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