Coarse Aggregate: Details & Tables
Complete Stone Guide 2026 — IS 383 Grading Tables for All Nominal Sizes, Physical & Mechanical Property Tables, Rock Type Comparison, Quality Limit Charts, Recycled Aggregate Guide & Aggregate Selection for All Concrete Grades per IS 383:2016, IS 2386, ASTM C33 & EN 12620
IS 383:2016ASTM C33
EN 12620:2022LA Abrasion
Flakiness & ElongationGrading Tables
RCA & Lightweight
🪨 Coarse Aggregate — 2026 Complete Overview
IS 383:2016 (Reaffirmed 2023)
IS 2386 (Parts 1–7)
ASTM C33/C33M-22
EN 12620:2013+A1:2022
IS 456:2000 Cl. 5.3
IS 10262:2019
Coarse aggregate is any aggregate retained on a 4.75mm IS sieve, typically comprising 40–55% of concrete volume and 60–70% of concrete mass. It is the dominant solid phase of concrete and directly influences compressive strength, elastic modulus, density, workability, cement demand, durability, and economy. Selection of the correct coarse aggregate type, nominal size, and grading zone is one of the most important — and most frequently under-specified — decisions in concrete mix design.
This 2026 complete guide covers every aspect of coarse aggregate: IS 383:2016 grading tables for all nominal sizes (10mm to 63mm), physical and mechanical property data for all major rock types, quality limit charts with traffic-light acceptance criteria, maximum size selection rules per IS 456, recycled and lightweight aggregate guidance, and a structured selection guide for all concrete grades from M15 to UHPC M100+.
40–55%of concrete volumeCoarse aggregate — largest single component
4.75mmIS sieveMinimum particle size — IS 383 definition
2.63–2.70Sg (SSD)Crushed granite — most common Indian CA
≤30%LA AbrasionRequirement for M40+ concrete
≤35%Flakiness + ElongationIS 383:2016 combined index limit
3/4 × barspacingIS 456 Cl. 5.3.1 maximum MSA limit
IS 383:2016 (Reaffirmed 2023) — Key 2026 Updates
IS 383:2016 was formally reaffirmed in 2023 with supplementary guidance on recycled coarse aggregate (RCA) in Annexure B, updated mechanical test requirements, and clarification of the 10% fines value test. The aggregate grading tables (Tables 1–3) remain unchanged from the 2016 edition. The reaffirmation confirmed IS 383 as the current and applicable Indian standard for all aggregate specification — no new IS aggregate standard is expected before 2027. EN 12620:2013+A1:2022 introduced revised RCA category classifications; ASTM C33/C33M-22 updated manufactured sand fines limits but coarse aggregate tables remain unchanged.
📊 IS 383:2016 Single-Sized Coarse Aggregate Grading Tables — Complete % Passing
IS 383:2016 Table 1 specifies grading requirements for six standard single-size coarse aggregates. Single-sized aggregates require blending or combination with graded aggregate for structural concrete — they are rarely used alone except in specialist applications. Grading verified by sieve analysis per IS 2386 Part 1.
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| IS Sieve Size | 63mm Single-Size | 40mm Single-Size | 20mm Single-Size | 16mm Single-Size | 12.5mm Single-Size | 10mm Single-Size |
|---|---|---|---|---|---|---|
| 80mm | 100 | — | — | — | — | — |
| 63mm | 85–100 | 100 | — | — | — | — |
| 40mm | 0–30 | 85–100 | 100 | — | — | — |
| 20mm | 0–5 | 0–20 | 85–100 | 100 | 100 | — |
| 16mm | — | — | — | 85–100 | — | 100 |
| 12.5mm | — | — | 0–30 | — | 85–100 | — |
| 10mm | — | 0–5 | 0–10 | 0–30 | 0–45 | 85–100 |
| 4.75mm | — | — | 0–5 | 0–5 | 0–10 | 0–20 |
| 2.36mm | — | — | — | — | — | 0–5 |
| Nominal Size (mm) | 63 | 40 | 20 | 16 | 12.5 | 10 |
IS 383:2016 Graded Coarse Aggregate — Table 2 (% Passing)
Graded coarse aggregates are the preferred form for structural concrete — they have a continuous particle size distribution that minimises voids, reduces paste demand, and improves packing efficiency. IS 383:2016 Table 2 specifies three standard graded sizes.
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| IS Sieve Size | 40–4.75mm Graded Large Pour | 20–4.75mm Graded Most Common | 12.5–4.75mm Graded Congested RCC | Typical Bulk Density |
|---|---|---|---|---|
| 63mm | 100 | — | — |
40–4.75mm: 1520–1700 kg/m³
20–4.75mm: 1550–1750 kg/m³ 12.5–4.75mm: 1500–1700 kg/m³ |
| 40mm | 95–100 | 100 | — | |
| 20mm | 30–70 | 95–100 | 100 | |
| 16mm | — | — | 90–100 | |
| 12.5mm | — | — | — | |
| 10mm | 10–35 | 25–55 | 40–85 | |
| 4.75mm | 0–5 | 0–10 | 0–10 | |
| Best For: | Raft foundations, dam concrete, large unreinforced sections | General structural RCC — slabs, beams, columns, walls | Thin sections, congested reinforcement, precast thin panels |
Visual Grading Comparison — 20–4.75mm (Most Used Size)
Percentage passing each sieve — IS 383:2016 Table 2 (20–4.75mm graded)
40mm100%100%
20mm95–100%97.5%
10mm25–55%25–55%
4.75mm0–10%0–10%
2.36mm0–5%0–5%
ASTM C33 Coarse Aggregate Size Number Grading — Key Sizes
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| ASTM Size No. | Nominal Size | % Pass 50mm | % Pass 37.5mm | % Pass 25mm | % Pass 19mm | % Pass 12.5mm | % Pass 9.5mm | % Pass 4.75mm | Approx. IS Equivalent |
|---|---|---|---|---|---|---|---|---|---|
| No. 3 | 37.5–19mm | — | 100 | 90–100 | 20–55 | 0–15 | — | 0–5 | ≈40–20mm blend |
| No. 4 | 25–12.5mm | — | — | 100 | 90–100 | 20–55 | 0–10 | 0–5 | ≈20mm graded |
| No. 57 | 25–4.75mm | — | — | 100 | 95–100 | 25–60 | — | 0–10 | ≈20–4.75mm graded |
| No. 67 | 19–4.75mm | — | — | — | 100 | 90–100 | 20–55 | 0–10 | ≈16–4.75mm |
| No. 7 | 12.5–4.75mm | — | — | — | — | 100 | 90–100 | 40–70 | ≈12.5–4.75mm graded |
| No. 8 | 9.5–2.36mm | — | — | — | — | — | 100 | 85–100 | ≈10mm single-size |
🔬 Coarse Aggregate Physical & Mechanical Properties — 2026 Complete Reference Table
Physical property data is required for absolute volume mix design calculations (specific gravity), water demand estimation (absorption), and quality assessment (strength, toughness, shape indices). All tests per IS 2386 Parts 1–7 or ASTM C127/C131/C88. Test your specific quarry materials — values below are typical ranges.
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| Rock / Aggregate Type | Sp. Gravity (SSD) | Bulk Density Loose (kg/m³) | Bulk Density Rodded (kg/m³) | Water Absorption (%) | LA Abrasion (%) | Aggregate Impact Value (AIV, %) | Aggregate Crushing Value (ACV, %) | Flakiness Index (%) | 10% Fines Value (kN) |
|---|---|---|---|---|---|---|---|---|---|
| Crushed Granite (Pink/Grey) MOST COMMON INDIA | 2.63–2.70 | 1500–1700 | 1650–1900 | 0.2–1.5% | 20–28% HARD | 12–20% | 18–28% | 20–35% | 250–350 kN |
| Basalt / Trap Rock | 2.70–3.00 DENSE | 1550–1850 | 1700–2000 | 0.5–2.0% | 15–22% HARDEST | 10–18% | 16–25% | 22–38% | 280–380 kN |
| Limestone (Crushed) | 2.55–2.70 | 1400–1650 | 1550–1800 | 0.5–3.0% | 22–35% | 18–28% | 20–32% | 18–32% | 180–280 kN |
| Quartzite | 2.60–2.68 | 1500–1700 | 1650–1850 | 0.3–1.2% | 18–26% | 14–22% | 18–26% | 15–28% | 240–340 kN |
| Gabbro / Dolerite | 2.90–3.10 | 1600–1900 | 1750–2050 | 0.3–1.5% | 12–20% | 10–15% | 15–22% | 18–32% | 300–400 kN |
| Sandstone (Crushed) | 2.20–2.65 | 1250–1600 | 1400–1750 | 1.0–5.0% | 30–55% WEAK | 25–40% | 28–45% | 20–40% | 100–200 kN |
| River Gravel (Rounded) | 2.60–2.68 | 1600–1800 | 1750–1950 | 0.3–1.2% LOW | 25–35% | 20–28% | 22–30% | N/A (rounded — no flakiness) | 200–300 kN |
| Recycled Concrete Aggregate (RCA) 2026 | 2.20–2.50 LOWER | 1150–1400 | 1300–1550 | 3.0–8.5% HIGH | 25–45% | 22–40% | 24–42% | Variable | 130–250 kN |
| Recycled Brick / Masonry (RMA) 2026 | 1.80–2.20 | 900–1200 | 1050–1350 | 6.0–20.0% VERY HIGH | 45–65% SOFT | 35–55% | 35–55% | Variable | 60–150 kN |
| Sintered Fly Ash (LYTAG) Lightweight | 1.50–1.80 | 700–950 | 800–1050 | 5.0–25.0% | 30–55% | 25–45% | 28–50% | N/A | 80–150 kN |
| Expanded Clay (LECA) Lightweight | 0.80–1.20 LIGHTEST | 300–600 | 350–700 | 8.0–30.0% | 40–65% | 35–60% | N/A | N/A | 50–100 kN |
Understanding LA Abrasion, AIV, ACV, and 10% Fines Value — What They Measure
LA Abrasion (IS 2386 Pt.4 / ASTM C131): Measures resistance to abrasion and impact. Lower % = harder aggregate. ≤30% required for M40+; ≤50% for general concrete; ≤40% for pavement surfaces.
AIV (Aggregate Impact Value, IS 2386 Pt.4): Impact toughness — lower % = tougher. ≤30% for structural concrete; ≤45% for general use. Correlates with AIV ≈ ACV for most rocks.
ACV (Aggregate Crushing Value, IS 2386 Pt.4): Resistance to crushing under load. ≤30% for M40+; ≤45% for general. Lower ACV = stronger aggregate = higher concrete strength potential.
10% Fines Value (IS 2386 Pt.4): Load (kN) required to produce 10% fines — higher is better. >150 kN for structural concrete; >100 kN minimum. Preferred over ACV for weaker aggregates.
🪨 Coarse Aggregate Rock Types — In-Depth Property Guide 2026
Detailed profiles for each major coarse aggregate rock type used in Indian and international construction, with specific property ranges, mix design implications, and 2026 availability notes.
🪨 Crushed Granite — Standard Structural CA
IS 383:2016IS 456 M40+Most Common India
The dominant coarse aggregate across India — produced from pink, grey, or black granite quarries in Karnataka, Tamil Nadu, Telangana, Rajasthan, and Andhra Pradesh. Angular particle shape provides excellent mechanical bond with cement paste (better than rounded gravel) but requires 20–25 L/m³ more water per IS 10262 Table 2.
Sg: 2.63–2.70 | Absorption: 0.2–1.5%
LA Abrasion: 20–28% | ACV: 18–28%
Flakiness: 20–35% (improve by VSI re-crushing)
Max concrete grade: M100+ (suitable for all grades)
ASR reactivity: Generally non-reactive (test new sources)
2026 availability: Abundant — primary Indian quarry product
⚫ Basalt / Trap Rock — Premium HSC Aggregate
M50–M100+Deccan TrapHigh Density
Available throughout the Deccan Plateau region (Maharashtra, Karnataka, Madhya Pradesh). Densest commonly available aggregate — provides higher concrete density and superior aggregate-paste bond for high-strength concrete. Excellent choice for M50+ where aggregate strength governs concrete strength.
Sg: 2.70–3.00 | Absorption: 0.5–2.0%
LA Abrasion: 15–22% (hardest common aggregate)
ACV: 16–25%
Max concrete grade: M120+ (UHPC capable)
Flakiness: Can be high (22–38%) — use VSI crushing
2026 availability: Good in western and central India
🟤 Limestone — Economical M15–M40 Aggregate
M15–M40RajasthanEconomy
Widely available in Rajasthan, Gujarat, Madhya Pradesh, and Andhra Pradesh. Softer than granite or basalt — LA abrasion 22–35% limits use to M40 maximum. Higher absorption than granite (0.5–3.0%) requires moisture correction. Often used as aggregate for road base, lean concrete, and M15–M30 structural concrete.
Sg: 2.55–2.70 | Absorption: 0.5–3.0%
LA Abrasion: 22–35%
Max structural grade: M40 (verify ACV <30%)
ASR reactivity: Usually non-reactive (no silica)
Bond with paste: Good — calcium carbonate surface
2026 cost: 15–25% cheaper than granite in proximity
🔵 River Gravel — Low Water Demand, Good Workability
Low Water DemandRounded ShapeAlluvial Rivers
Rounded particle shape reduces water demand by 20–25 L/m³ vs. crushed aggregate — a significant advantage for economy mixes. However, smooth surface reduces aggregate-paste bond, limiting practical maximum grade to M50 for critical structural elements. Requires alkali-silica reactivity testing — river gravels may contain reactive chert or opal.
Sg: 2.60–2.68 | Absorption: 0.3–1.2%
LA Abrasion: 25–35% | Shape: Rounded — no flakiness
Water saving vs crushed: 20–25 L/m³
Max practical grade: M50 (bond governs)
ASR risk: MUST TEST — chert/opal possible
Availability: Decreasing — river gravel extraction regulated
♻️ Recycled Concrete Aggregate (RCA) 2026
SustainableIS 383 Annex B30% max structural
Produced from crushed demolition concrete. Specific gravity lower than virgin aggregate (2.20–2.50) and absorption much higher (3–8.5%) due to old mortar adhering to original aggregate particles. Mandatory pre-wetting 24 hours before batching. Maximum 30% replacement of virgin CA for M25–M40 structural concrete per IS 383 Annex B and fib Model Code 2020.
Sg: 2.20–2.50 | Absorption: 3.0–8.5%
Pre-wetting: 24 hr mandatory before batching
Max replacement: 30% CA (M25–M40); 20% (M45+)
Strength impact: −5 to −10% at 30% replacement
Verify: Chloride, sulfate, and asphalt content of source
2026 cost: 40–65% cheaper than virgin granite CA
🟠 Lightweight Aggregate — LECA / Sintered Fly Ash
LWCASTM C330IS 9142
Expanded clay (LECA) and sintered fly ash (LYTAG) aggregates produce lightweight structural concrete (1200–1900 kg/m³) with improved thermal insulation and fire resistance. Very high absorption (5–25%) — mandatory pre-saturation 24+ hours before batching. Structural LWC achievable up to M40 with good mix design and adequate curing.
LECA Sg: 0.80–1.20 | LYTAG Sg: 1.50–1.80
Absorption: 5–25% (pre-saturate!)
Concrete density: 1200–1900 kg/m³
Max structural grade: M35–M40 (with good QC)
Standard: IS 9142 / ASTM C330 / EN 13055
Benefits: Thermal insulation; fire resistance; seismic mass reduction
🚦 Coarse Aggregate Quality Limits — IS 383:2016 Acceptance & Rejection Chart
All quality limits per IS 383:2016 and IS 2386 Parts 1–7. Traffic-light system: Green = Accept, Amber = Investigate, Red = Reject. For all concrete M25 and above — reject any aggregate that fails a red limit before approving for structural use.
LA Abrasion (M40+)✅ ≤ 30% — Accept⚠ 30–35% — Marginal; use for M30 max❌ > 50% — REJECT structural use
LA Abrasion (General)✅ ≤ 40% — Accept⚠ 40–50% — M20 max only❌ > 50% — REJECT
AIV (Aggregate Impact Value)✅ ≤ 30% (structural)⚠ 30–45% — Non-structural only❌ > 45% — REJECT all concrete
ACV (Aggregate Crushing)✅ ≤ 30% (M40+)⚠ 30–40% — M25 max; not HSC❌ > 45% — REJECT structural
Flakiness Index (IS 2386 Pt.1)✅ ≤ 25% (preferred)⚠ 25–35% — Increase water demand; adjust SP❌ > 35% — REJECT; return to re-crush VSI
Elongation Index✅ ≤ 25% (preferred)⚠ 25–35% — Monitor workability impact❌ > 35% — REJECT or blend with better-shaped material
Combined Flakiness + Elongation✅ Combined ≤ 35% (IS 383:2016)⚠ 35–45% combined — Significant water demand issue❌ > 45% combined — REJECT
Water Absorption (CA)✅ ≤ 2.0% (good)⚠ 2.0–3.5% — Apply moisture correction carefully❌ > 5% (non-RCA) — Investigate; likely porous/weathered rock
Soundness (MgSO₄, 5 cycles)✅ ≤ 12% loss (IS 383)⚠ 12–18% — Freeze-thaw exposure not suitable❌ > 18% — REJECT for any exposure concrete
Organic Impurities✅ Pass colorimetric test (IS 2386 Pt.2)⚠ Borderline — run mortar bar strength verification❌ Fail colorimetric — REJECT; organic matter retards and weakens
Chloride Content (CA)✅ Cl⁻ ≤ 0.03% by mass⚠ 0.02–0.03% — Verify total concrete Cl⁻ still ≤ 0.30 kg/m³❌ > 0.03% — Sea-dredged or contaminated; REJECT for RCC
ASR Reactivity (ASTM C1260)✅ ≤ 0.10% expansion at 16 days⚠ 0.10–0.20% — Potentially reactive; SCM mitigation mandatory❌ > 0.20% — Deleteriously reactive; REJECT without proven Li or SCM mitigation
Specific Gravity deviation from quarry cert✅ Within ±0.05 of certified value⚠ 0.05–0.10 deviation — Review mix design Sg assumptions❌ > 0.10 deviation — Different rock type supplied; REJECT and re-certify source
🚨 Alkali-Silica Reactivity (ASR) — The Silent Long-Term Failure
ASR is a chemical reaction between reactive silica in aggregate and alkali hydroxides from cement pore solution, producing an expansive silica gel that cracks concrete from within — typically appearing 5–15 years after construction. ASR testing (ASTM C1260 mortar bar method — 16-day accelerated test, or ASTM C1293 concrete prism method — 12-month test) is mandatory for every new aggregate source approval. ASR-reactive aggregates can still be used with proven mitigation: ≥25% Class F fly ash, ≥40% GGBS, or lithium nitrate solution. Never assume a new quarry source is non-reactive without testing — the geology of adjacent quarry faces can differ significantly.
📐 Nominal Maximum Aggregate Size (MSA) Selection — IS 456 Rules & 2026 Guide
IS 456:2000 Clause 5.3.1 sets three simultaneous criteria for maximum aggregate size selection. All three must be satisfied — the smallest (most restrictive) governs. Using oversized aggregate causes bridging around reinforcement, honeycombing, and inadequate cover — all serious durability failures.
IS 456:2000 Cl. 5.3.1 — THREE CRITERIA (ALL MUST BE SATISFIED):
MSA ≤ (a) 1/4 of minimum member thickness
MSA ≤ (b) Nominal cover to reinforcement (mm)
MSA ≤ (c) 3/4 of minimum clear distance between bars (mm)
Design MSA = minimum of (a), (b), and (c)
WORKED EXAMPLES:
Example 1 — 200mm RCC slab, 25mm cover, 12mm bars at 150mm c/c:
(a) 200/4 = 50mm
(b) 25mm cover
(c) (150−12) × 3/4 = 138 × 0.75 = 103.5mm
Governing MSA = 25mm → Use 20mm nominal size ✅
Example 2 — 600mm column, 50mm cover, 32mm bars at 80mm c/c:
(a) 600/4 = 150mm
(b) 50mm cover
(c) (80−32) × 3/4 = 48 × 0.75 = 36mm
Governing MSA = 36mm → Use 20mm nominal size ✅ (most conservative)
Example 3 — 1500mm raft slab, 75mm cover, 20mm bars at 150mm c/c:
(a) 1500/4 = 375mm
(b) 75mm cover
(c) (150−20) × 3/4 = 130 × 0.75 = 97.5mm
Governing MSA = 75mm → Use 40mm nominal size ✅
MSA Selection Quick Reference Table — Typical Applications 2026
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| Structure / Element Type | Typical Min Thickness (mm) | Typical Cover (mm) | Typical Bar Spacing (clear, mm) | Calculated Max MSA (mm) | Standard Nominal Size Used | Notes |
|---|---|---|---|---|---|---|
| Blinding / PCC (no reinforcement) | 75–150 | N/A | N/A | 37–75mm (size only) | 40mm | No bar spacing constraint — section size governs |
| Raft foundation / mass concrete | 600–2000 | 75mm | 80–150mm (clear) | 60–112mm | 40mm | Large MSA reduces cement demand and heat of hydration |
| Ground beams / deep beams | 450–1000 | 50mm | 40–100mm (clear) | 30–75mm | 20mm | Bar links reduce effective clear spacing — check stirrup cover |
| RCC columns — light reinforcement | 300–600 | 40mm | 60–120mm (clear) | 40–90mm | 20mm | Outer ring and stirrups reduce effective clear gap |
| RCC columns — heavy seismic reinforcement | 400–600 | 40mm | 20–50mm (clear) | 15–37mm | 12.5mm or 16mm | Congested reinforcement — critical to calculate actual clear spacing |
| Standard RCC slabs (residential) | 125–200 | 20–30mm | 80–150mm (clear) | 20–30mm | 20mm | Cover typically governs — 20mm cover → 20mm max MSA |
| Bridge deck slab | 200–350 | 50mm | 60–100mm (clear) | 45–75mm | 20mm | Durability-specified cover (50mm) typically governs |
| Retaining walls | 200–600 | 40mm | 80–150mm (clear) | 40mm | 20mm or 25mm | 40mm cover governs most cases; 20mm nominal standard choice |
| Precast thin panels / cladding | 60–120 | 20mm | 50–100mm (clear) | 15–20mm | 10mm or 12.5mm | Thin section governs — 60/4 = 15mm max; 10mm or 12.5mm required |
| UHPC (M100+) | Any | N/A (no coarse agg) | N/A | N/A | 0–2mm fine sand only | No coarse aggregate in UHPC — replaced by very fine sand and silica fume |
2026 Practical Tip — When 10mm or 12.5mm Aggregate Is Required
Highly congested reinforcement (seismic columns, transfer beams, precast prestressed beams) frequently requires 10mm or 12.5mm nominal aggregate. This has two important consequences: (1) Higher water demand — IS 10262 Table 2 shows 10mm MSA requires 222 L/m³ vs. 196 L/m³ for 20mm at the same slump — a 26 L/m³ increase that requires 58 kg/m³ more cement at w/c 0.45 to maintain strength. (2) Higher cost — 10mm and 12.5mm aggregate from some quarries costs 10–15% more than 20mm due to additional crushing stages. Always verify MSA early in the design process so mix design, cost, and structural detailing are coordinated. Never specify 20mm and then change to 10mm during construction without re-evaluating the mix design.
💧 Coarse Aggregate Effect on Water Demand — IS 10262:2019 Table 2 Adjustment Factors
The coarse aggregate type and nominal maximum size are the two largest variables affecting water content from IS 10262:2019 Table 2. Understanding these adjustments allows engineers to optimise mix designs and predict water demand for different quarry sources.
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| Aggregate Type / Size | Water at 75mm Slump (L/m³) | Water at 100mm Slump (L/m³) | Water at 125mm Slump (L/m³) | Adjustment vs 20mm Crushed at 100mm | Cement Content Impact (w/c 0.45) |
|---|---|---|---|---|---|
| Crushed Granite — 10mm MSA | 222 | 228 | 234 | +26 L/m³ | +58 kg/m³ cement |
| Crushed Granite — 12.5mm MSA | 213 | 219 | 225 | +17 L/m³ | +38 kg/m³ cement |
| Crushed Granite — 16mm MSA | 205 | 211 | 217 | +9 L/m³ | +20 kg/m³ cement |
| Crushed Granite — 20mm MSA REFERENCE | 196 | 202 | 208 | Reference (0) | Reference |
| Crushed Granite — 25mm MSA | 188 | 193 | 199 | −9 L/m³ | −20 kg/m³ cement |
| Crushed Granite — 40mm MSA | 172 | 176 | 181 | −26 L/m³ | −58 kg/m³ cement |
| River Gravel — 20mm MSA (rounded −25L) | 171 | 177 | 183 | −25 L/m³ | −56 kg/m³ cement |
| Basalt — 20mm MSA (similar to granite) | 196 | 202 | 208 | ≈ Same as granite | Reference (same) |
| Limestone — 20mm MSA | 198 | 204 | 210 | +2 L/m³ (slightly more) | +4 kg/m³ cement |
| Recycled CA (RCA) — 20mm (pre-wetted) | 196* | 202* | 208* | Same design water IF pre-wetted | +5–8% cement increase for strength loss compensation |
* RCA: design water same as virgin if 24-hr pre-wetted; additional water for RCA absorption is pre-wetting water, not mix water — do not add to batch water calculation.
The 40mm vs 20mm Water Saving — Practical Significance
Using 40mm MSA instead of 20mm for mass concrete (permitted by IS 456 where structural detailing allows) saves 26 L/m³ of water. At w/c 0.45, this saves 58 kg/m³ of cement — worth approximately ₹348/m³ at 2026 cement prices of ₹6/kg. For a 5,000 m³ raft foundation, this is a saving of ₹17.4 lakhs in cement alone. The larger aggregate also reduces heat of hydration (important for mass concrete crack control). Always check IS 456 Cl. 5.3.1 MSA limits before specifying 40mm — but where permitted, 40mm aggregate is a powerful cost and durability tool for large pours.
🎯 Coarse Aggregate Selection Guide — By Concrete Grade & Application 2026
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| Concrete Grade / Application | Recommended CA Type | Nominal Size (MSA) | Min Quality Requirements | Preferred Source (India 2026) | Special Considerations |
|---|---|---|---|---|---|
| M15 — Blinding, PCC | Limestone, granite, or local quarry | 40mm | LA Abrasion ≤ 50%; basic quality | Nearest economical quarry | No structural strength demand; economy first |
| M20 — Residential RCC | Crushed granite or limestone | 20mm | LA ≤ 40%; ACV ≤ 40%; Abs ≤ 3% | Granite (South / West India); Limestone (North / Central) | Verify ASR for new aggregate sources; check flakiness <35% |
| M25 — General Structural | Crushed granite (preferred) or limestone | 20mm | LA ≤ 35%; ACV ≤ 30%; FI ≤ 30% | Granite — most consistent quality | IS 456 Moderate exposure min grade; granite preferred for durability |
| M30 — Bridges, Commercial | Crushed granite or basalt | 20mm | LA ≤ 30%; ACV ≤ 28%; Abs ≤ 1.5% | Granite or basalt (Deccan region) | Severe/Very Severe exposure — verify chloride limits; ASR test mandatory for new source |
| M40 — High-Rise, Marine | Crushed granite or basalt | 16–20mm | LA ≤ 28%; ACV ≤ 25%; FI ≤ 25% | Basalt (Deccan) or hard granite | Very severe exposure — tightest quality limits; reject limestone for M40+ marine |
| M50–M60 — HSC, Precast | Basalt or hard granite only | 12.5–16mm | LA ≤ 25%; ACV ≤ 22%; Abs ≤ 1.0% | Basalt or select granite (tested specific gravity >2.65) | Aggregate strength can govern — verify aggregate-limited concrete strength by trial |
| M80+ / UHPC | Hard basalt or quartzite (coarse); quartz sand (fine) only | 9.5–12.5mm (or none) | LA ≤ 20%; ACV ≤ 18%; Abs ≤ 0.5% | Basalt or quartzite — selected and tested individually | In UHPC (>M100), no coarse aggregate — only fine quartz sand; aggregate quality is critical limiting factor for HSC < M100 |
| SCC — Self-Compacting Concrete | Crushed granite — reduced CA content | 16–20mm | LA ≤ 30%; FI ≤ 25%; Abs ≤ 1.5% | Granite | SCC: reduce CA by 8–12% vs standard mix; MSA often 16mm for easier passing ability; low flakiness critical |
| Mass Concrete — Dam / Raft | Granite, basalt, or limestone (select) | 40–80mm | LA ≤ 40%; ACV ≤ 35%; low absorption | Quarry nearest to dam site — transport cost dominates | Largest MSA permitted to reduce cement demand and heat of hydration; 80mm possible for cyclopean concrete |
| Lightweight Structural Concrete | LECA or sintered fly ash (LYTAG) | 10–16mm | ASTM C330 / IS 9142; pre-saturation essential | LECA (expanded clay) — Vizag or imported | Pre-saturate 24+ hr; AEA for freeze-thaw; strength limited to M35–M40 |
| Sustainable / RCA Mix | 30% RCA + 70% virgin granite | 20mm | RCA: Abs ≤ 8%; ACV ≤ 40%; test chloride/sulfate | Demolition waste processing plants near major cities | IS 383 Annex B; pre-wet RCA 24 hr; increase cement 5–8%; verify source concrete strength >20 MPa |
🔬 Aggregate Testing Reference — IS 2386 & ASTM Test Methods Guide 2026
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| Property Tested | IS Standard Test | ASTM Equivalent | Equipment | Frequency | Reporting Unit |
|---|---|---|---|---|---|
| Sieve Analysis (Grading) | IS 2386 Part 1 | ASTM C136 | IS sieves set, mechanical shaker, balance | Weekly; every delivery lot for new sources | % passing each sieve |
| Specific Gravity & Water Absorption | IS 2386 Part 3 | ASTM C127 | Wire basket, balance, water tank, SSD cloth | Source approval; every 1,000 tonnes or quarry face change | Sg (SSD), Sg (OD), Absorption % |
| Bulk Density (Loose & Rodded) | IS 2386 Part 3 | ASTM C29 | 15-litre cylinder, tamping rod, balance | Source approval; change of stockpile | kg/m³ (loose), kg/m³ (rodded) |
| Flakiness Index | IS 2386 Part 1 (slot sieves) | EN 933-3 (EN equivalent) | Flakiness gauge / slot gauge set | Source approval; monthly production check | % flaky particles |
| Elongation Index | IS 2386 Part 1 (length gauge) | EN 933-4 | Length gauge | Source approval; monthly | % elongated particles |
| LA Abrasion Value | IS 2386 Part 4 | ASTM C131 / C535 | Los Angeles abrasion machine, steel balls, rotary drum | Source approval; annually thereafter | % loss by mass |
| Aggregate Impact Value (AIV) | IS 2386 Part 4 | BS 812-112 (UK) | Impact testing machine, 14mm drop height, steel cylinder | Source approval; annually | % fines produced |
| Aggregate Crushing Value (ACV) | IS 2386 Part 4 | BS 812-110 | Compression testing machine, steel cylinder and plunger | Source approval; annually | % fines at 400kN load |
| 10% Fines Value (TFV) | IS 2386 Part 4 | BS 812-111 | Compression machine (calculate force for 10% fines) | Source approval | kN force |
| Soundness (Sulfate) | IS 2386 Part 5 | ASTM C88 | MgSO₄ solution, sieves, balance, drying oven | Source approval; new quarry or freeze-thaw exposure | % loss after 5 cycles |
| Organic Impurities | IS 2386 Part 2 | ASTM C40 | NaOH solution, glass bottles, standard colour | Source approval; visible change in aggregate colour | Pass/Fail vs. standard colour |
| Chloride Content | IS 2386 Part 2 | ASTM C1702 | Titration equipment, silver nitrate, potassium chromate | Source approval; marine/coastal aggregates — every lot | % Cl⁻ by mass |
| Sulfate Content (SO₃) | IS 2386 Part 2 | ASTM C1580 | Chemical titration / ICP analysis | Source approval; contaminated sites | % SO₃ by mass |
| Alkali-Silica Reactivity | IS 2386 Part 7 | ASTM C1260 (16-day); ASTM C1293 (12-month) | Mortar bar molds; NaOH solution bath; length comparator | Every new aggregate source approval — MANDATORY | % mortar bar expansion at 16 days |
| Surface Moisture (Site) | IS 2386 Part 3 / capacitance probe | ASTM C566 | Drying oven and balance; or calibrated capacitance probe | Every shift; after rain; before any pour | % surface moisture by mass |
📚 Coarse Aggregate Standards Reference 2026
Primary Standards for Coarse Aggregate Specification & Testing
IS 383:2016 (Reaffirmed 2023) — BIS: Specification for Coarse and Fine Aggregates from Natural Sources for Concrete. Tables 1 (single-sized), 2 (graded), and 3 (all-in aggregate) give grading envelopes. Annexure B covers recycled aggregates. Reaffirmed 2023 — no change to grading tables; RCA guidance supplementary.
IS 2386:Parts 1–7 — BIS: Methods of Test for Aggregates for Concrete. Part 1 (grading, flakiness, elongation), Part 2 (chemical tests — Cl, SO₃, organics), Part 3 (Sg, absorption, bulk density, moisture), Part 4 (mechanical — LA, AIV, ACV, 10% FV), Part 5 (soundness), Part 7 (ASR — chemical method).
ASTM C33/C33M-22 — ASTM International: Standard Specification for Concrete Aggregates. Coarse aggregate size numbers (No. 1–8 and 57, 67, 68), quality requirements, and deleterious substance limits. 2022 edition unchanged for coarse aggregate from 2018.
ASTM C127 — ASTM: Specific Gravity and Absorption of Coarse Aggregate — the fundamental physical property test required for all absolute volume mix designs.
ASTM C131 / C535 — ASTM: LA Abrasion (smaller / larger aggregate respectively) — toughness and wear resistance.
ASTM C1260 / C1293 — ASTM: Alkali-Silica Reactivity testing — 16-day accelerated mortar bar (C1260) and 12-month concrete prism (C1293) methods. Source approval mandatory.
EN 12620:2013+A1:2022 — CEN: Aggregates for Concrete. European classification — revised RCA (recycled aggregate) categories in A1:2022 amendment. Required for CE marking of aggregates in EU/UK markets.
IS 456:2000 Cl. 5.3.1 — BIS: Maximum aggregate size limitations — three-criteria rule governing MSA selection in all reinforced concrete. Mandatory compliance for all IS 456 structural concrete.
IS 9142:1979 — BIS: Specification for Artificial Lightweight Aggregates for Concrete Masonry Units — covers LECA and related lightweight aggregate requirements for Indian use.