Aggregate Grading Chart 2026 | Sieve Analysis & Particle Size Distribution

Aggregate Grading Chart 2026

Sieve Analysis & Particle Size Distribution

BS 882 & BS EN 12620 Grading Requirements

Aggregate grading, also known as particle size distribution, is critical for producing high-quality concrete with optimal workability, strength, and durability. Our aggregate grading chart provides comprehensive information on sieve analysis, grading curves, and compliance with British Standards BS 882 and BS EN 12620 used in 2026.

Proper aggregate grading ensures optimal particle packing, reduces voids, minimizes cement paste requirements, and produces economical concrete mixes. Understanding grading zones, fineness modulus, and sieve analysis is essential for concrete mix design and quality control in construction projects.

🔬 Sieve Analysis Calculator

Calculate fineness modulus and grading zone

Enter Cumulative % Passing

10 mm Sieve (%)

4.75 mm Sieve (%)

2.36 mm Sieve (%)

1.18 mm Sieve (%)

600 μm Sieve (%)

300 μm Sieve (%)

150 μm Sieve (%)

Understanding Aggregate Grading 2026

Aggregate grading describes the distribution of particle sizes in sand, gravel, or crushed stone. The grading directly affects concrete workability, strength, durability, and economy. Proper grading follows British Standards to ensure consistent concrete quality.

🔬 Key Grading Concepts:

Sieve Analysis: Laboratory test determining particle size distribution by passing aggregate through a series of sieves
Grading Curve: Graphical representation showing cumulative percentage passing each sieve size
Fineness Modulus: Single-figure index representing aggregate coarseness (sum of cumulative % retained ÷ 100)
Grading Zones: Classification system (Zones 1-4) defining acceptable particle size ranges for fine aggregate
Well-Graded: Contains all particle sizes in proper proportions for optimal concrete performance
Gap-Graded: Missing intermediate sizes - may cause segregation and workability issues

BS 882 Grading Zones for Fine Aggregate

British Standard BS 882 (now superseded by BS EN 12620 but still widely referenced) established four grading zones for fine aggregate. Each zone produces concrete with different characteristics suitable for specific applications.

Fine Aggregate Grading Limits

BS Sieve Size	Zone 1 (Coarse)	Zone 2 (Medium)	Zone 3 (Fine)	Zone 4 (Very Fine)
10 mm	100%	100%	100%	100%
4.75 mm	90-100%	90-100%	90-100%	95-100%
2.36 mm	60-95%	75-100%	85-100%	95-100%
1.18 mm	30-70%	55-90%	75-100%	90-100%
600 μm	15-34%	35-59%	60-79%	80-100%
300 μm	5-20%	8-30%	12-40%	15-50%
150 μm	0-10%	0-10%	0-10%	0-15%

Zone 1 (Coarse Sand)

2.36 mm 60-95%

600 μm 15-34%

300 μm 5-20%

Zone 2 (Medium Sand)

2.36 mm 75-100%

600 μm 35-59%

300 μm 8-30%

Zone 3 (Fine Sand)

2.36 mm 85-100%

600 μm 60-79%

300 μm 12-40%

Zone 4 (Very Fine Sand)

2.36 mm 95-100%

600 μm 80-100%

300 μm 15-50%

Grading Zone Characteristics

Each grading zone produces concrete with distinct properties. Understanding zone characteristics helps select appropriate aggregate for specific applications and adjust mix designs accordingly.

Zone 1 - Coarse Sand

Fineness Modulus: 3.2 - 3.6

Workability: Low - requires more water

Strength: Lower early strength, good long-term

Cement Requirement: Lower (economical)

Segregation Risk: Higher

Applications: Mass concrete, foundations, heavy-duty floors

Zone 2 - Medium Sand

Fineness Modulus: 2.6 - 3.2

Workability: Good - most versatile

Strength: Balanced strength development

Cement Requirement: Moderate

Segregation Risk: Low

Applications: General construction, structural concrete, RCC work

Zone 3 - Fine Sand

Fineness Modulus: 2.2 - 2.6

Workability: Very good - cohesive mix

Strength: Good early strength

Cement Requirement: Higher

Segregation Risk: Very low

Applications: Finishing work, plastering, thin sections, precast

Zone 4 - Very Fine Sand

Fineness Modulus: 1.8 - 2.2

Workability: Excellent but sticky

Strength: High early strength potential

Cement Requirement: Highest (expensive)

Segregation Risk: Minimal

Applications: Mortar, plaster, grouting, special finishes

Coarse Aggregate Grading Standards

Coarse aggregate grading follows BS EN 12620 specifications. Proper grading ensures optimal particle interlocking, void reduction, and economical concrete production. Common sizes include single-sized and graded aggregates.

BS EN 12620 Coarse Aggregate Sizes

Designation	Nominal Size	Typical Passing	Applications
4/10	5-10 mm	85% pass 10mm, 0-15% pass 5mm	Fine concrete, screeds, precast
4/20	5-20 mm	85% pass 20mm, 0-15% pass 5mm	General purpose concrete
10/20	10-20 mm	85% pass 20mm, 0-15% pass 10mm	Standard structural concrete
20/40	20-40 mm	85% pass 40mm, 0-15% pass 20mm	Mass concrete, large sections
4/40 (Graded)	5-40 mm mixed	Continuous grading	General construction, ready-mix
10 mm (Single)	6.3-14 mm	85% pass 14mm, 0-20% pass 6.3mm	Thin sections, reinforced work
20 mm (Single)	14-20 mm	85% pass 20mm, 0-20% pass 14mm	Standard structural work
40 mm (Single)	20-40 mm	85% pass 40mm, 0-20% pass 20mm	Mass concrete, dams

10/20 mm Aggregate

Nominal Size 10-20 mm

Application Standard structural

20/40 mm Aggregate

Nominal Size 20-40 mm

Application Mass concrete

4/20 mm Graded

Nominal Size 5-20 mm

Application General purpose

Fineness Modulus Calculation

The fineness modulus (FM) is a single-figure index representing aggregate fineness. It's calculated from sieve analysis results and helps classify sand coarseness for concrete mix proportioning.

✅ Fineness Modulus Formula:

FM = Σ (Cumulative % Retained) ÷ 100
Sum cumulative percentages retained on: 150μm, 300μm, 600μm, 1.18mm, 2.36mm, 4.75mm, 10mm sieves
Lower FM (2.0-2.5): Fine sand - high cement requirement
Medium FM (2.5-3.0): Medium sand - balanced properties
Higher FM (3.0-3.5): Coarse sand - economical but less workable
Consistency: FM variation should not exceed ±0.20 between batches

Worked Fineness Modulus Example

Example Sieve Analysis

Sieve Results:

10mm: 100% passing (0% retained)

4.75mm: 95% passing (5% retained)

2.36mm: 80% passing (20% retained)

1.18mm: 60% passing (40% retained)

600μm: 40% passing (60% retained)

300μm: 20% passing (80% retained)

150μm: 5% passing (95% retained)

FM Calculation Steps

Cumulative % Retained:

10mm: 0%

4.75mm: 5%

2.36mm: 20%

1.18mm: 40%

600μm: 60%

300μm: 80%

150μm: 95%

Sum: 300%

Fineness Modulus Result

FM = 300 ÷ 100 = 3.00

Classification: Medium to coarse sand

Grading Zone: Zone 2 (upper range)

Characteristics: Good workability, moderate cement requirement

Suitability: General structural concrete

Quality Control

Acceptable FM Range: 2.80 - 3.20

Variation Tolerance: ±0.20

Next Batch FM: Must be 2.80-3.20

Action Required: None - within spec

Adjustment: Mix design unchanged

Combined Aggregate Grading

Combining fine and coarse aggregates in proper proportions produces optimal particle packing, minimizes voids, and creates economical concrete. The combined grading curve should approach the Fuller ideal grading for maximum density.

Fuller's Ideal Grading Curve

Sieve Size (mm)	Fuller's Ideal % Passing	Practical Range (%)	Purpose
40 mm	100%	95-100%	Maximum size control
20 mm	70.7%	60-80%	Coarse aggregate balance
10 mm	50%	40-60%	Transition zone
4.75 mm	34.4%	28-42%	Fine/coarse boundary
2.36 mm	24.3%	18-30%	Medium sand content
1.18 mm	17.2%	12-22%	Fine sand balance
600 μm	12.2%	8-16%	Void filling
300 μm	8.7%	5-12%	Workability enhancement
150 μm	6.1%	3-8%	Fines control

40 mm Sieve

Fuller's Ideal 100%

Practical Range 95-100%

10 mm Sieve

Fuller's Ideal 50%

Practical Range 40-60%

4.75 mm Sieve

Fuller's Ideal 34.4%

Practical Range 28-42%

Effects of Grading on Concrete Properties

Aggregate grading significantly impacts concrete workability, strength, durability, and economy. Understanding these relationships helps optimize mix designs for specific applications and performance requirements.

Workability Impact

Well-graded aggregate: Smooth grading curve, good particle distribution

Benefits: Better workability, easier placing and finishing

Reduced water demand: 5-15 liters/m³ less than poorly graded

Cohesion: Reduced bleeding and segregation risk

Gap-graded issues: Harsh mix, difficult to work with

Strength Development

Coarse sand (Zone 1): Lower early strength, good long-term

Fine sand (Zone 3-4): Higher early strength, increased shrinkage

Optimal grading: Zone 2 provides balanced strength development

Particle packing: Better grading = denser concrete = higher strength

Strength variation: Can be 10-20% based on grading quality

Durability Effects

Dense packing: Reduced permeability, better durability

Excess fines: Higher drying shrinkage, cracking risk

Coarse grading: May leave voids, reduced paste coverage

Chloride resistance: Improved with well-graded aggregates

Freeze-thaw: Better grading improves resistance

Economic Considerations

Cement content: Well-graded aggregates reduce cement by 10-15%

Coarse sand advantage: Lower cement requirement, cost savings

Fine sand penalty: 30-50 kg/m³ more cement needed

Optimization: Proper grading can save 5-10% on concrete cost

Quality control: Consistent grading reduces batch variations

Segregation Resistance

Uniform grading: Better cohesion, less segregation

Gap grading risk: Increased segregation during placement

Excess coarse aggregate: Separation during transport

Fine content role: 8-15% passing 150μm improves cohesion

Pumping: Well-graded concrete pumps more easily

Finishing Quality

Surface finish: Finer sand produces smoother finishes

Bleeding control: Proper grading reduces surface water

Troweling: Zone 2-3 sand optimal for finishing

Exposed aggregate: Requires specific grading for aesthetics

Formwork surface: Grading affects honeycombing risk

Sieve Analysis Testing Procedure

Sieve analysis, conducted per BS EN 933-1, determines aggregate particle size distribution. This laboratory test is fundamental for quality control and ensuring aggregates meet specification requirements.

Equipment Required

Sieve set: Standard BS sieves (10mm, 4.75mm, 2.36mm, 1.18mm, 600μm, 300μm, 150μm)

Balance: Accurate to 0.1% of sample weight

Mechanical shaker: For consistent sieving action

Sample splitter: Ensures representative samples

Drying oven: 105-110°C for moisture removal

Sample Preparation

Sample size: Minimum 2 kg for sand, 10-20 kg for coarse aggregate

Drying: Remove moisture at 105°C until constant weight

Cooling: Allow to cool to room temperature

Splitting: Reduce to test size using quartering or splitter

Initial weight: Record accurately to 0.1g

Testing Procedure

Step 1: Stack sieves largest to smallest, pan at bottom

Step 2: Place sample on top sieve

Step 3: Shake for 10 minutes (mechanical) or hand sieve until <1% passes per minute

Step 4: Weigh material retained on each sieve

Step 5: Calculate percentages and cumulative values

Results Calculation

% Retained: (Weight on sieve / Total weight) × 100

Cumulative % Retained: Sum of all retained above current sieve

% Passing: 100 - Cumulative % Retained

Check: Sum of all retained should be 98-102% of initial weight

Accuracy: Report to nearest 1% for most applications

Common Grading Problems and Solutions

Aggregate grading issues can significantly affect concrete quality. Recognizing problems early and implementing corrective measures prevents costly concrete failures and ensures consistent performance.

⚠️ Grading Problems & Solutions:

Excess fines (>15% passing 150μm): Increased water demand, shrinkage, reduced durability → Wash aggregate or blend with cleaner material
Gap grading: Missing intermediate sizes causing harsh mix → Blend aggregates or add missing size fractions
Grading variation: Batch-to-batch inconsistency → Improve stockpile management, blend multiple sources
Oversized particles: Exceeding maximum specified size → Screen aggregate, adjust crusher settings
Segregation in stockpiles: Coarse and fine separation → Use proper stockpiling techniques, blend before use
Too coarse (all Zone 1): Poor workability, high water need → Blend with finer sand or increase fine content
Too fine (all Zone 4): Excessive cement required → Mix with coarser sand to achieve Zone 2-3

Quality Control and Testing Frequency

Regular grading analysis ensures aggregate consistency and concrete quality. Testing frequency depends on production volume, source variability, and project criticality.

Project Type	Testing Frequency	Sample Size	Acceptance Criteria
Small residential	Once per source approval	2-5 kg	Within specified zone
Commercial buildings	Weekly or per 500 m³	5 kg	FM variation <±0.20
Infrastructure	Every 250 m³ or daily	10 kg	Continuous compliance
High-rise/critical	Daily or per 100 m³	10 kg	Strict zone compliance
Ready-mix production	Daily per stockpile	5-10 kg	FM ±0.15 from target
Precast factory	Per batch or shift	5 kg	Very tight control (±0.10)

Commercial Buildings

Frequency Weekly/500 m³

Criteria FM <±0.20

Infrastructure Projects

Frequency Daily/250 m³

Criteria Continuous compliance

Ready-Mix Production

Frequency Daily per stockpile

Criteria FM ±0.15

Aggregate Grading FAQs

What is aggregate grading and why is it important?

Aggregate grading is the distribution of particle sizes within sand or gravel, determined through sieve analysis. It's critical because it affects concrete workability, strength, durability, and economy. Well-graded aggregates with proper particle distribution create optimal particle packing, minimize voids, reduce cement requirements, and produce concrete that's easier to place and finish. Poor grading leads to harsh mixes, high water demand, segregation, and increased costs.

What are the four grading zones for sand?

BS 882 defines four grading zones: Zone 1 (coarse sand, FM 3.2-3.6) has larger particles, requires less cement but lower workability, suitable for mass concrete. Zone 2 (medium sand, FM 2.6-3.2) is most versatile with balanced properties for general construction. Zone 3 (fine sand, FM 2.2-2.6) provides good workability and early strength but needs more cement. Zone 4 (very fine sand, FM 1.8-2.2) gives excellent workability but highest cement requirement, used mainly for mortar and plaster.

How do you calculate fineness modulus?

Fineness modulus (FM) is calculated by summing the cumulative percentages of aggregate retained on standard sieves (150μm, 300μm, 600μm, 1.18mm, 2.36mm, 4.75mm, 10mm) and dividing by 100. For example, if cumulative retentions are 95%, 80%, 60%, 40%, 20%, 5%, and 0%, the sum is 300, so FM = 300÷100 = 3.00. Lower FM (2.0-2.5) indicates fine sand, medium FM (2.5-3.0) medium sand, and higher FM (3.0-3.5) coarse sand.

What is the difference between well-graded and gap-graded aggregate?

Well-graded aggregate contains a good distribution of all particle sizes from coarse to fine, creating a smooth grading curve. This provides optimal particle packing, good workability, and economical concrete. Gap-graded aggregate is missing one or more intermediate size fractions, creating a discontinuous grading curve. This leads to harsh concrete, poor workability, segregation during placement, and difficulty in achieving proper compaction. Gap grading should generally be avoided except for specific special applications.

How much fine material (passing 150μm) is acceptable?

For fine aggregate (sand), BS EN 12620 allows maximum 10% passing 150μm sieve, with 3-8% being optimal for most applications. Material passing 150μm includes silt, clay, and very fine particles. Excess fines (>10%) increase water demand, shrinkage, and cement requirement while reducing durability. Too few fines (<3%) can make concrete harsh and prone to bleeding. For coarse aggregate, the limit is typically 1-2% passing 150μm. Always verify specific project specifications.

Can you mix different grading zones of sand?

Yes, mixing sands from different zones is common practice and often necessary to achieve optimal grading. Blending Zone 1 (coarse) and Zone 3 (fine) sand can produce Zone 2 characteristics. Calculate the blend ratio to achieve target fineness modulus. For example, mixing 60% Zone 1 (FM=3.2) with 40% Zone 3 (FM=2.4) gives FM = (0.6×3.2)+(0.4×2.4) = 2.88 (Zone 2). Always verify the resulting grading curve falls within specification limits.

What causes grading to vary in aggregate stockpiles?

Segregation is the main cause: coarse particles roll to stockpile edges while fines concentrate at the center or top. This occurs during dumping, especially from height. Wind can also blow away fines. Rainfall washes fines deeper into piles. Variations in quarry source rock affect grading. Poor crusher settings create inconsistent output. Solutions include: proper stockpiling techniques (cone method), drawing material from multiple pile locations, blending before use, covering stockpiles, and regular testing.

How often should aggregate grading be tested?

Testing frequency depends on project size and criticality. General guidelines: small residential projects - once per source approval; commercial buildings - weekly or every 500 m³; infrastructure - daily or every 250 m³; high-rise/critical structures - daily or per 100 m³. Ready-mix plants should test each stockpile daily. Additionally, test whenever: source changes, visual appearance differs, workability problems occur, or after heavy rain affecting stockpiles. Fineness modulus variation should not exceed ±0.20 between tests.

What is Fuller's maximum density curve?

Fuller's ideal grading curve represents the theoretical particle size distribution giving maximum density and minimum voids. It follows the formula: % passing = 100 × √(d/D), where d is sieve size and D is maximum aggregate size. For 40mm maximum size concrete, ideal passing values are: 20mm-71%, 10mm-50%, 4.75mm-34%, 2.36mm-24%. While perfect compliance is impractical, combined aggregate grading should approximate this curve for optimal concrete performance and economy.

How does aggregate grading affect concrete cost?

Grading significantly impacts concrete economy. Well-graded aggregates reduce cement content by 10-15% through better particle packing and lower void content. Coarse sand (Zone 1) may save 30-50 kg cement per m³ compared to fine sand (Zone 3), reducing cost by 5-10%. However, coarse sand may require more admixtures for workability. Gap-graded aggregates increase cement need and placement labor. Consistent grading reduces waste from rejected batches. Overall, proper aggregate grading can save £5-15 per m³ of concrete on typical projects.