Coarse Aggregate for Water Bound Macadam

IS 6579 - Scope: Key Specifications & Tables

Scope (Clause 4.1)

• Defines size and grading of coarse aggregates used in construction.
• Aggregates grading must follow Table 1 based on IS 460 (Part I) - 1978 sieve designations.

Table 1: Size and Grading of Coarse Aggregates

Additional Notes:

• Applies to WBM aggregates for sub-base courses.
• Includes requirements for abrasion value, impact value, flakiness index, and water absorption.
• Rounding of test values per IS 2-1960.

Summary Diagram: Aggregate Grading Flow

flowchart TD
    A[Coarse Aggregate] --> B{Select Grading No.}
    B -->|1| C[Sieve Sizes: 106, 75, 63, 37.5, 19 mm]
    B -->|2| D[Sieve Sizes: 75, 63, 53, 37.5, 19 mm]
    B -->|3| E[Sieve Sizes: 63, 53, 37.5, 19, 11.2 mm

IS 6579: Types of Coarse Aggregates – Key Specifications

1. Size and Grading (Clause 4.1, Table 1)

2. Physical Requirements (Clause 3.1)

• Aggregates must be hard, durable, and free from:
  • Excessive flat or elongated particles
  • Soft or disintegrated particles
  • Dirt or other impurities causing weakness

3. Notes

• Grading may vary if aggregates are prone to degradation during rolling.
• Sieve specifications per IS 460 (Part I)-1978.

This grading ensures proper particle size distribution for water bound macadam layers, contributing to strength and durability.

flowchart LR
    A[Coarse Aggregates] --> B{Grading No.}
    B -->|1| C[Max 106 mm, 55-80% pass 75 mm sieve]
    B -->|2| D[Max 75 mm, 90-100% pass 63 mm sieve]
    B -->|3| E[Max 63 mm, 95-100% pass 53 mm sieve]
    C & D & E -->

IS 6579 - Quality Requirements for Coarse Aggregates

1. Size and Grading (Clause 4.1, Table 1)

Coarse aggregates must conform to the following sieve grading by mass (% passing):

Note: For aggregates prone to degradation during rolling, grading may vary.

2. Physical Requirements - Soundness (Clause 5.5)

Aggregate soundness tested per IS 2386 (Part V)-1963:

• Loss after 5 cycles sodium sulphate: ≤ 20%
• Loss after 5 cycles magnesium sulphate: ≤ 30%

Note: Soundness testing is mandatory if aggregates undergo freeze-thaw cycles.

3. Sampling and Conformity (Clause 6.1)

• Follow IS 2430-1969 for sampling procedure and conformity criteria.

Summary Diagram

flowchart TD
    A[Coarse Aggregate] --> B[Size & Grading (Table 1)]
    A --> C[Soundness Test (IS 2386 Part V)]
    A --> D[Sampling (IS 2430)]
    B --> E[Grading No. 1, 2, 3]
    C

IS 6579: Size and Grading of Coarse Aggregates

Key Table: Size and Grading (Clause 4.1)

Notes:

• Sieve designations follow IS 460 (Part I) - 1978 wire cloth test sieves.
• For aggregates prone to degradation during rolling, grading limits may vary.
• Aggregates must be free from dust, foreign matter, and underburnt particles (see IS 1077-1976 for brick aggregates).

Summary:

• The grading number corresponds to specific sieve sizes and percent passing ranges.
• Proper grading ensures durability, workability, and strength in concrete and road construction.
• Use the table to verify aggregate size distribution compliance.

flowchart LR
    A[Coarse Aggregate] --> B{Grading No.}
    B -->|1| C[Sieve sizes: 106, 75, 63, 37.5, 19 mm]
    B -->|2| D[Sieve sizes: 75, 63, 53, 37.5, 19 mm]
    B -->|3| E[Sieve sizes: 63, 53, 37.5, 19

IS 6579: Mechanical Properties - Key Specifications

Though IS 6579 primarily details physical requirements and grading of coarse aggregates (Clause 4.1, Table 1), mechanical properties relate to aggregate strength and durability, typically assessed by:

Key Mechanical Property Tests:

• Abrasion Value (Los Angeles Test): Indicates resistance to surface wear.
• Impact Value: Measures toughness or resistance to sudden shock.
• Flakiness Index: Indicates shape quality affecting strength.
• Water Absorption: Should be low to ensure durability.

Relevant Specifications from IS 6579:

• Grading of Coarse Aggregates (Table 1):

Mechanical Property Formulas (General):

• Aggregate Impact Value (AIV)
  [ \text{AIV} = \left(\frac{\text{Mass passing 2.36 mm sieve after impact}}{\text{Total sample mass}} \right) \times 100% ]

• Aggregate Abrasion Value (LA Abrasion)
  [ \text{Abrasion Value} = \left(\frac{\text{Loss in mass after abrasion test}}{\text{Original mass}} \right) \times 100%

IS 6579: Sampling and Conformity Key Points

1. Sampling Procedure & Conformity Criteria

• Refer IS 2430-1969 for detailed sampling methods and conformity criteria of aggregates.
• Sampling must be representative of the batch to ensure test validity.

2. Soundness Requirements (IS 2386 Part V)

• Sodium sulfate test (5 cycles): Max 20% loss
• Magnesium sulfate test (5 cycles): Max 30% loss
• Soundness test required only if aggregates undergo freeze-thaw cycles.

3. Cost of Tests (Clause 7.4)

4. Size & Grading of Coarse Aggregates (Table 1, Clause 4.1)

Summary Diagram: Sampling & Conformity Flow

flowchart TD
    A[Sampling as per IS 2430] --> B[Test Aggregates]
    B --> C{Test Results}
    C -->|Complies| D[Cost borne by Purchaser]
    C -->|Does not comply| E[Cost borne by Supplier]
    B --> F[Soundness Test (if freeze-thaw)]
    F --> C

References:

• IS 2430-1969: Sampling & conformity
• IS 2386 (Part V): Soundness test
• IS 460 (Part I): Grading of aggregates

For precise test procedures, consult the respective

IS 6579: Supplier's Certificate and Cost of Tests (Clause 7)

• Supplier's Certificate (7.1):
  Supplier must ensure material conforms to IS 6579 and provide a certificate of conformity upon request.

• Material for Tests (7.3):
  Supplier supplies test material free of charge.

• Cost of Tests (7.4):

  Condition	Cost borne by
  Material does not comply	Supplier
  Material complies	Purchaser

• Sampling & Conformity:
  Follow IS 2430-1969 for sampling procedure and conformity criteria.

• Testing Methods Referenced:

  • Specific gravity, density, voids, absorption, bulking (Part III)
  • Soundness (Part V)
  • Sampling methods for aggregates

Summary Diagram of Cost Responsibility

flowchart TD
    A[Material Tested] --> B{Compliance?}
    B -- Yes --> C[Cost borne by Purchaser]
    B -- No --> D[Cost borne by Supplier]

Note: For detailed test methods, refer to IS 2386 (Parts III & V) and IS 2430 for sampling.