Specification for Artificial Lightweight Aggregates for Concrete Masonry Units
1979 Edition

Scope and Particle Size Distribution Requirements for Lightweight Combined Aggregates

Scope (Clause 3.1)

• Specifies grading parameters for lightweight combined aggregates utilized in concrete masonry blocks.
• Grading criteria based on particle size distribution determined through sieve analysis.

Grading Table (Table 1)

Additional Details:

• Fine aggregate size range: 0 to 4.75 mm
• Coarse aggregate size ranges: 4.75 to 12.5 mm or 2.36 to 10 mm
• Combined aggregate covers sizes from 0 to 10 mm

Bulk Density (Clause 4)

• Bulk density is a crucial physical parameter; further details are provided in subsequent clauses.

This grading framework ensures an optimal particle size distribution for lightweight concrete masonry units, promoting strength and workability.

General Characteristics of Lightweight Aggregates for Concrete Masonry Units

1. Grading Standards (Clause 3.1, Table 1)

2. Bulk Density (Clause 4.2)

• Bulk density must maintain uniformity, with successive batches not deviating more than ±10% from the accepted sample.

3. Harmful Substances

• Aggregates must be free from deleterious materials that could compromise strength and durability (refer IS 9142 for specific limits).

Summary:

• Grading controls particle size distribution vital for structural integrity.
• Uniform bulk density maintains consistent concrete quality.
• Cleanliness and absence of harmful impurities are essential.

flowchart LR
    A[Aggregate Delivery] --> B{Sieve Analysis}
    B -->|Meets Grading| C[Accept Batch]
    B -->|Fails Grading| D[Reject Batch]
    C --> E[Check Bulk Density]
    E -->|Within ±10%| F[Use in Concrete]
    E -->|Outside ±10%| D

This process guarantees quality lightweight aggregates for masonry per IS 9142.

Materials Criteria for Lightweight Aggregates in Concrete Masonry Units

1. Grading Standards (Clause 3.1, Table 1)

• Percentages reflect mass passing through IS sieves.

2. Bulk Density (Clause 4.2)

• Variability in bulk density between deliveries must not exceed ±10% relative to the accepted sample.

3. Deleterious Material Restrictions (Clause 5)

• Aggregates should be free from substances that impair strength or durability.

Summary:

• Follow Table 1 for controlling particle size distribution.
• Maintain bulk density uniformity within 10% tolerance.
• Ensure aggregates are uncontaminated and adhere to purity standards.

These specifications enable consistent performance of lightweight aggregates in masonry units.

Key Bulk Density Criteria for Lightweight Aggregates

• Bulk Density Measurement: According to Clause 7.3, test oven-dried aggregates following IS 2386 (Part III)-1963 which covers specific gravity, density, void content, absorption, and bulking.

• Bulk Density Limits:

  • Clause 4.1: The dry loose bulk density of combined aggregates should not exceed 1100 kg/m³.
  • Clause 4.2: Variation in bulk density between consecutive supplies must be within ±10% of the sample accepted.

Bulk Density Testing Overview (IS 2386 Part III)

Bulk Density Calculation Formula

[ \text{Bulk Density} = \frac{\text{Mass of oven-dry aggregate}}{\text{Container volume}} ]

flowchart LR
    A[Prepare Sample] --> B[Oven Dry Sample]
    B --> C[Fill Container Loosely]
    C --> D[Measure Mass]
    C --> E[Determine Volume]
    D & E --> F[Compute Bulk Density]

Summary: IS 9142 requires oven-dry loose bulk density not exceeding 1100 kg/m³ with uniformity within ±10%, tested per IS 2386 (Part III).

Specifications on Deleterious Components in Lightweight Aggregates

Essential Limits and Tests

• Clause 5.1: Lightweight aggregates must be free from excessive harmful materials.
• Organic Impurities (Clause 5.1.1):
  • Tested via a colorimetric method.
  • Aggregates are rejected if the test color is darker than the reference standard unless demonstrated to be non-detrimental.
• Sulphate Content (Clause 7.8):
  • Tested according to IS 4032-1968.
  • Typically, sulphate content should remain below 0.5% SO₄²⁻ by mass to ensure safety for lime concrete.

Bulk Density Uniformity (Clause 4.2)

• Successive batches must not deviate more than 10% in bulk density compared to the accepted sample.

Deleterious Substances Limits Summary

Notes:

• Suppliers must issue certificates confirming compliance (Clause 8).
• Testing ensures the durability and strength of lime-based concrete.

flowchart TD
    A[Lightweight Aggregate] --> B{Test for Deleterious Substances}
    B --> C[Organic Impurities Test]
    B --> D[Sulphate Content Test]
    C --> E{Color ≤ Standard?}
    E -->|Yes| F[Accept]
    E -->|No| G[Reject or Further Evaluation]
    D --> H{SO₄²⁻ ≤ Limit?}
    H -->|Yes| F
    H -->|No| G

This protocol guarantees lightweight aggregates are safe and reliable for lime concrete applications.

Requirements for Concrete Masonry Units Using Lightweight Aggregates

1. Aggregate Grading (Clause 3.1, Table 1)

The particle size distribution for lightweight aggregates employed in concrete masonry units must adhere to the following (% passing by mass):

2. Key Considerations:

• Sieve analysis must verify particle size distribution.
• Proper grading is critical for the workability, strength, and durability of masonry units.
• Artificial lightweight aggregates must comply with these gradation specifications to maintain uniform quality.

This grading guide assists in selecting and proportioning aggregates for producing quality concrete masonry units under this standard.

Procedures for Sampling and Testing Lightweight Aggregate Properties

Important Specifications and Tables

1. Sulphate Content

• Maximum allowed SO₃ content is 1% by mass (Clause 6.1.2).

2. Sampling Guidelines (Clause 7.1)

• Sampling should be conducted according to IS 2430-1969.

3. Grading Analysis (Clause 7.2)

• Sieve analysis following IS 2386 (Part I)-1963.
• Particle size distribution must comply with the table below:

Summary of Testing Standards

• Sampling: IS 2430-1969
• Grading: IS 2386 (Part I)-1963
• Sulphate Content: Chemical analysis ensuring ≤ 1% SO₃

flowchart TD
    A[Sampling Process] -->|IS 2430-1969| B[Sample Collection]
    B --> C[Grading Test]
    C -->|IS 2386 Part I| D[Sieve Analysis]
    D --> E[Verify % Passing against Table]
    A --> F[Sulphate Content Analysis]
    F -->|Chemical Testing| G[SO₃ ≤ 1%]

This ensures the quality of lightweight aggregates for concrete masonry units as per the standard.

Supplier Certification and Allocation of Testing Costs (Clause 8)

Key Points:

• Supplier Certification (8.1): The supplier must guarantee the material’s compliance with IS 9142 and provide certification upon request.

• Provision of Samples (8.3): Suppliers are required to furnish test samples free of charge.

• Testing Cost Responsibilities (8.4):

Associated Testing Standards:

• Sulphate content: IS 4032-1968
• Testing for deleterious materials and organic impurities: IS 2386 (Part II)
• Chemical analysis for hydraulic cement
• Specifications for lightweight concrete blocks

Summary Table on Cost Bearing

This framework ensures accountability and quality assurance during supply and testing as per IS 9142.