burnt clay facing bricks-Specification

IS 2691: Scope and Key Specifications

• Scope: Covers dimensions, tolerances, and physical requirements for specific construction components as per IS 2691:1988.

Key Dimensions & Tolerances (Clause 4.2)

Physical & Quality Requirements

• Definitions follow IS 2248:1981.
• Quality and testing conform to IS 2691:1988 reaffirmed in 2006.
• Ensures standardization in manufacturing and usage.

Summary: IS 2691 specifies dimensional tolerances for components (e.g., bricks or blocks) with ±2 to ±3 mm allowed variation, ensuring uniformity and quality in construction materials.

flowchart LR
    A[IS 2691 Scope] --> B[Dimensions & Tolerances]
    B --> C{Dimension}
    C -->|190 mm| D[±3 mm]
    C -->|90 mm| E[±2 mm]
    C -->|40 mm| F[±2 mm]
    A --> G[Physical Requirements]
    G --> H[IS 2248 Definitions]
    G --> I[Quality per IS 2691:1988]

IS 2691 - Definitions & Key Specifications

• Reference for Definitions:
  Per Clause 2.1, definitions follow IS 2248:1981 (Specification for concrete masonry units).

• Dimensions & Tolerances (Clause 4.2):

  Dimension (mm)	Permissible Tolerance (mm)
  190	± 3
  90	± 2
  40	± 2

• Physical Requirements:
  Covered under Clause 5 (details in IS 2691).

Summary:

• Use IS 2248:1981 for terminology and definitions.
• Maintain dimensional tolerances as per the table above.
• Ensure compliance with physical requirements and quality as per IS 2691 clauses.

flowchart TD
    A[IS 2691 Definitions] --> B[Refer IS 2248:1981]
    A --> C[Dimension Tolerances]
    C --> D[190 mm ± 3 mm]
    C --> E[90 mm ± 2 mm]
    C --> F[40 mm ± 2 mm]

IS 2691: General Quality Requirements - Key Points

1. Dimensions & Tolerances (Clause 4.2)

2. Physical Requirements

• Efflorescence (Clause 5.3):
  Must be NIL when tested as per IS 3495 (Part 3)-1976.

• Warpage (Clause 5.4):
  Maximum allowable warpage is 2.5 mm, tested as per IS 3495 (Part 4)-1976.

3. Reference Standards for Tests

• Compressive Strength: IS 3495 (Part 1)
• Water Absorption: IS 3495 (Part 2)
• Efflorescence: IS 3495 (Part 3)
• Warpage: IS 3495 (Part 4)

Summary Diagram of Quality Checks

flowchart TD
    A[Start: Brick Sample] --> B{Dimension Check}
    B -->|Within Tolerance| C{Efflorescence Test}
    B -->|Out of Tolerance| D[Reject Sample]
    C -->|NIL Efflorescence| E{Warpage Test}
    C -->|Efflorescence Present| D
    E -->|≤ 2.5 mm| F[Accept Sample]
    E -->|> 2.5 mm| D

This ensures bricks meet dimensional accuracy and physical integrity per IS 2691.

IS 2691: Dimensions and Tolerances for Facing Bricks

Key Specifications (Clause 4.2)

• Bricks must have plane rectangular faces, parallel sides, and sharp straight right-angled edges (Clause 3.2).
• Tolerances ensure uniformity for proper masonry bonding and aesthetics.
• Dimensions are in millimeters; tolerances are liberalized for the 40 mm thickness dimension (±2 mm instead of ±1.5 mm).

Additional Notes:

• Bricks should be free from cracks, flaws, nodules of free lime, and have an even texture.
• Facing bricks are intended for exposed masonry without further surface protection.
• Compliance values should be rounded as per IS 2-1960 rounding rules.

flowchart LR
    A[Brick Dimensions] --> B[Length: 190 mm ±3]
    A --> C[Width: 90 mm ±2]
    A --> D[Thickness: 40 mm ±2]
    B & C & D --> E[Ensures uniform masonry]
    E --> F[Better bonding & aesthetics]

This concise table and notes help maintain quality and dimensional accuracy for facing bricks per IS 2691.

IS 2691: Physical Requirements Summary

1. Dimensions & Tolerances (Clause 4.2)

2. Water Absorption (Clause 5.2)

• Maximum water absorption: 15% (after 24 hours immersion)
• Test method as per IS 3495 (Part 2) - 1976

3. General Quality Notes

• Dimensions in millimeters
• Compressive strength in N/mm²
• Facing bricks are for exposed masonry without additional surface protection.
• Tolerances liberalized for 40 mm dimension from ±1.5 mm to ±2 mm for manufacturing practicality.

Important Reference:

• Definitions as per IS 2248-1981
• Rounding off values as per IS 2-1960

flowchart TD
    A[Brick Manufacturing] --> B[Dimension Control]
    B --> C{Check Tolerances}
    C -->|Within ± tolerance| D[Accept Brick]
    C -->|Outside Tolerance| E[Reject Brick]
    A --> F[Water Absorption Test]
    F -->|≤ 15%| D
    F -->|> 15%| E

This ensures bricks meet physical standards for durability and dimensional accuracy.

IS 2691 - Sampling and Criteria for Testing

Key Reference:

• Clause 6.1: Sampling and testing criteria follow IS 5454:1978 (Methods of sampling and testing for burnt clay building bricks).

Sampling Procedure (per IS 5454):

• Samples shall be taken randomly from the lot.
• Minimum sample size depends on lot size (e.g., for lots up to 500 bricks, sample 20 bricks).
• Samples must represent the lot adequately to ensure uniformity.

Testing Criteria:

• Tests include compressive strength, water absorption, efflorescence, and warpage.
• Warpage limit: ≤ 2.5 mm (Clause 5.4, IS 3495 Part 4).

Dimensions and Tolerances (Clause 4.2):

Summary Table of Tests:

flowchart TD
    A[Sampling as per IS 5454] --> B[Testing]
    B --> C[Compressive Strength (IS 3495-1)]
    B --> D[Water Absorption (IS 3495-2)]
    B --> E[Efflorescence (IS 3495-3)]
    B --> F[Warpage (IS 3495-4)]
    F --> G{Warpage ≤ 2.5 mm?}
    G -->|Yes| H[Accept]
    G -->|No| I[Reject]

Note: Always refer to IS 5454 for detailed sampling plans and IS 3495 for test methods.

IS 2691 - Marking of Clay Building Bricks

Key Specifications for Marking (Clause 7.1 & 7.1.1)

• Each brick shall be marked with the manufacturer’s identification mark or initials.
• Bricks may also bear the BIS Standard Mark, indicating compliance with BIS quality and inspection systems.
• Use of the Standard Mark is regulated by the Bureau of Indian Standards Act 1986.

Dimensions and Tolerances (Clause 4.2)

Notes:

• The Standard Mark assures continuous quality control and conformity.
• Marking helps traceability and quality assurance.
• Refer IS 2248-1981 for definitions related to clay bricks.

flowchart LR
    A[Manufacturer] --> B[Mark bricks with ID/initials]
    B --> C{Use Standard Mark?}
    C -->|Yes| D[Apply BIS Standard Mark]
    C -->|No| E[Only Manufacturer Mark]
    D --> F[Quality Assurance & BIS Inspection]
    E --> F

This ensures traceability and compliance with IS 2691 standards.