IS 26911988AI Search Enabled✦ AI Generated

burnt clay facing bricks-Specification
1988 Edition

The 1988 edition of IS 2691 outlines the specifications for burnt clay facing bricks, detailing dimensional criteria, physical characteristics, and quality benchmarks to guarantee both longevity and visual appeal. This standard is essential for manufacturers, engineers, and quality assessors involved in selecting or producing facing bricks intended for exposed masonry without additional surface treatments.

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Overview

What This Standard Covers

The 1988 edition of IS 2691 outlines the specifications for burnt clay facing bricks, detailing dimensional criteria, physical characteristics, and quality benchmarks to guarantee both longevity and visual appeal. This standard is essential for manufacturers, engineers, and quality assessors involved in selecting or producing facing bricks intended for exposed masonry without additional surface treatments.

Audience

Who Uses This Standard

  • Structural Engineers
  • Design Architects
  • Building Contractors
  • Quality Assurance Inspectors
  • Brick Producers
  • Masonry Experts
  • Construction Material Distributors

Contents

Key Topics Covered

✓Composition and material standards
✓Specified brick dimensions and allowable variances
✓Minimum compressive strength criteria
✓Limits on water absorption
✓Standards for efflorescence control
✓Permissible warpage range
✓Identification and marking requirements
✓Sampling methods and testing protocols
✓Manufacturing process quality management
✓Consistency in surface texture and coloration
✓Application guidelines for exposed brickwork
✓Certification and licensing for BIS Standard Mark

Structure

Table of Contents

1Scope and Fundamental Specifications▼

Overview of IS 2691 covering the required dimensions, tolerances, and physical properties for burnt clay facing bricks used in construction.

Dimensional Tolerances (Clause 4.2)

Dimension (mm)Allowed Variation (mm)
190±3
90±2
40±2

Physical and Quality Criteria

  • Definitions aligned with IS 2248:1981.
  • Compliance with quality and testing reaffirmed in IS 2691:1988 (2006 revision).
  • Standardization ensures consistent production and application.
2Terminology and Definitions▼

Clarification of terms as per IS 2248:1981 referenced in Clause 2.1 of IS 2691.

Dimensional Allowances (Clause 4.2)

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

Physical Properties

Covered in Clause 5 of IS 2691.

3Overall Quality Specifications▼

Detailed requirements include:

1. Dimensions and Permissible Deviations (Clause 4.2)

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

2. Physical Characteristics

  • Efflorescence must be absent, tested according to IS 3495 (Part 3)-1976.
  • Maximum allowable warpage is 2.5 mm, per IS 3495 (Part 4)-1976.

3. Testing Standards Referenced

  • Compressive strength: IS 3495 (Part 1)
  • Water absorption: IS 3495 (Part 2)
  • Efflorescence: IS 3495 (Part 3)
  • Warpage: IS 3495 (Part 4)
4Brick Dimensions and Allowable Variations▼

Specifications for burnt clay facing bricks emphasize:

  • Rectangular, flat faces with parallel sides and sharply defined right-angled edges (Clause 3.2).
  • Dimensions in millimeters with specified tolerances, liberalized for 40 mm thickness to ±2 mm for practicality.
Dimension (mm)Tolerance (mm)
190±3
90±2
40±2

Additional requirements:

  • Bricks must be free from cracks, imperfections, and free lime nodules.
  • Even texture and thorough burning are mandatory.
  • Intended for use in exposed masonry without additional surface treatments.
5Physical Property Requirements▼

Key physical standards include:

Dimension (mm)Tolerance (mm)
190±3
90±2
40±2
  • Maximum water absorption is set at 15% after 24-hour immersion, tested per IS 3495 (Part 2)-1976.
  • Compressive strength and other physical properties as per IS 2691.
  • Bricks must maintain durability and dimensional precision suitable for exposed masonry applications.
6Sampling Techniques and Testing Standards▼

Sampling and test criteria adhere to IS 5454:1978.

  • Samples are selected randomly from production lots, with quantity based on lot size.
  • Tests performed include compressive strength, water absorption, efflorescence, and warpage.
  • Warpage limit is up to 2.5 mm maximum (Clause 5.4, IS 3495 Part 4).
Dimension (mm)Tolerance (mm)
190±3
90±2
40±2

Testing reference table:

TestStandard ReferenceAcceptance Criteria
Compressive StrengthIS 3495 Part 1Meets IS 2691 specifications
Water AbsorptionIS 3495 Part 2Within specified limits
EfflorescenceIS 3495 Part 3Absence of harmful deposits
WarpageIS 3495 Part 4≤ 2.5 mm
7Brick Marking Requirements▼

Per Clauses 7.1 and 7.1.1:

  • Each brick must bear the manufacturer's identification mark or initials.
  • Optionally, bricks may also display the BIS Standard Mark, signifying compliance with the Bureau of Indian Standards quality and inspection protocols.
  • The use of the Standard Mark is governed by the BIS Act of 1986.

Marking supports traceability and confirms ongoing quality control.

Frequently Asked

Popular Questions About IS 2691

?What are the prescribed dimensions and allowable variations for burnt clay facing bricks as per IS 2691?▼

IS 2691 specifies that burnt clay facing bricks should have nominal thickness of 40 mm with an allowable tolerance of ±2 mm, an overall length of 190 mm with ±3 mm tolerance, and width of 90 mm with ±2 mm tolerance. The bricks must have flat rectangular faces, parallel sides, sharp and straight right-angled edges, and should be free from cracks, defects, or free lime nodules with an even texture, ensuring suitability for exposed masonry applications without extra surface protection.

?According to IS 2691, what is the minimum compressive strength required for facing bricks?▼

The standard mandates a minimum average compressive strength of 10 N/mm² for facing bricks, as outlined in Clause 5.1. Testing is done following IS 3495 (Part 1) procedures. The bricks must be made from burnt clay, shale, or their combination, ensuring uniform quality and color suitable for exposed masonry without additional protective finishes.

?How is the water absorption of burnt clay facing bricks tested and what is the maximum permissible limit?▼

Water absorption testing is conducted according to IS 3495 (Part 2)-1976, where bricks are dried to a constant weight, immersed in water for 24 hours, then surface-dried and weighed again. The water absorption percentage is calculated by the weight difference relative to the dry weight. The maximum allowed water absorption is 15% by weight, ensuring the bricks' durability and resistance to weather effects.

?What are the IS 2691 requirements regarding efflorescence and warpage in burnt clay facing bricks?▼

Facing bricks must exhibit no harmful efflorescence as per testing under IS 3495 (Part 3), ensuring no visible white deposits or patches. Warpage should not exceed 2.5 mm in deviation from a flat plane, tested in line with IS 3495 (Part 4). Additionally, bricks must be free from cracks and flaws, maintain plane rectangular faces, parallel sides, and sharp, right-angled edges to guarantee proper alignment and durability in exposed masonry.

?What marking is required on bricks under IS 2691, and what does the Standard Mark represent?▼

Each brick must carry the manufacturer's identification mark or initials. Optionally, bricks can also bear the BIS Standard Mark, indicating compliance with IS 2691 standards and that production is under a regulated quality control and inspection system supervised by the Bureau of Indian Standards. The Standard Mark usage is license-controlled under the BIS Act 1986 and assures ongoing conformity and traceability.

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