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IS 13757:1993 is the Indian Standard (BIS) for burnt clay fly ash building bricks-specification. This standard specifies the requirements for dimensions, classification, physical properties, and testing of burnt clay bricks containing at least 25% fly ash. It covers crucial quality aspects like compressive strength, water absorption, and efflorescence for bricks used in masonry construction.
Burnt clay fly ash building bricks-Specification
Overview
Status
Current
Usage level
Frequently Used
Domain
Materials Science — Clay and Stabilized Soil Products
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! The use of fly ash is an environmentally friendly way to utilize industrial waste, often resulting in bricks with better finish and lower water absorption than traditional clay bricks.
! Always verify test certificates from the manufacturer for compressive strength and water absorption, as quality can vary significantly.
! For exposed brickwork, it is advisable to specify and select bricks with a 'Slight' or 'Nil' efflorescence rating, even though the standard permits 'Moderate'.
BS EN 771-1:2011+A1:2015BSI (British Standards Institution), UK / CEN (European Committee for Standardization), Europe
HighCurrent
Specification for masonry units - Part 1: Clay masonry units
Specifies requirements for clay masonry units, allowing for additives like fly ash for use in all forms of masonry.
ASTM C62-17ASTM International, USA
MediumCurrent
Standard Specification for Building Brick (Solid Masonry Units Made From Clay or Shale)
Covers solid bricks made from fired clay or shale, but does not explicitly mandate or focus on fly ash content.
AS/NZS 4455.1:2008Standards Australia / Standards New Zealand
MediumCurrent
Masonry units, pavers, flags and segmental retaining wall units - Part 1: Masonry units
Specifies requirements for clay and concrete masonry units, with provisions for durability and strength similar to the IS code.
Key Differences
≠The primary difference is the mandatory use of fly ash. IS 13757 requires a minimum of 25% fly ash content by mass, promoting waste utilization. Most international standards like EN 771-1 and ASTM C62 permit additives but do not mandate fly ash.
≠IS 13757 uses a prescriptive classification system based on minimum compressive strength (e.g., Class 10 for 10 N/mm²). In contrast, EN 771-1 uses a system of declared values by the manufacturer for strength, tolerances, and other properties.
≠The classification of bricks by ASTM C62 is primarily based on weathering resistance (Grades SW, MW, NW), which relates to durability in freezing climates. IS 13757 classification is solely based on compressive strength.
≠Dimensional tolerance requirements in IS 13757 are fixed percentage limits based on the brick class. EN 771-1 offers tolerance categories (e.g., T1, T2, Tm) that the manufacturer can choose to declare, providing more flexibility.
Key Similarities
≈All standards are fundamentally for burnt clay masonry units, where the primary raw material is clay or shale that is formed and fired in a kiln.
≈Core performance characteristics such as compressive strength, water absorption, and dimensional stability are specified in all standards as critical parameters for quality and structural suitability.
≈The underlying principles for key test methods are consistent, such as crushing samples for compressive strength and immersion-based methods for determining water absorption.
≈All standards include requirements to control deleterious materials and impurities. For example, IS 13757 includes a test for lime blowing, which is a durability concern also addressed by general soundness requirements in other standards.
Parameter Comparison
Parameter
IS Value
International
Source
Fly Ash Content
Minimum 25% by mass of total dry material.
Not a specified requirement. Permitted as a body modifier or pore-forming material, but no minimum content is mandated.
BS EN 771-1:2011+A1:2015
Minimum Compressive Strength (Average)
Defined by class designation (e.g., Class 7.5 = 7.5 N/mm²; Class 10 = 10 N/mm²).