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IS 3068:1986 is the Indian Standard (BIS) for broken brick (burnt clay) coarse aggregates for use in lime concrete. This standard specifies the requirements for coarse aggregates derived from broken burnt clay bricks (brick bats) intended for use in lime concrete. It covers physical properties, grading limits, water absorption restrictions, and limits on deleterious materials to ensure the durability of lime-based foundation and terracing concrete.
broken brick (burnt clay) coarse aggregates for use in lime concrete
Overview
Status
Current
Usage level
Rare
Domain
Materials Science — Building Limes and Gypsum Products
! Brick aggregates are highly porous; they must be thoroughly pre-soaked in water before mixing to prevent them from absorbing mixing water from the lime concrete, which would hinder the chemical setting process.
! Under-burnt or over-burnt (vitrified) bricks should be strictly rejected as they compromise the strength and weather resistance of the lime concrete mix.
! Though rarely used in modern reinforced concrete, this standard is vital for heritage building conservation, restoration work, and traditional roof terracing (e.g., Madras terrace).
BS EN 12620:2002+A1:2008BSI / CEN (British Standards Institution / European Committee for Standardization), UK/Europe
MediumCurrent
Aggregates for concrete
Covers requirements for coarse aggregates, including recycled aggregates from masonry, for use in concrete.
DIN 4226-100:2002-06DIN (Deutsches Institut für Normung), Germany
HighCurrent
Aggregates for concrete and mortar - Part 100: Recycled aggregates
Specifically addresses recycled aggregates, with classifications based on source material, including masonry/brick.
ASTM C33 / C33M - 18ASTM International, USA
LowCurrent
Standard Specification for Concrete Aggregates
Primary US standard for concrete aggregates; while it focuses on natural aggregates, it's the framework under which recycled materials are evaluated.
BS EN 13055:2016BSI / CEN (British Standards Institution / European Committee for Standardization), UK/Europe
LowCurrent
Lightweight aggregates
Covers manufactured lightweight aggregates made from expanded clay, which is a technologically related material to burnt clay bricks.
Key Differences
≠IS 3068 is specific to lime concrete, a traditional binder, while modern international standards are exclusively developed for use with Portland cement concrete.
≠IS 3068 treats broken brick as a primary, stand-alone aggregate type. International standards classify it as a 'recycled aggregate', often limiting its percentage in structural concrete.
≠The Indian standard specifies the Aggregate Crushing Value (ACV) for mechanical strength. European standards (e.g., EN 12620) primarily use the Los Angeles (LA) abrasion test for resistance to fragmentation.
≠International standards like EN 12620 have detailed categorizations for recycled aggregates based on the percentage of constituent materials (e.g., concrete, brick, asphalt), which is absent in IS 3068.
Key Similarities
≈All standards mandate grading requirements through sieve analysis to ensure a suitable particle size distribution for workable and dense concrete.
≈Both IS 3068 and international counterparts impose limits on deleterious materials like clay, silt, dust, and organic matter to ensure durability and proper bonding.
≈The principle of defining nominal aggregate sizes (e.g., 40 mm, 20 mm) is common across all standards to facilitate concrete mix design.
≈Testing for water absorption is a common requirement, as it critically affects the water-binder ratio and workability of the fresh concrete mix.
Parameter Comparison
Parameter
IS Value
International
Source
Water Absorption
≤ 25.0 % by weight
No absolute limit; must be declared. Values for recycled brick aggregate are typically high (e.g., 10-20%).
BS EN 12620
Aggregate Crushing Value (ACV)
≤ 45 %
ACV test is not primary. Equivalent Los Angeles (LA) value is used. For brick aggregate, LA > 40 would be typical (Category LA40 or higher).
BS EN 12620
Sulphate Content (Acid-soluble SO3)
≤ 1.0 %
Categorized, e.g., Category AS0.8 (≤ 0.8%). The 1.0% limit in IS 3068 is higher than the common international categories.
BS EN 12620
Fines Content (< 0.075 mm Sieve)
≤ 5.0 %
Categorized, e.g., Category f3 (≤ 3%) or f7 (≤ 7%) for recycled aggregates. The IS limit falls within this range.
BS EN 12620
Grading (40 mm Nominal Size, % passing 20 mm sieve)
25 - 55 %
Varies by grading curve, e.g., 0-20% for Gc 85/20 or 25-70% for a broader Gc 80/20 grading.
BS EN 12620
⚠ Verify details from original standards before use
Key Values3
Quick Reference Values
Maximum Water Absorption25% by mass after 24 hours of soaking
Fines passing 4.75 mm IS SieveMaximum 10% by weight
Standard nominal maximum size40 mm
Tables & Referenced Sections
Key Tables
Table 1 - Grading Requirements for Broken Brick Coarse Aggregates