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IS 5779:1986 is the Indian Standard (BIS) for burnt clay soling bricks - specification. This standard specifies the requirements for burnt clay soling bricks, which are used as a base course for ground floors and pavements. It covers classification (Class A and B), dimensions, tolerances, and physical characteristics such as compressive strength, water absorption, and efflorescence.
burnt clay soling 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
! Soling bricks are primarily used to create a firm, level base over compacted earth, not for structural masonry walls. Use IS 1077 bricks for walls.
! Class A bricks are stronger and less absorbent, making them suitable for industrial floors or areas with potential dampness. Class B is adequate for most residential floors.
! Ensure bricks are laid flat (soling) and tightly packed, with joints completely filled with coarse sand or a lean mortar mix to provide a stable sub-base.
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
burnt claybricksolingflooring base
International Equivalents
Similar International Standards
ASTM C902-20ASTM International, USA
HighCurrent
Standard Specification for Pedestrian and Light Traffic Paving Brick
Covers bricks intended for use as a paving material, a very similar application to soling.
BS EN 771-1:2011+A1:2015BSI / CEN, UK / Europe
MediumCurrent
Specification for masonry units - Part 1: Clay masonry units
A broad standard for all clay masonry; bricks suitable for soling would be a specific class within it.
ASTM C62-17ASTM International, USA
MediumCurrent
Standard Specification for Building Brick (Solid Masonry Units Made From Clay or Shale)
Covers general-purpose building bricks; its highest grade (SW, Severe Weathering) has properties suitable for ground contact.
BS 3921:1985British Standards Institution (BSI), UK
HighWithdrawn
Specification for Clay Bricks
The historical British equivalent which had specific classes (e.g., Engineering Bricks) used for similar purposes as soling.
Key Differences
≠IS 5779 specifies a single class of brick, whereas international standards like ASTM C902 have multiple classes and types based on traffic and exposure (e.g., Class PX, PS, PA; Type I, II, III).
≠The minimum compressive strength required by IS 5779 (5 N/mm²) is significantly lower than that required for comparable applications in international standards, such as ASTM C902 which requires over 55 N/mm² for its highest class.
≠IS 5779 does not include a requirement for freeze-thaw resistance, which is a critical parameter in ASTM and EN standards for bricks used in exterior, ground-contact applications in colder climates.
≠Water absorption testing methods and limits differ. IS 5779 specifies a 24-hour cold water immersion test with a 20% limit, while ASTM standards often use a 5-hour boiling test, which is more severe and has stricter limits (e.g., ~8%).
Key Similarities
≈All standards are based on burnt clay, shale, or similar ceramic materials as the primary constituent.
≈All standards specify controls on dimensional tolerances and warpage (concavity/convexity) to ensure the units can be laid flat and uniformly.
≈Compressive strength and water absorption are used as fundamental criteria for quality and durability assessment across all the standards.
≈The presence of an efflorescence test is common to assess the potential for soluble salts to mar the appearance, even though rating criteria may differ slightly.
Parameter Comparison
Parameter
IS Value
International
Source
Minimum Average Compressive Strength
≥ 5.0 N/mm² (50 kgf/cm²)
≥ 55.2 N/mm² (8000 psi)
ASTM C902 (Class PX)
Maximum Water Absorption (by weight)
≤ 20% (24-hour cold immersion)
≤ 8% (5-hour boil)
ASTM C902 (via ASTM C67 test)
Efflorescence Rating
Not to exceed 'Slight'
Typically 'Not Effloresced' for high-grade applications
ASTM C67 (Test for C902/C62)
Freeze-Thaw Resistance
Not specified
Required; must pass 50 cycles with minimal mass loss
ASTM C902
Dimensional Tolerance (Length)
± 8 mm (for 190 mm nominal length)
± 3.2 mm (1/8 in)
ASTM C902
Standard Sizes (mm)
190 x 90 x 90 OR 190 x 90 x 40
No single standard; specified by manufacturer (e.g., nominal 100 x 200)
ASTM C902
⚠ Verify details from original standards before use
Key Values7
Quick Reference Values
Standard Brick Size 1190 x 90 x 90 mm
Standard Brick Size 2190 x 90 x 40 mm
Min. Compressive Strength (Class A)5.0 N/mm²
Min. Compressive Strength (Class B)3.5 N/mm²
Max. Water Absorption (Class A)20 % by weight
Max. Water Absorption (Class B)25 % by weight
Efflorescence RatingSlight to Moderate
Tables & Referenced Sections
Key Tables
Table 1 - Dimensions and Tolerances for Burnt Clay Soling Bricks
Table 2 - Physical Requirements for Burnt Clay Soling Bricks
What is the difference between Class A and Class B soling bricks?+
Class A has a higher minimum average compressive strength (5.0 N/mm²) and lower maximum water absorption (20%) than Class B (3.5 N/mm² and 25% respectively), as per Table 2.
What are the standard dimensions of a soling brick?+
The standard modular sizes are 190 x 90 x 90 mm and 190 x 90 x 40 mm, as specified in Clause 4.1.
Can soling bricks be used for building walls?+
No, they are not intended for load-bearing or non-load-bearing masonry. Their primary use is as a base course for floors and pavements.
How is the quality of soling bricks checked on site?+
Visually check for uniform shape, size, and colour. Tap two bricks together; a clear ringing sound indicates good quality, while a dull thud suggests defects. Laboratory tests for strength and absorption are required for formal acceptance as per Clause 8.