Is this standard still in use?

No, IS 6441 (Part 1) has been withdrawn and superseded by IS 2185 (Part 3):2008.

What is the maximum allowed drying shrinkage for AAC blocks?

The maximum average drying shrinkage is 0.05 percent as per Clause 7.3.

What is the minimum compressive strength for Grade I AAC blocks?

The minimum average compressive strength is 3.0 N/mm² for blocks in the 651-750 kg/m³ density range (Table 3).

What is the tolerance on the length of a 500mm long AAC block?

The tolerance on length is ± 3 mm, as per Table 2.

IS 6441 Part 1

: 1998

Autoclaved Cellular Concrete Blocks for Masonry - Part 1: Specifications

CurrentSpecializedSpecificationBIMMaterials Science · Masonry and Bricks

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This standard specifies the requirements for autoclaved aerated concrete (AAC) blocks for use in masonry. It covers materials, dimensions, tolerances, classification based on density, and key physical properties like compressive strength and drying shrinkage. It also outlines methods for sampling and testing to ensure conformity.

Specifies dimensions, quality, and physical requirements for autoclaved cellular concrete (AAC) blocks.

Quick Reference Values

Maximum drying shrinkage0.05 %

Minimum average compressive strength (Grade I)3.0 N/mm²

Minimum average compressive strength (Grade II)2.0 N/mm²

Tolerance on length (up to 600mm)± 3 mm

Tolerance on height/width (up to 300mm)± 3 mm

Density range for Grade I651-750 kg/m³

Density range for Grade II551-650 kg/m³

Practical Notes

This standard is WITHDRAWN. Users must refer to its replacement, IS 2185 (Part 3):2008, for current specifications.

AAC blocks are lightweight and offer excellent thermal insulation but have lower compressive strength compared to dense concrete blocks, which must be accounted for in structural design.

Due to their porosity, AAC blocks are highly absorbent. They should be protected from rain during storage and construction, and may require wetting before mortar application to prevent rapid water loss from the mortar.