What type of mortar should be used for AAC block masonry?

Either a special thin-bed mortar (2-3mm thick) or conventional cement mortar of Grade M1 (1:1:6 Cement:Lime:Sand) or M2 (1:2:9) as per Table 2.

Do AAC block walls need to be cured after construction?

Yes, the masonry should be kept moist for at least 7 days to allow the mortar to cure properly and gain strength (Clause 5.5).

What is the maximum slenderness ratio for a load-bearing AAC wall?

For a wall in a building of one or two storeys, the slenderness ratio (effective height / effective thickness) shall not exceed 27 (Clause 6.4.1.1).

How much should an AAC block wall be supported on a concrete slab or beam?

The masonry wall should have a bearing of at least two-thirds of the thickness of the wall on the support, provided it is not less than 85 mm (Clause 6.3.1).

IS 6441 Part 2

: 1997

Autoclaved Cellular Concrete Blocks for Masonry - Part 2: Code of practice for use of AAC blocks

CurrentFrequently UsedCode of PracticeBIMStructural Engineering · Masonry and Bricks

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This code of practice outlines the requirements for the construction of masonry using Autoclaved Aerated Concrete (AAC) blocks. It covers specifications for mortar, workmanship procedures for laying and jointing, and structural design considerations including permissible stresses, stability, and crack control for both load-bearing and non-load-bearing walls.

Provides guidelines and recommendations for the design and construction using AAC blocks.

Quick Reference Values

Minimum curing period for masonry7 days (moist cured)

Thin-bed mortar joint thickness2 to 3 mm

Max slenderness ratio (load bearing, up to 2 storeys)27

Permissible axial compression (3N/mm² block, h/t=6)0.38 N/mm²

Typical cement mortar mix ratio (M1 Grade)1:1:6 (Cement:Lime:Sand)

Practical Notes

Pre-wetting of AAC blocks is essential to prevent rapid water absorption from the mortar, but they should not be saturated. A light sprinkle or quick dip is sufficient.

The use of manufacturer-recommended thin-bed adhesive mortar (2-3 mm thick) is highly preferred over traditional cement mortar for better dimensional accuracy, reduced dead load, and improved thermal insulation.

For cutting blocks and chasing for electrical/plumbing conduits, use a hand saw or a power tool with a masonry blade instead of a hammer and chisel to avoid damaging the blocks.