What is the recommended mortar mix for general AAC block masonry?

A cement-sand mix of 1:6 by volume is recommended for general work. For load-bearing walls, a richer mix like 1:4 may be required (Table 1).

Do AAC blocks need to be wet before laying?

Yes, the blocks should be dipped in water for a moment just before being laid to ensure the surfaces are well wetted (Clause 5.3).

What is the maximum permissible thickness for mortar joints?

The thickness of both bed and vertical joints should not exceed 15 mm (Clause 5.4.2).

How long should AAC block masonry be cured?

The masonry should be kept moist on all faces for a minimum period of 7 days to allow the mortar to cure properly (Clause 5.7).

IS 6041

: 1985

Code of practice for construction of autoclaved cellular concrete block masonry

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This code provides guidelines for the construction of masonry using autoclaved cellular concrete (AAC) blocks. It covers the specifications for materials like blocks and mortar, and details the workmanship including block laying, jointing, and curing to ensure quality construction.

Code of practice for construction of autoclaved cellular concrete block masonry

Quick Reference Values

General purpose cement-sand mortar ratio (by volume)1:6

Maximum mortar joint thickness15 mm

Minimum curing period for masonry7 days

Maximum height of masonry to be built at a time1 m

Practical Notes

Unlike clay bricks, AAC blocks should not be soaked for long periods. A quick dip in water just before laying is sufficient to prevent rapid water absorption from the mortar.

AAC blocks are relatively brittle and can chip easily; careful handling is required on-site to minimize wastage and ensure clean edges for proper jointing.

While this code specifies traditional cement-sand mortar, modern practice often involves using pre-mixed thin-bed block jointing mortar for better adhesion, faster construction, and improved thermal performance.