Should concrete blocks be soaked in water before construction?

No. Concrete blocks should not be soaked. Only slight moistening of the laying surface is permitted in very dry climates to prevent the block from absorbing too much water from the mortar.

What is the recommended thickness for mortar joints in block masonry?

The recommended thickness for both horizontal and vertical mortar joints is 10 mm.

Which code should be used for the structural design of block masonry?

IS 1905 is used for structural design considerations, while IS 2572 covers the construction practices.

How long should concrete block masonry be cured?

The masonry should be kept moist for a minimum period of 7 days after construction.

IS 2572

: 2005

Construction of hollow and solid concrete block masonry - Code of practice

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This standard provides comprehensive guidelines for the construction of load-bearing and non-load-bearing walls using solid and hollow concrete blocks. It outlines procedures for material selection, mortar proportioning, block laying techniques, jointing, and curing to ensure structural stability and mitigate shrinkage cracks.

Construction of hollow and solid concrete block masonry - Code of practice

Quick Reference Values

standard mortar joint thickness10 mm

minimum curing period7 days

interval before plastering3 to 4 weeks (to allow for initial shrinkage)

vertical joint staggering minimumOne-quarter of the block length

Practical Notes

Unlike clay bricks, concrete blocks must NOT be soaked in water before laying to prevent excessive drying shrinkage and subsequent wall cracking.

For hollow blocks, mortar is typically applied only to the face shells (face-shell bedding) rather than the cross webs, saving mortar and reducing thermal bridging.

Allow a sufficient time gap (preferably 3 to 4 weeks) after construction before applying plaster, so the masonry can undergo initial drying shrinkage.