What is the standard size of calcium silicate bricks as per IS 4139?

Modular sizes are 190 x 90 x 90 mm and 190 x 90 x 40 mm. Non-modular sizes like 230 x 110 x 75 mm are also permitted.

What is the maximum permissible water absorption?

20 percent by mass after 24 hours of immersion in cold water.

How is the class of the brick determined?

The class designation corresponds to the minimum average compressive strength in N/mm² (e.g., Class 10 has a minimum strength of 10 N/mm²).

IS 4139

: 1989

calcium silicate bricks

CurrentSpecializedSpecificationMaterials Science · Building Limes and Gypsum Products

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This standard specifies the requirements, dimensions, physical properties, and testing protocols for calcium silicate bricks (sand-lime and fly ash-lime bricks) used in building construction.

calcium silicate bricks

Quick Reference Values

Standard modular size190 x 90 x 90 mm or 190 x 90 x 40 mm

Standard non-modular size230 x 110 x 75 mm or 230 x 110 x 30 mm

Maximum water absorption20% by mass

Minimum compressive strength range7.5 to 35.0 N/mm² based on class

Practical Notes

Calcium silicate bricks have precise dimensions and smooth finishes, often eliminating the need for exterior plastering.

Unlike burnt clay bricks, calcium silicate bricks should not be thoroughly soaked in water before masonry work to minimize drying shrinkage; they should only be lightly moistened.