How are bricks classified according to IS 3102?

They are classified strictly by their minimum average compressive strength in kg/cm2, ranging from Class 35 to Class 350.

What does a Class 75 brick denote?

It indicates a solid burnt clay brick with a minimum average compressive strength of 75 kg/cm2 (approximately 7.5 MPa).

Does this standard apply to hollow or perforated bricks?

No, IS 3102 applies exclusively to burnt clay solid bricks.

IS 3102

: 1971

Classification of Burnt Clay Solid Bricks

CurrentFrequently UsedSpecificationMaterials Science · Masonry and Bricks

Archive.org BIS Portal Google

This standard classifies burnt clay solid bricks based on their average compressive strength. It provides a numerical classification system (ranging from Class 35 to Class 350) to replace older descriptive grading systems, ensuring standardized brick specification for structural and non-structural masonry work.

Lays down the classification of burnt clay solid bricks based on their compressive strength.

Quick Reference Values

Class 35 minimum average compressive strength35 kg/cm2 (~3.5 N/mm2)

Class 50 minimum average compressive strength50 kg/cm2 (~5.0 N/mm2)

Class 75 minimum average compressive strength75 kg/cm2 (~7.5 N/mm2)

Class 100 minimum average compressive strength100 kg/cm2 (~10.0 N/mm2)

Class 350 minimum average compressive strength350 kg/cm2 (~35.0 N/mm2)

Practical Notes

Avoid using outdated descriptive terms like 'First Class' or 'Second Class' bricks in BOQs and specifications; always use the specific strength-based classes (e.g., Class 75) defined in this code.

The class number directly corresponds to the minimum average compressive strength of the brick in kg/cm2.

Actual testing to verify the classification must be conducted in accordance with IS 3495.