Development of Draft Protocol for Testing of Structural Components and Systems

(a joint initiative of MoHUPA under technology submission of Pradhan Mantri Awas Yojna & IIT, KANPUR)

Common Burnt Clay Building Bricks

Common burnt clay bricks are the oldest and most extensively used construction material. It is used in constructing a variety of structural members like masonry walls, foundation, columns etc. A common clay brick manufacturing, dimensions and physical requirements shall conform to IS 1077: 1992, and are given as below:

  1. Classification
  2. Burnt clay fly ash bricks are classified on basis of average compressive strength.

    Table 1: Classes of burnt clay fly ash bricks (As per IS 1077: 1992)

  3. General Quality
  4. Bricks should be hand or machine molded and made of admixture of suitable soils. Bricks should be uniformly burnt, free from cracks and flaws such as nodules of stone, black coring and organic matter. Frog dimensions should same for both modular and non modular size bricks. Frog dimension should be either 10 or 20mm for and hand molded bricks of 90 or 70 mm height. No frog is provided for bricks of height 30 or 40 mm and for bricks made by extrusion process. Smooth rectangular faces with sharp corner should be provided to the bricks along with uniform color and shape.

  5. Dimensions:
  6. Dimension of modular bricks should be as follows:
       Length(mm)       Width (mm)       Height (mm)
        190                        90                       90
        190                        90                       40
    Non modular bricks of following size may also be used:
        230                        110                       70
        230                        110                       30
    Following sizes of non modular brick may also be used to obtain proper bond agreement and modular dimension for brickwork:
        70                        110                       280/3

  7. Tolerance
  8. Randomly select 20 bricks (or more according to the size of the stack) from the selected sample. Arrange these bricks on as level surface successively as depicted in 2A, 2B and 2C. Measure overall length of the assembly with a sufficiently long steel tape or with help of some other inextensible measure. If measurement of bricks in one row is not possible for some reason; sample may be divided into rows of 10 bricks and measurement should be done to the nearest millimeter. For modular size bricks (90mm high) the width and height should be 1800±40mm and length should be 3800±80mm. For 40mm high bricks the height should be 800±40mm, width and length should remain same as for 90mm high bricks. For non modular size bricks (70mm high) the length should be 4600±80mm and width should be 2200±40mm and height should be 1400±40mm. For 30mm high bricks the height should be 600±40mm, length and width should remain same.

    Figure 1

    Source: IS 1077: 1992
  9. Physical properties
  10. Bricks should have minimum compressive strength as mentioned in Table 1 for respective class when tested according to IS 3495 (1): 1992. Water absorption (IS 3495 (2): 1992) of bricks should not be more than 20% by weight up to class 12.5 and 15% for higher classes when bricks are immersed in cold water for 24 hours. Efflorescence (IS 3495 (3): 1992) should not be more than ‘moderate’ for class up to 12.5 and ‘slight’ for higher classes.

  11. Sampling and criterion for conformity:
  12. It should be in accordance with IS 5454: 1978.
For more information, refer to IS 1077: 1992.