QUALITY REQUIREMENTS OF COMMON BURNT CLAY BUILDING BRICKS
1. General Quality
- Bricks shall be free from cracks and flaws and nodules of free lime.
- Bricks shall have smooth rectangular faces with sharp corners
- Bricks shall be uniform in colour
- Frog size of a hand moulded brick having height of 90 mm or 70 mm shall be as per the figure shown below.
2. Dimensional Specification
Bricks can be of modular size or non-modular size. The size of individual brick must conform to the dimensions as given in the following table.
| Dimension for Modular Bricks | ||
| Length (L), mm | Width (W), mm | Height (H), mm |
| 190 | 90 | 90 |
| 190 | 90 | 40 |
| Dimension for Non-Modular Bricks | ||
| Length (L), mm | Width (W), mm | Height (H), mm |
| 230 | 110 | 70 |
| 230 | 110 | 30 |
3. Physical Requirements
When common clay building bricks are tested for its physical characteristics, they should satisfy the following quality requirements, as given in the table below.
| Compressive Strength | Compressive strength of any individual brick shall not be less than the minimum compressive strength for the corresponding class of brick. (See table below) |
| Water Absorption | Shall not be more than 20% by weight up to class 12.5 and 15% by weight for higher classes. |
| Efflorescence | Shall not be more than ‘moderate’ up to class 12.5 and ‘slight’ for higher class. |
4. Classes of Common Burnt Clay Bricks
On the basis of its average compressive strength, bricks are classified into following classes as shown in the table below. When tested for compressive strength test, brick should fall into any of the following classes.
| Class Designation | Average Compressive Strength | |
| N/mm2 | Kgf/cm2, (approx) | |
| 35 | 35 | 350 |
| 30 | 30 | 300 |
| 25 | 25 | 250 |
| 20 | 20 | 200 |
| 17.5 | 17.5 | 175 |
| 15 | 15 | 150 |
| 12.5 | 12.5 | 125 |
| 10 | 10 | 100 |
| 7.5 | 7.5 | 75 |
| 5 | 5 | 50 |
| 3.5 | 3.5 | 35 |
Reference
IS: 1077-1992
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