The clay have bulk Specific Gravity in range of 1.6- 2.5.
These bricks are widely in use because of economically they are cheap and are easy to do work with.
To get the quality of the work, the quality of brick should be maintained. For which we conduct different tests on the bricks.
For conducting the test, Bricks are picked on a random manner in a lot of
No of Bricks picked randomly (no’s) | Bricks taken from stack of (no’s) |
1) 20 | 2000-10000 Brick stack |
2) 32 | 10000 - 35000 Brick stack |
3) 50 | 35000-50000 brick stack |
Note - In the case of bricks less than 2000 no’s , The number of bricks taken for sample for the test should be taken between the mutual understanding of the contractor and the purchaser.
Different Testing Of Bricks
1) Water Absorption Test
(a) 5 Hours boiling Water test
- In this test firstly we take random 10 specimen (brick) and Dry each of them inside the Ventilated Drying Oven which maintains the temperature in the range of 110–1150C.The time usually takes in drying process is near about 48hrs.
- These bricks are cooled down and later the weight is taken.
- After the weight is taken, the specimens are immersed inside the tank filled with water, with a proper arrangement of maintaining a gap of 10 mm between the bricks so as there will be proper water circulation between the gaps of the bricks.
- The water is than boiled to for continuous 5 hrs and later the bricks are taken out and are cooled in the natural manner at room temperature, which usually takes a time of 16-19 hrs in cooling.
- After cooling, Specimen is wiped with a clean cloth and within 2 minutes, the bricks are weighted and the water absorption is find out.
(b) 24 Hours Immersed Water test
(i) The test is conducted to find out the strength of the brick,or the class of brick based on its absorption capacity. The Classification of bricks you can find here.
(ii) Bricks are immersed inside the water for 24 hours in this test.
(iii) The more the absorption will take in the brick. The faster the brick will loose its strength.
(iv) This test is conducted by keeping the temperature of water of +/- 270C
Brick Class | Water Absorption |
1) First Class Brick | 12% to 15% |
2) Second Class Brick | 16% to 20% |
3) Third Class Brick | 20% to 25% |
2) Compressive Strength Test
Compression Strength test is a method in which the compressive strength of the brick is found out.14 N/mm2 constant load is applied to the brick until failure in the brick is observed.
(i) The process is carried out by firstly immersing the brick in water for about 24hrs. After that the brick is taken out and the frogs on the bricks are filled with cement mortar in a ratio of 1 part of cement and 1.5 part of sand.The bricks are than kept for 24 hrs in area where the mortar can get water for the setting purpose and later they are immersed in water for another 6 days.
(ii) Now already the mortar achieve its strength in the time period of 7 days, the bricks are taken out and cleaned with dry cloth and later ready for the Compressive strength test.
(iii) The compressive test is found out with the formula
3) Warpage Test
Warpage mean checking out or observing the specimen on the basis of the twists or defects on the surface of the specimen.
For a brick it can be said as, it is the greatest distance in the brick from one point to the other point in as straight line with no single defect or twist.
The warpage of the speciment or the bricks are measured in a mesuring tool as a ruler shown in the image below.
The Warpage is measured in two types based on the physical characteristic of the brick which are
 |
| Concave & Convex Warpage |
(i) Concave Warpage.
(ii) Convex Warpage.
We will now take about how they work to find out the defect in the brick.
Concave Warpage
In the concave warpage method, the brick is rested on the surface of warpage, as shown in the photo above. After that the distance is measured from one corner of the brick to the point where the concave deflection of the brick starts.
Convex Warpage
In convex warpage method,the brick is placed in such a manner that the brick surface is kept on the plane surface and the convex defect of the brick at plane surface.
The Flat distance of the bricks in both the method determine the warpage of the brick.
4) Efflorescence test
The test is basically conducted to check out the alkalies present inside the bricks
Alkalis | They are normally present of about less than 10% of of brick composition. | The excess of them causes efflorescence in the brick which results in making the brick clay unstable. |
The process of this test is,
We take a dish of 150mm, and fill the dish with water upto 25mm. Now the brick is inside the dish and made the brick absorb all the water on the dish until the dish gets dry or the water gets evaporate.
Now again the same process is executed of filling the water till 25mm dept upto the absorption limit of brick and after this second time they are tested.
We classify the brick after test on the basis of
Classification of Bricks | % of Efflorescence |
Nil | Visual deposits are not observed |
Slight | < 10% |
Moderate | 10-50% |
Heavy | >50% |
Serious | Heavy & powdered |
5) Soundness Test
The test is widely used in field in which two bricks are taken randomly from the stack and are made to hit them with each other. If we observe the sound coming out of the bricks are kind of metallic sound, than they are considered to be good quality bricks.
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