Best bricks should have the following characteristics:
- Uniform Shape, Size, and Colour
Low-quality bricks not only affect the load bearing capacity of the wall but also the aesthetic appearance.
It should be well burnt and in uniform shape.
It should be uniform sized. No bulks on any side.
It should be in a uniform color. Mostly in deep red or copper. Any Other colors are the indication of under burnt or over burnt.
Should be free from cracks.
Should be sharply defined at edges.
- Dimensional Accuracy
Quality bricks should have an accurate dimension. +or- 3mm tolerance should be allowed.
Bricks are more economic material in construction. If we use low-quality bricks (uneven & bulky), we have to overcome the defects while plastering the work. Compared to brickwork plastering is costlier. Then the ultimate goal (economic) of using bricks as building components will fail at this moment.
Good quality bricks should be hard. There should be no impression left when you try to make a scratch with your fingernails
It should give clear ringing sound when struck with each other
It should not break when you drop it from 1.2 meter – 1.5-meter height on the hard ground (concrete floor) or on another brick.
- Water Absorption
Water absorption should not be more than 20% of its dry weight after immersion in water for 1 hour. If the bricks tend to absorb more water than this allowable limit. It will start to absorb the water from the cement mortar while construction. It will affect the strength of the brick bonds.
First, weigh the dry bricks and note down it as W1 (Kg)
Second, immerse the brick into water for 1 hour
Third, remove the brick from the water and weigh it and note down it as W2 (Kg)
Water Absorption = (W2 – W1) / W1 X 100
Note – In the lab, it should be allowed to immerse in water for at least 24 hours.
The permissible limit of absorption is 20% maximum. It should vary based on brick classes.
This is actually not a field test. But it is essential to know.
We can identify the defects by visual. If you see lots of white patches on the bricks (known as efflorescence) then the brick should be avoided. This is because the bricks are containing more amount of sodium and potassium salt.
Info – Bricks should be free from harmful salts (Sodium and Potassium). If we use these types of bricks in construction, the salt present in the bricks got dissolved while mixing with water and cause structural damage.