The good bricks which are used for the construction of important structures should possess the following qualities:
1- The bricks should be table-moulded. well burnt in kilns, Copper-coloured, free from cracks and with sharp and square-edged. The colour should be uniform and bright.
2- The brick should be uniform in shape and should be of standard size.
3- The brick should give clear metallic ringing sound when struck with each other.
4- the bricks when broken or fractured should show a bright homogeneous and uniform compact structure free from voids.
5- The brick should not absorb water more than 20% by weight for first-class bricks and 22% by weight for second class bricks when soaked in cold water for a period of 24 hours.
6- No brick should have crushing strength below than 5.50 N/mm²
7- The brick, when soaked in water for 24 hours, should not show deposits of white salt when allowed to dry in shade.
8- It should not break into pieces when dropped flat on the hard ground from a height of about one meter.
9- It should be sufficiently hard. No impression should be left on the brick surface when it.
10- It should have low thermal conductivity and it should be soundproof.