Table of Contents
Classification and Characteristics of Bricks as per IS 1077-1973
Tests for the acceptance of bricks for building construction are:
- Dimension and tolerance test
- Compressive strength test
- Water absorption test
- Efflorescence test
1. Dimension and Tolerance Test on Bricks
Take 20 bricks out of given sample. The dimensions of 20 bricks should be within the following limits.
|Class A||380 +/- 12mm i.e.|
368 to 392 mm
|180 +/- 6mm, i.e. 174 to 186 mm||174 to 186 mm|
|Class B||380 +/- 30mm, i.e. 350 t0 410 mm||80 +/- 15mm, i.e. 165 to 195 mm||165 to 95 mm|
The compressive strength of a common brick should be 50 kg/sq.cm
If the water absorption capacity of a brick is more, its strength will be comparatively low. For first class bricks, the water absorption capacity should not be more than 20% by weight.
4. Efflorescence Test on Bricks
This test is performed to know the presence of of any alkaline matter in the bricks.
- Take five bricks at random from the given sample.
- Place each brick on end in a dish containing distilled water ensuring depth immersion at least 2.5cm.
- Keep the dish in a ventilated room (temperature 20 deg to 30 deg C) till the whole of distilled water in the dish evaporates.
- Again pore 2.5 cm depth of distilled water in the dish and keep it till whole of water gets evaporated.
- Now examine the bricks for efflorescence as detailed below:
|No perceptible deposit||Nil – efflorescence|
|10% are covered with deposit of salts||Slight – efflorescence|
|50% area covered with deposits of salts without any powdering or flaking surface||Moderate – efflorescence|
|50 % area covered with deposit of salts accompanied by flaking of surface||Heavy – efflorescence|
|Heavy deposits of salts accompanied by flaking of the surface||Serious – efflorescence|
Terra Cotta made from a mixture of fine clay 60%, crushed pottery 20%, while sand 14% and powdered glass 6% with a quantity of desired colouring substance. It is baked earth of superior variety of clay.
Terra-cotta is used for architectural and ornamental parts of superior building as a substitute for stones. It is used as sound proof material and its hollow blocks prevent dampness in the structure.