Tests on Bricks

Tests on Bricks 

Bricks are artificial stones, these are usually made of clay. These are used in building construction and for monumental purposes. These are one of the basic material used for wall construction. These are easily available cheap and light-weighted. Different types of bricks can be manufactured from different material such as mud bricks, refractory bricks, silica bricks, cement and bricks, fire bricks etc.
              A brick undergoes following tests to find out its suitability for the construction work :

  1. Crushing Strength Test
  2. Water Absorption Test
  3. Presence of Soluble salts or Efflorescence Test
  4. Hardness Test
  5. Shape and Size Test
  6. Soundness Test
  7. Structure Test
  8. Colour Test
  9.  Impact Test

Tests on Bricks

1. Crushing Strength Test :

The minimum crushing strength of brick should be 105 kg/cm2. The crushing strength of brick can found out with the help of crushing testing machine. Brick is fixed to the crushing testing machine and then crushing force is applied to the brick during the testing operation.

Compressive Strength  =  Maximum Load at Failure(N/mm2) /                                                        Area of Specimen(mm2)

 Observation Table
Actual Size of Brick
(L x B) in mm
Compressive Load in KN
Compressive Strength in N/mm2
220 x 110
230 x 110
230 x 110
220 x 110
220 x 110

Average Compressive Strength   =    11.496 N/mm2

 Compressive Strength of Different Types of Bricks

  1. First-class brick                 =    105 kg/cm2 or 10.3 N/mm2
  2. 2nd class brick                    =    70 kg/cm2 or 6.86 N/mm2
  3. Common building brick      =     35 kg/cm2 or 3.43 N/mm2
  4. Sundried brick          =     15 to 25 kg/cm2 or 1.47 to 2.45 N/mm2

2. Water Absorption Test :

A brick is dried is weighted. It is then immersed in water for a period of 24 hours. It is weighed again and the difference in weight indicates the amount of water absorbed by the brick. It should not, in any case, exceed 20% of the weight of dry brick for first class.

Water absorption (%) = [(W2-W1)/W1] x 100

where  W1 = Dry Brick Weight (oven Dry Condition after 24 hours at temperature 110 to 150 °C)
            W2 = Wet Brick Weight ( After Immersion for 24 Hour)

3. Presence of soluble salt or Efflorescence :

For finding out the presence of soluble salts in brick, it is immersed in water for 24 hours. It is then taken out and allowed to dry. If white deposit covers about 10% surface, the efflorescence is said to be slight and it is considered as moderate when the white deposit covers about 50% of the surface. If white deposits are found on more than 50% of the surface, the efflorescence is heavy and it is treated as serious and brick is rejected.

Tests on Bricks

4. Hardness :

In this test, a scratch is tried to make on the brick surface with the help of a fingernail. If no impression is left on the surface, the brick is taken as enough hard.

5. Shape and Size :

In this test, a brick is closely observed. It should be of standard size and its shape should be truly rectangular with Sharp edges and corners. For this purpose, 20 bricks of standard size (190 mm x 90 mm x 90 mm) are selected at random and they are stacked lengthwise, along with the width and along with the height. For good bricks, the results should be  within the following permissible limits:

Tests on Bricks

Length: 3680 mm to 3920 mm
Width : 1740 mm to 1860 mm
Height: 1740 mm to 1860 mm

6. Soundness :

In this test, two bricks are taken and they are stuck, with each other, The bricks should not break and a clear ringing sound should be produced.

Tests on Bricks

7. Structure :

A brick is broken and its structure is examined. It should be homogeneous, compact and free from any defects such as holes, lumps etc.

Tests on Bricks

8. Colour :

A good brick should have a uniform deep red, cherry or copper colour.

Tests on Bricks

9. Impact Test

In this test, take a brick and drop it from a one-metre height. A good quality brick should not break at all. If the bricks are broken that means its impact value is low and it should be rejected.

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Also, Read – Requirements of Good Quality Bricks

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