Bricks – 8 reliable tests to confirm quality

Bricks are construction materials manufactured from clay and having a standard size. Furthermore, they are the fundamental elements of buildings. Brick is a construction material which is in use since ancient days. They act as a load-bearing unit and load transferring medium. The standard size of brick is 190 mm × 90 mm × 90 mm. Also, they are rectangular and have sharp edges.

REQUIREMENT OF GOOD QUALITY BRICKS

Following are the essential requirements for a good quality brick and it become inevitable to do the inspection and quality checks for bricks.

  • Bricks should be homogenous and compact.
  • They should have equal proportions of clay, sand, and silt. 
  • Bricks should have requisite plasticity.
  • They should be free from defects like lumps and holes. 
  • The shape of the brick should be rectangular. 
  • A good brick should not break if dropped from a one-meter height.
  • Brick should not possess internal cracking and shrinkage.
  • Brick should be fire and scratch-resistant.
  • Water absorption should not exceed 20 percent of its dry weight. 
  • The compressive strength of the brick should not be less than 3.5N/mm2.

Some tests are to be performed for maintaining these qualities. This article is about the tests conducted to maintain the quality of bricks.

Also Read : Building Materials and Construction – A comprehensive guide

Also Read : AAC Blocks vs Red clay bricks – An ultimate comparison

Good quality bricks
Good quality bricks

TEST ON BRICKS

In order to find the quality and sustainability of the bricks, Various tests are performed. Further in this article, we have listed few test procedures.

  • Water absorption test
  • Compressive strength test
  • Hardness test
  • Shape and size
  • Colour test
  • Soundness test
  • Structure of brick
  • Efflorescence Test

Must Read : Field tests for cement – A step towards quality.

Must Read : Manufacturing process of cement

Water Absorption Test

Absorption test is conducted to find out the moisture content absorbed under extreme conditions by a brick. This test is conducted for finding the durability of the bricks. A weighing machine and a drying oven are the important apparatus required for conducting the water absorption test. 

  • Firstly, the brick specimen is dried in a drying oven 
  • After that, weigh the dry specimen using the weighing machine and mark it as W1.
  • Secondly, immerse the brick in water for 24 hours.
  • Then take the brick out and drain the water.
  • Similarly, measure the weight and mark it as W2.
  • Finally using the formula determine the water absorption.

Water absorption = (W1 -W2) / W1 x 100

Therefore, the difference in the dry and the wet weight is the moisture content of the brick. For good quality bricks, the water absorption is less than 20% of the dry weight.

This test ensures the brick is durable and withstands extreme climatic conditions. 

Compressive Strength Test on Bricks (Crushing strength)

The ability of the brick to withstand a particular load without failure is the compressive strength of the brick.

A compressive testing machine is the apparatus for determining the compressive strength.

  • First, Take three sample specimens and submerge them in water. 
  • After 24 hours, drain the water. Fill the frog and void with mortar in the ratio of 1: 3. 
  • Subsequently, store the brick in jute bags for 3 days. 
  • Place the brick in compression testing machine with brick frog area facing upwards. After that apply the load slowly.
  • Note down the load at which the bricks break.
  • Finally, using the formula to determine the compressive strength. 

Compressive strength (N/mm2) = Maximum load at bricks fail/ Loaded area of brick

For good quality bricks, the compressive strength should not be less than 3.5 N/mm2 . 

Compressive test
Compressive test

Efflorescence test on bricks

A good quality brick should not contain any soluble salts. However if soluble salts are there, they forms a white color substance on the brick surface. This white formation is called efflorescence on brick.

  • First, take a brick specimen and submerge it in water for 24 hours. 
  • After 24 hours, drain the brick and allow them to dry.
  • Keenly observe the brick surface.
Brick surface conditionDegree of Efflorescence
No white substanceZero efflorescence
10% white substanceSlight efflorescence
50% white substanceModerate efflorescence
More than 50% white substanceHeavy efflorescence
Efflorescence Test on Bricks
Efflorescence

Hardness tests

The hardness test is a field verification test. Hence they are performed on-site. A good brick should resist scratches against sharp things. The following is the test procedure.

  • At first, choose a brick randomly from the stack.
  • Using a nail or finger make a mark on its surface. 
  • If there is no scratch, then it is a good quality brick.

Shape and size test

A good quality brick should be uniform in size and rectangular in shape. In order to check this, measure the brick on the field. The standard size of the brick is 190mm x 90mm x 90mm.

  • Randomly, choose 20 bricks from the stack.
  • Sort them in length, width and height wise.
  • If the sizes are the same, Then they are good bricks.
shape and size of bricks

Color test

Normally good quality bricks are deep red or copper colour. The colour test is a field test. Therefore, it can be observed visually.

Structure Test on Bricks

Homogeneity and compact structure are the quality of good bricks. 

  • Randomly, pick one brick from the stack.
  • Cut the brick into two pieces at the centre. 
  • Then observe its inner side.
  • They should be free from defects such as lumps, holes etc. 

Soundness test

The soundness test finds the strength of the bricks. Also, this is a field test.

  • In this test, choose two bricks randomly without damage or break.
  • Hit the bricks with each other. 
  • Then, listen to the sound the brick produce. 
  • If a metal ringing sound is produced, then it is good quality bricks. 

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