Bricks are one of the most commonly used building materials. Good quality bricks are essential for constructing durable and stable structures. There are several ways to test the quality of bricks before using them for construction. Here are the main methods for testing brick quality:
The first step is a visual inspection of the bricks. Check that the bricks have a uniform color and texture. There should be no cracks, flaws, or irregularities on the surface. Well-formed bricks will have sharp edges and an even shape. Avoid bricks that are chipped, broken, or have uneven sizes.
Check the surface of good quality bricks – it should be free of lime pits or particles. The presence of such defects indicates poor quality raw material was used. Examine if the bricks have the necessary markings indicating strength class, durability properties, etc. You can also take the help of Brick Experts to examine the quality of bricks.
The bricks should conform to the standard size dimensions as per the local building codes. To check dimensions, select 5-10 random bricks from the batch. Using a measuring tape, check the length, width, and height of each brick.
The actual dimensions should not deviate too much from the specified standard dimensions. The length tolerance could be +/- 3mm, width tolerance +/- 2mm, and height tolerance +/- 2mm. Any bricks that lie outside this tolerance limit indicate poor dimensional accuracy.
Check the weight of individual bricks using a weighing scale. Select 5 bricks randomly and weigh them individually. Good quality bricks will have a uniform weight throughout the batch, with no large differences between individual units.
If some bricks weigh substantially lower or higher than others, it indicates density inconsistency in that batch of bricks. The average brick density should be within the range of 1700 – 2100 kg/m3.
Tap the brick gently with a metallic object. A clear metallic ringing sound indicates good brick quality. A dull or hollow sound means the brick is porous, internally flawed, or of poor quality.
You can also strike two bricks together. The bricks should give a crisp clear sound without dullness or hollowness. This sound test helps to identify cracks or flaws in bricks that may not be visible externally.
Compressive strength is the most important parameter for bricks. The minimum strength class should be mentioned by the manufacturer. To verify this, do a simple manual test:
- Take 5 whole bricks and place them flat, one above the other.
- Place a metal plate on top and start loading weights slowly.
- Note down the total weight at which the brick stack fails and the bricks get crushed.
- Divide this failure weight by the total cross-sectional area of the 5-brick stack.
This gives an approximate compressive strength value that can be compared with the claimed strength class. The measured strength should be within 15-20% of the claimed compressive strength.
This test determines the porosity and water absorption rate of the bricks.
- Take 5 bricks and weigh them individually in dry condition. Note down their dry weights.
- Immerse the bricks completely in water for 24 hours.
- Remove the bricks, wipe off excess water, and weigh them again in wet condition.
The gain in weight indicates the amount of water absorbed. Good quality bricks should not have water absorption exceeding 20% of their dry weight. A lower absorption rate signifies denser bricks with low porosity.
This determines if harmful soluble salts are present in the bricks. To test efflorescence:
- Immerse 5 bricks in a tub of water for 24 hours.
- Remove the bricks and allow them to dry fully. Examine the external surfaces.
Good quality bricks will remain unchanged. If white patches or powdery deposits appear on the brick surface, it indicates efflorescence. This means there are high soluble salt concentrations which can damage the bricks and reduce their strength over time.
This verifies if the clay mixture and baking have resulted in a material of uniform consistency.
- Take a brick and strike it hard against a rigid vertical surface.
- The brick should not break apart or crumble due to the impact.
If the brick loses its integrity or pieces break off, it has poor internal cohesion of the clay particles. This simple test helps to eliminate weak or defective bricks.