Bricks are the building blocks of a building. If the quality of brick used in a structure is not good, it can cause serious damage to the building. Therefore it is necessary to check the quality of brick before using it in any construction work. There are some field tests that we can do in the field to check the quality of the bricks. These tests are as follows.
- water absorption
- Visual inspection
Field test on brick to check quality
1. Water absorption
5 bricks are taken and the bricks are dry weighed and the average dry weight of 5 bricks is calculated. The bricks are then immersed in water for a period of 24 hours. After 24 hours of immersion, the bricks are weighed again and an average of 5 bricks is counted. The difference between the final average weight and the initial average weight shows the amount of water absorbed by the bricks. It should in no case exceed 20 per cent of the average weight of dry bricks.
2. Visual Inspection
In this test the bricks are closely inspected for its size. Good quality bricks should be uniform in size and have a truly rectangular shape with sharp edges.
This test should be conducted in a well-ventilated room. The brick is placed vertically in a dish of 30 cm x 20 cm approx in size 2.5 cm by dipping it in distilled water. All the water is absorbed by the brick and evaporates through it. After the bricks are dry, the same amount of water is poured into the pot, and the water is allowed to evaporate as before. After the second evaporation the brick should be examined and reported as follows:
- Zero: When there is no perceptible deposit of salt
- Slight: When not more than 10% of the brick area is covered with salt
- Moderate: When there is a heavy deposit covering 50% of the area of the brick but not accompanied by powdering or flaking of the surface.
- Heavy: When compacted heavily to cover more than 50% of the area of the brick with a powder or surface layer.
- Severe: When there is heavy deposition of salts with surface powdery and/or flaky and this deposition increases with repeated wetting of the specimen.
Bricks for normal construction should have no more than modest to medium inflorescences.
4. Dimensional Tolerance
Twenty bricks are selected at random to check the measurements of length, width and height. As shown in the figure, these dimensions are to be measured in one or two lots of ten. Variation in dimensions is allowed only within narrow limits, ±3% for class one and ±8% for other classes.
In this test, scratches are made on the surface of the brick with the help of a fingernail. If no mark is left on the surface, the brick is considered to be sufficiently hard.
Two bricks are taken, one in each hand, and they are struck lightly with each other. A good quality brick should not break and a clear ringing sound should be produced.
A brick is broken and its structure has been examined. It should be homogeneous, compact and free from any defects like holes, lumps etc.