Testing to know the quality of materials is usually done in the laboratory. Most of the time, it is not possible to do laboratory tests physically on the site. In this case, we depend on experience to do it. In this article, I will show some simple ways one can determine the quality of some building materials on the site for common building materials.
A. Mild Steel:
Quality mild steel should have the following qualities:
- It should be free from cracks.
- The surfaces should be rust-free.
- The diameter of all steel bars should be equal.
- The weight should not be less than 7850 kgm-3
A simple test can also be done on the site to assess the quality of steel. It is called BEND TEST. In this test, a rod is bent from 900 to 1350 angle and then made straight again. If the rod retains its original shape and there are no cracks on the surface, then it is a good quality rod.
- The colour of good quality cement should be greenish-gray.
- It should be free from any hardened lump, dust, or other foreign materials.
- If the hand is inserted into a cement bag, quality cement should give a cool feeling.
- If a small quantity of cement is thrown into a bucket of water, it should float for a few minutes before sinking. Immediate sinking indicates the impurities of cement.
- When a pinch of cement is rubbed between the fore-finger and the thumb, it should give a smooth finish.
- The weight of good quality cement should not be less than 1440 kgm-3
The initial setting time of quality cement should not be less than 45 minutes and the final setting not be more than 10 hours.
C. Stone Chips (Chippings)
- Quality stone chips should be completely non-plastic.
- It should be free of all organic and other foreign materials.
- It should be well-graded.
- Weight should not be less than 1610 kgm-3
- Stone chips are often mixed with dust but the dust should not be more than 3% for a pass quality test.
Good quality sand must be free from organic materials and other dirt particles. Ways to check this:
- Rub a small quantity of sand between damp hands, if the hands become dirty, then it is low-quality sand and contains impurities.
- Put some quantity of sand into a glass of water. Shake it and then allow it to settle for some time. If a layer of impurities or clay is formed on the top of the sand, then it is low-quality sand.
- Fractures of a good stone should be sharp, even, and clear.
- The percentage of wear should be equal to or less than 3%.
- A good building stone should be compact, fine, and crystalline.
- The structure should be free from cavities, cracks, and loose materials
- Water absorption of a good building stone after 24 hours should not exceed 0.60 by weight.