Quality assessment of some basic building materials on site

As we all know that it is essential to use quality building materials for sustainable structure. Testing for knowing quality of materials is done in laboratory. But most of the time it is not possible to do laboratory test physically on site. Then, when we receive materials on project how we test the quality of materials. In this situation we depend on our experience to visually justify the quality of materials. Below are some processes for justifying quality of some basic building materials on site-

Mild Steel:

Quality Mile Steel should be-
  • Free from cracks.
  • Surface should be maximum rust free.
  • Dia all steel bars should be equal.
  • Weight not to be less than 7850 kg/cum.
However, a simple test can also be done on site to assess the quality of steel. It is called bend test. In this test a rod is bend from 90 to 135 degree angle. and then make it straight again. If the rod retains its orginal shape and there is no cracks on surface then it is the best quality rod.

Cement:

  • Color of good quality cement should be greenish gray.
  • It should be free from any hardened lump, dust or other foreign materials.
  • If hand inserted into cement bag, quality cement should give a cool feeling.
  • If small quantity of cement thrown into a bucket of water, it should float for few minutes before immerse. Immediate sinking indicates the impurities of cement.
  • When a pinch of cement rub between fingers it should give a smooth finish.
  • However, Weight of good quality cement not less than 1440 kg/cum.
  • Initial setting time of quality cement not less than 45 minutes and final setting time not more than 10 hours.

Stone Chips:

  • Quality stone chips should be completely non-plastic.
  • It should be free of all organic & other foreign materials.
  • Quality stone should be well graded.
  • Weight not to be less than 1610kg/cum.
  • Dust mixed not more than 3%.

Sand:

Good quality sand must be free from organic materials and other dirt particles. There are some ways to know the quality of sand on site-
  • Rub small quantity of sand between damp hands, If the hands become dirty then it is the low quality sand or contains impurities.
  • Another way can also be done on site. Putting 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 the low quality sand. 
To know more about stone Click here.

Brick (1st Class):

  • Best quality bricks should be well burnt and even color.
  • Free from cracks and surface flaws.
  • It should have uniform shape and size.
  • Quality brick edges should be sharp.
  • When struck with something or each other it will sound clearly.
  • Broken edge of quality brick should be bright, compact and homogeneous.
  • When it is scratched with finger nail, no impression should be left on brick surface.
  • Weight not less than 1856 kg/cum.
  • Should not absorb water more than 1/5 of own weight.
  • Good Bricks should be sufficiently hard. Quality Bricks should not break when dropped flat on hard ground from a height of about one meter.
  • If soaked in water for 24hours, it should not show deposits of white salts when allowed to dry in shade.

Stone:

  • Fracture of good quality stone should be sharp, even and clear.
  • The percentage wear should be equal to or less then 3 percent.
  • A good building stone should be compact, fine and crystalline.
  • Structure should be free from cavities, cracks and loose material.
  • Water absorption of a good building stone after 24 hours should not exceed 0.60 by weight.
By following these technics properly you should be able to select quality materials on site. The more your experience gather, the selection will be more accurate.
Now please share your experience-how you select the quality materials on site.

3 comments :

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