Selecting Building Materials :
Selecting the right building material is crucial for any construction. Although the contractor may be arranging the material, yet it is advisable for you as the house owner to be aware of methods to ascertain the quality of the material being used. This is especially important if you are not using ready-mix concrete.
In technical language, sand is referred to as Fine Aggregates. Size of particles is less than 5 mm. River sand is cheapest source of natural aggregates. It should be free from dust, clay, silt and organic impurities.
You can conduct a simple field test for sand:
Hold some of the sand in hand, rub it and just throw it. Check your palm. Good sand will not stick to the palm. Take some sand in a graduated, transparent measuring cylinder and pour double the quantity of water to it. Shake it vigorously for two minutes by keeping the palm on the top of the cylinder. Keep the cylinder for one hour in undisturbed condition. Different layers will be observed enabling you to check the quality of the sand.
Crushed hard stone and gravel are common materials used as coarse aggregates for concrete work in India. Aggregates are available in sizes of 40mm, 20mm and 10mm. For residential slab, beam and column work, 20mm and 10mm size of aggregates are generally used.
Aggregates should be hard, strong and durable. They must also be free of clay, loam, vegetable and other foreign materials. As far as possible, flaky and elongated pieces of stone should be avoided.
Municipal water supplied for drinking purpose is generally considered fit for construction purpose. Additionally, you can check if the water is free of oil, acids, salts and organic impurities. Sea-water and ground water should preferably not be used for construction purposes.
Bricks should be sound, hard and well burnt.
They should be free from effloresces and be uniform in size, shape and colour.
The bricks when struck together should produce a good metallic ringing sound.
They must not break when dropped from a height of approximately a meter.