BUILDING MATERIALS PART 3

SAND

Along with cement, sand is a very important ingredient in mortars and concrete. Therefore the proper selection of sand is critical in the durability and performance of  the concrete/mortar mixture.

River sand is the best for construction. However due to its scarcity and exorbitant price, filter sand and manufactured sand are also used nowadays. The price of sand includes three or four components - base cost, transportation, handling and number of intermediaries. Therefore procuring sand in bulk directly from the source will be cheaper than the neighbourhood dealer, except when you need smaller quantities.

Features of good quality sand:

• Must be clear, angular and hard.
• Must be free from clay, mica and soft, flaky material
• Should be graded, which means it should be a mix of fine, medium and coarse sand
• Must be free from contaminants like sea salt.
• Moisture (water) content must be consistent and should not exceed 7%. When mixing concrete the moisture content must be taken into consideration.

Selecting the right sand for house construction:

Even though good sand is very difficult to procure and the price is very high, it is better to use good sand rather than filter sand. But if the cost is a big factor, filter sand is available at a cheaper rate. It is sand mixed with dust/soil. Filter sand can be made better by washing off all the dust particles with water. You could also vary the type of sand that you use based on the type of work. For example, for rcc slabs, rough sand can be used whereas fine sand can be used for plastering. A simple way of checking the quality of the sand -  It should not be sticky when you hold it in your hand.

MANUFACTURED SAND:

Manufactured sand: also called M-sand is being promoted by the government as a cheaper alternative to natural sand because of the scarcity of good quality natural sand. Experts vouch that manufactured sand is not only a viable alternative to natural sand, but superior in many ways. Mortars and concrete using M-sand as fine aggregate are superior when compared to those using natural sand. The ready-mix concrete manufacturers are already using manufactured sand.

Advantages of manufactured sand:

• The appropriate quality of rock suitable for construction can be used for manufactured sand;
• There is no clay content in M-sand;
• M-sand is scientifically graded to comply BIS specifications;
• Customizing the different grades depending upon the need of construction ensures consistent quality throughout the construction cycle.
• M-sand is half the price of natural sand.