Fine Aggregates are of sizes ranging from 4.75 Millimetres’ to 150 Microns. The quality of fine aggregates greatly affects the quality of concrete. Ultra Tech expert will take you through the process of assessing the quality of fine aggregates. Natural Sands, Manufactured sand and crushed gravels are different variety of fine aggregates. Sand should be hard, clean and free from adherent coating, organic matter etc.
Fine Aggregates should not contain more than 5% of Silt and chemicals impurities. The silt content should not be more than 3% for river sand and 15% for manufactured sand. These materials adversely effects the hardening strength and also durability of concrete by initialization of corrosion of reinforcement.
Any organic impurities like leaves, grass root, decay vegetable will interfere with setting and binding property of concrete. Sea sand should not be used as it causes a flowsion, corrosion, reinforcement and reterred setting and hardening of concrete.
Damp sand exhibit more volume this is called bulking. When the damp sand is measured by volume upto 15% extra sand is to be added to compensate for bulking. Sand should be so staged that dust and other foreign matter are prevented from getting mixed with it. Due to adverse impact on environment by rampant mining of natural sand.
The government is encouraging the use of manufactured sand which is satisfactory for making concrete. Manufactured sand is scientifically produced in specially designed crusher to ensure the compliance with national standards. Users should not be confused between manufactured sand and crusher dust. Crusher Dust is a waste product from manufacturing of coarse aggregates which have very high silt content and fine particles.
Summary of Fine Aggregates
Fine aggregates, generally known as sand, plays a vital role in concrete and mortar.
It should be free from silt and impurities
Use of sea sand causes corrosion of reinforcement
In case of dame sand, upto 15% extra sand is to be added to compensate for Bulking
Manufactured sand be used but crusher dust should be avoided.