Fine Aggregate – Its [6 Properties & Role in concrete]
In concrete or mortar, the aggregate is a granular material, it is called fine aggregate when the particles of granular material are so fine that they can pass through a 4.75mm sieve. To increase the volume of concrete it is used in the construction industry and is cost-saving material.
It consists of crushed stone and sand and quality influence the properties of concrete and concrete or mixture can be made more durable and stronger if the selections of fine aggregates are selected on basis of grade zone, surface texture, particle shape, surface moisture, resistance, and absorption.
It should have a rounded shape for increased workability and for economical as reflected by the use of cement and the purpose of fine aggregates is to fill the voids in coarse aggregate. On resulting concrete, the properties of aggregates also have affected such as size, grading, shape, and strength of aggregates and texture, etc.
Role Of Aggregates In Concrete Mix:
You can have a significant impact on output depending on composition, properties of fine aggregates, size and shape, and fine aggregates are structural filler that occupies most of the volume formulas of concrete mix.
The fine aggregates result in;
- Provide dimensional stability to the mixture
- With it, the elastic modulus and abrasion resistance of concrete can be influenced
- The quality of aggregates also influence the hardening properties and mixture proportions
- On the shrinkage of concrete, the fine aggregate properties also have a significant impact.
Types Of Fine Aggregate uses:
In concrete or pavement construction usually, sand, crushed stone and crushed bricks are used as fine aggregates as given below;
Sand is used as a fine aggregate in concrete work and is an important engineering material. Sand is a form of silica and natural sand is formed from weathering of rocks and of various sizes or grade and these may be angular or rounded and sharp.
There are many classifications of the sand some are;
Coral sand, glass sand, gypsum sand, silica sand, river and sea sand, green sand, desert sand, heavy mineral sand, and volcanic sand, etc.
By screening crushed stones stone screening is obtained and are fine particles and in batter strength, to concrete, the grains are strong and sharp.
By grinding freshly burnt and well-burnt bricks surki is made and it should be clean and free from foreign matter and fine to pass through no 8 sieves. In the making of lime mortar, lime concrete and lime plaster surki are mostly used.
Grading Zone Of Fine Aggregates:
The concrete mix must include aggregates that are clean, strong, hard and free of absorbed chemicals and ignorance of these characters can cause the deterioration of concrete thus the grading zone of fine aggregates is decided by authorities. Each zone defines the percentage of aggregates:
- Zone i: 15% to 34%
- Zone ii: 34% to 59%
- Zone iii: 60% to 79%
- Zone iv: 80% to 100%
With the help of grading zones, you can access the quality of aggregate and you can also seek help from experts and they can find the best in class material.
Properties Of Fine Aggregates:
There are several properties of the fine aggregates as given below:
The size should be equal to or less than 4.75mm.
To completely round grained sand, the sand of irregular nodular shape is preferable and in coarse aggregates shape of aggregate plays an important role.
To the density of water, it is the ratio of the density of aggregate.
Weight of water absorbed to the weight of dry aggregate and measured in percentage.
Bulking means an increase in the volume of sand due to surface moisture.
- Surface texture
- Silt content.