Types of Aggregate: Definition, Types, and Uses

types of aggregates

Aggregation is a type of association relationship that connects two things. Aggregates are one of the most essential constituents of concrete as it is a binding material in concrete that makes it durable and strong. Aggregates occupy around 70% to 80% of the concrete’s entire volume, making it a significant factor that affects the concrete’s properties and characteristics.

Definition of Aggregate

Aggregates are a coarse collection of rock-like particles whose size ranges from 0.1 mm to 50 mm. These particles constitute synthetic aggregates, recycled crushed hydraulic cement concrete, sand, crushed rock, iron blast-furnace slag, and gravel.

Types of Aggregate

Types of aggregates are classified based on the results of the Sieve Analysis that grades the aggregates and assigns their group. Aggregation is a type of association relationship so aggregates are binding particles that form the structure of concrete. Here are its two major types:

Coarse Aggregate

Different types of coarse aggregates that won’t pass through a sieve with 4.75 openings are coarse aggregates. They will pass through a 3-inch screen and if it’s larger than the normal coarse aggregate size, the complete structure will lack strength because of voids and arches that get filled with fibre cement and sand particles. The desirable properties of coarse aggregates are

  1. Adhesion with bitumen
  2. Shape of aggregates
  3. Durability
  4. Toughness
  5. Hardness
  6. Strength

Fine Aggregate

Particles that pass through a ⅜ inch or 9.5 mm sieve or a no. 4 4.75 mm sieve are called fine aggregates. Different types of fine aggregates can be retained on the no. 200 75 micrometre sieve and are commonly used for economical and workability factors. Fine aggregates are mainly used to fill up the voids formed by coarse aggregates which is why it is also called the workability agent. Fine aggregates directly affect the properties of concrete. Its strength, shape, texture, grading, and size decide the properties of concrete.

Types of Aggregate: Uses

Different types of aggregates are used in concrete because of their economic factor in providing strength to the structure by reducing all kinds of cracks. Here are its mainstream uses:

  • They can be used as a surface, subbase, and/or base for roads.
  • It is used to distribute the load in railway and road ballast so that groundwater can run off the road.
  • Aggregates increase the volume of concrete by 60% to 70%.
  • They also provide dimensional stability.
  • It influences elastic modulus, abrasion resistance, hardness, and other properties to make concrete cheap, string, and durable.
  • Other uses of concrete include filtration, drainage, backfills, and fills.

The Bottom Line: Geology and Origin of Different Types of Aggregate

In general, aggregates are formed by crushing rocks that are found naturally such as metamorphic, sedimentary, or igneous. The evaluation of aggregates is done to determine their stability in their texture, grain size, and mineral composition. Petrographic descriptions of rock samples can also determine the rocks’ suitability for various applications.

Types of Aggregate FAQs

1) What are the different types of aggregates?

Aggregates are differentiated based on these classifications:
  • According to size
  • -> Coarse aggregate
    -> Fine aggregates
  • According to unit weight
  • -> Ultra weight aggregates (Gs > 2.4)
    -> Lightweight aggregates (Gs < 2.4)
    -> Normal weight aggregates (2.4 < Gs < 2.8)
    -> Heavyweight aggregates (Gs > 2.8)
  • According to shape
  • -> Rounded aggregates -> Elongated aggregates
    -> Angular aggregates
    -> Irregular aggregates
    -> Flaky aggregates
    -> Elongated and flaky aggregates
  • According to source
  • -> Natural aggregates
    -> Crushed rock aggregates
    -> Artificial aggregates
    -> Recycled aggregates

    2) What types of aggregates are used in construction?

    Aggregates commonly used in construction are
  • Burned clay
  • Burned shale
  • Boiler ashes (clinkers)
  • Broken blast-furnace slag
  • Gravel (pebbles)
  • Broken or crushed stone
  • Sand
  • 3) What types of aggregates are used in concrete?

    Concrete uses aggregates like crushed rock, sand, and gravel to get its geological properties. The size of these particles determines if they are fine or coarse aggregates. Depending on its application, concrete can be crushed or used in its original state.
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