What is Aggregate?


Definition: Aggregate is a granular material used in concrete and mortar. It usually comes from natural river sand and river pebbles, or from crushed natural rocks. Such as sand, crushed stone and gravel.

It is one of the main components of concrete and acts as a filler for concrete, not only giving them quality, but also providing strength and durability.

What is aggregate

What are the Different Types of Aggregate?

Aggregates as the collection of loose materials, can be classified according to many ways. This article will classify the source and grain size of the aggregate.

Types of Aggregates Based on Source

Based on the source, aggregates are divided into natural aggregates, artificial aggregates and recycled aggregates (Secondary Aggregates).

Natural Aggregate

Quarry plant

Using natural rocks (such as limestone, granite, basalt, etc.) mined as raw materials, aggregates made by physical crushing are called natural aggregates, such as sand, crushed stone, gravel, etc.

It is an important part of concrete and is widely used in urban road engineering, bridges, buildings and other infrastructure fields.

Read Also: Concrete aggregate processing technology

Artificial Aggregates / Manufactured Aggregates

Products manufactured in the industrial production process that can be used in construction, such as expanded shale, expanded perlite, sintered ceramsite, blast furnace slag, fly ash, etc.

Expanded shale is artificial light aggregate for structural use after shale is artificially heated and expanded.

Blast furnace slag is a by-product of the steelmaking process and is usually mixed with cement to make concrete.

Fly ash is the fine residue from the combustion of coal and can be used to make concrete or cement.

Recycled Aggregates / Secondary Aggregates

Construction waste recycling
Construction waste recycling

Recycled aggregates are secondary aggregates obtained by crushing construction waste (concrete, bricks and asphalt).

Compared with original aggregates, recycled aggregates have better economic benefits and are widely used. Mainly used for road construction (driveways and sidewalks), large-scale filling of concrete with 5-20 MPA strength, trench filling, etc.

Read Also: Advantages of recycled concrete aggregates, processing procedures and cases

Types of Aggregates Based on Grain Size

The original rock mined in the form of blasting, etc., is coarsely crushed and finely crushed by a crushing machine, and then divided into finished aggregates of different sizes using a vibrating screen. The types of these aggregates can be distinguished according to the grain size. There are 2 main grain grading sizes.

(The vibrating screen is screening the materials in the quarry)

Fine Aggregate

The particle size ranges from 0.15 mm to 4.75 mm. They can easily pass through a vibrating screen with a 4.75 mm sieve plate and gather on a 0.15 mm sieve plate. Such as artificial sand, natural sand, stone powder, etc. are all fine aggregates.

The fine aggregate plays a role in filling the voids with the coarse aggregate in the mortar.

Stone Dust0.5 mm – 5 mm
Coarse Sand0.5 mm – 2 mm
Medium Sand0.25 mm – 0.5 mm
Fine Sand0.06 mm – 0.25 mm

Coarse Aggregate

Rock particles larger than 5 mm, such as crushed stones, gravel and pebbles are coarse aggregates. It acts as a skeleton in the mortar.

Fine gravel4 mm– 8 mm
Medium gravel8 mm – 16 mm
Coarse gravel16 mm – 64 mm
Cobbles64 mm – 256 mm

In most cases, aggregates are classified according to size.

Read Also: How to Improve Aggregate Quality

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