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Concrete Aggregate

Concrete aggregate is a kind of granular loose material, which play a role of skeleton or filler in concrete. It is divided into two kinds: coarse aggregate, which includes scree, gravel, waste residue, etc., and fine aggregate which includes fine sand, coal ash, etc.

Classification of Concrete Aggregate

concrete aggregate processBased on the difference in grain sizes, concrete aggregate, of which the size is 0.15¡«4.75mm, is called as fine aggregate; and size over 4.75mm, coarse aggregate, such as gravel and crushed stone.

Functions of Concrete Aggregate

1. Under the condition that concrete¡¯s function is not affected, add as more aggregate as possible into the concrete so as to reduce its cost.
2. Aggregate can endow the concrete with fine stability and durability which is better than paste matrix.

Strength of Concrete Aggregate

The strength of concrete aggregate is influenced by bond strength of cement paste and aggregate. With enough strength, aggregate¡¯ strength cannot influence concrete¡¯s. The bond area of gravel and cement paste is large, also the bone strength. So the concrete which is made of gravel has higher compressive strength than that made of river pebble. In order to gain high strength, it is more affective to use gravel than river pebble.

The common gravel crushers are jaw crusher, impact crusher, cone crusher, sand-making machines, etc. Aggregate mobile crushing station is the most convenient crushing machine, which is widely used.

Recycled Aggregate Concrete

Through special treatment, crushing, classification and mixing as a certain proportion, the recycled aggregate, which also is the aggregate that meet different using demands, is produced. The concrete that is made of recycled aggregate is recycled aggregate concrete. Relative to recycled concrete, the concrete that made of natural aggregate is called as raw aggregate concrete.

Classification of Recycled Aggregate

According to the origins, the recycled aggregates are divided into three kinds: waste concrete aggregate, brick aggregate and other aggregate (which mainly refers to light recycled aggregate).

Waste Concrete Aggregate: Through crushing, classification and mixing as a certain proportion, the waste concrete block is made into waste concrete aggregate.

Brick Aggregate: Hard-burned brick, bad brick and crashed bricks generated in construction or dismantlement of buildings can be made into materials like foundation treatment or floor cushion; in addition, they can be used in preparation of coarse aggregate concrete to make concrete.

Other Recycled Aggregate: After processing, materials like bamboo, plastic, rubber can partly replace fine aggregate to be used in concrete member.

Lightweight Aggregate Concrete

Lightweight aggregate concrete is a kind of concrete with dry apparent density less than1950kg/m3. It is made of natural porous light aggregate or manufactured porcelain grain (as coarse aggregate), natural sand or light sand (as fine aggregate), Portland cement, water and additives (or no additives), which are all mixed as a required proportion.

Features of Lightweight Aggregate

Lightweight aggregate, which is applied to highrise or lone-span structures, features small density, good heat-insulating property, and good earthquake resistance.