Aggregates in Concrete

Concrete aggregates are composed of geological materials such as gravel, sand and crushed rock. The size of the particles determines whether it is a coarse aggregate (e.g. gravel) or a fine aggregate (e.g. sand). The resulting concrete can be used in its natural state or crushed, according to its use and application. Aggregates can be classified as following; 

Classification of aggregate According to size:

B. COARSE AGGREGATE

The aggregate having size of particles is more than 5.00 mm are called coarse aggregate.

Classification of aggregates 

According to source or nature of formation:

Classification of aggregate according to source or nature of formation are more classified in four type. These are explain below. 

a) Naturally-occurring aggregates-

The aggregates are found in the natural source like sea bed, slope deposits, river Basin e.g. sand and gravel, pit Run.

b) Recycled aggregates–

The recycled aggregate are manufactured by crushing inert construction and demolition waste.

c) Artificial aggregates-

The artificial aggregates are made up by various waste material iron ore, artificial cinders, Burnt clay, Steel rivet etc.

d) Crushed Rock aggregates-

Crushed rock aggregates is formed by crushing the various Rocks quarries e.g. stone aggregate.

Aggregates according to shape:

a) Rounded –

The shape of aggregate particles is almost circular with even smooth surface. It possess 33-35 % Void ratio. This type of aggregate is not suitable for concreting.

b) Angular –

The shape of aggregate friction is triangular with rough surface. It possess 38-41% void ratio.

c) Flaky-

The shape of aggregate particle is showing less thickness than length and breadth. It has highest percentage of voids. It is suitable for lower grade of concrete.

d) Elongated-

The shape of aggregate having more length than Breadth and thickness.

e) Irregular or partly rounded-

The shape of aggregate is partly rounded with uneven surface. It possess 35 to 37% void ratio. Useful for medium quality concrete.

Purpose Of Aggregates In Concrete