Core Building Construction Materials – Stone Chips

AGGREGATES (STONE CHIPS)

Usage of aggregates in concrete:

Stone chips, which are a key component of concrete and are technically called as coarse aggregates, give the material strength and solidity. The qualities of the aggregates used have a significant impact on the quality of the concrete.

The most frequently mined resource worldwide is aggregate. The term “construction aggregate” refers to a large range of granular raw materials used in building, including sand, gravel, crushed stone, slag, recycled concrete, and others. The following are some applications for aggregate in civil engineering:

Uses of Aggregates

In construction, aggregate can be applied in a variety of methods. Aggregates are used in road and railroad ballast to drain water from the surface, resist the overall (static as well as dynamic) stress, and distribute the load effectively to the supporting ground. Aggregate is used in concrete to reinforce the construction, save money, and decrease shrinkage and cracks. Moreover, they are employed in the operations of sewage and water filtering. The following three categories best describe how aggregates are used:

As a Load Bearing Material.
As a Filling Material.
As an Infiltrating Material.

Uses of Aggregate in Concrete

Aggregate is an essential ingredient of concrete. The uses of aggregates in concrete is:

decreases the cost by increasing the volume of concrete. 60–75% of the volume of concrete and 79–85% of the weight of PCC are made up of aggregates.
to offer a tight framework.
to lessen cracking and shrinking.
Many buildings and substructures, such as bridges, foundations, and various building components, employ concrete aggregate.
The surface area of the aggregate will increase with decreasing aggregate size, and more binding material (cement) will be needed, increasing cost.
The size of the voids will increase with the aggregate size, wasting binding material (cement).

Hence a mixture of coarse and fine aggregate is used in concrete to avoid both these problems.

Types of Aggregate

Based on the many factors, aggregates can be of many distinct types. These criteria may include things like shape, size, and strength. The aggregates can be broadly divided into two categories: fine aggregate and coarse aggregate. The following is an explanation of these aggregate kinds.

Fine aggregate: This category of aggregate has a size range of 4.75 to 0.075 mm. They also go by the name “sand.” These are the organic byproducts that mining can produce. The substance is made up of crushed stone or sand particles.

Large aggregate: These aggregates measure greater than 4.75 mm in size. The building of concrete structures uses these aggregates. These aggregates consist of rock strata-derived stone and river gravel.

Features of good quality aggregates:

Instead of being flaky or flat, stone chips should be angular or spherical.
They should be free of any other color’s traces or layers.
Mud and other impurities should not be present because they are bad for concrete. To remove dust, debris, and mud from the stone chips before mixing, it is advised to wash them.
They should be properly graded, which means that they should have diameters ranging from 5 mm to 20 mm in the right proportions, minimising voids.

Selecting the right aggregates for house construction:

In order to minimise voids, aggregates should be properly graded and should have sizes ranging from 5 mm to 20 mm in the right proportion. This will result in a solid and long-lasting concrete. Also, this will reduce the need for cement. Thus, always demand graded aggregates rather than “pure” aggregates, which cause greater voids in the concrete and increase cement usage. For the best pricing, one should purchase aggregates directly from the supplier.

Classification of Aggregate

Based on their place of origin, size, shape, and other features, aggregates can be divided into various categories. Here is a list of aggregates that are classified as essential.

Based on origin: Natural and artificial
Based on size: According to size, aggregates are classified as coarse aggregate, fine aggregate and all-in-aggregate
- The aggregate retained on the 4.75 mm sieve is identified as coarse aggregate.
- Aggregate passing through a 4.75 mm sieve is defined as fine aggregate.
- Naturally available aggregates of different fractions of fine and coarse sizes are known as all-in-aggregate.
Based on shape: Aggregates are classified as rounded, irregular, angular, and flaky.
- Rounded aggregate: These are generally obtained from rivers or sea shore and produce minimum voids (about 32 per cent) in the concrete.
- Irregular aggregate: They have about 36 per cent voids and require more cement paste than the rounded aggregate. Because of their irregular shapes, they develop a good bond and are suitable for making ordinary concrete.
- Angular aggregate: They have sharp, angular and rough particles having maximum voids (about 40 per cent). Angular aggregate provides a very good bond than the earlier two, are most suitable for high-strength concrete and pavements; the requirement of cement paste is relatively more.
- Flaky aggregate: The least lateral dimension of flaky aggregate (thickness) should be less than 0.6 times the mean dimension.

Advantages of Aggregate in Concrete structures

In civil engineering, aggregate refers to solid objects created by the crumbling of rocks. It can be applied while developing buildings made of concrete and other materials. It is a strong, long-lasting material. It has a lot of benefits for building concrete structures. Below are some benefits of concrete constructions depending on diverse aggregate qualities.

Concrete is given extra strength by the aggregates.
The compactness of concrete constructions is improved by the use of aggregates.
The amount of cement in the concrete mix is decreased by the use of aggregate.
Moreover, it lessens the amount of water needed in the concrete mix.
It lessens the shrinkage of dry-mix concrete.
It lessens the concrete’s voids.

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