What is: Aggregates

Aggregates are an essential component in the construction industry, playing a crucial role in the production of concrete and asphalt. They are granular materials, such as sand, gravel, crushed stone, and recycled concrete, that are used to create a solid foundation for various construction projects. In this article, we will explore the different types of aggregates, their properties, and their applications in the construction industry.

Types of Aggregates

There are two main types of aggregates: fine aggregates and coarse aggregates. Fine aggregates are small particles that pass through a 4.75mm sieve and are commonly known as sand. They are often used in mortar, plaster, and concrete to improve workability and reduce shrinkage. Coarse aggregates, on the other hand, are larger particles that are retained on a 4.75mm sieve. They include materials such as gravel, crushed stone, and recycled concrete, and are primarily used in the production of concrete and asphalt.

Properties of Aggregates

The properties of aggregates play a significant role in determining the quality and performance of concrete and asphalt. Some of the key properties include:

1. Gradation:

The gradation of aggregates refers to the distribution of particle sizes. A well-graded aggregate has a balanced distribution of different sizes, which helps in achieving a dense and strong concrete mix. On the other hand, a poorly-graded aggregate can result in a mix that is prone to segregation and low strength.

2. Shape and Texture:

The shape and texture of aggregates can influence the workability and strength of concrete. Angular and rough-textured aggregates provide better interlocking and improve the bond between the aggregate and the cement paste. Rounded and smooth aggregates, on the other hand, may reduce the strength of the concrete due to decreased interlocking.

3. Specific Gravity:

The specific gravity of aggregates is a measure of their density compared to the density of water. It is an important property that affects the weight and volume of concrete. Aggregates with a higher specific gravity are generally stronger and more durable.

4. Absorption:

The absorption capacity of aggregates refers to their ability to absorb water. Excessive absorption can lead to a higher water-cement ratio, which can affect the workability and strength of concrete. It is important to use aggregates with a low absorption capacity to ensure the desired performance of the concrete.

Applications of Aggregates

Aggregates are used in a wide range of construction applications, including:

1. Concrete Production:

Aggregates are a key component in the production of concrete, which is one of the most widely used construction materials. They provide strength, durability, and workability to the concrete mix, making it suitable for various applications such as buildings, bridges, roads, and dams.

2. Asphalt Production:

Aggregates are also used in the production of asphalt, which is used for paving roads, parking lots, and other surfaces. The aggregates provide stability and strength to the asphalt mix, ensuring a durable and long-lasting pavement.

3. Drainage Systems:

Aggregates are used in the construction of drainage systems to provide a permeable layer that allows water to flow through. This helps in preventing waterlogging and reduces the risk of flooding.

4. Landscaping:

Aggregates are commonly used in landscaping projects to create decorative pathways, driveways, and garden features. They add aesthetic appeal and can be customized to suit different design preferences.


In conclusion, aggregates are essential materials in the construction industry, playing a vital role in the production of concrete and asphalt. Understanding the different types and properties of aggregates is crucial for achieving high-quality and durable construction projects. Whether it is for concrete production, asphalt production, drainage systems, or landscaping, aggregates are versatile materials that contribute to the strength, stability, and aesthetic appeal of various structures.