Aggregates are natural raw materials extracted from pits and quarries, such as gravel, crushed stone, and sand, used in construction. They are mixed with a binding medium, such as water, cement, or asphalt, to make compound materials such as asphalt concrete and Portland cement concrete.
In order to make a standard concrete mix, aggregates must be free of absorbed chemicals, clay coatings, and other fine impurities that might cause concrete quality to deteriorate.
Construction jobs usually require the ability to classify aggregates based on their varying properties.
1. Classification based on grain Size
- Fine aggregate (material passing through the 4.75-mm (sieve No. 4) (ACI 221R).
- Coarse aggregate (material retained on the 4.75-mm (sieve No. 4)
Fine aggregates are often used to increase a concrete mix’s workability. On the other hand, coarse aggregates are used to make concrete mixes with less water, which may make them harder to work with but enhances their strength.
2. Classification based on density
There are three weight-based aggregate variations:
- High density
Lightweight and ultra-light aggregates are permeable, making them ideal for green roofs, concrete blocks, pavements, insulation, and fireproofing. Aggregates with a high density are used to make heavyweight concrete for projects that need strength and durability.
3. Classification based on geographical origin
- Natural: Aggregates from rivers, quarries, and mines. Sand, gravel, stone, and rock are the most prevalent and might be fine or coarse.
- Processed: Also called “artificial” or “by-product” aggregates, they are made from industrial or engineering waste to make high-quality concrete aggregates. Processed aggregates are used both for light and dense concrete.
4. Classification based on shape
Shape is one of the most effective methods for differentiating aggregates. The selected shape will affect the workability of the concrete. When buying aggregates in bulk from a reliable supplier, the shapes may be the same, but they can also be mixed.
The different aggregate shapes include:
- Flaky and elongated
Aggregate has several uses that construction jobs applicants should know. In road and railway ballast, aggregates drain water, withstand static and dynamic loads, and distribute the weight equally to the supporting ground, thereby reducing shrinkage and cracks. They are also used to filter sewage and water. Aggregate uses may be summarized as:
- load-bearing material
- Filling material
- Infiltrating material
Kilgore Companies has a proven track record of service performance, offering construction jobs listings, aggregates, ready-mix concrete, paving, and construction services at competitive pricing. For more information about our services, get in touch with our team of professionals today.