Aggregate is arguably the most basic requirement for any construction project. Types of aggregate include materials such as gravel, crushed stone and sand. Aggregate creates the base to construct a strong foundation for projects such as roads and pathways. 

Cement and other materials are held together by aggregate to establish high-quality, long-lasting results, and in certain projects, such as pathways, it is used as a drainage application. Manufacturing aggregate is a refined process that takes patience and time, but the results are well worth the effort. 

Manufacturing aggregate – the process

Aggregate is essentially a combination of mined materials broken down into numerous sizes for construction implementation.

During the process of manufacturing aggregate, the materials are refined down to their most common use. Some might be left as various sized pieces of concrete and some may be distilled down to a form of powder. Aggregates must be processed properly to maintain the highest quality performance. 

Often, when producing different types of aggregate, companies will use many processing systems and store each type separately to preserve the quality of the materials and equally avoid mixing the products. 

After the natural materials are gathered, the aggregate is processed, screened and washed to remove any unwanted coatings or chemicals. 

When processing, aggregates are fed through a primary crusher which will reduce the size of the concrete into chunks. After inspection for large usable products, the remaining materials from the primary machine are then transferred via a conveyor belt to a second feeder for secondary crushing and further screening – which entails reducing and separating the aggregate into more usable products. 

Aggregates hugely impact concrete properties and mixture proportions, which is why it is essential to consider the selection of aggregate used in any process. Although some differences are expected, properties considered include:

  • Durability
  • Surface texture
  • Weight
  • Surface moisture
  • Grading
  • Absorption
  • Abrasion resistance

Measurements matter

The internal structure of aggregate is made up of solid material and other properties that may or may not contain water. The amount of water in the aggregate mixture adjusts depending on the level of moisture in the concrete. 

When used in concrete, aggregate must be skid and abrasion-resistant due to the risk of abrasion in heavy-duty pavements. Different minerals used in the aggregate means that the concrete can wear or polish can occur at different rates. Harder aggregate can be used in highly abrasive conditions to prevent wear and tear. 

Freshly mixed concrete can be heavily influenced by shape and surface texture. Rougher textured particles require more water to create a smoother, rounded compact aggregate. 

Common types of aggregate 

There are six well-known types of aggregates including sand, Type 1 MOT, crushed concrete, gravel, ballast and topsoil.


Sand is formed when rocks break down gradually over tens of thousands of years by water, wind and gravity. Sand is regularly used as an aggregate in brickwork, concrete components, agriculture and water filtration. 

Type 1 MOT

MOT Type 1 aggregate is an approved granular sub-base material that is created using recycled crushed concrete and rubble. It’s made up of a mix of larger 40mm pieces right down to dust which compacts well to form a solid base

For a product to be classed as Type 1, it must comply with the Department of Transport Specifications of Highway Works. Type 1 MOT is often used as a replacement for limestone and granite, due to those types of aggregates having limited availability and are expensive to transport. 

Crushed concrete

Crushed concrete is recycled concrete that has been repurposed for use as aggregate. Crushed concrete is good to use for trench fills, overseer fills and as a granular sub-base for deeper areas. It is usually recycled from demolished sites or old construction materials. 


Gravel is a tough material made up of loose stones and fragments of rocks. It is a natural source found in many natural geological formations but can also be man-made by crushing larger rocks down into smaller pieces. Gravel is often used for driveways, drainage and decorative garden paths. 


Ballast is made of crushed stone but can also consist of clay. It is the most coarse aggregate and is mostly poured into concrete mixes used for pathways and heavy-duty projects. 


Topsoil is naturally found in nature and there are many different types with different solutions. This type of aggregate is often used for gardens because it helps support soil health. The clue is in the name, topsoil is the top layer of soil in which all plants grow. 

Since it makes up around 60-80% of concrete, high-quality aggregate is the essential foundation for any construction project. 

Aggregate from K&B Crushers

All of our aggregates at K&B Crushers are recycled. Recycled aggregates are a cheaper, more sustainable and more environmentally friendly alternative to newly extracted quarry materials. 

All our recovered and reclaimed aggregates are treated using advanced processes and material screening techniques, to exactly match your specifications. Recycling materials in this way reduces the burden that primary aggregate quarrying has on the planet – a problem that must be addressed to ensure sustainable living.

We accept and source materials from across the country, offering nationwide site clearance, foundation removal, backfilling and compacting services to name but a few. From our base at Southampton Docks, Gate 20, we crush and sort materials, ready to build with. Get in touch with us today for more information.