Aggregates

Aggregates used in concrete consist of geological materials such as gravel, sand and crushed rock. Specific aggregates, or combinations of aggregates, are selected for their durability, strength, and ability to achieve specific project outcomes.

The size of the aggregates selected will be the main factor determining the strength of the concrete, so the right size of coarse aggregates to use will depend on the demands of your project. If you’re looking for a mid-strength concrete, we’d recommend 40mm aggregates, but, if you’re looking for high strength, then 20mm aggregates are best.

Aggregates are classified as either ‘coarse’ or ‘fine’ and both are further categorised further into classifications based on size. Heidelberg Materials Aggregates produces and distributes many sizes and types of aggregates, including crushed rock, sand and gravel and recycled aggregates from a network of quarries, depots, and wharves.

Coarse aggregates are granular particles that are greater than 4mm with a usual range of between 6mm and 31.5mm in diameter. Fine aggregates usually consist of sand or crushed stone, less than 4mm in diameter. While the size required varies depending on the application, the most commonly used size in construction is 20mm. The largest sizes are more commonly associated with use in mass concrete or for roads.

The four main types of aggregate used in landscaping and construction are gravel, sand, crushed rock, and concrete fill. These vary in material type and size, with each type of aggregate serving a unique purpose within specific applications.

Commonly referred to as MOT Type 1, Type 1 aggregate is used as a base layer for pavements, roads, drives, trench fills, patios and a range of other applications. Heidelberg Materials is one of the UK’s largest suppliers of bulk construction aggregates and supplies various sizes of aggregate for a range of core applications, including MOT Type 1 sub base.