Exposed aggregate is a fantastic building material – it is strong, versatile, and it looks good to boot! 'Aggregate' refers to the stones that are used to make concrete. With exposed aggregate, these stones are left intact, resulting in a very characteristic look and finish. Exposed aggregate concrete is durable and hard-wearing, making it the perfect material for driveways, patios, and swimming pools. Use these tips to successfully pour concrete – and expose the aggregate – in the location of your choice:

Lay a Solid Gravel Foundation

The gravel will serve as a foundation for the aggregate, so you will need to pour around 6 inches of gravel as the base layer. To smooth it out, use a rake or a shovel. Try to avoid any lumps and holes – it's very important that the gravel foundation is as smooth as possible before you proceed with pouring the concrete.

Pour Out the Base Concrete

Once your gravel foundation is in place, you will want to pour your concrete mix into the concrete forms. As you pour, make sure to even out the concrete using a trowel.

Do not fill the forms up to the top with concrete – you will want to leave a gap (half an inch to an inch) in which you will pour your aggregate mix.

Pour the Decorative Aggregate

The final space left in the concrete forms will be filled with your concrete mix that is embedded with the decorative aggregate.

Once the concrete is in place, you will want to act very quickly to expose the aggregate – the more the concrete dries, the harder it will be to remove the surface mortar.

Exposing the Aggregate

There a number of methods that you can use to expose the aggregate within the concrete. With every method, your end goal is to remove surface mortar until around one third of the aggregate particle is exposed; if you remove too much, you face the risk of having the aggregate particles come loose.

The simplest way to expose the aggregate is to simply wash away a layer of the surface mortar as soon as you lay the concrete. Simply spray the concrete with water and scrub away the mortar with a broom. If you opt for this method, be careful not to scrub too vigorously, as you may remove too much mortar and dislodge some aggregate.

Alternatively, you can use abrasive blasting to expose the aggregate after the concrete has set. Here, you would use a sandblaster to remove the surface level of concrete and expose the aggregate; unfortunately, this method can dull and damage the aggregate particles, so it should not be used if the aesthetic appearance of the aggregate is very important.

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