Exposed Aggregate Concrete

Everything You Need to Know Before Starting on Your Next Project

Exposed aggregate has become a popular decorative concrete choice due to its aesthetic appeal and durability. Completely customizable and easy to install, this is a cost-effective option for decorative concrete around the home.

Keep on reading and find out all there is to know about exposed aggregate concrete, including its different uses, the different types, and the benefits of using it.

What Is Exposed Aggregate?

Exposed aggregate is a style of decorative concrete created by removing the top layer of cement paste to reveal the aggregate in the concrete mix. You can place the aggregate in fresh concrete, too.

Common aggregates used in exposed aggregate concrete include:

Exposed aggregate concrete is not only used for its aesthetic appeal, but it is also durable and skid-resistant, helping to make walkways, driveways, pool decks, and patios safer.

Types Of Exposed Aggregate

There are several methods for creating exposed aggregate concrete, including:

Standard

This one is the most common method for exposed aggregate. It involves mixing or batching the aggregate in the concrete mix at the concrete plant first before delivering and laying the concrete at the project site. Pea stone is one of the most common aggregates used in the standard method.

Topping

Also known as a concrete overlay, this method is used for upgrading the look of existing concrete that is still in good condition. Aggregates are mixed into a concrete overlay batch and applied to an existing concrete slab in a thin layer that is 1 to 1.5-inches thick.

Seeded

For the seeded method, the decorative aggregates are placed by hand or broadcast on the surface of the freshly-poured concrete and then floated into the concrete by hand.

Polished

The polished method is the most common technique for exposed aggregate concrete inside homes. This method is similar to the standard and topping methods. But instead of leaving the aggregate exposed with a textured, slip-resistance surface, a grinder or sander is used to work the top layer down.

Several clear coats of sealer are applied to create a shiny, polished surface. But if you want a matte finish, you can skip this step.

How To Expose Aggregate

There are several ways to expose the aggregate in concrete. And a general rule of thumb is to remove the surface cement paste at a depth that is no more than one-third of the aggregate’s diameter.

Brushing And Washing

This method requires washing away a thin layer of the surface cement paste by spraying it with water and scrubbing it with a broom until the desired depth of aggregate is exposed.

This method is best for small jobs and can begin as soon as the surface cement can be removed without dislodging or overexposing the aggregate. To test if the concrete is ready, lightly brush away a small area of the surface cement paste using a stiff nylon-bristle broom.

Using A Surface Retardant

After placing the concrete, the top layer of cement paste is kept soft by spraying on a surface retardant to slow down the curing process of the surface as the underlying concrete hardens, locking in the aggregate and reducing the risk of dislodging aggregates.

After several hours, once the underlying concrete sets, the top layer of cement paste is rinsed off with a pressure washer, garden hose, or is scrubbed off using a broom and water.

Abrasive Blasting

Once the concrete has set and hardened, you can expose the aggregate using abrasive blasting, such as sandblasting or shot blasting. This method is not recommended if you want to preserve the colour and shape of the exposed aggregate since it can fracture and dull the appearance of aggregate.

Uses For Exposed Aggregate

Here are some of the most common uses for exposed aggregate concrete around the home:

Driveways

Along with boosting your home’s curb appeal, an exposed aggregate driveway provides traction for vehicles, which is especially useful in slippery conditions, such as rain, snow, or ice. This traction also helps you get in and out of your vehicle safely with a more secure footing.

Swimming Pool

Exposed aggregate pool decks create a beautiful and safe surface to walk on, even when wet. To enjoy the slip-resistant and aesthetic benefits of exposed aggregate concrete without being too rough to walk on barefoot, you can opt for smaller aggregates or aggregate that is not deeply exposed.

Sound Barriers

The uneven surface of exposed aggregate concrete works well as a sound barrier for homes since it absorbs sound waves and reduces echoes. Exposed aggregate concrete is also often used as sound barriers along highways.

Patio

An exposed aggregate patio can bring your whole outdoor living space together by complementing your outdoor décor with this customizable decorative concrete. Its durability and low maintenance make for a stress-free patio material option that will look great for years to come.

Benefits Of Using Exposed Aggregate

There are many benefits to using exposed aggregate as a decorative concrete option for your home. These benefits include:

Aesthetics

Exposed aggregate is aesthetically-pleasing decorative concrete. Exposed aggregate concrete uses decorative aggregates in various shapes, sizes, and colours to match any exterior décor.

This completely customizable concrete can blend well with other types of decorative concrete around your home, making for an attractive unique look that boosts your home’s curb appeal.

Durability

Exposed aggregate concrete has the structural integrity of concrete, so it is highly durable and can last for 40 years or longer. It holds up well to heavy traffic and can handle exposure to all the elements, including extreme weather, rain, sun, snow, and ice.

Low Maintenance

Exposed aggregate requires little maintenance aside from cleaning with water on occasion and re-sealing every three to five years to protect it and maintain its glossy appearance.

Cost-Effective

Exposed aggregate concrete is relatively easy and cost-effective to install. Since few additional materials are needed to create exposed aggregate concrete, you can get this decorative concrete at a reasonable cost.

Skid-Resistant

The skid-resistant quality of exposed aggregate makes these types of surfaces safer to walk and drive on, especially in wet conditions. The exposed aggregate contains small stones that give the surface texture, making it skid-resistant and reducing the risk of slips and falls.

Optimal Concrete Mixing Tips

The concrete mix should be low-cost, easy to work with, easy to pump and won’t shrink when dry. However, to achieve the perfect consistency, you need a little bit of math:

But, not all aggregates are created equal. The aggregates you choose contribute to overall consistency, strength, workability, and durability. Also, the gradation, size, weight, and moisture content of aggregates directly affect the character and performance of your final concrete mix.

READ MORE: Tips For Mixing And Working With Concrete

Is Exposed Aggregate Concrete Worth it?

Even though it is durable, exposed aggregate is more prone to damage on the top layer.  It is also more likely to trap dirt which makes it a bit harder to clean sometimes. Moreover, it’s wise to hire a professional to do it, so you must be careful who you’re going to put your trust in. It is important to have people who know what they’re doing to take care of this task since there can be problems in the future if it’s not installed properly.

On the other hand, the maintenance itself is not as hard as with other types of flooring and it doesn’t take a lot of time. If installed and sealed properly, you won’t have to think about maintenance that much. Exposed aggregate concrete is a good option for anyone looking for a cost-effective, durable and stylish solution. If you like the look of it, you won’t mind a bit of extra cleaning here and there.

Conclusion

Consider the many uses and benefits of exposed aggregate for your next decorative concrete project. Exposed aggregate is a cost-effective option for decorative concrete that will look great, make surfaces safer, and last for decades with minimal maintenance. However, it does need sealing often so it does need a bit more maintenance than concrete. Find out more about sealing concrete for your next project, and if you need help, don’t hesitate to reach out.