Concrete Highlights: Exposed Aggregate

Exposed aggregate concrete is a form of decorative concrete achieved by removing the top layer of cement paste and revealing the underlying aggregate. It’s a great choice for landscaping because not only is it easy to customize but it’s stain and skid resistant too.

In recent years, industry leaders have pushed the boundaries with exposed aggregate design elements. For example, some producers use rocks with glow-in-the-dark properties that light up at night. Others have used translucent rocks combined with glass or plastic fibers in the cement blend to create light-transmitting concrete. The fibers transfer light from one side of the concrete to the other, making it ideal for installation on top of in-ground solar panels.

Even if you or your client are more down-to-earth, exposed aggregate designs still have beneficial features. For instance, exposed aggregate concrete pairs well with just about any material. From wood dividers to natural stone to water features, visible aggregates allow for complete customization, so concrete slabs can be the center of attention or compliment other elements.

Best exposed aggregate applications

  • Sidewalks
  • Driveways
  • Pool decks
  • Patios

Installation process

  1. Depending on the size of the project, lay the cement as usual, using rebar that allows for expansion to keep it in place.
  2. Clean the rocks you’ll be using. This can be done by placing them in a plastic bag with holes smaller than the rocks and running water through the bag until the water is clear. Give the bag a good shake and repeat a few times. Cleaning aggregates increases its binding power with cement.
  3. After the cement has cured enough to bear weight without denting, you can seed the top with small pebbles, rocks or stones.
  4. Use a bull float or hand trowel to push aggregates just below the cement’s surface. Don’t push too far, or you won’t be able to expose them.
  5. Gently rinse the cement to expose the top of aggregates. If cement is being stubborn, instead of increasing the flow of water, use a dense, thick brush to help it along.
  6. Once the aggregates are evenly exposed, use your favorite sealant to protect the design and give it a clean sheen.

Exposed aggregate designs take longer to install, but they keep their look for years. While there is nothing wrong with a simple slab of concrete, any cosmetic issues are easily noticeable. Because of the diversity with exposed aggregates a scratch, or stain blends with the rest of the design. We highly encourage you to give exposed aggregates a try for your next project.

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