Exposed Aggregate Installation Tips

Seeding the Surface

• One of the simplest ways to expose aggregate is to cover the wet concrete with a thin, even layer of decorative stone and press them in. Lay a wood board over the surface one section at a time and apply even pressure to ensure the stones will be level. This method gives you more control over the final result. You should add fewer stones if you want a subtle contrast of color and texture and many stones for a pebbled surface. After the concrete dries for about two hours, brush off the top layer of concrete from the stones to accentuate their shape.

Don't Overexpose

• The most difficult part of installing exposed concrete is getting the correct depth of exposure. If you don't remove enough of the surface concrete paste, the decorative aggregate will not show. If you remove too much, the aggregate can loosen or dislodge from the concrete and leave pits behind. Use a soft-bristled brush to remove the top layer of concrete and hose it off as you work so you can see the progress.

Work in Sections

• Pouring a large concrete surface by yourself is a challenge because you need to pour and manipulate it in the short window of time before it begins to harden. Ask a few people to help you to ensure that the surface is level. It is also helpful to work in sections and expose aggregate in the same order the concrete was poured. Working in sections allows you to focus on gently exposing the stones in each area without getting overwhelmed, rushing and missing a spot.

Slow-Dry

• Once the aggregate is exposed, you can increase the pavement's strength and longevity by slow-drying it. If concrete dries out too quickly, it will be weak and vulnerable to weather damage and wear and tear. If exposed aggregate dries out too fast, the bond adhering the stones to the concrete weakens and the stones can dislodge. A simple way to slow-dry exposed aggregate is to cover it with a damp, breathable material and keep it constantly moist for a week. Canvas and burlap work well, but you can also use straw to retain moisture.