How to Install Exposed Aggregate Concrete
- 1). Measure the site with a tape measure and add 2 inches to every side for the form boards. Outline the site with wood stakes and a string.
- 2). Dig out soil from the outlined site using a shovel. Remove 10 inches and cut straight down along the sides so the walls are vertical. Tamp the dirt across the bottom with a tamper tool to force out excess moisture and air pockets.
- 3). Fill the hole with 3/4-inch gravel and tamp it down. Continue adding gravel until you have a 6-inch-thick layer. The gravel base allows underground water to drain away and supports the concrete surface.
- 4). Set 2-by-4-inch form boards on their sides against the inner walls of the concrete. Nail the form boards together with a hammer. Insert stakes around the outside perimeter of the forms to brace them from the pressure of wet concrete.
- 5). Mix concrete powder with water in a wheelbarrow until you have a thick blend. Use a paddle bit and drill to stir the concrete.
- 6). Pour the wet concrete over the gravel and spread it into corners with a gauge rake. Level the surface by dragging a clean straight-edge across the top.
- 7). Sprinkle a single layer of small stones or pea gravel over the top of the wet concrete with a shovel and broom. Press the gravel into the concrete with a wood board, applying even pressure over it so the surface will be level. Wait about two hours for the concrete to begin to harden.
- 8). Push a soft broom over the surface to remove concrete powder around the top edges of the stones. Sweep gently so you don't dislodge the aggregate. Hose off excess material from the top layer.
