Completely clear the area for the concrete, including the space for the concrete hose to reach the site. Remove any debris – in this project, the old paver patio – as well as plants, loose rocks and other items. Concrete needs a level surface, so any mounds of dirt or dips in the ground need to be moved and filled. Since the base rock will fill in small gaps, the ground doesn't have to be completely level, just even.
Spray-paint an outline of the desired patio shape onto the ground and build a wooden form matching the outline. Since the patio for this project had dramatic curves, the crew used sturdy bender boards to capture the outline. Secure the forms with stakes pounded into the ground with about one foot between stakes.
Concrete doesn't sit directly on dirt; it needs a layer of rock underneath. Spread a two- to three-inch layer of 3/4" base rock inside the concrete forms. Base rock compacts under pressure and makes a strong foundation for the concrete. For this project, the crew brought the base rock up to the bottom of the wooden concrete forms.
Rebar makes concrete much stronger and keeps it from cracking over time – especially important in large areas of concrete such as a patio. Lay out the rebar in a grid patter, with one pole about every two to three feet. Use pliers and metal rebar ties to tie the rebar pieces together where they cross.
The backyard in this project has easy access, so the concrete company was able to pump the concrete directly from the truck into the forms. If this isn't possible, the work crew would use wheelbarrows to bring the concrete back to the forms one load at a time. As concrete starts going into the forms, start moving it around in the space so that it fills the forms evenly. Using trowels and concrete floats, level out the concrete for a smooth surface.
Powdered concrete color is an interesting and simple way to tint concrete. Once the concrete has dried slightly, begin tossing handfuls of color powder onto the concrete with a dice-throwing motion. Smooth the powder into the concrete using concrete floats. Always wear safety glasses and a dust mask when working with powdered concrete color. Also, be sure to wear rubber gloves to prevent staining hands.
To add texture, throw mineral salt crystals in a pattern around the concrete, then press the salt into the concrete with a flat concrete hand tool. Let the salt sit overnight while the concrete sets. For this project, the crew used the salt finish around the edges of the patio but left the middle smooth.
Once the concrete is dry, carefully remove the concrete forms. Follow the supplier's instructions on how long to let the concrete set before removing the forms. Sweep the salt from the concrete to reveal the porous texture left behind. Be sure to keep the salt away from plants.