Screeding
The first thing you will want to do is screed the concrete as it is poured into the form. This is done by dragging a screed (nothing more than a straight 2x4) across the top of the form in a sawing motion. This will push the extra concrete along in front of the screed while showing you where the low spots are. Screeding only levels off the concrete, it does not smooth, or finish, the surface.
Floating the Surface
As soon as you have all the concrete in the form and it has been screeded, you want to float the surface of the concrete. A wood or metal float is used to push the aggregate into the concrete and flatten the surface. This is done by gliding the float back and forth over the concrete with the leading edge of the float slightly raised. A bull float is used to reach the center of large slabs.
Floating will not give you a smooth surface, but it will get the surface ready for smoothing. Once you are finished floating, you will notice that there is water sitting on the surface of the concrete. This is bleed water brought to the surface by floating. You need to wait till the bleed water has evaporated before you can move to the next step. This can take up to an hour or more, depending on the weather. If you have ever watched concrete pros finishing concrete, you will have seen them cleaning tools and sitting around drinking coffee. All of the sudden...it's a mad rush to finish the concrete.
Finishing the Surface
You can leave the surface as it is after floating. On a slab, the marks left be the bull float will be straight across the surface, while a sidewalk that has been hand floated will have arcs left by the float.
You can drag a damp, stiff broom lightly over the surface of the concrete, creating fine lines running in the same direction. This is the best surface for sidewalks, since it leaves a non-skid surface once the concrete dries.
After you screed the concrete, you can spread decorative aggregate over the surface of the concrete and then push them just below the surface with a float. Once the concrete sets, use a broom and a fine spray of water to go over the surface, washing away the top film of concrete and exposing the decorative aggregate.
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