Step 13: Trowel Finish
A rougher finish may be good for outdoor slabs, as they provide more traction. But using a trowel will give you a smoother surface, if that's what you're looking for. Again, wait for the surface water to disappear. Trowel the edges, then sweep the surface in wide arcs. If you can't avoid sweep lines, wait 15 minutes and trowel again.
Concrete cures best between 50 F and 70 F. It achieves most of its strength--60 to 75 percent--during the first week, and about 95 percent over the first three weeks. To make sure the concrete dries correctly, keep the job damp for five days by covering it evenly with a plastic vapor barrier or by using a sprinkler. Alternatively, you can also apply a curing-and-sealing compound.