The surface of any concrete you lay can be finished in a number of different ways. Ideally, concrete should be made slightly rough to give a better grip if it is to be walked on, and although you can do this by “sawing” a length of wood back and forth across the surface of the setting concrete, there are also other options.
If you need the concrete to be flat and smooth, it is best to use a float or even a large trowel. Let the concrete dry out a little to avoid bringing too much moisture to the surface with the float. If too much water is brought to the top of the concrete it will weaken it. Bridge the concrete with a plank if it is too wide to reach the middle from the edge, and work from one end to the other. You can buy long handled floats called Skip Floats for smoothing large areas of concrete.
To give the surface of the concrete a fine texture without making it too bumpy, use a stiff yard broom. Flatten the concrete with a float to start with and then draw the broom across the surface in long straight sweeps. Hold the broom at a low angle to avoid ‘tearing’ the concrete.
Exposed Aggregate Finish
For a better looking concrete surface, whilst still retaining a good amount of grip, you can put down a layer of small stones or pebbles. This takes a bit of practice and care, but can give a very nice finish. Lay your concrete and then scatter an even layer of your chosen stones across the top. Tamp this down over the whole area until the pebbles are flush with the surface.
Allow the concrete to harden slightly and allow the surface moisture to evaporate. Now spray the surface with a fine water spray and brush with a medium stiffness broom or handbrush. This will remove some of the cement from around the stones, exposing them. Cover the concrete with polythene or tarpaulin for 24 hours, then wash the surface carefully to remove any cement from the actual pebbles. Cover it up again and leave until completely hard.