For outdoor applications, the liquid oxide is mixed into the concrete. This is because oxide does not break down and the color remains vibrant even the concrete is exposed to scratching and chipping.
For outside concrete usually used in pavements, porch areas, the aggregate is preferred to be exposed.
For this reason, concrete is polished with blades of low grit. Before polishing you must decide how much aggregate you want to be exposed. Aggregate can be exposed from nil level to full stone exposure. This gives the concrete a natural look with a great amount of slip resistance.
For outdoor walls, usually paint is also mixed within the concrete. Although the finish level in this case is again a matte.
You would usually hear people saying that outdoor concrete does not polish. Well, that is not correct. Polishing makes the concrete strong, smooth, and much more resistant to stains-hence making it easy to maintain and clean.