sand/polish concrete wall

Originally Posted by Renomaster

Doing some renovation with my rampus. As you can see current the green paint on it start to peel off, also there are some water mark.
I would like to sand/polish it (it's located very close to floor, just like the kick board), and want to seal it to make it waterproofed then paint. (not quite sure the surface is concrete or motar).
What is most easiest way to do it?

Looks very much like straight concrete.

A trip to your local hire shop should get you a good slow running hand grinder with diamond blades which will be ideal to polish the concrete, or you could simply use a sander/polisher to remove the paint, patch with a poly patch, resand, and paint..