I poured a +/- 75 sq. foot concrete slab yesterday and am not satisfied with how the finish turned out. I gave it a "broomed finish" and it's too rough. How can I smooth it out? This new slab also butts up to an existing slab with a satisfactory finish, so I need to be careful at that edge as to not impact the existing slab. Can I sand it, or is there some sort of clear sealer that will fill in and smooth out the imperfections?