How clean does the grinder make the surface look? And do you have any recommendations as to brands/make/models? Just to give me a start to see where I can rent one.
It was also suggested I could cover the concrete porch with another layer of concrete. Now knowing a bit about thermal expansion coefficients, I immediately thought this was a bad idea, but if the two materials bonded, and could act as one it may work. I figured I'd ask anyway.