I washed a lady’s driveway and she was happy with the results but she wanted to know what this was left over? Its only on one section and is hard as rock. I think its some type of coating? Is there a way to remove it? I would like to help her out
The last picture is a boot or a hiker. Hope that helps 
Looks like paint, you didn’t see that in the before? In the first pic if you zoom in on it you can see tire prints/tracks. It might also be where the paint/surface coating is expanding and contracting causing the wrinkles.
Saw a concrete walkway today with a surface coating on there that is flaking off. He said how much to remove it, and I said how much you got? He laughed and I said I’ll just clean it but some more will flake off.
