Why ask him if you know he's not handy? I'll bet he thought he was doing something for you. It's almost as if you set him up for failures. You know where he's lacking. He doesn't have the attention to detail that you have.
You can't have been married this long and not know that he will screw it up and use something inappropriate.
You should have made other arrangements for the clean up (do it yourself, since it bothered you, get the workers to come back and clean up, find the "tar remover" and THEN ask him to clean it, if he's capable, etc.)
I'm starting to feel sorry for this guy.
M:63 H:53 S:41, SS:28, SS:25, SD:23 M:15 T:16
Bomb:12/17/11, "I think we should go our separate ways." H moves to his mother's house, 4/1/12 12/21/12: H moves back home, piecing