Pressure washer, a big one, and HOT water would be my first shot. They make good soaps to add to the pressure washer for your purpose.

The muriatic if you use it needs to be done really carefully, mixed thinner than you think. Gulo before I used muriatic or anything for that matter I'd talk to whatever resurfacing outfit your considering. They can tell you what residue is compatible with your product, and you will have residue.

I just helped a friend Monday who went after his garage floor with a number of things including muriatic acid. More is not better. What a mess. I use acid when washing out new concrete for an exposed Ag finish so I'm not opposed to the product itself, I'm thinking there are better options for your use. Again, talk to the finish surface guys.

Osky