I wouldn't call it sand-based, the sand or other filler is really irrelevant here. The $64 question is, what binder or paint did they use? A urethane? Modified epoxy
? Conventional deck
I think I'd try carefully masking around the area (taping down poly tarp) and then using one of the strippers that you cover with a special "paper", which allows the peeling paint, stripper, and paper all to be peeled off and thrown out in a wad. Some of them are pretty good about taking off difficult paints, others apparently not so good. But that should also do a lot to contain the mess, and leave the rest of the deck paint intact.