[stomachmonkey]

Anything thick will have to be dense / solid / not deform under weight.

Visqueen or similar pliable coverings may be a problem rolling over unless it's been glued down.

The material will push in front of the wheels of anything heavy. Doubt you could easily roll a standard floor jack around on it.

You could always build a form, line it with a barrier and pour a new floor on top. Pouring it over the liner will make it removable, maybe not easily but can be broken up and hauled out.