Does anyone have any experience with a company called ARDEX? They sell a product called ARDEX 300 and claim you can level concrete up to 1/2 inch with this. I have had an ongoing problem with a sloping concrete porch and am trying to find an alternative to tearing it up and replacing. I'd rather just level off the slope to solve the problem. The ARDEX folks claim that another product, ARDEX Poly-Top, can be mixed with aggregate and then used to level up to 2 inches.