I have a sandpile dumped on the property that I'd like to keep from freezing up as much as practicable. It's going to be applied mostly on dirt road, so I'd like to add as little salt as possible to it so as not to melt the frozen road surface. I have a tri-axle load of mixed sand and granite dust. I have tractor with a bucket as well to mix with. About how much salt would you think I should use? I've got 50lb bags of Halite.