re: Refinishing stained concrete and overlay

use the chemicals and pressure wash first by all means. THEN see if you need to step it up to a sandblaster rental. Bottom line is that to fix your original problem of the salt and mineral content leeching out to the concrete surface, you have to remove the sealer that's trapping it on the surface of the concrete. Then pressure wash off the mineral scale. Unfortunately, the chemical stripper could also degrade the stain color. Check with HD or Lowes to see if they carry something that can do this--doesnt have to be Prosoco, but the good stuff that works costs $$.