Put on gloves to protect your hands while mixing and applying the cleaner.
Combine 1 cup of vinegar and 1 cup of phosphoric acid-based cleaner with 19 cups of water in a large bucket.
Soak the rags in the solution and lay them over the stains. Allow the solution to soak into the concrete for 15 minutes. Rinse with clean water and reapply if necessary.
Pour an inch of acrylic concrete stain into a small bowl.
Dip the paintbrush into the stain and apply it to discolored sections of concrete. Larger sections can be spray painted with an airbrush to save time and allow for more even coverage. Cover with a tarp to protect the stain while drying.
Allow to dry overnight. Apply an additional coat or two of stain, if necessary. Don't drive over the newly painted surface for at least a week.