Muriatic acid is commonly recommended to clean and remove rust stains from concrete. It is also the primary component in most concrete-staining products. In these products, the muriatic acid is mixed with a stain color. The muriatic acid etches the concrete, allowing the color to seep into the concrete. Whether your concrete floors were intentionally stained with muriatic acid or you were trying to remove a rust stain from your driveway or garage, remove the stain using the same method.
Vacuum the concrete to remove all particles and debris.
Pour chemical floor stripper on the concrete. Choose a stripper that is recommended for concrete. Scrub the stripper into the floor with a stiff-bristled scrub brush.
Attach a scrub pad to a floor buffer. Turn on the buffer. Lower the machine to the floor. Scrub the floors thoroughly. The stain will begin to lift from the floor. Continue across the floor until you have removed the stain.
Rinse the floors with clean water. Work in a 6- to 8-foot area at a time. Fill a bucket with water. Pour the water on the floor. Scrub with a scrub brush to remove all of the chemicals.
Remove standing water with a wet-dry vacuum. Repeat across sections of the floor until the chemical stripper is completely removed. Use towels to mop up water from areas that you can't reach with the vacuum.