Cement stains are among the most difficult types of stains to remove. This is because a cement stain can settle more quickly than the stains of many other materials. Removing cement stains can be especially difficult when they are on aluminum doors or siding. This is because concrete has an etching effect on aluminum which can permanently damage its surface. The best method for preventing this damage from happening is taking steps to avoid concrete splatter prior to the cement's application. However, if the damage is already done, there are a few measures that you can take to minimize the appearance of cement stains.
Fill a bucket with 1 gallon of water.
Mix 1/4 cup of laundry detergent with the water. This mixture will serve as your aluminum cleaning solution.
Apply the cleaning solution to the aluminum with a scrub brush. Scrub in a circular motion for one to two minutes.
Leave the solution on the aluminum surface for up to one hour.
Rinse the solution off with plain water. The cement stain should be noticeably diminished.