For big, persistent stains you'll need to move on to the heavy-duty cleaners. Rinse off the concrete and let it dry before applying any of the following chemicals, and be sure to follow safety precautions:  Work in a well-ventilated area. Wear gloves and eye protection. Stick to long sleeved shirts and pants to protect your skin. These sprays are often used to scrub sinks without scratching them, and they will quickly lift up rust stains.  They often come in liquid or powder form. Spray or sprinkle the cleaner on the rusted surface. If the cleaner is made of powder, wet it with water. Allow the mixture to sit for several minutes before continuing. Mix 1/2 cup (118.29 ml) of TSP with 1/2 gallon (1.89 L) of hot water. TSP can be purchased at a home improvement store, and needs to be mixed at home.  Put on gloves before handling TSP. Pour the mixture on the rusted surface. Allow the mixture to sit for 15 to 20 minutes. Just like with your gentle stains, do not use metal bristles, as this can remove the top paste layer in the cement. Instead, us a stiff nylon brush and work in circles to lift up the stain. Rinse away all the cleaner when you're done, taking care to remove all of it. If left on the concrete for too long it may cause discoloration. Hydrochloric acid, in some tests, is the most effective way to remove rust stains. However, left too long to soak this acid can tint your concrete blue, so you need to act quickly. Dilute the acid a bit with 1 cup of water for 2 cups of acid to give yourself more time and avoid re-coloring your surface; always mix acid to water to avoid a violent reaction.  Let the acid soak into the stain for 5-10 minutes. Scrub away the rust stain, working quickly. Rinse the surface thoroughly with water. Repeat as needed. If you're having trouble getting to a stain, or can't scrub any harder, leave your acid on the stain for 10 minutes and set up a pressure water. The high-powered hose not only rinses away all the acid for you, it puts concentrated force on the stain to easily lift it off the surface.
قم بالانتقال إلى المنظفات التجارية إذا كان الخل وعصير الليمون لا يعملان. قم باستخدام منظف يحتوي على حمض الأكساليت مثل سينجرمان وغالبًا ما تستخدم تلك الرشاشات لتنظيف المصارف دون خدشها لإزالة بقع الصدأ بسرعة. قم باستخدام فوسفات الصوديم لإزالة الصدأ الثابت من الأسمنت. قم بفرك السطح بفرشاة نايلون ذات شعيرات جافة ثم اشطف السطح بعد وضع المنظف. قم بالتحقق بعناية من حمض الهيدروكلوريك لإزالة أي بقع. قم باستخدام الغسل بالضغط للبقع الصعبة أو التي يصعب الوصول إليها.