How to remove rust from concrete
Power Wash the Slab
The first thing I did was power wash the slab to get rid of any surface dirt. I’m not sure power washing is important, but I figured any surface dirt might insulate the rust deposits preventing them from being dissolved by the next step: the acid.
Load Up Pump Sprayer
In a pump up sprayer, I mixed a 50/50 solution of water and a product called Acid Magic. Acid Magic is a brand name for hydrochloric acid, with a stronger pH than the very same acid you have in your stomach, so always wear rubber gloves and eye protection.
dampening concrete
The next day, I began the process by dampening the concrete with water from the garden hose.
scrubbing concrete with stiff brush
About halfway through, I scrubbed all of the concrete with a stiff brush. Then I rinsed everything off and let it dry. I saw that there were a few spots that needed retreating so I gave them another shot with the sprayer, let them soak, scrubbed again and rinsed it all off.
soaking grass
I was afraid that all that acid would kill the grass growing against the concrete so I gave it a soaking for about an hour with a little sprinkler to dilute all that acid runoff.
FAQ
The grass did die a few inches away from the concrete but seems to be coming back two weeks later. In hindsight, a longer soaking would be a good idea.
By the way, my rust stain issues are now over because I added a water softener, which removes the iron from the well water.
How do I keep concrete from staining?
Prevent concrete from staining by regularly applying a sealant. Also, clean up spills quickly, prevent standing water with proper drainage and promptly remove leaves.
How can I change the color of my concrete?
Concrete can be stained, painted, dyed or overlayed to change the color. Before changing the color, you'll need to remove any previous coatings and complete necessary repairs.
