I had this car battery that flipped in my car trunk. When I got it out of there it spilled some acid on the pavement. It's a sulfuric acid battery. I added some baking soda on it and poured some more water+baking soda to make sure the acid was neutralized.
However there is still a brown-rusty stain on the pavement. I tried water and a big broom brush but it still there.
Any idea what I can use to clean up the pavement to its original color?