How do you remove stains from concrete ?

Stains can be removed from concrete with dry or mechanical methods , or by wet methods using chemical or water .

Common dry methods include sandblasting ,flame cleaning and shotblasting , grinding , scabbing , planning and scouring . Steel-wire brushes should be used with care because they can leave metal particles on the surface that later may rust and stain the concrete .

Wet methods involve the application of water or specific chemicals according to the nature of the stain . The chemical treatment either dissolves the staining substance so it can be blotted up from the surface of the concrete or bleaches the staining substance so it will not show .

To remove blood stains , for example , wet the stains with water and cover them with a layer of sodium peroxide powder ; let stand for a few minutes , rinse with water and scrub vigorously . Follow with the application of a 5 percent solution of vinegar to neutralize any remaining sodium peroxide .