Small amounts of concrete can be dissolved with acid-based concrete cleaners and stiff brushes. The process is hazardous and requires safety goggles, drop cloths, a respirator mask and heavy rubber work gloves as well as ready access to a hose.
Removing spilled or spattered concrete from unwanted locations means working with powerful acids. Always add acid to standing water rather than adding water to standing acid, as the latter sequence could cause an explosion when the two substances meet.
- Prepare the area
- Safety and acid prep
- Apply to clean
Wet the concrete in question with a garden hose. Drop cloths and tarpaulins can protect surrounding areas and materials from becoming soaked. Take care to preserve the surroundings as they could experience acid dripping or splattering.
Don safety gear and add one part acid-based cleaner to five parts water in a sturdy plastic bucket, modifying solution per part according to instructions on the cleaner bottle. Wet the stiff brush in the resulting solution.
Brush the unwanted concrete with the solution and scrub vigorously until it begins to break up and part from the surfaces to which it has bonded. Repeat immersion and scrubbing for as long as is required before the concrete breaks up completely, then remove the drop cloths and other preventative measures and dispose of the acid solution safely.