Dried Cement on a Tarmac Driveway?

My boyfriend works as a cement truck driver, so I asked his advice on this. He said that they use hydrochloric acid to dissolve the dried up cement that builds up on the trucks. He's not sure how the tarmac would react to the hydrochloric acid though, so he says you should definitely do an acid test somewhere on the tarmac where it can't be seen first before attempting this procedure, just in case. He said to chip off as much of the dried cement as you can first, using a hammer and an old skrewdriver or something like that. Hydrochloric acid is a very strong acid so don't forget to use acid-safe rubber gloves and avoid breathing in the fumes, so do it on a windy day.

He said you could alternatively try using acetic acid instead which is a weaker acid and less "dangerous". (If the tarmac can stand the acid test at all, that is.) It will be safer for you, but will take longer to dissolve the cement. Afterwards, soak up as much of the dissolved cement as you can using cat-litter or old rags to avoid too much acid being rinsed off into the flowerbeds. Afterwards, you should rinse, rinse and rinse again with water to remove and dilute as much of the acid residue as possible. Good luck!