how do you remove concrete stains from a tarmac path?

Yes. Go to your local builders supplies outlet and buy a tin of mortar remover (either 2.5ltr or 5ltr tin)
Be very careful and read the instructions fully. This liquid is a very strong acid and it will break down the alkali base if the cement without damaging the tarmac underneath.
It will froth whilst it reacts with the lime in the cement but when it has broken the cement down you should hose it all down with plenty of water.
Do not leave the area unattended. Wear rubber gloves, wellingtons, old clothes and eye protection. Keep pets well clear until you have hosed the area well.
Of course, you could always ring up your handyman and tell him what a mess he made of your communal path- then tell him how he can put it right at his expense!!

Geoff in Wales (do it right 1st time)
August 2011