I have a large concrete drive which is stable apart from a 3' x 15'area at one side. This strip does not really bear the weight of a car, usually just for walking on (it was added to the drive by the original builders and, though complete, has sunk about 1") Is it possible to cover the whole area with black tarmac or the like, it would be quite a job removing all the present concrete, I thought if it was well roughed first ??