Bricks, Masonry, Asphalt and Concrete - cleaning concrete

we recently had some hotmix overlay done in our developement and the contractor let some of the asphalt "tack" run down on to an aged cement drive. we have yet to find anything that will clean it up. it just seems to smear out but gets lighter in color. a local concrete guy says the only fix is a concrete saw. what do you think?

You may find the following info helpful: http://w3.gsa.gov/web/p/hptp.nsf/0/839d2f7078530d05852565c50054b1c7?OpenDocument

Removing asphalt from concrete can be difficult. The Portland Cement Association cautions against the use of solvents as they tend to drive the stain deeper into the concrete and make it impossible to remove the stain. They recommend first trying scouring powder and water. If that does not work, then a poultice made with a powdered inert material and impregnated with toluene (toluol) or benzene (benzol), which is derived from coal tar and not to be confused with benzine (an extremely volatile substance). The poultice needs to be on the stain 24-48 hours. Then, scrub with scouring powder again.

I know my uncle used to clean peoples driveways and concreted areas with a high powered jet washer. It really gets tough stuff off but Im not sure about asphalt. Maybe you could find someone in your area who does those kind of services for a fee and ask them. Or maybe higher a jet washer for a day and try it.

or

call the people that did the tar work and have them clean it up. They are responsible for this.