Removing tape residue from colored concrete?

[Gwoody]

I have masking tape residue on multiple sections of our colored concrete. I have tried everything from pressure washing, to goo-gone, mineral oil, citrus oils, lacquer thinner, to gasoline. I stopped short of oxacilic acid. The gasoline has worked the best so far, but nowhere near even partially removing it. Both the goo-gone and gas did a well enough job of lightening the tape marks, but in turn, smeared the residue and discolored the concrete. Our concrete is not polished/smooth concrete, and we do not wish to grind it down and seal it. That would simply remove the aesthetics of what we want our concrete to look like. Any ideas? 

[mbossard]

You might want to try nail polish remover.  When I use it for residue for sticky labels it softens the residue then you take your finger and push to form a little "roll" that you can pick up with your fingernails.  It doesn't "dissolve" it, just makes it so you can ball it.

[speerd]

I'd try rubbing alcohol with at least 90% isopropanol content.  Hard to know for sure without knowing what the nature of the adhesive is, but Isopropanol works really well with pine sap.  

[chemicalman]

It sounds like you have both a solubility problem and a mechanical problem.  Judging by your photo, the tape adhesive has probably had time to both harden and adhere tightly to the rough and porous concrete surface.

A prior suggestion to soften the adhesive so that you can roll it up is a good one, since then it would not pass deeper into the surface as a solution.

A technique without solvents is to use another type of tape that has strong adhesive, maybe a packaging or duct tape, and use it to lift the old adhesive.  Also try using heat to soften the old adhesive and then take it up with the other tape at "just the right temperature," not too cold to work, not so hot to make everything gooey.

Maybe you could press good quality printer paper onto heat softened adhesive to transfer it to the paper; try using a clothes iron.

Some other chemicals you could test: non-flammable brake cleaner, since they usually contain chlorinated solvents that can swell (soften) polymers like adhesives, or paint remover.  You would want to try these early in the day when the pavement is at its most cool and the sun is not shining on it, making it hot.  After applying the test material, cover it with a fairly wide piece of aluminum foil to limit evaporation.  Time a waiting period and then check the progress.

Good luck!