I am having a recently installed engineered floor removed by the company that installed it incorrectly. I have read the information on this site about how hard it can be to remove a glue-down.

What is the best way to remove any residual adhesive after scraping the concrete?

I believe that the concrete should be returned, at least, to its original condition so that the new installer will have a reasonable surface to start with. Is that a reasonable expectation?

Thanks,

Sandblasting is one way. Just plain sanding is another. There are adhesive removers for concrete. Perry (Floorguy) advocates encasulating slab contaminents with a skimcoat of Ardex. Personally, I am not sure you need to get EVERY trace of adhesive off. Are you planning on having more hardwood glued down? If so, get existing adhesive off using razor scrapers. Then, if they used a moisture-cured urethane adhesive like Bostick's Best, the small amount left on the surface will act like a vapor barrier to a degree. Simply use the same adhesive over it. But you will need to run this by your installer.

If you want to get down to the bare concrete you can use a floor buffer.But if you use the sameglue there wont be a problem.