If you have ever walked out of a convenience store or into the parking lot of your grocery store and stepped into a glob of stuck gum you know how irritating it can be. Gum removal is one of those things that requires special chemicals and a certain process that makes it both time consuming and costly.
The hardest thing about getting all of that gooey sticking junk up off of your concrete or asphalt is that it almost always requires you to use steam or hot water. Trying to use a cold water pressure washer and a really concentrated stream water tip will only result in eating divots into the surface of your concrete. The best thing that you can do is get a cheap paint scraper, some hot water, a rag,pressure washer with a fan tip and a general degreaser.
If you can scrap most of the glob of gum up do so first. If it is an old flat piece of gum that has been there for a while then spray a little degreaser on it and get the rag and dip it into the hot water and lay it over the gum and surrounding pavement. Wait for a couple of minutes and as soon as you pull the rag off of the gum use the scraper to try and get an edge of it up. If your successful try and scrape the rest up as quickly as possible. Sometimes you will have to reapply the rag of hot water a couple of times to get the process rolling.
If you are able to only get a little bit of the edge up or not at all stick your chemical uptake hose of your pressure washer into the hot (not boiling) water and go about trying to blast it off. You will not achieve the same effect of using a hot water pressure washing system but it will help warm the water to an extent.
Once the bulk of the gum is up go back again with the degreaser and try to get the residue and dark spot that is left behind. Sometimes this is not achievable and will just have to have repeated applications to fully come out.