You may be able to choose between several effective methods of removing glue from your concrete floors. The specific method that will be quickest and easiest depends upon several factors, including the amount of glue, the type of glue, the material glued to the concrete, and the tools available to you.
Scraping the Glue
Scraping is usually the first method employed in the task of removing old glue from concrete. In some instances, a simple hand scraper will lift the glue off the floor. A hand scraper consists of a metal blade mounted on a handle or pole, but it can also be used with an electrically powered drill. If you are using a hand scraper, first you need to moisten the glue. This serves as a lubricant and also assists in the removal of the dried glue fragments from the floor. If you are using an electric scraper, it should be used on a fairly low setting to avoid gouging the concrete surface.
Scrapers should only be operated at angles less than 45 degrees to avoid gouging the concrete floors. If you are using a hand scraper, it may be necessary to follow up with a floor grinder and abrasive disk (between 36 and 60 grit) to remove any glue that remains after scraping.
Saturating the Glue
Using steam or hot water is usually an effective method of saturating the glue on the concrete surface. This causes any remaining glue to swell up, making it easier to remove. You can apply steam using an industrial steamer or even a simple home clothes iron that has been set for use with steam. The safety instructions that accompany your clothing iron will indicate the maximum amount of steam it is designed to produce. If the steam option is not available to you, hot water may be used instead. You can use a pressure washer or simply place the floor area under the faucet and allow the hot water to spill over the surface.
Gluing over the Glue
If there is excess glue on your concrete surface, adding another layer of adhesive may be an effective method of removing it. The glue manufacturers will usually recommend the best type and thickness of adhesive for this purpose, but you could also use a construction adhesive or even carpet glue. You should not attempt to spread any type of glue on your concrete surface that is thinner than that recommended by the manufacturer. Usually, the thicker the application, the easier it will be to remove. However, allow the glue to completely dry before attempting to scrape off.
If you are using a hand scraper or any other scraping tool, you should moisten the glue before scraping, just as if this was an initial removal phase. If the amount of old glue is very small, you can just sweep it off the floor using a broom. For larger areas, use a wet/dry vacuum cleaner attachment to do this job.
Removing Glue from Concrete Floors Using Steamers and Solvents
In some cases, it may be necessary to combine several of these procedures in order to remove all the glue. You can saturate the glue with a solvent or a steamer before scraping off the excess. Repeat if necessary. Another method of combining these procedures includes applying a steam cleaner to the floor and allowing it to sit for several minutes before wiping off any excess glue with paper towels. In many cases, this step will remove most of the glue residue from the concrete surface, but you should still follow up with a scraping tool to remove the remainder.