Step 1
Heat the plastic with a heat gun. Hold the heat gun approximately 10 to 12 inches away from the plastic to avoid overheating it. You do not have to liquefy the plastic -- you simply need to heat the plastic until it is pliable. If you do not have a heat gun, you can use a hair blow dryer. A blow dryer will take longer to heat the plastic.
Step 2
Scrape the plastic off the concrete with a putty knife.
Step 3
Reheat the area with the heat gun and remove any excess plastic with the putty knife.
Step 4
Sand the surface of the concrete with a concrete floor sander. If the area is small or you do not care about inconsistencies in the surface smoothness of the concrete area, you can use a small orbital sander to sand just the area that had the plastic on it. Start with a 60-grit paper and graduate to an 80-grit and then a 100-grit. The only plastic that will remain is the plastic that melted deep into the pores of the concrete.
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