ᐅ Resin flooring – and the hollow space beneath it

Hello everyone. We have had a resin floor in our garage for about a year now. Unfortunately, it turned out that a cavity has formed between the concrete slab and the resin floor over an area of about 0.5 m² (5.4 sq ft). The resin floor does not seem to be properly bonded to the concrete slab at this spot. When you tap on this area, it sounds hollow. What solutions are there to fix this problem? Thanks for your responses. Best regards

The epoxy probably did not adhere to the concrete due to moisture. The water needs to be removed. Grind the surface with a floor grinder, let it dry, then apply a deep-penetrating primer for floors, which binds the remaining moisture. After that, apply the epoxy again.

Water cannot be the issue because the foundation slab has been in place for a long time, and the garage was already covered before the resin floor was installed. Therefore, the substrate was completely dry. I believe the primer did not adhere properly, which caused the void. Approximately, what would it cost if I hire a different company? Is the only option to sand down and apply a new primer or floor?

Would it be possible to open a small section, inject a material, and then try to distribute it as evenly as possible before pressing the area firmly down? Basically, like a type of adhesive?

Injection usually doesn’t work.
Possibly liability issues because there was oil/grease on the concrete?
Removing and replacing is definitely the safest option.

Are there any other options besides a complete renovation?

I don’t see the problem with removing and replacing it. The material doesn’t stick to the floor, right? So use a chisel to lift it and break it out. Sand the edges where it adheres thoroughly, remove the dust, and fill any gaps.