A method for repairing a portion of a floor where one or more tiles have become separated from the underlying subfloor of concrete or the like, the method comprising the steps of: - determining the position of a void between said one or more tiles and said subfloor; - drilling an injector hole of 1-2.5 mm in the filler material between tiles positioned above said void; - providing an apparatus comprising: a) a needle-shaped injection nozzle with a hollow shaft and a hub; wherein said hub is threaded and adapted for being directly or indirectly fastened to the outlet of said cartridge, wherein the hollow shaft is configured as a needle of 1.0-2.5 mm in thickness; b) a cartridge with a water based polyvinyl acetate adhesive or a liquid cyanoacrylate adhesive in its lumen, said adhesive having a shear-thinning and thixotropic rheological behavior, said cartridge comprising a threaded outlet; and c) a caulking gun or the like adapted for forcing said adhesive out of the outlet of said cartridge; - injecting said polyvinyl acetate adhesive or liquid cyanoacrylate adhesive of said apparatus into said void via said injector hole and via said needle-shaped injection nozzle of said apparatus, said injection nozzle having a diameter corresponding to said injector hole; - removing said injection nozzle from said injector hole to allow said polyvinyl acetate adhesive or liquid cyanoacrylate adhesive to increase in viscosity; and - allowing said polyvinyl acetate adhesive or liquid cyanoacrylate adhesive to set. - determining the position of a void between said one or more tiles and said subfloor; - drilling an injector hole of 1-2.5 mm in the filler material between tiles positioned above said void; - providing an apparatus comprising: a) a needle-shaped injection nozzle with a hollow shaft and a hub; wherein said hub is threaded and adapted for being directly or indirectly fastened to the outlet of said cartridge, wherein the hollow shaft is configured as a needle of 1.0-2.5 mm in thickness; b) a cartridge with a water based polyvinyl acetate adhesive or a liquid cyanoacrylate adhesive in its lumen, said adhesive having a shear-thinning and thixotropic rheological behavior, said cartridge comprising a threaded outlet; and c) a caulking gun or the like adapted for forcing said adhesive out of the outlet of said cartridge; a) a needle-shaped injection nozzle with a hollow shaft and a hub; wherein said hub is threaded and adapted for being directly or indirectly fastened to the outlet of said cartridge, wherein the hollow shaft is configured as a needle of 1.0-2.5 mm in thickness; b) a cartridge with a water based polyvinyl acetate adhesive or a liquid cyanoacrylate adhesive in its lumen, said adhesive having a shear-thinning and thixotropic rheological behavior, said cartridge comprising a threaded outlet; and c) a caulking gun or the like adapted for forcing said adhesive out of the outlet of said cartridge; - injecting said polyvinyl acetate adhesive or liquid cyanoacrylate adhesive of said apparatus into said void via said injector hole and via said needle-shaped injection nozzle of said apparatus, said injection nozzle having a diameter corresponding to said injector hole; - removing said injection nozzle from said injector hole to allow said polyvinyl acetate adhesive or liquid cyanoacrylate adhesive to increase in viscosity; and - allowing said polyvinyl acetate adhesive or liquid cyanoacrylate adhesive to set.