38G Dark Grey Concrete Effect Floor & Wall Tile. Epoxy Repair Putty - Chip,Crack

Excellent adhesion to all ceramic, concrete, slate and similar surfaces. Whilst workable the putty can be wiped with a wet finger or spatula to achieve a smooth finish. This step is optional: you can lightly rub down the surface with 400 grit Wet & Dry to provide better adhesion.

eBay