Here you can see how i patched some holes in my concrete sub-floor. I attempted to use 3 methods but in the end, it were only 2.
The steps would be the same if you were about to patch some cracks.
Things you will need:
-Angle Grinder with a concrete cutting disc
-Hammer and Chisel
-Concrete/Wooden Board/Sheetmetal (depends on how you want to cover your hole)
Step 1: Enlarge the Hole or Spot You Want to Patch.
Start by marking where you want to cut and proceed to cut as deep as needed (depends on patching method).
Then remove the concrete.
Step 2: First Method
After blocking the original holes you are about to patch (with a thin piece of hardboard) pour concrete and smooth it out.
For this method your enlarged hole should be about 2 Inches or 5cm deep.
Step 3: Seconed Method
Cover your hole with a piece of sheetmetal. Someone must have cut something out of my piece...was it me? noooooo! So i made my enlarged hole deeper and used the 3rd method.
For this method, your enlarged hole needs to be as deep as your sheetmetal is thick.
Step 4: Third Method
Cover your holes with an OSB board.
Of course, your enlarged hole needs to be as deep as your OSB board is thick. In my case that has been 18mm or about 3/4 Inches.
Step 5: Have Fun With Your Now Hole-less Floor
These holes were in the sub floor of my barn and i am currently setting up my new shop there. And now i dont have to trip over that holes or drop stuff in there :)