To repair cracks in concrete floors, chip the crack into an inverted V shape, clean it using a brush, apply bonding adhesive on the crack's sides, and fill it with a patching compound. Apply the compound over the crack, and make it smooth.
To chip a crack in the concrete floor, chisel in an outward direction to a depth of minimum of 1 inch. Use a chisel along with a hammer for this purpose. Ensure that the crack's bottom is wider than its surface. The inverted V shape thus created ensures that the concrete patching compound remains in its position.
Remove loose rubble to the extent possible from within the crack using a wire brush. Apply one layer of a bonding adhesive on the crack's sides using a paint brush. This adhesive holds the patching compound in position.
Combine the patching compound as per the directions of the manufacturer. Using a trowel, fill the compound in the crack to the top. Add the compound gently, and ensure that air pockets do not form.
Next, thinly layer some compound on the crack's surface. Finally, smooth the compound so that it becomes even with the surface of the concrete.
Repair cracks in concrete floors as quickly as possible to prevent them from expanding.