Fill concrete floor gap

[Kirsty1981]

How can I fill this gap in the floor beside patio doors.

 

[Kirsty1981]

Images here

 

[AC Power]

Assuming your putting those laminate flooring boards back upon the void that is pictured: I would use cement grout (parging mix). It has no aggregate, other than sand, easy to level and workability for a homeowner.