Yes, it is possible.
Make sure you have the latest update installed for both ARCHICAD and the Grasshopper-ARCHICAD Connection.
Then you will see there are "Deconstruct" Component in the ARCHICAD Toolbar in Grasshopper. You can use these ARCHICAD Deconstruct Components to obtain the geometry (surfaces) of those Column and use that for the creation of those Slabs from Grasshopper.
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