bill,
section 709.6 calif.bldb. code(1997 ubc)addresses the firestopping methods.in concrete walls ;concrete,grout,or mortar the full thickness of the wall or the thickness required to maintain the rating is o.k.fire caulking or other listed systems are acceptable in other types of walls.
the material used to fill the annular space shall prevent the passage of flame and hot gases sufficient to ignite cotton waste when subjected to ubc standard 7-1 time temperature fire conditions under a minimum positive pressure differential of 0.01inch of water column(2.5pa)at the location of the penetration for the time period equivelent to the fire rating of the construction penetrated.that's the technical explanation!
