a second zone mixing and discharge of the materials occur in a third zone the invention provides for air or water cooling of the gases in the drum mixer upstream of the point of entry of the asphalt this cooling reduces the formation of smoke which would otherwise be generated by excessive heating of the asphalt the apparatus according to a preferred embodiment employs an axially positioned air duct the outlet end of which discharges cooling air into the drum just upstream of the area of entry of the recycled material application_number US 3938379 A description referring to the drawings a drum mixer according to a preferred embodiment of the invention is illustrated the drum generally designated 10 is in the form of a rotatable cylinder 10a including an inlet end 11 and an outlet end 12 a plurality of flights or vanes are mounted on the inside of the drum wall these flights which are in various shapes defining sections 13 through 18 are provided for lifting the aggregate and for dropping the same through the hot gases the drum is inclined for advancing the material downstream from the inlet end to the outlet end positioned at the inlet end is a stationary burner assembly 19 which produces a high temperature flame 20 projecting into the drum for heating virgin aggregate which is introduced through a stationary hopper 21 the flame and hot gases from the burner project for some distance into a first heating zone 22 of the drum mixer defined generally by vane sections 13 16 the virgin aggregate is thus heated to a desired temperature in the zone 22 located intermediate the ends of the drum is a stationary hopper 23 through which recycled material.