Abstract: A pre-heating chamber of transversely arcuate shape adapted to be mounted above a longitudinal portion of a rotary dryer chamber adjacent the combustion chamber of a drying apparatus for drying aggregate, such as used in the manufacture of asphalt paving composition, in which ambient air is circulated through the pre-heating chamber and then discharged through a duct means to the air intake of the combustion chamber.The pre-heating chamber is preferably divided into a radially outer air intake passage communicating at one end with a radially inner air discharge passage to provide a more effective heat transfer between the pre-heating chamber and the rotary dryer chamber.