Abstract: A drum mixer having an countercurrent flow drying zone and a parallel flow mixing zone is provided for producing an asphaltic composition. The drum mixer utilizes a heat source located at an intermediate position therein for generating three streams of hot gases. The first stream of hot gases is directed towards the receiving end of the drum mixer in a countercurrent direction to the flow virgin aggregate entering the drying zone of the drum mixer. Recycle material is introduced into the drum mixer between the heat source and the discharge end thereof. The recycle material and the heated virgin aggregate are combined within the mixing zone. As both materials travel towards the discharge end of the drum mixer the second stream of hot gases is directed towards the discharge end of the drum mixer in a parallel direction to the flow of the mixing materials for heating said materials.

Abstract: A drum mixer having a internal combustion gas cylinder extending substantially the length of the drum mixer is provided. Hot combustion gases are generated by a flame within the cylinder. The combustion gases within the cylinder flow in a countercurrent direction the to the flow of material within the drum mixer. The combustion gases exit the cylinder generally at the receiving end of the drum mixer and are directed towards the discharge end thereof in a parallel relation to the flow of material. The horizontal position of the flame within the drum is adjustable and a valve for mixing the gases within the drum adjacent the discharge end thereof with the flame is also provided.