Abstract: Apparatus for use in combination with a road working machine for mixing a liquid plasticizing agent within a layer of scarified road surface materal is disclosed. The apparatus includes an array of discs for lifting and turning the scarified road surface material and a nozzle supported in a position for spraying the liquid plasticizing agent upon the road surface material as it is lifted and turned by the discs. In a preferred embodiment, the discs are secured to a rotatable shaft which is mounted for angular movement through a plane lying transverse to the direction of travel so that the disc assembly may follow longitudinal undulations in the road surface.