While the recycling material containing bitumen would “burn” with direct firing or undergo an adverse change to its properties, the hot gas generator heats it only indirectly, gently bringing it up to its optimum application temperature.
At the same time, the process reduces emissions – for example because the total carbons in the exhaust flow are largely burnt off.
The recycling material is heated to the optimum processing temperature of 160 °C. All emissions are kept in the standard range and the contained bitumen is not burnt.
The hot gas generator technology allows fresh asphaltic mixtures to consist of 100 % reclaimed asphalt.