FLUXING OF CHIPSEAL BINDERS

Current New Zealand practice is to add automotive gas oil (AGO). commonly called diesel, to bitumen used in chipsealing. This process is called fluxing and is used to obtain a softer residual bitumen. It was assumed that AGO was non-volatile and had a permanent softening effect. However, recent research in New Zealand and Australia has shown that the majority of the AGO is lost within the first few years of the surfacing's life. The implications of these findings are: (a) even if the residual AGO in the seal is sufficient to modify the bitumen to obtain a satisfactory life, a large amount of expensive AGO is simply being wasted, and in the process polluting the environment; (b) a smaller amount of a non-volatile flux could replace AGO at the current dosage, and obtain a similar working life without hazard to the environment; and (c) a non-volatile flux used at the current AGO levels would produce a significantly longer lifetime. The purpose of the research described in this report was to establish the long term fluxing effect achieved with AGO, and to investigate possible non-volatile fluxes which could be used as an alternative to AGO. (a) For the covering entry of this conference, please see IRRD 895316.