A field trial of hot mix asphalt using distillation residues was undertaken to investigate the potential of bitumen extenders for use of the vacuum distillation residues (called 'waste oil distillation bottoms' or WODB), produced during the re-refining of waste lubricating oils.
The construction of the field trials is described. Three sections of hot mix asphalt pavement were laid at a site on a roundabout in Hamilton, New Zealand, in May 1991. The trial consisted of hot mix asphalt manufactured using 80/100 bitumen on a control section, and using blends of 180/200 bitumen with 9% and 20% of WODB respectively, air-blown to a nominal 80/100 grade penetration, on two sections.
The physical properties of the mixers were monitored at 14 months (1.3 years) and after 57 months (4.7 years). The WODB-blended mixes did not show greater levels of surface deterioration, cracking or rutting compared to the control.
The WODB were known to contain lead (from petrol additives) and metals from engine wear. After 57 months, analysis of lead, chromium and zinc contents of the hot mix asphalt in the trial sections showed that up to 25% of the zinc had been lost, while lead and chromium levels were similar (95% confidence level) to those initially present in the asphalt.
Keywords: Aging, asphalt, bitumen, New Zealand, oil, recycling, roads, waste oil