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Investigations into the cohesive properties and oxidation resistance of an acid-cured, epoxy-modified open-graded porous asphalt (EMOGPA) were undertaken, and an associated field trial constructed on State Highway 1 in Christchurch in December 2007.

Open-graded porous asphalt (OGPA) specimens were treated in an oven at 85 degrees celsius for up to 171 days, resulting in oxidation equivalent to approximately 20 years in the field. The modulus (25 degrees celsius) of the oxidised epoxy mixture (12,000MPa) was also much higher than that of the control OGPA (7800MPa). Results from the Cantabro test at 10 degrees celsius indicated that the cohesive properties of the oxidised epoxy OGPA were markedly superior to those of conventional OGPA. On the basis of the Cantabro test results, lifetimes of up 144 years were estimated for an increase in cost of up to 2.3 times that of conventional OGPA. Similarly, the fatigue life of oxidised EMOGPA was found to be more than 25 times that of the control. Epoxy bitumen diluted with up to 75% standard 80-100 penetration grade bitumen had an estimated life of up 93 years for 1.3 to 1.6 times the cost of conventional OGPA. The fatigue life of the oxidised 25% and 50% EMOGPA mixes were similar to that of the control.

The field trial demonstrated that full-scale manufacture and surfacing construction with epoxy OGPA could be easily undertaken without any significant modification to plant or the necessary operating procedures. Epoxy OGPA sections with 20% and 30% air voids were constructed. Monitoring of the trial site for 27 months showed no difference in performance compared with the control section.

Keywords: durability, epoxy-modified bitumen, open-graded porous asphalt