Long-term durability of epoxy-modified open-graded porous asphalt wearing course

The durability of epoxy-modified open-graded porous asphalt (EMOGPA) was measured against mixes using unmodified 80-100 penetration grade base binder as well as modified binder with 4% Sytrene-butadiene-styrene (SBS) polymer. Multiple tests were conducted to verify the durability of EMOGPA aged up to 194 days at 85 degrees C using an OGPA mix design (20% air void) typical of that used in New Zealand. Generally the indirect tensile moduli of the mixes improved as the concentration of epoxy bitumen increased. The fatigue life of EMOGPA was significantly better than those without epoxy modification. A modified abrasion test was developed and used to support claims that epoxy bitumen is less prone to oxidative ageing and thus can extend the life of standard porous asphalt. Even with substantial dilution of the binder with standard bitumen (as a potential means of reducing cost), the diluted EMOGPA mix was more durable than the 4% SBS binder mix both in terms of Cantabro loss and fatigue life but the SBS mix did perform better than the 80-100 control mix.