INVESTIGATION OF UTILIZING A NEW FOOD WASTE BIO-OIL (FWBO) AS A POTENTIAL ASPHALT BINDER REJUVENATOR

Abstract

Interest in recycling has been on the rise in the past decades, accompanied by research for sustainable practices to mitigate the negative impact of various wastes on the environment. State departments of transportation (DOTs) limit the amount of Reclaimed Asphalt Pavement (RAP) to be utilized in a ton of asphalt mixture due to the potential adverse effects of RAP on the performance of the resulting pavement. However, most DOTs allow up to 20% RAP with the asphalt mixtures used. So far only a few researchers have studied the utilization of highly recycled asphalt mixtures with high percentages of RAP. Rejuvenators are an essential part of 100 % recycled asphalt production due to their ability to increase the RAP content for conventionally produced asphalt mixtures significantly. Accordingly, this study explores the use of new food waste bio-oil (FWBO) as an asphalt binder rejuvenator. Food waste is considered to have detrimental effects on the environment. Food waste contains oils and other compounds that make the soil more acidic. When landfilled, this creates acidic leachate (liquid), which can damage the surrounding soil. Most importantly, the decomposition of food waste in landfills also generates greenhouse gases such as methane, which is more harmful than carbon dioxide and contributes to climate change. Food waste was collected from a local campus shop and used after drying. Dried food waste is processed using Soxhlet extraction to obtain the lipids for use as an asphalt binder rejuvenator. The Soxhlet extractions were conducted at four, twelve, and twenty-four hours to determine the highest yield percentage. The twelve hours extraction process showed the highest oil yield percentage. However, it was found that it is more efficient to proceed with four hours extraction process for high amounts of oil extraction over the same period. This research relied on three different binders for the binder testing: two unmodified PG 64-22 binders and a Polymer Modified Asphalt (PMA) PG 76-22 binder. Moreover, a field extracted RAP binder evaluates the rejuvenators' efficiency. FWBO rejuvenator is compared against two market rejuvenators. The experimental program relied on aging control binder samples for each asphalt type with no rejuvenation using the Rolling Thin Film Oven (RTFO) test, followed by the Pressure Aging Vessel (PAV) test for 20 hours to create Artificial RAP (ARAP) binder. Then, ARAP and RAP binders were blended with 5% by the weight of one of the two market rejuvenators (#1, #2) or the proposed FWBO rejuvenator. Testing results reveal that low-temperature relaxation was significantly improved. Further, samples' master curves were used to calculate the Glover-Rowe (G-R) parameter, Crossover frequency, and modulus (ωc, Gc*). The results showed the ability of the FWBO rejuvenator to reduce the aging rate and improve the rheological properties of RAP binders. Further, Fourier Transform Infrared Spectroscopy (FTIR) test shows that the FWBO rejuvenator reduces the oxidation levels of the aged RAP binders as suggested by the carbonyl index. The same findings were observed with the mixture testing levels. When introduced to 50% and 100% RAP mixtures, the FWBO rejuvenator maintains acceptable performance levels for the intermediate temperature and low temperature as suggested by the flexibility index, fracture energy, and fracture toughness obtained from the semi-circular bend (SCB) test. On the other hand, the FWBO rejuvenator has a high softening effect on the mixtures, which dropped its high-temperature performance to a rutting resistance category of intermediate traffic roads, such as major collector and minor arterial roads. Keywords: Asphalt; Recycling; Reclaimed Asphalt Pavement (RAP); Asphalt Aging; Rejuvenator.