Biobased Epoxy Asphalt Binder (BEAB) for Pavement Asphalt Mixtures

In recent years, there have been significant concerns about environmental issues, sustainability of infrastructure, and depletion of nonrenewable resources for pavement construction. These concerns have led to substituting petroleum-based paving materials with their biobased counterparts. Research efforts have attempted to produce asphalt from renewable bio-resources. As a special modifier for asphalt, petroleum-based epoxy resin has been used in a few asphalt paving projects that require superior performance of asphalt mixtures. This study attempts to develop a biobased epoxy modifier for asphalt, which may improve asphalt performance at lower economic and environmental costs. Based on the findings from research in the chemistry industry, an epoxidized soybean oil (ESO) and a biobased curing agent, maleic anhydride (MA), were selected to develop the epoxy modifier for asphalt. The proper proportions of ESO, MA, and a base asphalt (PG 67-22) were determined to achieve a homogenous biobased epoxy asphalt binder (BEAB) with the desired properties evaluated by a rotational viscosity test, a penetration test, and a dynamic shear rheometer test. Pavement performance related properties of asphalt mixtures using such a BEAB were also evaluated using a Marshall stability test. It was found that the optimum ratio of MA:ESO:Asphalt in the BEAB is 0.45:1:8, and the asphalt mixture containing such a binder has a higher Marshall stability and higher rutting and fatigue cracking resistance indicators than the mixture using a neat asphalt (PG 67-22). In addition, the BEAB with the optimum formula has a curing time (i.e., the time when the binder viscosity increases to 1 Pa·s) of at least 50 minutes, which is sufficient for construction of typical epoxy asphalt pavements