Determination of Pre-Treatment Procedure Required for Developing Bio-Binders from Bio-Oils

Most bituminous adhesives or binders that are used for pavement materials are derived mainly from fossil fuels. Due to the availability of large quantities of biorenewable sources such as triglyceride oils, proteins, starch, and other carbohydrates from different organic sources, there are virtuous technical and economic prospects in utilizing them to produce bio-binders. Recently, through the application of scientific research and development, a range of different vegetable oils have been investigated to determine their physical and chemical properties to study their applicability to be used as bio-binders. Bio-binders can be utilized in three different ways to decrease the demand for fossil fuel-based bituminous binders: a direct alternative binder (100% replacement), a bitumen extender (25% to 75% bitumen replacement), or a bitumen modifier (<10% bitumen replacement). In this paper, only the applicability of developing biobinders from bio-oils to be utilized as a direct alternative (100% replacement) has been investigated. Recently, according to Superpave specifications and requirements, the design of pavement material should be based upon the pavement distresses. Hence, investigating the rheological properties of a pavement binder is very important in order to determine the pavement distresses and hence, to predict and evaluate the pavement performance. Temperature and the addition of polymer modifiers play major roles in changing the viscosity and the rate of aging of the bio-oils. The rheological properties, mainly viscosity, of three different types of bio-oils have been investigated to determine the pretreatment temperature and duration required to develop bio-binders. The three different types of bio-oils used are oak flour, switchgrass, and corn stover. In addition, three different polymer modifiers, two polyethylenes, and an oxidized polyethylene, have been blended with the bio-oils to study their effect on the rheological properties of the bio-oils. Notably, the rates of aging and oxidation due to temperature have been studied through measuring the viscosity of the bio-oils during eight hours and then determining the aging index.