# Effect of Chemical Composition of Bio- and Petroleum-Based Modifiers on Asphalt Binder Rheology
## 2 Materials and Methods
### Asphalt Binder Modification  
Modifier blending methodology, binder heating cycles, temperatures applied during splitting process, and storage are discussed in this section. A high shear mixer (Cafarmo BDC1850) with a Heidolph PR31 ringed propeller (33-mm diameter fan) was used for blending. The blending was performed at a steady temperature of 130 \(\pm\) 10 \({}^{\circ}\)C. The temperatures were maintained using a Glas-Col  
\begin{table}
\begin{tabular}{c l} \hline \hline
**Modifier** & **Type 1** \\ \hline A & NA 2 \\ C & Fatty acid derivative \\ D & Bio-oil blend \\ E & Modified vegetable oil \\ G & Glycol amine \\ K & ReOB \\ \hline \hline \end{tabular} 1 as reported by suppliers (from US); 2 not provided by the suppliers.  
\end{table}
Table 1: Modifiers used in this study and their classification.  
LLC heating mantle capable of handling 1-L capacity aluminum can. The methodology is illustrated in Figure 1.  
The following were the steps for modifying binders used for chemical and rheological characterization:  
1. PG 64-22 binder was sampled from the refinery terminal in 110-3.8 L cans. They were labelled from 1 to 110 in the order they were collected. The base binder was then grouped in five different sets as shown in Figure 1a.
2. Binder from each set was split to 6 cans of around 500 g each (Figure 1b). Each can was heated to 135 \({}^{\circ}\)C for 2 h to reach a flowing state and was stirred prior to splitting. The split samples were then stored for modification.
3. Before modification, the split base binder (S1) was heated for 30 min in a heating mantle (Figure 1c) to reach 130 \(\pm\) 10 \({}^{\circ}\)C to ensure that material was steadily flowing prior to blending.
4. The modifier was added (weight measured with a 0.01 g readability scale), the propeller was inserted half-way into the depth of the material and was set to 1000 rpm for 20 min. During blending, the temperature was maintained at 130 \(\pm\) 10 \({}^{\circ}\)C and formation of vortices was prevented to avoid air bubbles in the blend.
5. After blending, the MAB was divided into 4-240 mL cans (Figure 1d).
6. Steps 3 to 5 were repeated for the binders from different sets mentioned in Step 1 for obtaining representative samples.
7. Later, 3-240 mL cans from different batches of each MAB were combined to proceed with aging conditioning (Figure 1e).  
Aging conditions used in the study were: Unaged (UA), Rolling Thin-Film Oven (RTFO) in accordance with American Association of State Highway and Transportation Officials (AASHTO) specification T240-13, 20-h Pressure Aging Vessel (PAV) including vacuum degassing and in accordance with AASHTO specification T28-12, 2 PAV and 3 PAV. 2 PAV and 3 PAV conditions were obtained by running continuous 40-h and 60-h PAV cycles, respectively. Once samples reached their required aging conditions, they were stored in small 30 mL cans until tested to avoid multiple heating cycles. To avoid changes in chemical and rheological properties, cans once heated for testing were not re-used. Same treatment was given to the unmodified base binder S1 and unmodified reference binder S5.  
Figure 1: Modifier blending approach (**a**) labelled cars of base binder divided in five sets; (**b**) 3.8 L cans split into 6–1.0 L cans; (**c**) shear mixer for blending and modifier addition; (**d**) modified binder split into 4–240 mL cans; and (**e**) 3–240 mL cans from different sets combined to produce materials for all aging conditions.