## 2 Research Methodology  
### Case Study  
The aim is to build a model to measure the social contribution of innovative additives used in asphalt mixtures in Chile. Specifically, four additives used in hot mix asphalt (HMA) were evaluated: Fityre, fiberglass, polyester fiber, and aramid fiber. Fityre is an additive of Chilean origin made from TfELTs, asphalt cement, and rubber powder to form a granular mass and not specifically a fiber. This additive emerged from the innovation and development of FONDEF project ID 20 10160, which was funded by the Chilean Government [20]. The remaining additives correspond to imported fibers; their raw materials are extracted from virgin sources. The optimum amount of additive used in HMA is added according to the weight of the binder, which, in the case of Fityre, is 2% [20]. Following [PERSON] et al. [34], 2.3% is defined as the optimum percentage of fiberglass addition, consistent with the results of [PERSON] et al. [35]. Polyester fiber is included at 4%, aligning with the intermediate utilized by many authors. Indeed, [PERSON] and [PERSON] [36], [PERSON] et al. [37], and [PERSON] et al. [38] used 1%, 4%, and 7% polyester fiber addition, respectively. In studies involving aramid fiber, an additive percentage of 0.05% is used based on the weight of the mixture [11,39,40]. However, it is important to consider that the percentage relative to the binder will vary depending on the binder dosage in each mixture. Asphal mixtures move between binder dosages of approximately 4.5 and 5.5%. In this context, the aramid dosage by binder weight varies in the range of 1 to 1.2%; hence, an intermediate value of 1.1% was chosen for the analysis. Table 1 shows the technical characteristics of each additive evaluated.  
This study examines the assessment criteria and indicators that distinguish the role of the fibers in Table 1 in the life cycle of raw material extraction, pellet additive manufacture, and HMA production. The pavement placement and operation stages require long-term pavement performance studies in an uncontrolled environment, which is beyond the scope of this study.  
Figure 1 represents the six stakeholders involved in developing an additive evaluation model for asphalt mixtures. Recyclers are the companies that specialize in the recycling of ELTs, and their role in the production process and use of fibers is to extract the TfELTs throughout the recycling process. Researchers investigate developments in technology to incorporate waste into asphalt mix components and enhance asphalt pavement performance. The additive producers are the companies that currently offer imported additives  
and those interested in producing the new TfELT-based additive (Fityre). Asphalt mix producers are companies that produce asphalt mixes and use fiber additives during the manufacturing process. Their interests are exclusively technical and economic, concerning the improvement the additives would give their end product. Consumers of asphalt mixtures require the use of mixtures and the inclusion of additives for asphalt formulations. It should be noted that the main consumer of asphalt mixes in Chile is the Ministry of Public Works (MOP) for their own projects or indirectly through a concession or bidding process. The Regulators consist of the Ministry of the Environment and the Ministry of Public Works, which serve as the government entities responsible for technical standardization and authorizations regarding the use of fibers in asphalt mixtures for public paving projects.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Additive** & **Ref.** & \
\begin{tabular}{c} **Density/Length/** \\ **Diameter** \\ \end{tabular} & **Advantages** & **Disadvantages** \\ \hline \multirow{4}{*}{
\begin{tabular}{c} **Conf.** \\ **Conf.** \\ **Conf.