## 6 Conclusions  
In this research the performance and costs efficiency of three different fiber-modified mixtures including BF, CF, and GF have been compared against the SBS-7% only mixture. Since procurement costs for the polymer-modified mixtures are higher, such mixtures are only used on major highways or airfields. Fiber-modified mixtures can provide an alterative to the increased costs of polymer-modified mixtures. Therefore, life cycle cost analysis has been performed based on the procurement costs and corresponding initial construction costs for each scenario. Initial construction costs for each scenario consisting of BF, CF, and GF have been calculated for a pavement section of 100 km. Furthermore, the relevant maintenance interventions have been scheduled based on the performance characteristics of each fiber type taken from lab tests and finite element modelling. The performance efficiency of each scenario has been evaluated based on the degree of performance enhancement each scenario has to offer depending on the initial construction and maintenance costs. Pavement life cycle analysis has been performed in two different forms. In the first part maintenance interventions are performed to yield a maximum salvage value at the end of the analysis period. In the second part, maintenance interventions are scheduled to yield an extended pavement life for each scenario under consideration.  
Figure 7: Performance efficiency of different mixtures.  
Based on the cost component and performance efficiency of each scenario, BF mixtures offer higher performance when compared to fiber-modified mixtures, including CF and GF mixtures, at lower costs. Fiber-modified mixtures, however, perform significantly better than the SBS-7% mixture, where further maintenance interventions are required to keep the pavement functional until the analysis period of 40 years. All the fiber-modified mixtures required fewer maintenance interventions and have a longer maintenance free period, with an average of 4 years more than that of the SBS-7% mixture due to the least number of passes to fatigue and rutting damage to the pavement. Furthermore, extra major maintenance interventions are required for the SBS-7% mixture that lead to a further increase in pavement life cycle costs by 63%. The BF-modified mixture, however, provides a good balance in terms of reduced initial construction costs, pavement life cycle costs, and increase in pavement life in terms of higher number of passes to fatigue and rutting damage with longer maintenance-free period.  
Currently, the fibers lack standardization and are mostly used in research based scenarios. Moreover, these fiber types are not mass produced; therefore, they might not be available in some regions, whereas SBS is mass produced and available with any major petroleum supplier. Fibers still need more standardization and specific and approved testing methods to be used more globally. Furthermore, another reason is the limited awareness of the significance of fibers when it comes to the improvement in the asphalt mixture's performance.  
The research highlights the economic worth of the usage of each fiber scenario when it comes to project scheduling and creating a budget for highway construction projects. The costs for material procurement play a big role in defining the budget constraints for any project; however, the performance efficiency of each scenario also affects the selection of a particular binder type scenario. In terms of the limitations of this research, the effect of temperature variations in the extremes of high and low ranges has not been included as part of the scope of this research. Future research includes an evaluation of environmental impact of each scenario, where further interventions lead to higher greenhouse gas emissions.