# Laboratory Evaluation and Finite Element Modeling of SBS and Basalt Fiber Modified Mixtures
## 4 Conclusions and Findings  
In this research, basalt fiber has been used with SBS-modified mixtures to evaluate the performance gains by decreasing the amount of SBS modifier required. Two variations of samples have been prepared, one consisting of 7% SBS and the second one consisting of 3% SBS with the addition of 0.3% basalt fiber. Since SBS modification increases in costs as its percentage is increased in mixtures, the addition of basalt fiber to polymer-modified mixtures provide a cost-effective option for enhancing asphalt mixture's performance. Marshall tests have been performed in order to analyze the volumetric properties of the two aforementioned variations. Dynamic stability tests have been conducted using wheel tracking equipment and rutting progression has been measured. Furthermore,  
Figure 8: Comparison of number of passes to fatigue damage. Figure 9: Comparison of number of passes to rutting damage. low-temperature performance has been evaluated using bending beam equipment. Finite element analysis has been performed using the Modified Burger's Logit model, and corresponding rutting and fatigue damage has been determined. The addition of 0.3% basalt fiber to 3% SBS-modified asphalt results in higher flexural strength and increased dynamic stability compared with the 7% SBS mixture. Based on the lab results and data from finite element simulations, improvement during high- and low-temperature conditions can be observed for fiber-reinforced asphalt mixtures. The use of fibers in asphalt mixtures further increases the cohesion and interlocking of aggregates and binders, leading to an increase in permanent deformation resistance. Magnitudes of microstrains further decrease rapidly for fiber-reinforced mixtures as a result of proper load distribution throughout the asphalt layer. Although SBS polymer enhances the interlocking and cross linking of carbon chains in the bitumen, which inherently leads to an improved elastic response, the use of basalt fiber also enhances the elastic response; however it also shows enhancements in terms of the interlocking and bonding of aggregates with the asphalt binder. Therefore, the same performance enhancement can be achieved by decreasing the percentage of SBS and adding 0.3% of basalt fiber, as is the case in this research. The use of basalt fiber increases the fatigue durability of asphalt mixtures in low-temperature conditions and increased stability and rutting resistance in high-temperature conditions. The findings are as follows:  
1. Addition of 0.3% basalt fiber enhances the rutting resistance and stability of asphalt mixtures, with the 0.35% SBS mixture showing a 47% improvement in dynamic stability of asphalt mixtures. 2. Based on the Marshall tests results, usage of 0.3% basalt fiber with an SBS-modified mixture can further enhance the stability and permanent deformation of asphalt mixtures. 3. Based on finite element simulations, fatigue damage is reduced by 25% when the 3% SBS with 0.3% BF mixture is used. 4. Usage of 0.3% basalt fiber with 3% SBS-modified mixtures offers a cost-effective solution in terms of modification of asphalt mixtures. 5. A 16% flexural strength gain can be observed with the addition of 0.3% BF when compared with SBS only-modified mixtures. 6. Rutting magnitude increases by 47% in the case of the 7% SBS mixture when compared with the 3% SBS with 0.3% BF mixture. 7. Use of the 0.3% BF with 3% SBS asphalt mixture show a 25% overall improvement in fatigue properties when compared with the 7% SBS mixture. 8. Flexural strength increases by 16% when using the 0.3% BF with 3% SBS asphalt mixture. Conceptualization, M.F. and N.R. ; methodology, M.F. ; software, M.F. ; validation, M.F. ; formal analysis, M.F. ; investigation, M.F. ; resources, N.R. ; data curation, N.R. ; writing--original draft preparation, M.F. ; writing--review and editing, M.F. ; visualization, M.F. ; supervision, M.F. ; project administration, M.F. All authors have read and agreed to the published version of the manuscript. This research received no external funding.