# Laboratory Evaluation and Finite Element Modeling of SBS and Basalt Fiber Modified Mixtures
## 1 Introduction  
Different modifications in asphalt mixtures can be performed to enhance the high and low temperature performance of asphalt mixtures. Polymer and crumb rubber-modified bitumen mixtures have been used to enhance the viscoelastic properties of asphalt mixtures. Although polymer and crumb rubber-modified mixtures exhibit promising performance in terms of fatigue and rutting resistance, due to rising material costs, some alternative options are available for further optimization of the asphalt mixtures' performance. The alternative is to reduce the percentage of polymer or crumb rubber used in the mixtures and, furthermore, the reduction in polymer or crumb rubber can be compensated for by adding fibers to the mixture without compromising the performance of the asphalt mixtures. Furthermore, the performance of completely pure SBS-modified asphalt mixtures and fiber-reinforced-modified asphalt mixtures can be compared in terms of rutting and fatigue damage. Different forms of fibers are commercially available involving basalt fiber, polyester fiber and xylogen fiber [1]. The usual percentage of these fibers varies from 0.15% to 0.45% depending on the characteristics of the asphalt mixtures. In terms of the significance of this research, an alternative option is necessary for decreasing the procurement costs of SBS-7% mixtures, since these types of mixtures are mostly used in major highways and airport projects. Therefore, an alternative option is the use of fiber modifications to asphalt mixtures and subsequently decreasing the amount of SBS polymer, thereby improving the economic efficiency of the mixtures. Lab tests andfinite element modeling further enhance the rutting depth performance comparisons of SBS-modified mixtures with different percentages and fiber modifications. The performance of basalt fibers (BFs) is sensitive in terms of the diameter of fibers used in the asphalt mixtures. Commercially available BFs are available with diameters of 7 \(\upmu\)m, 16 \(\upmu\)m and 25 \(\upmu\)m. The performance of basalt fibers also varies with the proportions of BFs used in the mixtures, with a recommended percentage of 0.3% [2]. When compared with polyester fiber and xylogen fiber, BF exhibits superior performance in terms of high and low temperature strength enhancement and decreased water sensitivity [3]. Commercially available fibers can also be obtained in organic and inorganic forms. Lignin fiber has been previously used in the modification of the properties of asphalt mixtures due to its readiness to decompose early [4]. However, inorganic fibers outperform organic fibers in terms of increased water damage resistance. Furthermore, the use of organic fibers results in increased tensile strength, increased stiffness modulus, increased elasticity, and constancy in physical and chemical properties of asphalt mixtures [5]. In terms of fibers with inorganic origins, BF is produced from natural basalt. Basalt fiber offers added strength and durability to asphalt mixtures and has good alkali and acidity resistance [6]. BFs provide better strength than conventional steel-formed fibers and have lower environmental impact when it comes to CO\({}_{2}\) emissions [7]. Furthermore, in terms of cost efficiency, basalt fibers are less expensive to procure than carbon fibers [8]. The properties of basalt fibers include being incombustible and resistance against extreme temperature variations. Basalt fiber has been previously used for performance enhancement of pavements in terms of avoiding raveling in pavements, specifically for porous asphalt pavements and open-graded friction course [9]. In case of stone matrix asphalt (SMA) mixtures, the introduction of BF can also improve the ductility of asphalt mixtures and enhance the dynamic modulus, compressive strength and temperature sensitivity by providing an adequate operational temperature range [10].