Comparative Study on the Strengthening Mechanisms of Basalt Fiber and Graphene in the Asphalt Matrix

<jats:title>Abstract</jats:title> <jats:p>Although both basalt fiber (BF) and graphene (GR) have been proven as effective modifiers for enhancing the mechanical properties of asphalt binders, their strengthening mechanisms still need to be studied further. Therefore, the present study conducted a comparative analysis of the micromorphologies and mechanical properties of the two composite systems to reveal their differences in effect mechanism. Stable three-dimensional network structures (TDNS) were found to be composed of BF, whose integrity and stability are correlated positively with fiber content. In addition, BF absorb free asphalt and oil components, boosting the proportion of structural asphalt, and augmenting the stability of basalt fiber–reinforced asphalt (asphalt-BF). In contrast, intercalated structures is the main form of high-strength asphalt-GR. Both strengthening phases significantly improve the viscoelasticity of asphalt matrix. The rutting factor of Asphalt-3% BF and Asphalt-3% GR increased by 28.82% and 20.38%, respectively, compared with unmodified asphalt at 46°C. In the same concentration conditions, basalt-reinforced asphalt has significantly higher specific surface area than Asphalt-GR. The strengthening phase area proportion of Asphalt-3% BF and Asphalt-3% GR were 16.64% and 1.58%, respectively. This significant difference in specific surface area results in the more effective enhancement of the high-temperature rutting resistance (HTRR), creep resistance (CR), and fatigue resistance (FR). Therefore, BF is a better choice as strengthening phase when designing roads with frequent heavy loads or high-temperature areas. The addition of GR gives asphalt electrical conductivity and better mechanical properties and is worth further studying for future smart pavement development. In addition, this study provides theoretical bases to the future composition designing and mechanical property improvement of this material series.</jats:p>