Composite Granular Fiber-Reinforced Asphalt Mixture: Preparation, Performance, and Mechanism

Steel fiber (SF) has been widely used in asphalt mixtures to provide efficient induction heating and improve performance. However, the application of SF in asphalt mixtures still faces the issues of mixing difficulty, further performance improvement, and increased cost. To try to alleviate these issues, brucite fiber (BF) and fiber granulation technology have been adopted. First, SF and BF were mixed into the mixture according to different volume ratios. Based on the research results of engineering performance, the optimal total content and optimal volume ratio of SF and BF were determined. respectively. Then, SF and BF were prepared into a composite granular fiber (CGF). Finally, the performance of the mixture including CGF was verified, its economy was evaluated, and its mechanism was analyzed. The results show that the optimal total content of SF and BF is 0.6% and the optimal volume ratio of SF to BF is 3:2. The high-temperature rutting resistance, low-temperature cracking resistance, and moisture sensitivity of CGF are superior to that of the control sample and SF asphalt mixture, with percentages of 15.1%, 4.2%; 49.4%, 23.4%; 14.5%, 6.7% respectively. A mechanistic analysis described why CGF performed better than SF. The cost performance of the asphalt mixture with CGF surpasses that of SF, with CGF being 32.2% higher.