Laboratory Evaluation of Fiber-Modified Asphalt Mixtures Incorporating Steel Slag Aggregates

Vigorous and continued efforts by researchers and engineers have contributed towards maintaining environmental sustainability through the utilization of waste materials in civil engineering applications as an alternative to natural sources. In this study, granite aggregates in asphaltic mixes were replaced by electric arc furnace (EAF) steel slag aggregates with different proportions to identify the best combination in terms of superior performance. Asphalt mixtures showing the best performance were further reinforced with polyvinyl alcohol (PVA), acrylic, and polyester fibers at the dosages of 0.05%, 0.15%, and 0.3% by weight of the aggregates. The performance tests of this study were resilient modulus, moisture susceptibility, and indirect tensile fatigue cracking test. The findings of this study revealed that the asphalt mixtures containing coarse steel slag aggregate exhibited the best performance in comparison with the other substitutions. Moreover, the reinforced asphalt mixtures with synthetic fibers at the content of 0.05% exhibited an almost comparable performance to the unreinforced asphalt mixtures. Modifying the asphalt mixtures with PVA, acrylic, and polyester fibers at the proportion of 0.15% have improved the fatigue cracking resistance by 41.13%, 29.87%, and 18.97%, respectively. Also, the fiber-modified asphalt mixtures with PVA, acrylic, and polyester have enhanced the fatigue cracking resistance by about 57%, 44%, and 39%, respectively. The results of the resilient modulus demonstrated that as the fiber content increase, the resilient modulus of the reinforced asphalt mixtures decreases. Therefore, introducing synthetic fibers at the content of 0.3% has slightly decreased the resilient modulus in comparison with unreinforced mixtures. On the other hand, the results of the mechanistic-empirical pavement design showed that the reinforced asphalt mixes with a high content of synthetic fibers have shown lower service life than the control mixes due to the low resilient modulus. On the contrary, based on the laboratory results, the asphalt mixes incorporating PVA, acrylic, and polyester fibers at the proportion of 0.15% have shown the potential to reduce the thickness of the asphalt layer by about 14.9%, 11.80%, and 8.70%, respectively.