Evaluation of the Road Performance and Engineering Applications of Asphalt Mixtures Incorporating Straw Fiber

In this paper, wheat-straw fiber (WSF) was added to asphalt mixtures to improve their high-temperature stability and recycle crop waste resources. The main performance indices of the WSF were analyzed, and the main factors and mechanisms that affect the high-temperature performance and modification mechanism of asphalt mixtures with WSF were studied, based on an example of a highway project in Qinba mountainous area, China. It was concluded that the charring effect of WSF was not significant when the ambient temperature was lower than 140°C, but was significant when the temperature was higher than 180°C. For every 0.1% increase in the WSF admixture, the AC-13 asphalt mixtures’ ρf index decreased by an average of 0.03 g·cm3, the asphalt mixture’s VV index increased by 1.30%, and the optimal dosage of asphalt increased by 0.1%–0.3%. The optimum amount of asphalt for rutting tests and Marshall tests of asphalt mixtures with WSF differed by 0.2%–0.3%. The dynamic stability of the asphalt mixtures with WSF increased by 20.4% compared to that of ordinary asphalt mixtures. For the AC-13 asphalt mixture, it is recommended that the WSF’s dosage is 0.1%–0.2%, the appropriate length of WSF is 15 mm, and the moisture content is approximately 10%. The study provides new ideas for the recycling of wheat-straw waste resources and the improvement of asphalt pavement’s high-temperature performance.