Study on Design and Pavement Performance of Rice Straw Fiber Asphalt Mixture Based on Response Surface Methodology

To improve the improvement effect of rice straw fiber on asphalt mixes, a surface response experimental design method was used to study and the optimal blending method of rice straw fiber asphalt mixture was obtained. The fiber asphalt mixes were prepared according to the optimized scheme and analyzed by rutting test, direct tensile test, water immersion Marshall test, freeze–thaw splitting test, and four-point bending fatigue test for related road performance. The results showed that the optimal solution for the fiber ratio of rice straw fiber asphalt mixture was that the fiber length was 9 mm, the fiber content was 4%, and the oil-to-stone ratio was 5.16%. Rice straw fiber can improve the high-temperature performance and water damage resistance of the asphalt mixture. The stability of the mixing material, the stability of the residual stability and the frozen split intensity of the mixing material were 130.6%, 114.1%, and 116.9% of the matrix asphalt mixture, respectively. At the same time, the fiber can enhance the low-temperature performance of asphalt mixes and extend the fatigue life of asphalt mixes. However, when the fiber and dosage were too large, it would weaken the effect of improving the high- and low-temperature performance and water stability of asphalt mixes.