Experimental Study of the Effect of High Length of Glass and Polypropylene Fibers on Asphalt Mixture Characteristics

Fibers are commonly used to improve the performance of bituminous mixtures by addressing issues caused by traffic loads, environmental changes, and material limitations. This manuscript aims to compare the effect of adding various amounts of polypropylene and glass fibers with a length of 35mm on the performance and strength of bituminous mixtures. With an optimal bitumen content of 5% and dry mix method, fiber-reinforced mixtures were prepared by incorporating fibers in amounts ranging from 0.25% to 1.5% of the total aggregate weight, with a constant increase of 0.25%. The effect of high length fibers on the mechanical properties and cracking behavior of bituminous mixtures was evaluated by implementing a laboratory testing program from Marshall stability, volumetric properties analysis, compressive strength, immersion Marshall, freeze-thaw splitting, static creep and Indirect Tensile Asphalt Cracking (IDEAL-CT). Adding 1.5% polypropylene fibers increased stability, flow, and final static creep stiffness by 49%, 14 %, and 39%, respectively, compared to the mixture without fibers. Regarding improving crack resistance, glass fibers demonstrated superior performance in enhancing flexibility and crack propagation resistance compared to polypropylene fibers. The addition of 1% glass fiber increased the Fracture Strain Tolerance (FST) and Crack Resistance Index (CRI) by 134 % and 135%, respectively, compared to the mixture without fibers. Damage cost analysis indicated that incorporating polypropylene and glass fibers in amounts up to 1.5% resulted in an acceptable increase of 18.8% and 13.2%, respectively, the significant improvement in performance and mitigation of damage that reduces pavement lifespan make this approach compelling.