Investigation of the effects of polypropylenefiber dimensions on asphalt wearing layercarrying capacity

Located between pavement types of flexible pavement compared with other types of coatings in Turkey was more preferable excels. Asphalt pavement, which is used as a flexible pavement coating, decreases resistance to deformations due to natural conditions, high temperatures and long loading times, and many deformations occur, especially wheel tracks. Sub-base deformations, infrastructure works on roads, repairs, heavy traffic loads and many similar applications negatively affect the geometric standards of the road and cause economic losses. Many additives are used in bituminous hot mixtures to prevent the formation of traces and road deformation. While some of these additives improve the mixture properties by modifying the bitumen, some additives directly added to the mixture improve the engineering properties of the coating. In this study; Polypropylene fibers, which is a thermoplastic material used in the construction industry and in different fields due to its physical and high mechanical properties, are produced in four different sizes (6, 12, 19 and 54 mm lengths) and 5 different products with an increase of 0.5% between 0.5% and 2.5%. It was used directly in the asphalt wear layer in mixing ratios. For the Marshall test, 100 samples with additives and reference samples were produced for 80 pieces of 3 point beam bending tests, their engineering properties were compared and their effects on bending strength and fracture behavior were investigated. Beam bending test results showed that the propylene (PP) fibers studied did not contribute significantly to the wear layer in terms of strength, but they could make more deflection without deteriorating the layer. It has been determined that wear layers reinforced with 19 mm and 12 mm PP fiber additives have tensile strength equivalent to those without additives. In addition, it was determined that the formula used in the beam bending test results could be misleading by itself, and the maximum single load should also be taken into consideration. Contrary to the 3 point beam bending test results, the stability values of 12 and 19 mm PP fiber added samples were higher than those without PP fiber. It has been determined that the use of 19 and 12 mm PP fibers in wear layers will be beneficial provided that the underlying layer is strong. Keywords: Asphalt Wear Layer, Polypropylene Fiber, Deformation, Marshall Stability, 3-Point Beam Flexure Test