Composite materials using recycled high-density polyethylene plastic for railway sleepers

Given the substantial increase in railway load, speed and traffic, there is a notable demand for materials with high durability, long life and good damping. Such materials can be realized through composite materials that contain recycled high-density polyethylene, polypropylene (PP), mica, glass fiber and compatibilizers. In this study, extruded pellets containing the aforementioned materials and produced using a twin-screw extruder were utilized to assess their mechanical performances and microstructures. Composite materials containing 62.5% glass fiber and 20% PP demonstrated remarkable performance for manufacturing sleepers. The addition of 62.5% glass fiber in composite materials containing PP enhanced the flexural strength, flexural modulus, tensile strength and compressive strength by 315, 623, 296 and 40%, respectively, as compared with those of the original composite materials containing PP without glass fiber. Furthermore, the incorporation of glass fiber and the subsequent improvements met the requirements stipulated by the Ministry of Housing and Urban–Rural Development of the People’s Republic of China and International Organization for Standardization standards. This favorable result can be attributed to the good compatibility between the matrix and the glass fiber, as noted from the uniform distribution of glass fiber in the resin matrix in scanning electron microscopy images. The findings of this study highlight the potential of utilizing recycled materials in rail-track-manufacturing applications.