An Experimental Study on Bitumen Properties Modified with Polypropylene Polymer from Waste Disposable Cups for Flexible Pavement Applications

Waste disposal, especially plastic waste, is of great concern worldwide due to its non-biodegradable nature. Because these wastes remain on Earth for thousands of years without any degradation or decomposition, they pose health, environmental, and social concerns and occupy valuable space. Also, the significantly higher axle load and traffic volume beyond design limits result in serious pavement deterioration problems. Consequently, incorporating these waste plastics into road construction may present environmental and engineering benefits. Thus, this investigation assesses the impact of including waste plastic cups as bitumen modifiers. Firstly, FTIR analysis was carried out in the laboratory on the waste modifier material showed it mainly comprised of polypropylene. Secondly, a study conducted on the physical features of bitumen with and without the modifier discovered that the modifier decreased the penetration, specific gravity, and ductility by 69.90%, 3.40%, and 42.60%, respectively, whereas it increased the softening point by 48.0%. Therefore, a substantial enhancement in temperature vulnerability and stability of the bitumen can be achieved by incorporating the modifier. Thirdly, the FTIR analysis conducted on the pure and modified bitumen showed the presence of extra new peaks in the structure of the modified bitumen. Thus, the features of this modified bitumen with increasing modifier content resulted from the chemical change in its structure. Finally, the One-way analysis of variance (ANOVA) conducted at various bitumen contents revealed less than a 5% significant level, indicating that the modifier had a substantial impact on pure bitumen. The findings from this study present an vital reference for the improvement in hot mix asphalt properties as well as solid waste management and utilization

Experimental Study on the Sliding of WJ-8 Small Resistance Fastener Composite Pad

Under long-term temperature loading, long bridges stretch and deform, causing the beam and rail to move relative to each other. This phenomenon could cause a gradual slide of the rail relative to the fastener composite pad and ultimately results in the slipping out of the fastener pad at the end of the ballastless track bridge changes. The slipping out of the fastener composite pad changes the longitudinal resistance of the fastener and causes shock of the train on the rail structure due to direct contact between the rail and the tie, thus inhibiting the normal use of the line. In this paper, a reciprocating tensile test was carried out on a WJ-8 small resistance fastener to explore the breaking process of the fastener composite pad, identify the interaction mechanism of the fastener composite pad under the rail, and ultimately determine the influence of the pad on the longitudinal resistance of the fastener. The results show that the two factors that affect the longitudinal resistance of the fastener under reciprocating loading are the surface roughness and displacement of the fastener composite pad. While the surface roughness of the fastener composite pad is the main influencing factor in the early stage, the displacement of the composite pad has a greater impact on the later stage. The research results of this paper can provide an important reference for the maintenance and repair of ballastless track fasteners on bridges