Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Civil and Environmental Engineering | en_US |
| dc.contributor.advisor | Leng, Zhen (CEE) | en_US |
| dc.creator | Xu, Jiaqiu | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/14453 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Low-carbon asphalt mixture with SOLID waste fillers : composition-performance relationship investigation and optimization | en_US |
| dcterms.abstract | Asphalt mastic, composed of bitumen and filler, plays an important role in the overall performance of asphalt mixture, as the bitumen-filler and mastic-aggregate interfaces are often weak locations where the deterioration of asphalt mixture initiates. Meanwhile, facing the challenges of global warming and climate change, recycling solid wastes into pavement, including using solid waste fillers, has become an effective approach for the transportation industry to achieve the carbon neutrality goal. However, solid waste differs significantly from traditional mineral fillers in terms of its physical and chemical composition, which can significantly affect the physico-chemical interactions at the bitumen-filler interface, and consequently the cohesive and adhesive properties of asphalt mastic. | en_US |
| dcterms.abstract | Currently, a comprehensive understanding of the interfacial interactions between bitumen and solid waste fillers, as well as the composition-performance relationships governing the performance evolution of asphalt mastic under complex service conditions, has not been achieved yet. Furthermore, a holistic framework for the value-added application of solid wastes as fillers in asphalt pavement construction, including the evaluation of the mechanical properties of asphalt mastic and mixtures, environmental impact assessment, and life cycle assessment, is still missing. | en_US |
| dcterms.abstract | To fill the above research gaps, three conventional mineral fillers (granite, basalt, and limestone) and five solid waste fillers (steel slag, desulfurization gypsum, blast furnace slag, expired cement, and iron tailings) were selected and investigated in this study. A multiscale approach was adopted to understand the behavior of the bitumen-filler interface, and elucidate the composition-performance relationship of asphalt mastic from two perspectives: qualitative analysis based on raw material characteristics and quantitative assessment based on micromechanics calculation. The investigation unfolds in a sequential manner. First, molecular dynamic (MD) simulation was conducted to reveal the interaction and failure mechanisms at the bitumen-filler interface. Then, the composition-performance relationship between the composition of asphalt mastic and its mechanical performance was investigated through microscopic and macroscopic tests combined with multifactorial statistical analysis. Further, the micromechanical theory was applied to develop the composition-performance relationship between the microstructural parameters and the macroscopic modulus attributes of asphalt mastics. Finally, the optimum strategy for utilizing solid wastes as bitumen fillers in asphalt pavement systems was developed through comprehensive asphalt mixture tests, life cycle assessment (LCA), and leaching behaviour analysis. | en_US |
| dcterms.abstract | Based on the analysis at the molecular level, it was found that mineral composition of the filler plays a crucial role in the interaction between bitumen and fillers. Compared with conventional mineral fillers, the rock-forming minerals of solid waste fillers exhibit significantly stronger interactions and adhesion properties with bitumen molecules. The failure mode of the bitumen-filler interface transits from pure adhesive failure to a combination of adhesive and cohesive failure, and eventually to complete cohesive failure as the tensile rate decreases. The results of microscopic and macroscopic tests validated the findings from the MD simulations. The synergistic evaluation framework developed in this study offers an accurate and comprehensive characterization of the interfacial interactions between bitumen and filler by integrating surface free energy theory, pull-off tests, rheological characterization, and the essential work of fracture theory. Unlike mineral fillers, solid waste fillers exhibit chemical reactions with weakly acidic bitumen, presenting more complex micro-morphologies that effectively increase the interaction area between bitumen and fillers. The high-temperature rutting resistance of asphalt mastic is jointly governed by the penetration of the bitumen and the particle size of the filler. The fatigue resistance shows a significant positive correlation with the resin content of the bitumen, as well as the specific surface area and fine particle content of the filler. The low-temperature property depends on both the penetration of the bitumen and the particle size parameters of the filler. Compared with classical micromechanical models, the modified Ju-Chen model (MJCM), which incorporates enhancements by solving the radial distribution function, achieves the highest accuracy in modulus prediction among all models, with an average fitting coefficient of 0.984 for all asphalt mastics. The combination of the two-step homogenization method and the MJCM overcomes the limitations of traditional micromechanical models, which enables precise prediction of the dynamic modulus of asphalt mixtures across the entire frequency range and successfully establishes the composition-performance relationship between the microstructural parameters of the mixture and its modulus. Asphalt mixtures with solid waste fillers, especially steel slag, expired cement, and iron tailings, exhibit superior resistance to rutting, moisture damage, and fatigue compared with those with conventional mineral fillers. Furthermore, LCA reveals that the use of solid waste substitution technology systematically optimizes key environmental indicators, such as ecosystem quality and resource availability, throughout the service life of pavement materials, providing a reliable technical pathway for green pavement construction. The outcomes of this study can serve as a reference for improving the theoretical system of bitumen-filler interface behaviour, improving the moisture stability of asphalt pavements, and enhancing the sustainability and durability of road infrastructure. | en_US |
| dcterms.extent | xviii, 218 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2026 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.accessRights | open access | en_US |
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