Laboratory Performance and Micro-Characteristics of Asphalt Mastic Using Phosphorus Slag Powder as a Filler

To evaluate the possibility of using phosphorus slag powder instead of mineral powder as a filler in asphalt mastic, this study investigates the micro-characteristics of phosphorus slag powder and its viscoelastic mechanical properties in asphalt mastic. A systematic approach combining macro and micro test methods was used to analyze the physical and surface characteristics, void structure, and surface energy of phosphorus slag powder. The viscoelastic mechanical properties of phosphorus slag powder were evaluated using appropriate indexes. Meanwhile, the correlations between and limitations of various evaluation indexes and the high-temperature rheological properties were identified. The results demonstrate that phosphorus slag powder exhibits low density, small overall particle size, difficulty in forming agglomerates, developed pores, large specific surface area, and high surface energy, which is suitable for replacing mineral powder as a filler in asphalt mastic. The main factors affecting the viscoelastic properties of asphalt mastic are the particle size and dosage of phosphorus slag powder. Generally speaking, phosphorus slag powder asphalt mastic with particle sizes ≤ 18 μm exhibits the best performance. In practical engineering applications, the appropriate dosage (7%, 10%, 13%) can be selected based on different regions and specific design and construction requirements. Additionally, zero-shear viscosity (ZSV), non-recoverable creep compliance (Jnr), and creep recovery percentage (R) exhibit a strong correlation with the high-temperature rheological properties of asphalt mastic. At the same time, the rutting factor (G*/sin δ) presents certain limitations.

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