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<p>To address the issues of water-induced softening, structural instability, and severe moisture damage associated with Flue gas desulfurization (FGD) gypsum-filled asphalt pavements, this study proposes a hydrophobic and dissolution-resistant modification method and systematically investigates the water stability, interfacial mechanisms, and performance effects of modified FGD gypsum in asphalt mixtures. Through polar component analysis, adhesion work calculations, and interfacial transition zone measurements, the physicochemical changes before and after gypsum modification were assessed. Additionally, immersion residual stability tests and freeze-thaw splitting tests were conducted to evaluate the application feasibility of modified FGD gypsum in asphalt mixtures. The results indicate that asphalt mixtures containing unmodified FGD gypsum fail to meet road performance standards under water exposure, due to particle dissolution and asphalt film stripping. After 600&#xa0;h of immersion, the filler particle count decreased by 52.60%, significantly impacting pavement performance. In contrast, the hydrophobic and dissolution-resistant modification reduced the polar component of FGD gypsum by 72.46%, increased adhesion work with asphalt by 11.15%, and expanded the interfacial transition zone thickness by 546%. These modifications effectively enhanced the asphalt-filler adhesion, inhibited water-induced structural damage, and improved the water resistance of the asphalt mixture. The silane coupling agent facilitated a dehydration-condensation reaction on the gypsum surface, grafting silanol groups and forming a hydrophobic coating layer, which reduced material hydrophilicity, enhanced water damage resistance, and minimized moisture displacement of the asphalt film. Consequently, the water stability and durability of the asphalt mixture were significantly improved. This study provides theoretical support and technical guidance for the high-value utilization of FGD gypsum in asphalt pavements and introduces a new approach for the resource recovery of industrial by-product gypsum. Additionally, it contributes to the green and sustainable development of road engineering, promoting the efficient application of solid waste in transportation infrastructure.</p>

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Mechanism Study on the Enhancement of Asphalt Pavement Water Stability Using Hydrophobic Modified FGD Gypsum Filler

  • 期刊论文

  • 发表日期：

    2025年12月9日

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  • Kun Yang,
  • Hongjun Lu,
  • Yi Liu

摘要

To address the issues of water-induced softening, structural instability, and severe moisture damage associated with Flue gas desulfurization (FGD) gypsum-filled asphalt pavements, this study proposes a hydrophobic and dissolution-resistant modification method and systematically investigates the water stability, interfacial mechanisms, and performance effects of modified FGD gypsum in asphalt mixtures. Through polar component analysis, adhesion work calculations, and interfacial transition zone measurements, the physicochemical changes before and after gypsum modification were assessed. Additionally, immersion residual stability tests and freeze-thaw splitting tests were conducted to evaluate the application feasibility of modified FGD gypsum in asphalt mixtures. The results indicate that asphalt mixtures containing unmodified FGD gypsum fail to meet road performance standards under water exposure, due to particle dissolution and asphalt film stripping. After 600 h of immersion, the filler particle count decreased by 52.60%, significantly impacting pavement performance. In contrast, the hydrophobic and dissolution-resistant modification reduced the polar component of FGD gypsum by 72.46%, increased adhesion work with asphalt by 11.15%, and expanded the interfacial transition zone thickness by 546%. These modifications effectively enhanced the asphalt-filler adhesion, inhibited water-induced structural damage, and improved the water resistance of the asphalt mixture. The silane coupling agent facilitated a dehydration-condensation reaction on the gypsum surface, grafting silanol groups and forming a hydrophobic coating layer, which reduced material hydrophilicity, enhanced water damage resistance, and minimized moisture displacement of the asphalt film. Consequently, the water stability and durability of the asphalt mixture were significantly improved. This study provides theoretical support and technical guidance for the high-value utilization of FGD gypsum in asphalt pavements and introduces a new approach for the resource recovery of industrial by-product gypsum. Additionally, it contributes to the green and sustainable development of road engineering, promoting the efficient application of solid waste in transportation infrastructure.