Water drives the decay of road subgrades such as frost heave in cold areas and collapse in saline soil areas, which influences the safety and comfort of vehicle transportation. This paper proposes a novel geotechnical material, namely hydrophobized soil, as a subgrade fill material to mitigate water-induced degradation of subgrade. Hydrophobized soil has a low affinity to water and therefore can prevent the subgrade from water infiltration, enhancing the volume stability of subgrades. To demonstrate its feasibility, the hydrophobicity and its durability were investigated in this study. A one-year outdoor weathering test on hydrophobized soil columns was conducted, with the hydrophobicity measured. The results show that hydrophobized sand has different durabilities and exhibits different degradations depending on the chosen hydrophobizing agent and its concentration. Based on the testing results and capillary rise model, the design of hydrophobic hydraulic barrier in subgrade was discussed at the end.

水导致道路路基腐烂，如寒冷地区的冻胀、盐渍土地区的塌陷等，影响车辆运输的安全性和舒适性。本文提出了一种新型岩土材料，即疏水土，作为路基填充材料，以减轻水引起的路基退化。疏水土与水的亲和力较低，可以防止路基水的渗透，提高路基的体积稳定性。为了证明其可行性，本研究对其疏水性及其耐久性进行了研究。对疏水土柱进行了一年的户外风化试验，测量了疏水性。结果表明，根据所选择的疏水剂及其浓度，疏水砂具有不同的耐久性并表现出不同的降解性。最后根据试验结果和毛细管上升模型，对路基憎水水力屏障的设计进行了讨论。