Abstract Stabilization of the loose and fragile Pisha with the hydrophilic polyurethane material has been proved to be a time and cost-efficient protocol for the conservation of soil and water. However, the undesirable durability performance of the original W-OH binder material deteriorate its long-term conservation ability, especially under the freeze-thaw cycles. This study aims to improve the freeze-thaw durability performance of the W-OH composites through mixture design optimization and material modification. This study first investigates the correlation between the freeze-thaw resistance of the W-OH/Pisha sandstone composites and the concentration of the applied W-OH solution. The test results indicated both the compressive strength and elastic modulus of the W-OH based composites would decrease with freeze-thaw cycles and the samples prepared with higher concentration W-OH solution own better freeze-thaw resistance. Meanwhile, the elastic modulus of the W-OH composites decreased almost linearly with the freeze-thaw cycles, which is in accordance with the linear increase of the porosity of samples determined with the ultra-depth-of-field microscope. Based on these mechanism analyses, the modification of the W-OH material was further conducted with the Ethylene-vinyl acetate (EVA) and air entrainer. The compressive strength test results indicate both the added EVA can enhance the freeze-thaw durability of the W-OH composites, which can be caused by the improved cohesion strength of the W-OH binder due to enhanced density. Similarly, the freeze-thaw durability of the W-OH composites was also enhanced with added air entrainer, which provided extra space for the freezing expansion. The research results of this study can enhance the freeze-thaw durability of the stabilized Pisha sandstone and its long-term conservation ability on soil and water.

中文翻译：

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水土保持用聚氨酯稳定皮沙砂岩冻融耐久性性能评价与改进

摘要 用亲水性聚氨酯材料稳定松散易碎的 Pisha 已被证明是一种节省时间和成本的水土保持协议。然而，原始 W-OH 粘合剂材料不良的耐久性性能降低了其长期保存能力，尤其是在冻融循环下。本研究旨在通过混合物设计优化和材料改性来提高 W-OH 复合材料的冻融耐久性性能。本研究首先研究了 W-OH/Pisha 砂岩复合材料的抗冻融性与应用的 W-OH 溶液浓度之间的相关性。测试结果表明，W-OH 基复合材料的压缩强度和弹性模量均会随着冻融循环而降低，并且用较高浓度的 W-OH 溶液制备的样品具有更好的抗冻融性。同时，W-OH复合材料的弹性模量随着冻融循环的进行几乎呈线性下降，这与超景深显微镜测定样品孔隙率的线性增加一致。基于这些机理分析，使用乙烯-醋酸乙烯酯 (EVA) 和加气剂进一步对 W-OH 材料进行了改性。抗压强度测试结果表明，添加 EVA 可以提高 W-OH 复合材料的冻融耐久性，这可能是由于 W-OH 粘合剂由于密度增加而提高的内聚强度造成的。同样，W-OH 复合材料的冻融耐久性也通过添加引气剂得到增强，为冷冻膨胀提供了额外的空间。本研究的研究成果可以提高稳定化皮沙砂岩的冻融耐久性及其对水土的长期保持能力。