Effect of Freeze-Thaw on Compressive Strength of Clayey Soils Reinforced with Wool

ABSTRACT

Reinforcing clayey soil using synthetic and natural fibers has been widely used as soil improvement methods in recent years. The usage of wool, which is inside the natural fibers, as a reinforcing material is seen as an economic, sustainable, and environmentally friendly solution. The compressive strength parameters of clayey soils (CS) equipped with wool were determined by a series of free pressure strength tests before and after freeze-thaw (F-T). The F-T cycle was repeated 12 times in cycles 1, 7, and 28 days. The highest strength increase was attained after 28 days of curing. The compressive strength increase of CS samples prepared with four different wool additives (0.5%, 1%, 1.5%, and 2% dry weight) occurred between 16.9–68.7% and 13.3–62.7% before and after F-T, respectively. The highest compressive strength increase before and after F-T occurred in CS+1.5% wool mixture. In addition, the wool ratio and the number of freeze-thaw cycles were determined to be important parameters in the increase in compressive strength. In summary, it is concluded that wool-supported CS can be used in the basic design of engineering structures and in shallow depths especially in regions with cold climates.

摘要

以纸莎草纸纤维和天然橡胶为原料, 制备了完全可生物降解的绿色复合材料. 采用酶降解法从塞浦路斯纸莎草属植物中提取纸莎草属纤维. 对纤维的物理、力学、化学和热性能进行了表征. 以纸莎草纸纤维增强天然橡胶复合材料（PNRc) 为研究对象, 采用三种不同纤维含量和纤维长度的模压成型工艺制备了PNRc鞋底. 以纯天然橡胶鞋底为对照. 采用ISO标准对制备的样品的抗弯强度、抗拉强度、耐磨性、密度和硬度进行了表征. 进一步研究了材料的热阻、吸水性和表面形貌. 结果表明, 纸莎草纤维增强天然橡胶复合材料具有最佳的硬度, 比纯橡胶提高了18.70%. 抗弯性能提高20%. 热重分析结果表明, 纸莎草纸纤维的加入提高了鞋底的热稳定性. 最佳纤维体积和纤维长度分别为16.5%和10mm, 固化温度110℃, 压力150kpa, 时间4min. 研究表明, 在满足外底标准方面取得了令人鼓舞的成果, 这意味着这些复合材料可能成为鞋业的替代解决方案.

KEYWORDS:

• Clay
• wool
• freeze-thaw
• soil improvement
• swelling
• pH

关键词:

• 纤维增强复合材料
• 天然橡胶
• 外底
• 纸莎草纤维