Effect of Freezing-Thawing on Clayey Soils Reinforced with Human Hair Fibers

The reinforcing of fine-grained soils using natural or synthetic fibers has been successfully applied today. The use of waste human hair fibers among natural fibers is seen as a sustainable solution as a reinforcing material. A series of free pressure tests were performed before and after the freezing-thawing cycle in order to examine the strength properties of the clayey soil (CS) reinforced with human hair fibers (HHF). Before freezing-thawing, clayey soil samples prepared with four different mass ratios of human hair fibers (0.5%, 1%, 1.5%, and 2% by dry weight) indicated 14–54% increases in strength, 7–49% increase were obtained after freezing-thawing. The highest strength increases before and after the freezing-thawing cycle has occurred in the mixture of CS+1.5% HHF. In addition, it was determined that the increase in pressure stress is remarkably increases with increasing human hair fiber ratio and cure time and freeze-thaw cycles. As a result, it is concluded that the CS reinforced with HHF can be utilized in cold climate zones.