Experimental Study on the Frost Heave Characteristics of Silt Clay Modified With Hydrophobic Nano-ZnO

Silty clay is widely distributed in seasonally frozen zones in China and frequently engages in engineering projects. Nevertheless, it exhibits significant frost susceptibility and generates substantial related freezing damage. To address this problem, this study investigates the impact of nano-zinc oxide (ZnO) on silty clay's frost heave characteristic. We conducted tests on silty clay with varying nano-ZnO contents, assessing plasticity limit, liquid limit, frost heave, and uniaxial compressive strength. The findings reveal that: (1) the addition of nano-ZnO can decrease the free water content, and result in both the plastic limit and the liquid limit increase, and further accelerate the freezing process, which is helpful to mitigate the frost heave caused by water migration; (2) the frost heave ratio decreases with increasing nano-ZnO content within the tested range, 4.0% addition of nano-ZnO can significantly reduce frost heave by 66.96%, and transform the silty clay from extreme frost heave to frost heave; (3) with the nano-ZnO content increases, the uniaxial compressive strengths of the specimen initially increases (0%-3.0%) and subsequently decreases (4.0%), and the brittleness also becomes more pronounced. According to the results of mechanical and frost heave tests, the optimal content of nano-ZnO is ascertained to be 3.0%. The results of this study provide a promising solution to mitigate the frost heave of silty clay, particularly in regions with limited coarse-grained soil.