Bio-Mediated Technique to Control Phase Changes of Porous Media in Seasonally Frozen Ground

This award will develop a bio-mediated technique to reduce freezing and ice lens formation in soils using antifreeze proteins (AFPs) from psychrophilic (cold-loving) microorganisms. The moisture in the seasonally frozen ground, when subjected to freeze-thaw cycles, can develop large ice lenses that degrade the performance of civil infrastructure and affects land surface characteristics such as radiation balance and latent heat exchange. A significant amount of rehabilitation efforts, chemicals, and conservative design approaches are currently used to maintain cold-region infrastructure in serviceable conditions. Our solution is to extract AFPs from psychrophiles and use them to change the freezing characteristics of water in soil to prevent the formation of the detrimental ice lenses. The research will be complemented by establishing an educational and outreach program to engage undergraduate students in convergence research on bio-inspired solutions to complex engineering problems and incorporate cold-region bio-geotechnics in the curriculum. The goal of this project is to investigate, optimize, and develop a bio-mediated sustainable approach to control the phase change transformations of the pore-water present in the porous media of seasonally frozen ground. The growth of ice-lenses in porous soil media is a complex thermomechanical process that depends on freezing rate, heat extraction, the equilibrium of thermal, mechanical, and chemical forces, and effective stress on soil skeleton. We will investigate the following specific objectives: (1) characterize the antifreeze properties of moderate to hyperactive AFPs from different psychrophiles; (2) investigate the bio-treated soils’ thermal characteristics including thermal hysteresis, phase changes, freezing point and evaluate corresponding ice inhibition, ice shaping, and ice recrystallization activities; and (3) evaluate the resiliency of the bio-mediated technique to freeze-thaw cycles and investigate the strength and deformation characteristics of the untreated and bio-treated soils. This project will advance the knowledge base in applications of AFPs, ice mechanics, and soil-ice interfaces to enhance resiliency of cold region infrastructure. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.