Collaborative Research: Engineered Water Repellency to Mitigate Frost Susceptibility: Decoupling Osmotic and Matric Potential

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Frost heaving has a significant effect on civil infrastructure such as buildings, roads, and bridges. It causes excessive settlement, foundation instability, and even structural failure. This research will investigate the extent to which water repellent additives (e.g., organo silanes) mitigate frost heaving while identifying the controlling physical and chemical mechanisms. This research has the potential to dramatically extend the service life of civil infrastructure while introducing a new approach to soil and foundation improvement. This research provides a basis to extend the concept of engineered water repellency to other areas of geotechnical engineering, including applications in slope stability, road construction, and solid/hazardous waste management. More broadly, this research may enhance our understanding of carbon dioxide emissions from permafrost as it thaws during climate change. The research may also inform our understanding of frost formation on the Earth's Moon, Mars, and other extraterrestrial bodies. This project supports a unique experience for Cadets from the U.S. Military Academy, to be paired with Veterans from both collaborating institutions for an experience at these organizations as well as at the U.S. Army Corps of Engineers Engineer Research and Development Center Cold Regions Research and Engineering Laboratory (ERDC-CRREL) Laboratory in Hanover, New Hampshire. The research team, inclusive of the Principal Investigators, Cadets, Veterans, and Graduate Students will also complete an active-learning based seminar entitled "Leading at the Speed of Trust." This training emphasizes trust and character development; both of which have emerged as critical attributes as the work of engineers intersects the public with mass produced products and mega-sized projects. The primary focus of this research is the relative contribution of osmotic and matric potential on ice lens formation and growth, with and without engineered water repellency. This represents a critical link in the dynamic thermo-hydro-mechanical (THM) system. A secondary focus evaluates the net effect of osmotic and matric potential on these two soil systems (with and without water repellency) as interpreted from direct physical measurements (in the lab and in the field). Multi-physics modeling will supplement this work via parametric and related analyses. The research plan is conceived to follow three phases (1) characterization, (2) performance and (3) model application and field testing. Data from the characterization phase will quantify osmotic/matric potential as a function of water repellency. Experiments in the performance phase will evaluate how varied potential and water repellency affect frost heave and the relationship between frozen and unfrozen water content. The parameters which describe the frozen/unfrozen water content relationship will be modified to reflect the relative contribution of osmotic and matric potential and will then be used in models to predict behavior under a wider set of climatic conditions. These predictions will be compared with field data from four sites (Michigan, New Hampshire, North Carolina, and Alaska) whose frost exposure varies by three orders of magnitude.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.