Freeze-thaw action in soils, a process where soil moisture freezes and thaws, causes significant heave and settlement, leading to substantial damage to pavements and infrastructure, particularly in seasonally freezing regions. This increases maintenance costs, reduces structural integrity, and shortens roadway and other important infrastructure lifespans. In 2013 alone, U.S. state highway agencies reported spending approximately $27 billion on pavement maintenance, and freeze-thaw damage is considered one of the factors responsible for these expenses. Addressing this issue is essential for infrastructure durability and performance in affected areas, decreasing economic costs and improving safety. This dissertation explores an innovative solution known as engineered water repellency to mitigate the impacts of freeze-thaw cycles on soils. The study also investigates the impact of salt concentrations in soil caused by road deicing operations on freeze-thaw action in soils. An extensive literature review provides a comprehensive understanding of the mechanisms of frost action, its impacts on infrastructure, and existing mitigation strategies.The research employs both experimental and large-scale testing methodologies to evaluate the efficacy of organosilane (OS) treatments in reducing frost heave and moisture migration in frost-susceptible soils by imparting water repellency to the soil. A novel large-scale soil test box simulates realistic environmental conditions, providing valuable insights into the freeze-thaw action in soil and the practical application of OS treatments. Results from the study demonstrate that OS treatments significantly mitigate frost heave and improve soil stability by reducing moisture migration. Specifically, OS-treated soils showed a reduction in maximum soil heave by up to 96% and water migration by up to 97% compared to untreated soils. The large-scale test box, which provided controlled yet realistic top-down freezing conditions, revealed that treated soils maintained higher minimum temperatures and lower moisture content above the hydrophobic layer thereby reducing the heave monitored at 0.15 m depth. However, the importance of integrating proper drainage systems was highlighted to prevent excessive moisture accumulation and ensure the effectiveness of water-repellency treatments in real-world applications. The present study also investigates the effects of varying sodium chloride (NaCl) concentrations on freeze-thaw behavior, revealing that higher salt levels effectively lower the freezing point, reduce heave rates, and decrease water intake. The study emphasizes the importance of simulating realistic temperature gradients to understand the effect of salt concentration on freeze-thaw behavior in soils. For instance, soils with 5% NaCl concentration showed significant freezing point depression and reduced heave rates to 11.3 mm/day (ASTM) and 1.5 mm/day (low-temperature gradient) from 22.5 mm/day and 17.2 mm/day, respectively, in the control. Additionally, salt treatments effectively decreased moisture content and water migration, with the highest salt concentration demonstrating the most substantial reductions. However, salt migrates toward the freezing front, increasing soil salt concentrations in the upper layers. An economic analysis using life cycle cost analysis (LCCA) confirmed that engineered water repellency is a cost-effective long-term solution compared to traditional methods. While initial costs might be higher, the lower equivalent uniform annual costs (EUAC) and net present values (NPV) of OS treatments make them economically viable over the long term. These findings collectively advance the understanding of soil behavior under freeze-thaw conditions and propose practical, economically viable strategies for improving infrastructure resilience in cold climates. Future research should focus on field validations and long-term monitoring to refine these strategies and ensure their effectiveness across diverse environmental conditions.
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