Use of Water-Repellent Additives to Mitigate Freeze-Thaw Damages of Pavement Systems

Abstract: The presence of frost-susceptible soil causes significant damage to pavements in regions with seasonal subfreezing temperatures. Frost heave in such soils is primarily driven by a hydraulic gradient that develops within the frozen fringe. Water-repellent additives can effectively disrupt this gradient and limit water movement toward the fringe by inducing soil hydrophobicity. In this study, frost-susceptible soils from Iowa were stabilized with silane to enhance water repellency. Laboratory testing was conducted on cylindrical soil specimens (14.6 cm diameter, 15.2 cm height) treated with silane. The influence of silane incorporation on water migration, frost penetration, and heave rate was evaluated. Results showed a significant reduction in water migration, with treated layers maintaining lower moisture content than untreated layers. The heave rate was reduced to 2.5 mm/day, compared to 16 mm/day in untreated soils. Field test sections were constructed using a similar silane concentration based on the promising laboratory results. These sections were instrumented with moisture sensors, shape array accelerometers (SAA), and field evaluations, including Light Weight Deflectometer (LWD) testing, Nuclear Density Gauge (NDG) measurements, and visual inspections, were conducted both before winter and after spring thaw. The field data suggested the effectiveness of silane in reducing frost heave potential, providing valuable insights for agencies aiming to minimize the frost heave potential in new construction as well as rehabilitation of existing pavements.