Frost-heave and thaw-weakening of pavement foundation materials

Freeze-thaw cycles are common in cold regions and lead to frost heave and thaw weakening that influence pavement construction, maintenance, safety, and longevity. Because there is limited research about frost heave and thaw weakening of pavement foundation geomaterials, this research focused on the frost heave and thaw weakening performance of geomaterials stabilized with various combinations of fly ash, cement, fibers, and fibers with cement. The first objective of this research was to conduct laboratory tests according to ASTM D5918 to compare the effects of these stabilizers on frost susceptibility. The second objective of this research was to further associate laboratory results with in situ freeze-thaw performance of pavements with similar stabilized foundation geomaterials. For sandy lean clay, fly ash decreased frost susceptibility, and 15% fly ash performed better than 5%, 10%, and 20% fly ash. Cement decreased the frost susceptibility to very low to negligible levels for both sandy lean clay and silty sand with gravel. For silty sand with gravel, fibers alone did not significantly affect frost susceptibility, but fibers with cement performed better than the other stabilizers. Findings related to variations in compaction delay, cure time, setting time for chemical stabilizers, and cost are also reported. In situ stiffness testing conducted during frozen and after thaw conditions indicated that frozen pavements were stiffer than after thaw pavements. The trends in seasonal variation in stiffness were similar for pavement systems with all kinds of stabilization. Layers stabilized with cement and cement with fibers had the lowest stiffness changes after freeze-thaw cycles. These findings correlate with laboratory test results. This research provides guidance for selecting stabilizers to improve the frost susceptibility of pavement foundation materials