Resilient Response Characterization of Pavement Foundation Materials Using a Polyacrylamide-Based Stabilizer

The demand for stable and high-quality granular materials for the construction of flexible granular pavements is constantly increasing due to population growth and the ever-expanding urbanization of the planet. Thus, the function of material stabilization to improve the quality and enable the use of available low-quality granular materials is becoming increasingly important. Traditionally, cement-based additives have been used for such stabilization. However, alternate additives such as polymers have recently been shown to also enhance strength and stiffness characteristics. Furthermore, as an added benefit, the use of polymer-based additives results in a far lower carbon footprint than cement-based additives. In the study reported herein, an extensive laboratory investigation was carried out to evaluate the use of polymeric stabilization to improve engineering properties of pavement materials. The engineering properties of three types of soils were evaluated after being treated with a polyacrylamide (PAM). Strength and stiffness properties were determined by conducting unconfined compressive strength (UCS) and repeated load triaxial (RLT) tests. The experimental program showed that the addition of PAM consistently enhanced the strength properties of all tested soils. The PAM-treated samples also showed improvements in the resilient moduli when compared to samples treated with traditional additives of lime and cement. Furthermore, multiple regression models were developed and the resulting three-parameter model revealed an excellent fit to actual resilient moduli. Finally, resilient modulus values were used to analyze the structural coefficient of a granular subbase layer and the results confirmed the improvements in structural capacity of all treated samples.