Evaluating the Resilient Performance of Unpaved Road Materials under Freeze-Thaw Effects
Celso Bilynkievycz dos Santos, Umar Farooq, Bora Çetin, Jeramy C. Ashlock, Mahsa Belalzade, Kanika Lamba
Abstract
Unpaved roads constitute nearly 35% of the roadways in the United States. In Iowa, specifically, approximately 74% of the roadways are unpaved. As the surface layer is the main load-carrying component in these types of infrastructure, the coarse aggregate materials used for its construction regularly break down, resulting in high sand and fines contents. Consequently, the road surfacing materials become more susceptible to the effects of freeze-thaw leading to a decrease in strength and stiffness and resulting in material degradation and surface damage. Previous studies have been conducted on improving the performance of unpaved roads. However, in such studies, CBR tests were typically used instead of resilient modulus, which is a crucial test to evaluate the performance of unbound granular material. In this research, the effect of freeze-thaw (FT) cycles on the stiffness of silty sand geomaterials was evaluated based on their density. Two geomaterials were collected, one from a quarry and one from an unpaved roadway. These materials were tested for their index properties and resilient modulus and were subjected to two and five FT cycles. The results show that the denser material exhibited a higher MR initially. However, when exposed to FT cycles, the stiffness of the denser material decreased more significantly than that of the less dense material. Additionally, two FT cycles had a greater effect on the stiffness of both materials compared to five FT cycles, which did not present any significant additional effects.