INFLUENCE OF FREEZE-THAW CYCLES ON THE MECHANICAL CHARACTERISTICS OF SAND REINFORCED WITH CSA CEMENT AND POLYPROPYLENE FIBER

Abstract

Earth structures like rail and roads are undergoing recurring freeze-thaw cycles in regions with seasonal variation. Most issues related to these structures originate from the limited scope of design guidelines, which solely focus on strength and spurn long-term stability and durability considerations. The soil stabilization approach can be applied to enhance the properties of the soil. Ordinary Portland cement (OPC) is frequently used for these applications. OPC cement emits considerable carbon dioxide, even though it is an excellent binding material. One possible substitute for OPC is calcium sulfoaluminate (CSA) cement. This investigation aims to determine the consequence of cyclic freeze-thaw action on the sample treated with CSA cement and fiber. Samples were prepared using 3% and 5% CSA cement with 0, 0.25%, 0.5%, 0.75%, and 1% polypropylene fiber (PPF) and then subjected to 0, 1, 3, 5, and 7 F-T cycles after 3, 7, and 14 days of curing period. UCS and UPV tests were conducted to monitor the change in soil strength by increasing the fiber content under F-T cycles. The results demonstrated that the optimum fiber content can vary for different cement ratios, and excess may have a negative impact on strength development. The UPV value increases with a rise in fiber content until the optimum value. For soil stabilized with 3% CSA cement, the UCS strength increases with fiber content up to 1%; however, with 5% CSA cement content, the UCS strength first increases with 0.25% of fiber, followed by a decrease in strength. After F-T cycles, a considerable decrease in strength was observed for soil samples without fiber reinforcement, as compared to fiber-cement-stabilized samples. The influence of fiber content and F-T cycles on soil structure was also determined by scanning electron microscopy, which shows that the void and pores are the reasons behind the decrease in strength. The study aims to contribute to creating more enduring and environmentally friendly construction techniques by offering insightful information about how these composite materials behave when cold outside