Use of hydrophilic polymeric stabilizer to improve strength and durability of fine-grained soils

Various additive materials are conventionally utilized to improve geotechnical properties of poor soils. Polymeric additives recently are used for soil stabilization, because they are more comfortable, effective and environment-friendly. In current practice, the effect of water-soluble cationic polyacrylamide (PAM) polymer on physical and mechanical properties of a fine-grained soil was investigated in unfrozen and freeze-thaw conditions. For this purpose, different amounts of PAM additive was added to high plastic fine-grained soil and a series of Atterberg limits, compaction, unconfined compression strength (UCS) and freeze-thaw tests were conducted on the soil samples. In addition, using various spectroscopic and microscopic techniques such as field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Brunauer, Emmett, and Teller (BET) surface area analysis and Fourier transform infrared spectroscopy (FTIR) analysis are used to investigate microstructural characteristics of PAM effect on the soil. The results showed that the hydrophilic property of PAM leads to an increase in the plasticity index of the soil. Despite of increasing plasticity index due to PAM inclusion, PAM additive conferred a significant and rapid improvement in compressive strength of the soil and UCS values increased with an increase in PAM content. Moreover, when the soil samples are subjected to the freeze-thaw phenomenon, a considerable reductive occurs on the strength and durability of untreated and treated samples, especially after the first cycle; and PAM additive enhances the freeze-thaw durability of the soil.