Shear Strength of Medium Plastic Expansive Soil Reinforced with Polyester Fibers

This Expansive soils are very problematic as they are prone to substantial settlements, heave, and possess low bearing capacity. These soils cover more than 20% of the land cover of India and cause obstructions in the development of road networks, railways, and various other construction activities. They make soil stabilization essential. An investigation was carried out to determine the effect of various proportions of randomly-oriented polyester fibers on the shear strength of expansive soil. The unconfined compressive strength of reinforced soil was determined by incorporating four fiber contents, i.e., 0.25%, 0.50%, 0.75%, and 1%, with varying aspect ratios. The effect of various aspect ratios of 20, 40, and 60 were studied in the present work. The stress-strain relationship for different aspect ratios and fiber contents is also presented in the study. The optimum quantity of fibers was found to be 0.75% of the total weight of the soil. A maximum enhancement in the strength of the soil was achieved with fibers with an aspect ratio of 40. The effect of the aspect ratio is significant with a fiber content of 0.50 to 0.75%. The peak strength of untreated soil is found at strain levels of 6-8%, whereas it increases to 10-12% in reinforced soil. A statistical analysis was also performed to develop a regression equation to predict the improvement in the strength of the medium plastic expansive soil used in the study.