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Recently, natural and environmentally friendly materials have been highly considered for soil reinforcement and stabilization in road and geo-environment infrastructures and constructions. In the present research, laboratory experiments are conducted to evaluate the potential of combining barley fibers and nanoclay to enhance the mechanical properties of clay subgrade while maintaining its affordability and environmental sustainability. Also, it is aimed to explore the potential for extensive use of barley fiber waste, which ranks as the second most abundant agricultural product globally. The laboratory samples were produced by including nanoclay at concentrations of 0.5%, 1%, and 1.5% and barley fibers at concentrations of 0.3%, 0.6%, and 0.9% with fiber lengths of 5 mm, 10 mm, and 15 mm. The primary objective was to determine the optimal content of nanoclay and the most effective fiber length through the unconfined compressive strength (UCS) test. Afterward, the nanoclay was used at its optimal concentration along with different ratios of fibers to perform California bearing ratio (CBR), direct shear, indirect tensile strength, and freeze/thaw (F/T) tests. In addition, scanning electron microscopy (SEM) imaging was employed to examine the mechanism of soil reinforcement by incorporating fibers and the enhancement achieved by the nanoclay introduction into the prepared samples. The results revealed that adding nanoclay to clay caused the development of a cohesive gel between particles and fibers, resulting in improved interlocking and friction. The results also demonstrated a significant increase in the UCS by 142%, tensile strength by 178%, CBR by 120%, and shear strength characteristics. Furthermore, the samples containing an appropriate amount of nanoclay exhibited enhanced durability and greater strength when subjected to F/T cycles. This research determined the optimal fiber length and dose as 10 mm and 0.6%, respectively. Additionally, the highest UCS was achieved with a nanoclay concentration of 1%. Overall, the test results illustrate the effectiveness of these stabilizers in improving the mechanical properties of clay subgrades.

来源平台：GEOTECHNICAL AND GEOLOGICAL ENGINEERING