Experimental Study of Surface Reinforcement of Soil Slopes Using Carbon Fiber-Reinforced Stabilized Soil

Rainfall-induced erosion and deformation of soil slopes remain important concerns for long-term slope stability, highlighting the need for effective surface reinforcement methods. This study experimentally investigated the mechanical and rainfall-resistant performance of carbon fiber-reinforced stabilized soil for slope surface protection. Four soil types were initially evaluated using unconfined compression tests with different Eco Soil Binder (E.S.B.) contents, and well-graded sand (SW) with 20% E.S.B. was selected for further testing. Carbon fiber contents ranging from 0 to 1.2% were considered; however, stable specimens could not be formed at 1.2%, while 0.6% provided the highest compressive strength among the valid test conditions. The selected mixture of SW, 20% E.S.B., and 0.6% carbon fiber was further characterized through triaxial compression tests, yielding an apparent cohesion of 0.152 MPa and a friction angle of 37.23°. Artificial rainfall tests were then conducted using 1:50 geometrically scaled slope models with berm lengths of 0.05 and 0.15 m under a rainfall intensity of 20 mm/h for 48 h. Under the tested small-scale conditions, the stabilized slope models exhibited approximately 47-60% lower settlement than the unreinforced models, together with lower final moisture contents and less visible surface deterioration. Because the two model configurations differed in both material composition and initial unit weight, these results should be interpreted as descriptive comparative observations rather than as isolated effects of E.S.B. and carbon fiber.