Triaxial response of natural clay reinforced with hemp fibers under fully drained conditions.

Abstract

Different soil improvement techniques have been utilized to enhance the engineering properties of soft soils. Soil reinforcement by fibers is viewed as a viable and efficient ground improvement technique which is gaining more interest in the geotechnical community. Reinforcement of soils with discrete natural or synthetic fibers has been shown to increase soil strength and load-bearing capacity for applications involving earth retaining systems, pavement systems, earth slopes, and compacted clay liners and cover systems. An investigation of the published literature reflects a significant effort to study the response of fiber-reinforced clays using triaxial tests. Such tests are generally limited to investigating the undrained response of Kaolin clay and synthetic fibers with few tests targeting natural clay and natural fibers under fully drained conditions. There is a need for studying the response of fiber-reinforced clay systems under fully drained conditions to quantify the expected increase in shear strength for long-term stability assessment. In particular, there is a need for expanding the knowledge on the response of natural fibers within a drained testing setting whereby durability issues might affect the response of the composite. The objectives of this dissertation are to (1) investigate the drained shear strength of clays that are reinforced with natural hemp fibers and which are compacted to different initial water contents, (2) quantify the level of improvement in the drained shear strength due to the addition of fibers, and (3) investigate the durability of hemp fibers for long term stability applications involving compacted clay systems. To achieve these objectives, a comprehensive and wide-reaching experimental drained triaxial testing program was conducted to study the load response of natural clay specimens that are reinforced with “natural” Hemp fibers. The parameters that were varied are the fiber content, confining pressure, and compaction water content. Results indicated that