Soil strength enhancements due to polymer infused roots & permanency performance of polymer infused roots
Soil instability is a worldwide problem. As such, there is a need for new technologies for soil stabilization. This research investigates the use of polymer infused plant roots for soil stability applications. By infusing polymer into the roots of plants through the easily accessible above surface plant stems, subsurface geotextile structures can be created without subsurface excavations. Evaluation of this technique involves identifying beneficial soil enhancements due to infusions of roots and assessing the permanency of the new material. Soil enhancements are characterized by measuring soil shear strength using a vane shear apparatus and by measuring indirect soil tensile strength using a compression machine. Permanency of the infused plant is characterized by mass loss resistance and strength loss resistance of the acid treated samples. Permanency is also characterized by aging this hybrid material before shear strength testing.
Shear strength enhancements are measured in three different soil settings. Infusion of roots provided 3.3 to 13.1 kPa of soil shear strength to low plasticity clay and 22 kPa of soil shear strength to elastic silt. Tensile strength enhancements are measured on root laden soil cylinders at two different moisture contents. Infusions of roots provided 13.6 kPa of soil tensile strength to low plasticity clay.
Polymer infusions provided better permanency to the plant material. Infused stems incubated in acid for 15 weeks lost 29% mass, while non-infused stems lost 60% mass. Infused roots incubated in acid for 24 hours had a retained tensile strength of 25 MPa, while non-infused acid treated roots had tensile strength of 12 MPa. In comparison to non-infused plants which provided no enhancements to the soil, the infused plants, after 8 weeks of aging, provided 44% enhancement to soil shear strength.