Development of bio-based, biodegradable geotextiles for the revegetation of stabilized landslide-prone areas

Abstract

High-tensile steel nets have established themselves as a solution for stabilising landslide-prone areas. To return an engineered slope as much as possible back to a natural look, thoughts of revegetation should always accompany such stabilisation projects. Different factors play a role in natural revegetation, such as the inclination and orientation of said slope and the erosion potential through water percolation. Sometimes it is necessary to help revegetation when a combination of unfavourable factors is present. This can be achieved by adding a geotextile.When vegetation might take several years to grow, a long-term geotextile is required, which does not degrade in the first years. In such a long-term geotextile, 3D mats out of polypropylene were quite successful. Unfortunately, when it comes to its degradation, sometimes after decades, microplastics are released into the environment. This added an essential aspect to the constantly growing need for substituting petrol-based polymers with nature-based materials. This work highlights the different trials with materials to obtain a controlled degradation of the geotextile material into non-hazardous components. By applying biobased, biodegradable polymers for such applications, the need for material recollection is eliminated, and plastic waste’s impact on the environment is significantly reduced. In this work, biopolymer blend fibres were produced and evaluated in terms of mechanical properties and biodegradability. The blends were based on bio-polyester blends, and the properties were tailored by adjusting the composition of the blend fibres to resemble the existing polypropylene product. The degradation rate of the blend fibres was observed by artificial weathering and hydrolytic degradation tests. As a result, a relation between material structure, fibre strength and durability period was obtained and a complete 3D mat could be produced. Once the material was thoroughly tested in the laboratory, a first small-scale field test was set up in 2020, followed last summer with a large-scale 1:1 field test in southern Switzerland, where careful monitoring assesses the stability of the material as well as the stability of the soil beneath it. The development of the material in the laboratory as well as the first results from the large-scale field test will be presented.