Biodegradable Geosynthetics for Geotechnical and Geo-Environmental Engineering

Among the commonly used plastic materials in geotechnical engineering, the most significant fraction consists in the geosynthetics. The use of these products involves environmental risks associated with their degradation. Hence, a strong interest in biodegradable polymers of natural origin has been increasing, for finding alternative materials with adequate mechanical properties for geotechnical and geo-environmental applications. The main aim of this study is to test a bio-based, biodegradable and eco-compatible polymer, able to replace polypropylene and other synthetic materials in the production of geosynthetics. For this purpose, Poly(lactic acid) or PLA, one of the most common bioplastic polymer material commonly used as filament for 3D printers, was investigated. The chemical structure of PLA was determined by 1H NMR and the optical purity determination by polarimetry. PLA filament was used to print samples of uniaxial and biaxial geogrid at 1:5 scale using a professional 3D printer. Subsequently, tensile tests were performed on the filament and on prototype geogrids. Tensile tests measured a maximum tensile resistance of 51.96 MPa for the filament and 12.96 kN/m for uniaxial geogrid prototypes. The mechanical properties of PLA were found to be comparable to petroleum derivatives. These results are encouraging and can support the utilization of PLA for innovative biodegradable geosynthetics production, which could represent an alternative to non-biodegradable products, particularly when used in combination with live plants. In view of practical applications, however, research is still needed to determine the degradation of their mechanical properties over time.