Vegetable fiber based geotextiles with adjusted durability

摘要

Geotextiles produced from plant fibers for soil erosion control and vegetation establishment were treated to enhance their durability. Biodegradable geotextiles based on coir, jute and flax were acetylated to increase their service life. Depending on the degree of modification by changing the processing conditions, the lifetime of the fiber products can be adjusted. Untreated and treated samples were examined on laboratory scale with an accelerated soil burial test under controlled conditions. At regular intervals weight loss and tensile strength of buried materials were analyzed. About 10 percent (w/w) acetylation resulted in substantial (3-5 times) enhanced durability for coir and jute based geotextiles compared to the untreated materials. The service life of flax geotextile was also enhanced but to a minor extent (2 times). At lower degrees of acetylation (5 percent) no improvement of the durability for flax can be observed. So, the degree of modification influences the velocity of biodegradation and by changing the acetylation processing conditions functional durability can be controlled. Untreated, treated and commercially available geotextiles based on coir, jute and flax are presently evaluated in a field trial on the slopes of a brook with fluctuating water levels. Both fabrics and non-woven geotextiles were studied. During this trial service life, soil erosion and vegetation establishment is monitored. On the waterline of the brook first the untreated flax, then the acetylated flax, which showed an enhanced durability, and after approximately the same time untreated jute have been degraded. After 15 weeks no degradation of acetylated jute has been observed. The positive effect of acetylation on the durability of vegetable fiber based geotextiles found with the laboratory soil burial tests has also been found in the field trial. After 15 weeks of the field trial no degradation of the natural fiber based geotextiles on the slopes of the brook has been observed. Woven coir and jute soil saver demonstrated a better vegetation establishment than jute fabric. Rubberized coir pad and flax non-woven showed the poorest vegetation establishment. Preliminary conclusions after the monitoring period are that a number of the natural fiber based products show good to excellent performance in hydraulic applications and that for a guaranteed prolonged functional lifetime the acetylation of the fiber products is a very suitable method, For good comparison of the different geotextiles in the field trial extended monitoring is performed.