Geosynthetic materials as soil reinforcement has been widely used as an efficient means of improving the performance of shallow foundations. Geosynthetic materials like geotextiles, geogrids etc. generally provide better performance but are costly and non-eco-friendly. Natural geotextiles are manufactured mainly from jute and coir fibers, among which coir fiber (obtained from coconut husk) is the strongest and most durable owing to its high lignin content [1]. However, its benefit as a potential reinforcement applicant is underutilized. Studies on various forms of geosynthetic reinforcement were conducted by [2-8]. A few studies have been conducted on reinforced soils under square footing [9-11]. Omar et al. [12] observed that the zone up to which the reinforcement effect was smaller for sand beds under square footing compared to strip footings. Its use as a reinforcement material for slope protection, in erosion-controlling blankets, and for subgrade stabilization has been studied in [13-16]. Tension and pullout behavior of coir geotextiles were investigated in [17]. Studies of various researchers have shown that the durability of coir is sufficient for long-term reinforcement applications [18, 19]. Generally, the lifetime of coir geotextiles is around 10-12 years, but it can be enhanced by various treatment methods (i.e., cement coating, bitumen coating, biological treatment, etc.) [20]. Literature survey shows that the use of coir geotextile in reinforcing sand foundations is underexplored. This paper reports a set of laboratory experimental results of woven coir geotextile reinforced footings. The results reveal the potential of coir geotextiles as an efficient low-cost reinforcement material for shallow foundations. The optimum layout for the placement of geotextile was found.

Materials

The sand used for the tests had a specific gravity of 2.65, effective size 0.32, coefficient of uniformity 2.56, coefficient of curvature 0.88, and friction angle 38.5o . Classification according to the Unified Soil Classification System (USCS) is SP (poorly graded sand). The grain size distribution curve of sand is illustrated in Fig. 1. The maximum and minimum dry densities obtained were 16.4 and 14.9 kN/m3 respectively. All tests were done at a relative density of 60% to simulate medium dense condition. The properties of woven coir geotextiles were determined as per Indian standards: mass 720 g/m2 , ultimate load 12.6 kN/m and failure strain (warp direction) 22%, ultimate load 7.2 kN/m and failure strain (weft direction) 23%, aperture size 610 mm, thickness 6.4 mm.