Sustainable soil solutions: the role of coir in geotechnical engineering

Abstract

Agricultural waste holds significant potential as natural fibers in geotextiles due to their excellent mechanical properties. Materials such as jute, coir, sisal, kenaf, banana stem, and pineapple are either in use or have potential for this purpose. Coir, a natural fiber with properties suited for geotextile applications, was studied in this research for its effectiveness in improving clay soil. In clay soils, coir enhances drainage and soil structure. This study aimed to evaluate the performance of different coir mat layers applied to clayey soil by analyzing the chemical composition of coir fibers, physical soil properties, and strength characteristics. Laboratory tests conducted included specific gravity, Atterberg limits, and California Bearing Ratio (CBR). Results identified the soil as organic clayey (A-7-5) with a specific gravity of 2.09 and a plasticity index (PI) of 30. Treated control samples with single and double layers of coir geotextiles achieved CBR values of 76.28% and 80%, respectively. The 4% increase in CBR with double layers highlights enhanced load-bearing capacity, facilitating the construction of stable, durable pavements, embankments, and foundations on weak soils. This study confirms that coir fibers are an effective natural geotextile for improving clay soil stability.