Use of Sand-Coir Fiber Composite Columns in Stabilization of Soft Clay Deposits

Coir, the processed fiber from the husk of coconuts, is reputed to be the strongest and most durable natural material and is abundantly available at low cost in many Asian countries. A few studies have been conducted in the past to examine the potential of coir as a random reinforcing material. This paper reports the degree of improvement obtained by using sand-coir fiber composite in the form of columnar reinforcement in plate load tests on soft clay beds. Influence of area as well as configuration of columns on the pressure versus settlement behavior of soft clay is identified and isolated. The study indicates that strength improvement sufficient enough to eliminate the need for a deep foundation is achievable through the use of the proposed technique. The provision of four identical sand-coir fiber columns just inside the corners of the loaded area is the optimum configuration as far as soil improvement is concerned. This paper also discusses the mechanism of soil improvement and the possibility of expressing the degree of improvement as a unique function of relative column area and normalized column depth.