Utilization of Coir Fibers to Improve the Bearing Capacity and Tensile Strength of Expansive Clay

Abstract

Reinforcement is a method to improve soils with low bearing capacity and tensile strength. Coconut coir waste is an alternative reinforcement material because coir fibers have high tensile strength, high shear strength, and high resistance to compressive stress. This study performed the soaked and unsoaked California Bearing Ratio (CBR), the swelling, and the indirect tensile strength tests focusing on expansive clay reinforced with coir fibers. The content of coir fibers was between 0.00% to 1.25% by weight of the mixture. The fibers were cut into 30 mm to 50 mm long pieces, then mixed randomly into the soil in various content. The mixture was compacted based on the maximum dry density and the optimum moisture content of the clay. The test results revealed that the soaked and unsoaked CBR reached the maximum values at 1% fiber content. Originally of poor quality, the soil condition became quite good after being reinforced with an optimum fiber content of 1%. All specimens swelled when soaked. The swelling values tended to increase with the addition of coir fibers. Hence, the expansive clay must be chemically stabilized to reduce swelling. The tensile strength reached the maximum value at 0.6% fiber content.

Increasing Unconfined Compressive Strength of Soft Clay Stabilized with Coir Fiber and Bagasse Ash Mix

“…By incorporating coir fibers at random into the soil, the fibers and the soil will have a larger surface area to touch with, enhancing their interaction and interlocking and strengthening the soil to bear the imposed load [11] [12]. The California Bearing Ratio (CBR) [13][14], shear strength [15][16], tensile strength [17], and unconfined compressive strength (UCS) [18] [19] have all risen in soft soil reinforced with coir fiber.…”

“…Several UCS tests have also been carried out using a combination of coir fiber reinforcement and chemical stabilization. The stabilizer materials used include rice husk ash [22][23], coir-wood ash [24],…”

Combination of Coir Fiber Waste and Coir-Wood Ash for Expansive Clay Stabilization

“…As a result, therefore, the soil becomes more flexible and resilient, exhibiting characteristics of more excellent ductility [29][30]. However, the fibers could not reduce the swelling caused by water [31]. Therefore, the mixture should be combined with the chemical stabilizer.…”