Investigation of the Load Settlement Behaviour of Shallow Foundation on Latex-Coated Coir Needle Felt Reinforced Soil Bed

Abstract

For a sustainable planet, the need for geosynthetics has been increasing day by day. Also, geosynthetics plays a crucial part in enhancing soil properties and can effectively improve bearing capacity of structures erected on sandy ground. Therefore, the study aims to investigateeffect of latex-coated coir needle felt reinforcement on BCR(Bearing Capacity Ratio) and SRF(Settlement Reduction Factor) of shallow foundation in a sand bed. A square footing with a thickness of 25mm and a size of 200mm was employed to conduct model plate load experiments on a sand bed that was reinforced with uncoated, single side latex-coated, double side latex-coated coir needle felt each having 1000 GSM in a test tank of dimension 500 x 500 x 500 mm. The number of layers of coir needle felt in planar, wave and looped configurations were theparameters that were examined. Bearing capacity(BC) of reinforced sand was approximately 30.43%-67.34% greater than that of unreinforced sand. SRF of reinforced sand has beenelevated by approximately 15% to 43.22% in comparison to unreinforced sand.

Introduction

Geosynthetics are increasingly used in sustainable construction to reinforce soil foundations (GRSFs), aiming to improve load-bearing capacity and reduce settlement. Though soil reinforcement has ancient roots, modern methods developed significantly in the 1960s–70s, focusing on optimizing parameters like reinforcement depth, width, layering, footing size, type, and spacing.

Reinforcing weak soils with geosynthetics is cost-effective and enhances resistance to chemical damage, making it popular in applications such as bridge foundations and highways. Natural geotextiles (e.g., coir and jute) are gaining preference due to their biodegradability, though they sometimes require reinforcement for heavy loads. Coir Needle Felt (CNF), a natural fiber product, can be coated with latex to enhance durability, combining mechanical strength with improved longevity.

This study evaluates uncoated and latex-coated CNF’s effect on shallow foundation performance in sandy soil. Locally sourced inadequately graded sand was characterized for key physical properties. CNF samples were tested for thickness, tensile strength, and puncture resistance. Latex coating was applied in single and double layers to enhance durability.

Using a lab setup with a steel test tank and model footing, plate load tests were performed under different CNF layouts—planar (free ends), wave (one end wrapped), and looped (both ends wrapped)—to assess bearing capacity and settlement reduction. Results showed significant improvements in load-bearing capacity and settlement control for reinforced soils, with latex-coated CNF and looped layouts providing the best performance.

Conclusion

This study investigates the efficient utilization of Coir Needle Felt-reinforced sand foundations through laboratory model tests on square footings. It analyzes the effects of several reinforcement layers(N) as well as latex coating in different reinforcement layouts – planar, wave and looped layouts

References

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Copyright © 2025 Abi R S, Aswathy Sasikumar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.