**4. Conclusion**

The thermoplastic was used as a treatment of the OPEFB fibres. The ABS coated fibres had an acceptable effect on the protection of fibre as the same as other treatment techniques. The water absorption of the coated fibre decreased due to protection capacity of the coated layer. The ABS coated fibre was found to be more durable compared to uncoated due to the condition of fibre. Morphological studies revealed that the coating modifies and protects the fibre surface entirely and the covered structure of the ABS over fibres can be seen from the respective scanning electron micrographs, also FTIR studies shown the chemical modifications within the ABS thermoplastic and fibres. From the tensile test it was found the Young's modulus of the coated fibre shown improvement due to ABS coating. However, the tensile strength of the fibre indicated less increase in comparison to untreated fibre.

The previous studies describe that inclusion of OPEFB fibres can significantly increase the peak shear strength of silty sand soil (Ahmad et al., 2010). The fibre content increment leads to increasing the shear strength and consequently stabilized the reinforced soil. Coated OPEFB fibres increased the shear strength of silty sand compared to uncoated fibres. Coated fibres shown higher interface friction between fibre and soil particles by increasing the surface area.
