Influence of Bamboo Fibre on Engineering Properties of Lateritic Soils as Highway Pavement Materials

Lateritic soils commonly used in road pavement construction often exhibit inadequate strength and excessive plasticity, leading to poor performance under traffic and environmental loads. The study investigated bamboo fibre's (BF) ability to stabilize lateritic soils. The natural lateritic soils used were classified as clayey gravel and A-2-6(0) according to Unified Soil Classification System and AASHTO respectively. They were treated with 0 – 1.0 % (at 0.25% increment) of BF by dry weight of the soil. Liquid limit decreases with increase in fibre up to 0.5%, plastic limits decreased with increase in BF content but rises at 1%, while the plasticity index (PI) decreased with increased BF content up to 0.5% and increases at higher BF content. Maximum dry density increases with increased fibre contents to maximum of 2.207 g/cm3 and 2.092 g/cm3 at 0.75% for heavy and light compaction respectively and decreases with further fibre increment. Optimum moisture content decreased continually for all compaction efforts with higher fibre contents. Generally, soaked and unsoaked CBR increases from 15-25% and 20 - 29% (from 0-0.75% fibre) and slightly decrease at 1.0%, while UCS of the treated soil increased from 1130 to 2000 KN/m2 at (0-0.50% fibre contents). The UCS CBR developed relationships were of the second order polynomial form with R² values of 0.89 and 0.97 for soaked and unsoaked conditions respectively. The statistical analysis (Fcal > Fcrit) confirmed significant effects of BF on soil properties. Overall, 0.75% BF provided optimal improvement and is recommended for use in sub-base layers of road pavements. Long-term durability and field performance were not evaluated; therefore, further in-situ validation is required.