Prediction of Compression Index from Secant Elastic Modulus and Peak Strength of High Plastic Clay Ameliorated by Agro-Synthetic Waste Fibers for Green Subgrade

Agro-synthetic stabilization of high-plastic clay is trending due to its vital role in sustainable geotechnical construction and maintenance of clay subgrade. Remoulded samples of high plastic clay (C), ameliorated by optimal doses of 1.2% polyester (P) and 0.9% banana (B) at maximum dry density (γ dmax ) and optimum moisture content (OMC), were subjected to swell potential, unconsolidated undrained (CU) triaxial, consolidation, and California bearing ratio (CBR) tests. The outcome of this research presents that the use of an optimal clay-polyester-banana (CPB) mix enhanced the secant elastic modulus (E 50 ), peak strength (S p ), and CBR by 2.5, 2.43, and 2.7 times, respectively; increased E 50 /C c increased from 12.29 to 53.75 MPa; and lowered the swell potential by 48% and compression index (C c ) by 42.8%. It was also observed that the increase in moisture content (m c ) of the optimal CPB mix from 20% (unsaturated phase) to 32% (wet phase) decreased S p from 212 kPa to 56 kPa and E 50 from 8.42 MPa to 2.16 MPa, whereas C c was increased from 0.16 to 0.26, depicting the potential use of the CPB mix as a stable and sustainable geotechnical material even in wet seasons. Novel correlations are developed for the prediction of C c from m c , E 50 , and S p for an optimal CPB mix to achieve sustainable geotechnical systems and designs in sustainable geo-environmental engineering.