Sustainable Application of Wool-Banana Bio-Composite Waste Material in Geotechnical Engineering for Enhancement of Elastoplastic Strain and Resilience of Subgrade Expansive Clays

Abstract

Agro-biogenic stabilization of expansive subgrade soils is trending to achieve cost-effective and sustainable geotechnical design to resist distress and settlement during the application of heavy traffic loads. This research presents optimized remediation of expansive clay by addition of proportionate quantities of waste renewable wool-banana (WB) fiber composites for the enhancement of elastoplastic strain (ԐEP), peak strength (Sp), resilient modulus (MR) and California bearing ratio (CBR) of expansive clays. Remolded samples of stabilized and nontreated clay prepared at maximum dry density (γdmax) and optimum moisture content (OMC) were subjected to a series of swell potential, unconfined compressive strength (UCS), resilient modulus (MR) and CBR tests to evaluate swell potential, ԐEP, MR, and CBR parameters. The outcome of this study clearly demonstrates that the optimal WB fiber dosage (i.e., 0.6% wool and 1.2% banana fibers of dry weight of clay) lowers the free swell up to 58% and presents an enhancement of 3.5, 2.7, 3.0 and 4.5-times of ԐEPT, Sp, MR and CBR, respectively. Enhancement in ԐEP is vital for the mitigation of excessive cracking in expansive clays for sustainable subgrades. The ratio of strain relating to the peak strength (ԐPS) to the strain relating to the residual strength (ԐRS), i.e., ԐPS/ԐRS = 2.99 which is highest among all fiber-clay blend depicting the highly ductile clay-fiber mixture. Cost-strength analysis reveals the optimized enhancement of ԐEPT, Sp, MR and CBR in comparison with cost using clay plus 0.6% wool plus 1.2% banana fibers blend which depicts the potential application of this research to economize the stabilization of subgrade clay to achieve green and biogeotechnical engineering goals.