Development of Eco-Friendly Polymer Composite Materials for Soil Stabilization in Civil Infrastructure

Abstract

Soil stabilization is a critical process in civil infrastructure, particularly in enhancing the load-bearing capacity, durability, and resilience of subgrade materials in roads, embankments, and foundations. Conventional soil stabilization techniques commonly employ chemical additives such as cement, lime, or synthetic polymers, which, while effective, contribute significantly to environmental degradation due to high carbon emissions, toxicity, and non-biodegradable residues. In response to the growing demand for sustainable engineering solutions, this study investigates the development and performance evaluation of novel eco-friendly polymer composite materials tailored for soil stabilization applications. The research focuses on the formulation of polymer composites derived from biodegradable and renewable sources, including natural rubber latex, starch-based polymers, lignin derivatives, and agricultural byproducts such as rice husk ash and coir fiber. These components were selected for their environmental compatibility, binding potential, and availability in regions prone to geotechnical instability. The polymer composites were synthesized under controlled laboratory conditions and integrated into clayey and silty soil samples in varying proportions to assess their influence on key geotechnical properties such as unconfined compressive strength (UCS), California Bearing Ratio (CBR), permeability, plasticity index, and durability under wet-dry and freeze-thaw cycles. Comprehensive laboratory testing revealed that the inclusion of eco-polymer composites substantially improved the strength and cohesion of weak soils, with some formulations demonstrating up to a 300% increase in UCS and a marked reduction in plasticity and water absorption. The reinforced soils exhibited enhanced resistance to erosion and maintained structural integrity under repeated environmental stresses, indicating strong potential for long-term application in diverse climatic zones. Additionally, microstructural analysis using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of stable polymeric networks within the soil matrix, contributing to improved mechanical behavior and stability. The study underscores the dual benefits of environmental sustainability and engineering performance in the use of bio-based polymer composites for ground improvement. The proposed materials offer a viable, cost-effective alternative to traditional stabilizers while significantly reducing the ecological footprint associated with civil construction practices. The findings advocate for broader implementation of green polymer technologies in infrastructure development and call for further field-scale validation and lifecycle assessment to optimize formulations for specific geotechnical conditions.