Enhancing the Mechanical and Microstructural Properties of Low Expansive Clay Subgrade with Vinyl Acetate-Ethylene Polymer Incorporation

Abstract

In recent years, the construction industry has shifted toward sustainability, replacing traditional binders with eco-friendly alternatives. One such alternative is vinyl acetate-ethylene (VAE) polymer, known for its hydrophobic properties and used in various construction materials. This study explores the potential of VAE polymer to stabilize expansive clay as road subgrade material. VAE polymer was introduced into low-plasticity clay in varying percentages (1%, 1.5%, and 2% by dry weight of clay), and the mixtures underwent a series of geotechnical tests (compaction, unconfined compressive strength (UCS), California bearing ratio (CBR), resilient modulus, shrinkage-swelling, and soil-water retention curve) and microstructural and chemical analyses [x-ray diffraction (XRD), x-ray fluorescence (XRF), microcomputed tomography (MicroCT), and thermogravimetric analysis (TGA)]. The results show that 1 adding 1% polymer resulted in the highest increase in mechanical strength (UCS, CBR, resilient modulus) by 34%, 40%, and 51%, respectively. Moreover, the incorporation of 2% polymer reduced the swelling-shrinkage potential by 67%. Microstructural analyses support these findings.