Comparative Evaluation of Geopolymer and Conventional Concrete

<p><span lang="EN-US">Concrete plays a vital role in modern construction, but the production of Ordinary Portland Cement (OPC) contributes substantially to global CO₂ emissions. In pursuit of sustainability, geopolymer concrete (GPC) has emerged as a promising alternative, utilizing industrial by-products like fly ash activated by alkaline solutions to create a strong and durable matrix without cement. This study investigates and compares the mechanical performance of GPC and OPC, with a particular focus on shear behavior, a critical factor in structural applications such as beams and slabs.</span></p> <p><span lang="EN-US">The experimental program involved testing 12 cubes, 12 cylinders, and 15 beams, designed with varying percentages of waste plastic granules as partial replacements for fine aggregates. These specimens were cured at 7, 14, and 28 days and assessed for compressive, split tensile, and flexural strength. GPC demonstrated a consistent improvement in performance across all tests, with shear strength up to 12% higher than that of OPC beams. Furthermore, GPC beams exhibited delayed crack initiation, narrower crack widths, and more ductile failure modes, indicating enhanced load distribution and improved interfacial transition zones (ITZ).</span></p> <p><span lang="EN-US">The inclusion of plastic waste not only enhanced certain mechanical properties but also supported environmental sustainability by reducing plastic pollution. Despite slightly reduced workability due to the high viscosity of alkaline solutions, GPC mixtures were manageable and compatible with standard casting techniques. The study confirms the potential of ambient-cured GPC for widespread structural use, especially in applications where both performance and sustainability are priorities.</span></p>