Research Paper

Review of Geopolymer Concrete: Reaction Mechanisms, Mechanical Behavior, and Environmental Benefits

Oumar AI.

J. Civil Eng. Urban., 15(1): 40-64, 2025; pii:S225204302500004-15

DOI: https://dx.doi.org/10.54203/jceu.2025.4

Abstract
Geopolymer concrete (GPC) presents itself as a sustainable construction material that replaces traditional Ordinary Portland Cement (OPC) concrete by reducing carbon emissions while preserving structural strength and durability. Its strength derives from geopolymerization a chemical reaction in which aluminosilicate-rich industrial by-product (such fly ash, GGBFS, and metakaolin) react with alkaline activators (sodium or potassium hydroxide and silicate solutions) to create a strong three-dimensional aluminosilicate network. This process known as alkali activation transforms raw materials into a strong three-dimensional aluminosilicate network, which consists of silicon and aluminum atoms bonded through oxygen atoms, imparting high strength and chemical stability. The development of gel structure and reaction kinetics depends heavily on the precursor composition, as well as activator concentration, curing regime, and mix design parameters. Nanomaterials such as nano-silica enhance matrix densification and improve early-age strength by filling micro-pores and refining the microstructure. The addition of fiber reinforcements including basalt, polypropylene fibers significantly increase resistance to cracking and improves the material’s ductility. Furthermore, the use of tailored aggregates optimizes particle packing, thereby contributing to the overall strength and durability. Recent research indicates that GPC can achieve compressive strength up to 50 Mpa whereas OPC concrete bearly reaches 40 Mpa. Tensile strength improves from about 4.0 to 5.5. Mpa, and flexural strength increases from 6.0 to 8.0 Mpa. Durability of GPC enhanced, with up to 20% demonstrating superior resistance against sulfate attack, chloride ingress, thermal loading, and acidic environments. The paper combines research about rheological optimization and ambient curing feasibility, and shrinkage behavior. The material demonstrates its ability to meet advanced construction needs through its applications in 3D-printed GPC, fiber-reinforced composites and carbon-enhanced formulations. Technology faces ongoing difficulties related to long-term field performance and precursor variability, as well as the absence of unified standards. The long-term field performance of GPC remains insufficiently documented, with uncertainties regarding durability, exposure, such as creep, shrinkage, and resistance to environmental cycles, which could affect the reliability, setting and mechanical properties, posing challenges for quality control and large-scale implementation. To address these issues, further research is needed on extended field trials, standardized characterization of raw materials, and the development of guidelines for mixed design and performance assessment. The review presents current GPC technology developments while identifying essential steps for standardization and scalability, and sustainable infrastructure system integration.

Keywords: Geopolymer concrete, mechanism, sustainability, alkali activation, geopolymerization, durability, nanomaterials, fiber reinforcement, standardization

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