Effect of various nano materials in enhancing the strength, microstructural, mineralogical, and durability properties of geopolymer binder – a comprehensive review

The growing need for sustainable building materials has resulted in an increased academic and industrial emphasis on geopolymer concrete as a potential alternative to traditional Portland cement systems. However, substantial drawbacks, such as lower compressive strength at early ages, a shorter retention period, high porosity, efflorescence effects, and durability concerns, restrict the widespread use of geopolymer concrete. Recent literature shows the promise of introducing nanoscale additives, such as nano-silica, nano-alumina, nano-clay, carbon nanotubes, and titanium dioxide, in increasing the mechanical strength, microstructural integrity, and long-term functionality of geopolymer binder. This review provides a critical assessment of the role played by these nanomaterials in influencing mechanical properties, hydration kinetics, pore structure refinement, and longevity in the presence of hostile conditions. It focuses on their contribution to microstructure densification, improvement of interfacial bonding properties, and reduction of strength at high temperatures. The experimental findings from the extensive literature established that, with the right levels of nanomaterials, mechanical properties can be significantly enhanced to improve resistance to durability aspects. This review concludes that nanomaterials can improve the engineering performance of geopolymer binder, as well as its sustainability in construction practice, by reducing dependence on Ordinary Portland Cement (OPC) and promoting the use of industrial by-products.