Geopolymer concrete containing nanomaterials-a step toward sustainable construction

Geopolymer concrete (GPC) utilizes industrial wastes such as fly ash, bottom, ash, and slag instead of conventional Portland cement as the primary binder, and thus promote a sustainable solution for bulk concrete works. Nanomaterials (NMs) have often been linked with developing these sustainable high-strength mixes. Furthermore, NMs have been proven to imbibe enhanced physio-mechanical properties, often eliminating the need for thermal curing. This not only reduces total energy demand for concrete production but also offers enhanced durability due to denser inter-particle packing of the mix. This review meticulously summarizes the performance of GPCs dosed with different types of NMs including nano-silica (NS), nano-alumina (NA), nano-titanium di oxide (NT), nano-clay (NC), nano-graphene oxide (NG), and carbon nanotubes (CNT). The reported findings of previous studies were carefully studied and compiled in a systematic manner in terms of physio-mechanical, durability, and microstructural properties. It was observed that addition of NM, in general, leads to a slight reduction in the mix's workability; however, the same can be counteracted by use of suitable superplasticizers. Furthermore, inclusion of NMs in GPC offers the distinct advantage of high density and impermeability, resulting in enhanced mechanical and durability characteristics. Two distinct multi-criteria decision making (MCDM) techniques were employed in this study to statistically analyze the most preferred NM for GPC. It was found that addition of NS (2%) yields the most desirable outcomes. Finally, limitations and challenges associated with production of NM dosed GPC along with scopes for future works are presented toward the end of this review.