Nanomaterials in geopolymer composites: A review

Nanomaterials (NMs) are being used to enhance the properties of construction materials. This review focuses on the use of NMs to improve the characteristics of fresh and hardened Geopolymer Composites (GC). Over 335 research publications are reviewed to detail the benefits and drawbacks of the integration of NMs in GC. More specifically, this review outlines the effects of numerous NMs such as Nano Silica (NS), Nano Alumina (NA), Nano Titanium dioxide (NT), Carbon Nano Tubes (CNT), Multiwall Carbon Nano Tubes (MCNT), Nano Calcium Carbonate (NCC), Nano Zinc oxide (NZ), Graphene Oxide (GO), Nano Metakaolin (NMK), Nano Fly Ash (NFA), Nano Glass Powder (NGP) and Nano-clay(NC) on Geo-polymer Paste (GPP), Geo-polymer Mortar (GPM) and Geopolymer Concrete (GPC). The presence of NMs was found to enhance the geo-polymerization reaction and result in a denser matrix. The presence of NMs also enhances the durability of GC by preventing micro-pores interconnectivity. In hindsight, our review indicates that the addition of NMs is directly tied to producing highperformance GC, which the construction industry can effectively readily adopt. Additional insights, challenges, and future research directions are identified and discussed toward the end of this review.