Advancements in Geopolymer Concrete: A State-of-the-Art Analysis of Its Mechanical and Durability Features

Geopolymer concrete (GPC) is a sustainable substitute for ordinary Portland cement (OPC) concrete in the construction field. It makes use of materials abundant in alumina and silica that combine with an alkaline solution to form aluminosilicate gel which combines the aggregate and binder, forming three-dimensional polymeric bond structures, ultimately creating geopolymer concrete. GPC effectively tackles the challenges posed by exhausting natural resources and the high carbon dioxide emissions associated with cement production. Sodium hydroxide and sodium silicate are commonly used as alkaline activators in the production of GPC. To achieve the desired outcomes in GPC, a variety of binders, including waste materials such as fly ash, ground granulated blast furnace slag, metakaolin, and rice husk ash, can be utilized either individually or in combination with additives. GPC generally outperforms OPC in terms of properties. It exhibits higher compressive strength, especially with an increased fluid–binder ratio. GPC's numerous Al–O and Si–O structures make it resistant to acid attacks, ideal for acid-resistant products. It also has lower water absorption due to a denser microstructure. Adding fibers, such as steel fibers, can enhance certain properties. Also, extended curing time and high temperatures improve GPC properties. However, GPC is susceptible to carbonation, leading to a decrease in pH and corrosion of rebars. Overall, GPC offers better performance than OPC and addresses environmental concerns associated with cement production. It is a widely accepted sustainable alternative in academia and research, but it faces challenges in industrial applications due to its varied raw materials and the need for significant investment in their development and certification. The construction and manufacturing sectors typically exhibit a cautious approach when it comes to embracing novel products, and geopolymer concrete might not completely align with regulatory standards, especially regarding its rheological properties and chemical composition. Extensive laboratory and field investigations are going on to collect comprehensive information regarding the engineering characteristics and durability of these composites in different service conditions, laying the foundation for their practical use in the construction industry.