Behavior of Fiber Reinforced Geopolymer Concrete Circular Columns Reinforced with GFRP Bars and GFRP Helices under Different Loading Conditions

Geopolymer concrete (GPC) is a sustainable alternative to ordinary Portland cement (OPC) concrete. The production of GPC requires two main components: aluminosilcate source materials and alkaline activator. The aluminosilcate materials must be rich in aluminate (Al) and silica (Si) and can be industrial by-products such as slag and fly ash. The alkaline activator is produced by combining either sodium silicate and sodium hydroxide or potassium silicate and potassium hydroxide. However, the selection of the aluminosilcate material and alkaline activator for the production of GPC depends upon several factors including cost, application and availability of materials. The main role of the alkaline activator is to facilitate the polymerization process. Since GPC is produced without any cement, GPC offers a significant reduction in CO2 emissions compared to OPC and is known as earthly concrete or green concrete. The mechanical properties of ambient cured GPC are comparable with the mechanical properties of similar strength OPC concrete. The GPC offers higher fire resistance with low susceptibility to shrinkage and creep than OPC concrete. Thus, GPC has emerged as a cement-less concrete for the development of new infrastructure in the construction industry. Apart from several advantages, however, some of the challenges in the use of GPC include the need for special handling, high brittleness, low tensile strength, and lack of ductility. The addition of non-metallic fibers, such as polypropylene fiber (PF) and glass fibers (GF) is one of the solutions to overcome the brittleness of GPC. The incorporation of fibers enhances the energy absorption capacity by controlling the development of the cracks, ultimately increasing the tensile and flexural strengths of GPC concrete.