A Comparative Study on Geopolymer Concrete Using Fly Ash and GGBS

The environmental concerns associated with the high carbon footprint of Ordinary Portland Cement (OPC) have intensified research into alternative, sustainable construction materials. Geopolymer concrete (GPC), synthesized from industrial by-products such as fly ash (FA) and ground granulated blast furnace slag (GGBS), has emerged as a promising eco-friendly alternative binder system. This review paper provides a comprehensive comparative analysis of FA-based, GGBS-based, and blended FA-GGBS geopolymer concretes, focusing on their mechanical properties, durability, microstructural characteristics, curing conditions, and sustainability. The analysis highlights that while FA-based systems demonstrate superior long-term performance, they often require elevated temperature curing. In contrast, GGBS-based geopolymers provide high early strength and ambient curing capabilities. Blended systems offer a balanced performance profile, combining the advantages of both precursors. Additionally, the review discusses the influence of key parameters such as activator concentration, precursor ratio, curing method, and the use of additives. The findings emphasize the need for mix design optimization and standardized practices to enable the large-scale implementation of geopolymer concrete as a sustainable construction material.