Strength, durability, and economic analysis of GGBS-based geopolymer concrete with silica fume under harsh conditions

Introduction

Concrete usage has witnessed a significant surge in recent years, leading to a corresponding increase in the demand for cement as a binding material. Globally, cement consumption has been on a steady rise, with over 2.8 billion tons of cement produced annually to meet the growing needs of the infrastructure sector, experiencing an annual growth rate of approximately 3%^{1, 2–3}. Notably, the production of each ton of cement results in the release of approximately one ton of carbon dioxide (CO₂) into the atmosphere annually. Given the extensive reliance on concrete, there is a compelling imperative to explore alternative binding materials^4,5. One such alternative gaining prominence is geopolymer, a novel binder that offers a viable substitute for cement in the construction industry. Geopolymer is formed through the combination of alumino-silicate source materials with an alkaline solution, resulting in the formation of a precipitate that solidifies into geopolymer concrete (GPC), boasting lower carbon emissions compared to conventional cement-based concrete^6,7. GPC also mitigates issues such as shrinkage-induced cracking commonly associated with excessive cement use. The formation of GPC entails the creation of a network comprising alumina and silicate, characterized by the formula Mn-[-(SiO₂)_z-AlO₂]n.wH₂O, where ‘n’ and ‘M’ denote the degree of polycondensation and monovalent cations (K⁺, Na⁺), respectively⁸.

A diverse range of materials, including fly ash, rice husk ash, red mud, silica fumes (SF), ground granulated blast furnace slag (GGBS), and natural zeolites like metakaolin, serve as viable sources for GPC production^9,10. Incorporating GGBS and other industrial byproducts into alkali-activated concrete facilitates the development of a compact microstructure under ambient curing conditions¹¹. This densification of the matrix significantly enhances the material’s mechanical properties, contributing to improved overall performance¹¹. In addition to the aforementioned materials, natural zeolitic substances such as metakaolin are utilized as source materials due to their significant chemical composition and amorphous structure¹². GGBS are particularly favored due to their abundant availability and high silica and alumina content, thereby addressing the challenge of industrial byproduct disposal. GPC exhibits favorable physical properties, including robust compressive strength and resilience to harsh conditions such as acid corrosion, high temperatures,...