Strength and Microstructural Properties of Phosphogypsum/GGBS-Based Geopolymer Concrete

Geopolymer concrete serves as an eco-friendly substitute for traditional Portland cement-based concrete, notorious for its high carbon footprint due to substantial carbon dioxide emissions during production. Phosphogypsum and ground granulated blast slag are industrial wastes that can be used as an alternative to cement, along with micro silica. Phosphogypsum and ground granulated blast slag can be developed into geopolymer concrete with alkali solutions. This work investigates the replacement of phosphogypsum with ground granulated blast slag and micro silica. For the purpose of the study, strength and durability were tested through mechanical properties, rapid chloride penetration test, water absorption and porosity. The maximum strength achieved was 60.88 MPa in the case of replacing 20% micro silica for phosphogypsum, while this result corresponded to minimal values for rapid chloride penetration test, water absorption, and porosity when phosphogypsum was replaced with 20% micro silica. Moreover, scanning electron microscope images illustrated the gel formation in the geopolymer concrete that contributed to strengthening the samples. Additionally, extreme gradient boosting was also analyzed for statistical means. The R² value of 0.9999 signifies that the extreme gradient boosting accounts for accurate in training cases for compressive strength.