Valorization of phosphogypsum waste through acid geopolymer technology: synthesis, characterization, and environmental assessment

Phosphogypsum (PG) constitutes the principal by-product of the phosphate industry which largely restricts its wide development. The incorporation of PG as a reinforcement agent into geopolymer cement, can play however a significant role to enhance their mechanical and microstructural properties and to develop a sustainable geopolymer-PG based circular economy. In this study, geopolymer reinforced PG composites were prepared at different PG content according to PG/MK ratio in the range of 0-1. The mechanical properties of the composites were tested under compressive and flexural strength. The results show a significant enhancement of compressive and flexural strength from 40.14 MPa to 48.43 MPa and 5.13 MPa to 9.1 MPa respectively with addition of 20.6 % and 77.3 % compared standalone geopolymer. This improvement was linked systematically with crack selfhealing mechanism due to PG rod-like morphology and its high adhesion to the geopolymer matrix. The heavy metals leaching test show that most of the developed acidic geopolymer- PG composites have a leaching value lower than the international recommendations. Thus, geopolymer- PG composites can constitute an efficient and sustainable alternative to conventional building materials and can be extended to divers' industrial applications.

Automated summary

Phosphogypsum (PG) is a major by-product of the phosphate industry, which limits its wide development. Incorporating PG as a reinforcement agent into geopolymer cement can significantly enhance its mechanical and microstructural properties, contributing to a sustainable geopolymer-PG based circular economy. In this study, geopolymer reinforced PG composites were prepared at different PG contents, and their mechanical properties were tested. The results showed a significant improvement in compressive and flexural strength with the addition of PG, attributed to the crack self-healing mechanism and the high adhesion between PG and the geopolymer matrix.