Feasibility of using phosphate wastes for enhancing high-temperature rheological characteristics of asphalt binder

The huge amount of wastes is produced annually from the phosphate extraction process which causes environmental problems in terms of energy and pollution. Using these wastes for producing asphalt mixtures can be a cost-effective and eco-friendly solution for managing them. The aim of this study is to investigate the feasibility of using phosphate wastes for fabrication of bituminous materials. Furthermore, the study objective is to discover the most effective waste to be included in asphalt mixtures. These wastes were acquired from the phosphate extraction plant, Ben Guerir city, Morocco. Phosphogypsum, fly ash, and dry phosphate sludge were the materials selected to be used as filler. Four samples were prepared, including an original asphalt binder as well as phosphogypsum, fly ash, and phosphate sludge asphalt samples. Classical characterization, viscous flow, frequency, and temperature sweep tests were carried out on these samples. The results showed that the viscous flow behavior of the asphalt binder containing phosphogypsum and fly ash wastes has been substantially more improved compared with binder with phosphate sludge filler. It was also shown that phosphogypsum waste enhances the mechanical properties of asphalt binder as well as its performance against rutting more than fly ash and phosphate sludge wastes.