Recycling phosphogypsum in road construction materials and associated environmental considerations: A review

Phosphogypsum (PG) is a major hazardous by-product of the phosphate industry. The whole world is facing the challenge of increasing stockpiles of PG, which significantly affect safety and the environment. Recycling this material may be an environmentally friendly and safe solution to this challenge. In this paper, we searched the Web of Science database for 2369 articles from 1975 to 2022 using "phosphogypsum" as the keyword. Using the VOSviewer as the literature visualisation tool, density visualisation was performed with keywords as the analysis units, and it was found that the researchers focused mainly on PG applications in construction and radionuclides. Over the years, different routes to PG valorisation have been developed in the agricultural, construction, environmental and energy sectors, and these topics are described in this review. As infrastructure projects, highway engineering is characterised by a large land area and high resource consumption. Therefore, applying PG to road materials can significantly increase the reuse and consumption of PG and reduce PG stockpiles. We hope that PG can be used for road construction on a large scale in the future. This paper focuses on the latest developments in PG as road materials. The most serious difficulty in using PG as road materials at present is that it contains radionuclides and heavy metal impurities, which can be purified by pretreatment methods. However, how to scale it up requires continuous research.