Geotechnical properties of phosphogypsum and its use in road engineering

Abstract

Phosphogypsum is an industrial waste generated during the production of phosphoric acid. Its amounts in the world are significant and still increase. This waste is mainly stored and its storage is a problem for the natural environment. Road construction industry allows for the use of large amounts of industrial waste, such as fly ash, coal mining waste and metallurgy industry by-products. However, due to its properties, phosphogypsum is a waste with high limitations for use. The research of technical and chemical properties of Phosphogypsum is still being carried out. According to previous studies, the use of unprocessed phosphogypsum in building materials causes deterioration of their properties, therefore processing is required. The paper presents the results of testing phosphogypsum-fly ash mixture and this mixture processed into a granular form with sulphur and various additions of a modifier. The solidification of phosphogypsum into granules was aimed at improving geotechnical properties and reducing the leaching of heavy metals. The paper discusses the geotechnical properties of the mixture before and after granulating it in terms of the possibility of use its in road engineering as the geotechnical structures. The presented research was carried out as part of the RID-6 (Road Innovation Development) research project “Use of recycled materials”.