Preparation of phosphogypsum (PG) based artificial aggregate and its application in the asphalt mixture

Abstract

How to massively consume phosphogypsum (PG) has attracted worldwide attention since this industrial by-product occupies considerable land resources and causes serious environmental problems. This study adopted PG to partly prepare the artificial aggregate to replace the natural aggregate in the asphalt mixture. The disk granulation and the jaw crusher produced two aggregates (D and C). Morphology, strength, internal structure and hydration products of the aggregate were characterized, and its influences on the properties of asphalt mixture were also evaluated. The optimal composition of the aggregate was recommended with a high PG utilization rate (80%) and sufficient strength. Both C and D aggregates had a low level of texture and were not suggested to be used on the surface layer of asphalt pavement. C aggregate had an excellent angularity and imparted the asphalt mixture with a better rutting resistance than D aggregate did. However, C aggregate easily got crushed during the Marshall compaction. The continuous hydration of D aggregate improved the moisture resistance of the mixture. Since it decreased the fracture energy of the mixture, especially at low temperatures, the artificial aggregate was not suitable to be used in the cold region. Overall, the PG-based artificial aggregates can partly replace the natural aggregate to be used in the asphalt mixture. This technology could be an economical alternative for massively consuming PG and saving natural resources.