Study on the properties of an excess-sulphate phosphogypsum slag cement stabilized base-course mixture containing phosphogypsum-based artificial aggregate

Phosphogypsum (PG) was used to produce an excess-sulfate phosphogypsum slag cement (ESPSC) and artificial aggregates and then co-utilized for road base mixtures to enhance their recycling efficiency. Their hydration process, strength development, volume stability, compatibility, etc., were investigated. The experimental results showed that the wet grinding process resulted in improved strength of the ESPSC mortar with finer ettringite hydrates. The base-course mixture prepared with ESPSC and artificial aggregate exhibited better volume and mechanical properties than that prepared with cement and artificial aggregate. In addition, it showed a narrower interfacial transition zone than that prepared with natural aggregate and ESPSC. The base-course mixture made of ESPSC and artificial aggregate containing 40 wt% PG showed a compressive strength higher than 3 MPa at 7 days, which met the highway base course specifications. This combination can significantly reduce material cost and improve the utilization of PG.