Calcium sulphoaluminate cements made with phosphogypsum: Production issues and material properties

Phosphogypsum (PG) is an industrial waste from the production of phosphoric acid. The impurities in PG limit its utilization in building materials, and make PG decompose easily at high temperatures. Calcium sulphoaluminate (CSA) cements are insensitive to the presence of impurities and show some desirable performance. The aim of this paper is to study the potential of producing CSA cement with PG and the decomposition behavior of PG during the production of CSA cement. Experimental results indicated that PG can be utilized to produce CSA cement, and the suitable firing temperature is between 1250 and 1300°C. Results also show that the decomposition of PG is closely connected to the firing temperature and the mix proportion. The decomposition of PG has a significant effect on the formation of calcium sulphoaluminate, and decreases compressive strengths of CSA cement.