Phosphogypsum for the production of construction materials

This study was dedicated to the use of phosphogypsum - waste from the production of phosphoric fertiliser, lime production waste and gold mining sand to form new construction materials. The results obtained in the uniaxial compressive strength tests reached 8.3 MPa on the 3rd day of curing and 13.5 MPa on the 90th day. The material had a water resistance coefficient of 0.95 at 28 days, water absorption of 8.6% and expansion values on the 3rd day of 1% and 1.5% after a year and a half of curing. The mechanical properties of the materials developed met the requirements of NBR 7.170/83 for solid bricks in classes A, B and C and ceramic blocks in classes 15 and 25. Using XRD, XRF, SEM and EDS, the physico-chemical processes involved in the formation of structures in the new materials were investigated, due to the transformation of crystalline minerals and the synthesis of amorphous substances, similar to the structures present in gypsum.