Valorization of phosphogypsum in cement-based materials: limits and potential in eco-efficient construction

Abstract

Phosphogypsum (PG) is a type of synthetic gypsum generated during the production of phosphoric acid. Each ton of phosphoric acid generates 5 tons of phosphogypsum. This industrial process has caused significant environmental problems worldwide. After an extensive literature review, it was possible to verify that both sedimentary and igneous PG can be used as in materials building components. The use of PG up to 50% meets the limits required for index I, with a radioactivity equivalent to radio-226 and a concentration of radon-222. The data found on bricks (0,11-0,41 Bq m-2 h-1) and plate (0,16-0,41 Bq m-2 h -1) show a lower exhalation rate. It is also found that calcination contributes to the reduction of PG impurities and to the of mechanical strength increase. Mortars and concretes produced with PG-based cementitious systems cementitious systems based on PG achieve high strength (60 MPa, 70 MPa, 80 MPa) and meet the technical feasibility criteria of European standards EN 998-1, EN 998-2, EN 13813, Eurocode 1992 and the American standard ASTM C270. The setting time is influenced by the mineral phase of the PG. It is concluded that cementitious materials produced from phosphogypsum are technically viable and achieve a satisfactory performance. It is possible to advance the following lines: PG-based concrete with high performance, PG-based hydration cement, stabilized mortar, PG-based concrete with high workability and studies about chloride ingress, carbonation, sulfate attack and acid attack in PG-based concrete.