The Characteristics of Cement Mortars Utilizes the Untreated Phosphogypsum Wastes Generated From Fertilizer Plant, Aqaba- Jordan

Huge amounts of phosphogypsum (PG) are produced as by-products of phosphoric acid manufacture process in Jordan. Millions of tones of PG w astes are stockpiled over open areas. Major negative environmental impacts are highly expected due to dissolution of various hazardous chemicals the stockpiled contains. This will cause a serious threat to the soil, surface and groundwater bodies. X-Ray Fluorescence revealed that the main oxides were SO3 and CaO with 39% and 31.9%, respectively. What reflected its mineralogy were gypsum, as main phase, and calcite, quartz and apatite, as minor. Two PG samples were used, first dried to 60°C (PG1) and then heated up to120°C (PG2). Both samples were used in sand-clinker and clinker–sandpozzolanic tuff mortars to investigate compressive strength, setting time, consistency and other physical properties. The results showed that the addition of 2-4% of PG1 gave an average of 52 N/mm2 and 46.4 N/mm2 at 28 days for the two mixing ratios, respectively. Meanwhile, PG2 showed lower compressive strength values. Moreover, lower consistency was achieved with PG1 more than with PG2 samples, due to the fact that PG2 contains more anhydrite. Setting time is higher and shows an increasing trend in PG1, which contradicts PG2 samples. The result approves the possibility for the utilization of raw untreated PG wastes instead of expensive pure gypsum in cement industry, because it showed good setting time, minimizes the W/C ratio, and increases the compressive strength of the mortars. Besides, it will decrease the production cost and convert these wastes into useful industrial material.