Study on the hydration and properties of multiphase phosphogypsum synergistically activated by sodium sulfate and calcium sulfate whisker

Multiphase phosphogypsum (MPPG) is prepared by high-temperature calcination of phosphogypsum (PG). Its mechanical properties are influenced by the hydration of internal hemihydrate gypsum and anhydrite. This paper reported the effect of synergistic activation of MPPG by sodium sulfate (NS) and calcium sulfate whisker (CSW). Compatibility and modification ability of NS and CSW to MPPG were evaluated in terms of various parameters such as the setting time, mechanical strength, water resistance, degree of hydration, and pore structure. The results showed that NS and CSW exhibited sound synergistic effects. The addition of 0.4% NS and 2% CSW sufficiently improved the mechanical strength, water resistance, and pore structure of MPPG. The NS and CSW together accelerated the early hydration and completed the subsequent hydration of the MPPG. The obtained conclusions were expected to be a reference for expanding MPPG applications.