Effect of modified phosphogypsum on the hydration properties of the phosphogypsum-based supersulfated cement

Supersulfated cement (SSC) is a kind of environment-friendly cement with less or even no clinker, which could consume a lot of phosphogypsum (PG). In order to improve the property of original PG, two modification methods have been taken to study the hydration properties of SSC containing PG with or without modification. The results show that the compressive strength of SSC with modified PG improves at some extent. The pore structure of SSC with modified PG at 90 days also can be optimized, especially for SSC with burnt PG, its porosity, average pore size, threshold aperture, the most probable pore size and the pore volume fraction of microscopic pore all perform best. For early hydration, SSC with burnt PG delays the early hydration and prolongs its induction period, while SSC with neutralized PG accelerates its early hydration. The final hydration products of all SSCs are mainly ettringite and C-S-H gels, while the quantity of ettringite of the control is relative low. Modification treatments can make ettringite more stable especially for SSC with burnt PG.