Effect of Modified Phosphogypsum on Hydration Characteristics of Supersulfated Cement

The influence of modified phosphogypsumson early hydration heat, compressive strength, pH of the pore, hydration products and microstructure characteristics of supersulfated cement (SSC) were studied. SSC system had lower early hydration rate, lower hydration heat, longer induction period, and delayed second exothermic peak, which showed lower early hydration characteristics comparing with common Portland cement (CPC). Modification methods of phosphogypsum could regulate the early hydration rate and the hydration activity of the system. The main hydration products of SSC were AFt and C⁃S⁃H gels, the pH value was stable at 11, and its strength was depended on the characteristic of phosphogypsum. Calcination could improve the strength at the middle and late ages, while lime neutralization could improve the strength through the whole age. After treatment, the activity of phosphogypsum increased, resulting in more AFt and C⁃S⁃H gels, which made the structure dense and strength increasing. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.