Abstract: The effects of phosphogypsum, anhydrite and dihydrate gypsum with same content of P2O5 on hydration mechanism of supersulphated cement(SSC) were investigated, the P2O5 of anhydrite and dihydrate gypsum were incorporated by solubility and analytical pure P2O5.The compressive strength and pore solution pH value in various age of three series of SSC specimens were tested.And the differences of early hydration exothermic process were compared.The hydration products and microstructure were analyzed by XRD and SEM.Results show that compressive strength and pore solution pH value in various age of anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 based SSC specimens are close together.Comparing with phosphogypsum based SSC, anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 decrease the pore solution pH value in various age of SSC.And they slow down the early strength development of SSC, but obviously promote the long-term strength development of SSC.The exothermic analysis show that anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 quicken the appearance of the second exothermic peak of SSC, and shorten the setting time of SSC.XRD and SEM analysis show that anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 have a better activation effect than phosphogypsum on SSC, SSC paste with anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 can produce more C-S-H and ettringite with higher density in late stage.

Key words: P2O5;gypsum;supersulphated cement(SSC);hydration heat;hydration product