Effect of waste gypsum on the setting and early mechanical properties of belite-C(2.75)B(1.25)A(3)$ cement

摘要

Belite-barium calcium sulfoaluminate (C(2.75)B(1.25)A(3)$) cement was belite-rich cement containing C(2.75)B(1.25)A(3)$ mineral of 9 mass%. Due to the differences in dissolution velocity and element sulfur content, the effects of citro-, phosphor- and FGD gypsum on the setting and early mechanical properties of belite-C(2.75)B(1.25)A(3)$ cement were investigated. The experimental results showed that citrogypsum had the fastest dissolution velocity among all the waste gypsum. This resulted in the short initial and final setting time of belite-C(2.75)B(1.25)A(3)$ cement with citrogypsum. Moreover, the early compressive strength of belite-C(2.75)B(1.25)A(3)$ cement with citrogypsum was high, owing to that much content of AFt and C-S-H gel was formed at an early age. In summary, the later compressive strength of belite-C(2.75)B(1.25)A(3)$ cement with any type of waste gypsum was superior to that of cement with reference natural gypsum. Also, the early compressive strength of cement with any type of waste gypsum was comparable to that of cement with reference gypsum. Therefore, citro-, phosphor- and FGD gypsum all could replace natural gypsum as an adjusting agent of belite-C(2.75)B(1.25)A(3)$ cement.