Effects of slag and limestone powder on the hydration and hardening process of alite-barium calcium sulphoaluminate cement

For the existence of C2.75B1.25A3S¯ mineral, alite-calcium barium sulphoaluminate cement has dual priming action of alkali-activated effect and sulfate-activated effect on mixed material. When the total amount of added mixed material is unchanged, the effects for ratio of slag to limestone powder on water requirement, setting time, mechanical performance, hydration products and hydration heat of alite-barium calcium sulphoaluminate cement are investigated. The experimental results show that the water requirement and setting time decrease with the decrease of the ratio of slag to limestone powder. The compressive strength of specimen cured for 90 days with 50% cement, 30% slag and 20% limestone powder is higher than that of pure cement. Slag and limestone powder prompt the second exothermic peak to appear early and shorten induction period. Furthermore, slag and limestone decrease rapidly hydration calorimetric of cement, especially for its early hydration calorimetric. Meanwhile, it is concluded that alite-calcium barium sulphoaluminate cement has dual priming action of alkali-activated effect and sulfate-activated effect.

► Slag and limestone prompted the second exothermic peak of cement to appear beforehand, shortened induction period and setting time.
► Slag and limestone powder decrease the hydration calorimetric of cement, especially for its early hydration calorimetric.
► Appropriate ratio of slag to limestone powder can endow cement with obviously compressive strength.