Development of a new calcium sulfoaluminate (synthetic ye’elimite) blended PII 52.5 cement

The aim of this paper is to examine the effect of a blending dose of calcium sulfoaluminate (synthetic ye’elimite, C₄A₃$) and gypsum on the hydration and hardening properties of a new ye’elimite (C₄A₃$) blended PII 52.5 cement. By using X-ray diffractometry, mercury intrusion porosimetry, thermogravimetry and scanning electron microscopy, it was revealed that the hydration of tricalcium silicate (C₃S) is significantly retarded by the lack of gypsum; the renewed hydration of tricalcium aluminate (C₃A) was retarded in cement pastes containing a high amount of C₄A₃$. The dosage of C₄A₃$ and the ratio of gypsum/C₄A₃$ both have a notable influence on the hydration heat, hydration products and the compressive strength and linear expansion. The cement paste containing 3% C₄A₃$ at gypsum/C₄A₃$ ratio of 2 exhibited the best performance, in terms of both high early and long-term compressive strength and acceptable linear expansion (0·04% on 300 d); the cement can therefore be adopted in industrial structures.