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

Abstract

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.