Influence of iron content on processing conditions and early age hydration of ye’elimite

Abstract

Ye’elimite is the primary reactive component in calcium sulfoaluminate-belite (CSAB) cement, and it has relatively lower raw material carbon footprint compared to Portland clinker phases. Ye’elimite produces ettringite when hydrated in the presence of calcium sulfate, and monosulfate in the absence of a sulfate source. The early age hydration properties in CSAB based binders are mainly controlled by the amount and reactivity of ye’elimite in the system. The reactivity of the ye’elimite can be affected by the presence of minor elements in raw mix during clinkering and distribution of other phases in the binder. This paper aims to study the formation and hydration o f ye’elimite incorporated with iron, which is commonly found in industrial by-products suitable for CSAB cement production. The influence of iron on the clinkering conditions and its incorporation in the ye’elimite phase are investigated using characterization techniques such as X-ray diffraction and thermogravimetric analysis. The iron-incorporated ye’elimite, synthesized using laboratory-grade chemicals, is examined for early-age hydration using isothermal calorimetry to study the effect of iron content on the hydration reactivity of ye’elimite. The iron content in the raw mix was found to affect clinkering reactions by accelerating the decomposition of calcite and calcium sulfate. The iron incorporation also resulted in changes in the crystal structure and early age hydration of ye’elimite.