Characterisation of iron inclusion during the formation of calcium sulfoaluminate phase

• Published in: Cement and concrete research 2010-08, Vol.40 (8), p.1314-1319
• Main Authors: Idrissi, M., Diouri, A., Damidot, D., Greneche, J.M., Talbi, M. Alami, Taibi, M.
• Format: Article
• Language: English
• Subjects: 3CaO·3Al 2O 3·CaSO 4 (D); ABSORPTION SPECTROSCOPY; ALKALINE EARTH METAL COMPOUNDS; ALLOYS; ALUMINIUM COMPOUNDS; ALUMINIUM OXIDES; Analysis of cement phases and constituents; ANHYDRITE; Applied sciences; BUILDING MATERIALS; Buildings. Public works; Calcium; Calcium carbonate; CALCIUM CARBONATES; CALCIUM COMPOUNDS; CALCIUM OXIDES; CARBON ADDITIONS; CARBON COMPOUNDS; CARBONATES; Cement concrete constituents; CEMENTS; CHALCOGENIDES; Civil Engineering; COHERENT SCATTERING; DIFFRACTION; DISPERSIONS; EDX (B); ELECTRON MICROSCOPY; ELEMENTS; Engineering Sciences; Exact sciences and technology; FERRITIC STEELS; HEAT TREATMENTS; HOMOGENEOUS MIXTURES; INCLUSIONS; INFRARED SPECTRA; IRON; IRON ALLOYS; IRON BASE ALLOYS; IRON COMPOUNDS; IRON OXIDES; MANUFACTURING; MATERIALS; MATERIALS SCIENCE; MELTING; METALS; MICROSCOPY; Microstructure (B); MINERALS; MIXTURES; MOESSBAUER EFFECT; OXIDES; OXYGEN COMPOUNDS; PHASE TRANSFORMATIONS; Properties of anhydrous and hydrated cement, test methods; REACTIVITY; SCANNING ELECTRON MICROSCOPY; SCATTERING; SOLID SOLUTIONS; SOLUTIONS; SPECTRA; SPECTROSCOPY; STEELS; STOICHIOMETRY; SULFATE MINERALS; SULFITES; SULFUR COMPOUNDS; SYNTHESIS; TEMPERATURE RANGE; TEMPERATURE RANGE 1000-4000 K; Thermal treatment (A); TRANSITION ELEMENT ALLOYS; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; X-RAY DIFFRACTION; X-ray diffraction (B); X-rays
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2010.02.009

The iron distribution among the sulfoaluminate clinker phases and its ability to enter the calcium sulfoaluminate lattice in solid solution can have a significant influence on manufacturing process and reactivity of calcium sulfoaluminate (CSA) cements. X-ray diffraction (XRD) analysis, Mössbauer spectroscopy, scanning electron microscopy (SEM) equipped with an energy dispersive X-ray analysis system (EDAX) and infrared spectroscopy were used to identify the mineralogical conditions of iron inclusion during the formation of calcium sulfoaluminate (C 4A 3S) phase from different mixtures in the CaO–Al 2O 3–Fe 2O 3–SO 3 system. The mixtures, heated in a laboratory electric oven, contained stoichiometric amounts of reagent grade CaCO 3, Al 2O 3, Fe 2O 3 and CaSO 4·2H 2O for the synthesis of Ca 4Al (6 − 2 x) Fe 2 x SO 16, where x, comprised between 0 and 3, is the mole number of Al 2O 3 substituted by Fe 2O 3. With x increasing from 0 to 1.5, both the iron content of C 4A 3S phase and the amounts of side components such as C 2F and CS increased. For x values included in the range of 1.5–3.0, at temperatures higher than 1200 °C, melting phenomena were observed and, instead of the C 4A 3S solid solution, ferritic phases and anhydrite were formed.