Chloride ion binding capacity of aluminoferrites

• Published in: Cement and concrete research Vol. 31; no. 4; pp. 577 - 588
• Main Authors: Csizmadia, Jolán, Balázs, György, Tamás, Ferenc D
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Ltd 01.04.2001; Elsevier Science
• Subjects: Analysis of cement phases and constituents; Applied sciences; Buildings. Public works; Calcium aluminoferrite; Cement concrete constituents; Cements; Chloride; Exact sciences and technology; Hydration; Materials; Properties of anhydrous and hydrated cement, test methods; Thermal analysis; X-ray diffraction; X-ray diffraction; Calcium aluminoferrite; Chloride; Thermal analysis; Binding; Thermogravimetric analysis; Hydration; C4AF phase; Chlorides; Reaction product; Gypsum; Differential thermal analysis; Phase analysis; Experimental study; X ray diffraction
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/S0008-8846(01)00458-6

The hydration of aluminoferrites (C 4AF, C 6AF 2 and C 6A 2F) and their mixture with gypsum (up to 10/5 ratio) was investigated as well as their chloride binding capacity (after immersion in 10% NaCl solution) by thermal tests (DTG and TGA) and X-ray diffraction (XRD). Hydration products of these aluminoferrites are similar to that of C 3A, but amorphous AH 3 and/or FH 3 are formed, and transformation of metastable (hexagonal hydrates) to the stable (hydrogarnet) phase is slower. Iron content of aluminoferrites determines the rate of hydration reactions: hydration rate increases in the order C 6A 2F>C 4AF>C 6AF 2. In the case of C 4AF+gypsum mixtures, monosulfate was found prior to the total exhaustion of gypsum. After salt treatment, iron-containing Friedel's salt or Kuzel's salt was found. Characteristics of DTG peaks are described and interpreted.