Chloride ion binding capacity of aluminoferrites

The hydration of aluminoferrites (C(4)AF, C(6)AF(2) and C(6)A(2)F) and thei r 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 the se aluminoferrites are similar to that of C(3)A, but amorphous AH(3) and/or FH3 are formed, and transformation of metastable (hexagonal hydrates) to t he stable (hydrogarnet) phase is slower. Iron content of aluminoferrites de termines the rate of hydration reactions: hydration rate increases in the o rder C(6)A(2)F > C(4)AF > C(6)AF(2) In the case of C(4)AF + 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. Chara cteristics of DTG peaks are described and interpreted. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.