ON THE CARBONATION MECHANISM OF CALCIUM ALUMINATE HEXAHDRATE IN HYDRATED HIGH-ALUMINA CEMENT

Strength regression of high-alumina cement concretes under certain conditions has been mainly attributed, until now, to the transformation of hexagonal calcium aluminate hydrates into cubic hydrates. The present paper try to show the great influence of the action of CO2 on C3AH6, leading to its total degradation and that of high-alumina cement to calcium carbonate and aluminium oxyde as final products. To study the mechanism of this degradation caused by CO2 on the cubic phase C3AH6, several samples of high-alumina cement previously hydrated at 20 degrees C, 43 degrees C and 216 degrees C (autoclave) were submitted to a sequence of treatments. This sequence included a treatment with humid CO2 followed by a vacuum extraction of the CO2 more weakly fixed and a final drying in a CO2 atmosphere. Experimental results confirm the observations made by Smolczyk (1) and Lach (2) and afford the concept of "CO2-hydrogarnet", a new element for the knowledge of the carbonation process mechanism of C3AH6 and high-alumina cement.

• Supplemental Notes:
  • Presented at the 6th International Congress on the Chemistry of Cement, September 1974, Moscow, USSR.
• Corporate Authors:

  Instituto Torroja de la Construccion y del Cemento

  Apartado 19.0002, Costillares-Chamartin
  Madrid 33,   Spain 
• Authors:
  • Gauna, ARde
  • Trivino, F
  • Vasquez, T
• Publication Date: 1975-11

Media Info

• Features: Figures; References;
• Pagination: 28 p.

Subject/Index Terms

• TRT Terms: Aluminates; Aluminum oxide; Calcium carbonate; Carbonation; Cement; Hydrates
• Uncontrolled Terms: Degradation
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00141674
• Record Type: Publication
• Report/Paper Numbers: Res Working Paper 31
• Files: TRIS
• Created Date: Dec 22 1976 12:00AM