L. Fernández-Carrasco, F. Puertas, M. Blanco-Varela
May 1, 2004
Citations
0
Influential Citations
28
Citations
Journal
Cement and Concrete Research
Abstract
Potassium dawsonite is formed as an intermediate compound during the alkaline hydrolysis (AH) in calcium aluminate cements (CACs). A synthesis method of potassium dawsonite has been developed. The crystal structure of potassium dawsonite KAl(CO3)(OH)2 has been solved by direct methods from X-ray powder diffraction data and refined with the Rietveld method. It crystallises in the orthorhombic Cmcm space group with unit cells parameters a=6.3021(3) A, b=11.9626(5) A, c=5.6456(3) A and Z=4. The structure consists of carboaluminate chains, formed by the basic unit [Al2(OH)4(CO3)2]2− arranged along the c axis. The carbonate groups are placed in an alternate manner at both sides of the carboaluminate chains. The carboaluminate chains are also held together by the K+ cations that are located in the middle of three such chains. Finally, the chemical reactions explaining the AH process in CACs are postulated.