Belite-calcium aluminate as an additive

(22) 07.05.2014

(43) 21.04.2016

(57) The present invention relates to the use of a belite calcium aluminate obtainable in a method comprising the following steps:

a) providing a starting material that has a molar Ca/(Si+Al+Fe) ratio from 1.0 to 3.5 and a molar Al/Si ratio from 100 to 0.1,

b) mixing the raw materials,

c) hydrothermal treating of the starting material mixture produced in step b) in an autoclave at a temperature from 100 to 300° C. and a residence time from 0.1 to 24 h, wherein the water/solids ratio is 0.1 to 100,

d) tempering the intermediate product obtained in step c) at 350 to 600° C., wherein the heating rate is 10-6000° C./min and the residence time is 0.01-600 min

as an accelerator for Portland cement.

(71) HeidelbergCement AG, Heidelberg (DE)

(73) HeidelbergCement AG, Heidelberg (DE)