Belite-calcium aluminate as an additive

摘要

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.

主权项

1. A method for accelerating the early stiffening/setting and/or the hardening of Portland cement comprising adding to the Portland cement a belite calcium aluminate accelerator produced according to the following steps:
(a) providing one or more raw materials selected from the group consisting of Ca-, Al-, Fe-, and Si-containing solid materials, (b) mixing the raw materials to form a starting material mixture, wherein the starting material has a molar Ca/(Si+Al+Fe) ratio from 1 to 3.5 and a molar Al/Si ratio from 100 to 0.1, (c) hydrothermally treating 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 hours, wherein a water/solids ratio is 0.1 to 100, to form an intermediate product, and (d) tempering the intermediate product obtained in step (c) at 350 to 600° C., wherein a heating rate is between 10-6000° C./min and a residence time is between 0.01-600 min to form the belite calcium aluminate accelerator.