Sulfate-free and alkali-free setting and hardening accelerator

Abstract

Described are setting and hardening accelerators for hydraulic binders and said binder comprising compositions that are free of sulfates, alkali metals and chlorides. The setting and hardening accelerators comprise, as main component, water-soluble fluoride comprising aluminum salts and optionally complexing agents and/or amines. In comparison with alkaline accelerators, said accelerators result in an essential shortening of the setting time and a fast development of compressive strengths. In comparison with commercially available alkali-free accelerators based on aluminum sulfate and organic acids, by the accelerator of the present invention the later formation of ettringite is prevented.

Dependencies are inferred from the claim text.