Setting and hardening accelerators for sprayed concrete

The requirements placed on modern accelerators for shotcrete are not only that they should provide virtually instant setting of concrete mixes and early strength at a moderate price, but also that they should not have any adverse effect on the properties of mature concrete and should not cause a reduction of its durability.
The analysis of the patent literature over the past 10—15 years shows that most of these requirements are met by alkali-free water-based compositions based on highly-active aluminium compounds. Accelerators produced commercially by well-known manufacturers often contain aluminium sulphates and hydroxysulphates, as well as high-level amorphous hydroxides.

Author: A.S. Brykov, A.S. Vasilyev

Section: Concrete

Keywords: shotcrete, alkali-free accelerators, aluminum sulfate