From Caltra, manufacturers of Calumex and other products, come two amorphous calcium aluminate (ACA) additives designed to accelerate setting times, compensate shrinkage and increase both early and late strength development. ACA, C12A7, is the most effective set accelerator known.
CALUMEX SC-A® is used to make extremely fast-setting cementitious mortars, concrete and shotcrete. It also reduces shrinkage and cracking and improves density in both indoor and outdoor applications. Depending on application, replace at approximately 10% by weight.
Calumex® XT-20 provides approximately four times the working time of Calumex SC-A, even without the addition of retarders. Between 5-20% of binder weight can be replaced by, depending on the desired effect.