The workability of concrete is governed by the amount of aggregate in the mix. Air-entraining agents, when used, are plasticizers. Other substances include calcium chloride, lime, fly ash, and other pozzolans.
Calcium chloride is also an accelerator.
Lime increases the cementing properties of cement, as do pozzolans combined with lime. It changes both the plastic and the hardened properties of concrete. Fly ash improves workability and reduces segregation, bleeding, and the heat of hydration. The concrete will not be as watertight as a cement-only concrete, nor will it have as much initial strength. Additional tests may have to be made to determine when to remove the forms.