To convert concrete powder into concrete, simply insert a single piece of concrete powder into the first slot of a water tank. The water tank will harden the concrete, emptying 1/3 of a bucket from the tank. Cement mixers work with all types of concrete powder.
A Water Tank Converting Concrete Powder to Concrete
Technical Details
When switching from convert concrete powder into concrete to filling the water tank, the water tank must be empty for up to 16 game ticks.