Cement, ground granulated blast furnace slag, silica fume and flyash batching are especially sensitive to aeration. Aeration can cause up to a 35 pounds per cubic foot difference in the unit weight of the substance. The most accepted systems for batching cementitous materials are: gates, valves, screw feeders, vane feeders, air slides, and pneumatic transfer systems.

Gates and valves are used for batching directly from overhead storage. Because of the variable flow characteristics of cementitous materials the weighing must be done in two stages. It begins fast and is finished in a slow rate. The characteristics of each speed must be taken into account when calculating the delivery rate.

As long as there is a constant supply of cement and fly ash, the screw feeder will have a constant delivery rate. The discharge rate of a screw feeder can be predicted very easily. it is just a function of screw diameter and other physical characteristics of the system. Multiple screws can be used to increase productivity.

Vane feeders are used with overhead storage bins. They are very unpredictable and not widely used. Air slides use low pressure air as a lubricant permitting the cement to fall downward. This creates the desired fluidlike flow.