ACPA Revises Its Statement on Water Priming

Always prime the pump and placing line before you begin to pump concrete through the system.

Concrete pumping works because when pressure is applied to concrete in a pipe, the finest material of cement and water are forced to the pipe wall, making a slippery layer for the concrete in the pipe to slide on. When you prime, the slippery material is already present in the pipe before concrete hits it. If you don’t prime, the finest material is taken from the concrete to make the slippery layer, causing some amount of concrete to have nothing but rock and coarse sand left in the mix. Rock and sand will NOT pump, and blockages happen.

The optimal priming method is using a thin slurry containing Portland cement because it’s the same material that the pipe walls would take from the mix. In most cases, water priming is not recommended by the ACPA. See the graphic for more information.