Transport of Concrete by Pumps:

Concrete pumps are used to deliver concrete for concreting densely reinforced structures, internal structural components of buildings and huge mass concrete structures. These are additionally used for concreting of tunnel linings. Such pumps cover a horizontal distance of 300 to 400 m and a vertical distance of 40 to 50 m. Pumping is a procedure of transporting concrete without unloading and reloading in a vertical or horizontal direction and without a harmful effect on its quality.

In this method, the concrete is charged into the receiving hopper and kept mixed continuously by the paddles in order to retain uniformity of mix and to prevent segregation. The impeller blades by the open suction valve push the concrete within the barrel of the pump. The suction valve closes while the plunger moves to the left. The pressure valve opens that moves the concrete from the barrel into the pipeline. A diameter of the pipeline depends upon the size of the aggregate used but it does not exceed 30 cm within any case. The slump should not be less than 5 cm and more than 8 cm. The water-cement ratio should remain among 0.5 to 0.65. Stiff mixes are not suitable to be delivered through pumps because their pumping properties are not good. Sharp turns and bends should be prevented in the pipeline. The number of bends within a pipeline should be as small as possible.