Effects of an externally imposed electromagnetic field on the formation of a lubrication layer in concrete pumping

•It needs to improve efficiency of concrete pumping in a large scale construction.•The externally imposed electromagnetic field enhances the pumpability of concrete.•The properties of the lubrication layer are changed by the electromagnetic field.

During concrete pumping, a lubrication layer is formed at the interface between the concrete and the pipe. The pumpability highly depends on the characteristics of this layer. In this study, a method to enhance the pumpability by externally imposing an electromagnetic field on the pipe was suggested and experimentally verified. The electromagnetic field activates the free movement of the water molecules so that the layer is expected to become more slippery. Pumping tests with a 1000 m long pipeline were conducted with and without applying an electromagnetic field. When the electromagnetic field was imposed, the same discharge rate could be obtained with a 30% reduction in the pump pressure, and a 15% increase in the velocity under the same pump pressure was observed. The tests revealed that the imposition of an electromagnetic field was very effective in improving the pumpability.