Design of concrete pumping circuit

Pumping is a technique used for the transport of freshly-mixed concrete, allowing the supply of fresh material in the formwork without the use of any bucket or conveying belt. This article reports on a study on pressure and flow during concrete pumping. The authors used a 150 m-long experimental pumping circuit to carry out a number of full-scale pumping tests. In addition, the fresh concrete rheological and steel-concrete interface behaviors were measured in the laboratory with a rheometer equipped with accessories. The authors showed that, in many cases, concrete is not sheared in a pipe during pumping. The concrete goes ahead by slip, due to a grout layer that forms close to the pipe wall. The losses of pressure are due to the deformations by shear located in this layer. The characterize this steel-concrete interface, the authors developed the coaxial cylinder tribometer to measure the yield stress and the viscous constant of the interface. The results were analyzed and further validation was acquired on two real job sites. The authors note that a complete set of tools (guide, laboratory devices, and software) is now available to apply this method in practice.