Recent Developments in Evaluating Pumping Behavior of Flowable and Self-Consolidating Concretes

In this paper, recent developments in evaluating pumping behavior of flowable and self-consolidating concrete (SCC) are discussed. First, a brief overview of the underlying physics of pumping of concrete is given to introduce the concepts of friction, flow, hydrodynamic and hydrostatic pressure and to present the concept of the lubrication layer. Various methods to assess the lubrication layer properties are then discussed, including tribology and different visualization techniques for the velocity profile. Using tribology on the one hand, or by combining the rheological properties of the concrete and its constituent mortar and knowing the thickness of the lubrication layer on the other hand, it is shown that pressure losses during pumping of concrete can be successfully predicted. An overview is also provided to discuss the influence of flow rate, pipe diameter and critical SCC properties influencing the pressure during pumping