Pumping of Concrete: Understanding a Common Placement Method with Lots of Challenges

Several million cubic meters of concrete are pumped daily, as this technique permits fast concrete placement. Fundamental research has been performed and practical guidelines have been developed to increase the knowledge of concrete behavior in pipes. However, the pumping process and concrete behavior are not fully understood. This paper gives an overview of the current knowledge of concrete pumping. At first, the known physics governing the flow of concrete in pipes are introduced. A series of experimental techniques characterizing concrete flow behavior near a smooth wall to predict pressure-flow rate relationships are discussed, followed by recent developments in the use of numerical simulations of concrete behavior in pipes. The influence of the pumping process on concrete rheology and air-void system is reviewed, and the first developments in active rheology control for concrete pumping are introduced. The last section of this paper gives an overview of open research questions and challenges

Metrology Needs for Predicting Concrete Pumpability

With the increasing use of pumping to place concrete, the development and refinement of the industry practice to ensure successful concrete pumping are becoming important needs for the concrete construction industry. To date, research on concrete pumping has been largely limited to a few theses and research papers. The major obstacle to conduct research on concrete pumping is that it requires heavy equipment and large amounts of materials. Thus, developing realistic and simple measurement techniques and prediction tools is a financial and logistical challenge that is out of reach for small research labs and many private companies in the concrete construction industry. Moreover, because concrete pumping involves the flow of a complex fluid under pressure in a pipe, predicting its flow necessitates detailed knowledge of the rheological properties of concrete, which requires new measurement science. This paper summarizes the technical challenges associated with concrete pumping and the development in concrete pumping that have been published in the technical literature and identifies future research needed for the industry to develop best practices for ensuring successful concrete pumping in the field

Cross-property correlations and permeability estimation in sandstone

We computationally investigate cross-property correlations linking fluid permeability to conductive properties in sedimentary rock for a number of pore size parameters based on three-dimensional digitized rock images. In particular, we focus on correlations based on the pore volume-to-surface-area ratio (VpS), a critical channel diameter c associated with mercury porosimetry measurements, length scales associated with the nuclear magnetic resonance relaxation time T2, as well as the mean survival time τ. Differences between the length scales are discussed. All these correlations yield good agreement with our simulations, but permeability estimates based on the critical diameter ""c are found to be most reliable

Virtual Permeametry on Microtomographic Images

We show that accurate numerical micropermeametry measurements can be performed on three-dimensional (3D) digitized images of sedimentary rock. The sample size can be very small, making it possible to predict properties from core material not suited for laboratory testing (e.g., drill cuttings, sidewall core and damaged core plugs). Simulation of fluid permeability on microtomographic images of Fontainebleau sandstone on sample sizes of less than 1 mm3 are in good agreement with experimental measurements over a wide range of porosities