Pumping of Fresh Concrete: Insights and Challenges

Schutter, Geert De; Feys, Dimitri

doi:10.21809/rilemtechlett.2016.15

Cited by 79 publications

(33 citation statements)

References 21 publications

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“…In reality, wall slippage is not expected to be present in case of cementitious paste suspensions or even mortars and concrete, e.g. self-compacting concrete [20][21][22][23]. Even if wall slippage would occur, still, the flow behaviour for a thixotropic bulk can be anticipated via an adopted approach as done by [21].…”

Section: Thixotropic Poiseuille Flow Extensionmentioning

confidence: 99%

“…That is why for self-compacting concrete compared to traditional concrete a wider pipe diameter is usually chosen. Since self-compacting concrete has a higher plastic viscosity, one can decrease the pumping pressure contribution by the plastic viscosity µ, while sustaining a high discharge rate Q with reasonable required pumping power [22,31,34,42].…”

Section: Pumpbability Contributionmentioning

confidence: 99%

“…For a Bingham model, the analytical solution for Poiseuille flow was originally developed by Buckingham and Reiner[22,26,31,33]. Hence the pressure loss discharge relation was named after both, namely the Buckingham-Reiner equation.…”

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confidence: 99%

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Insights in thixotropic concrete pumping by a Poiseuille flow extension

Schryver

Schutter

2020

Applied Rheology

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Thixotropy is a reversible time-dependent phenomenon in fluids, in which an internal structure grows due to flocculation and breaks down under shear action. Numerous fluids are thixotropic, e.g. concretes and cementitious suspensions. Pumping of concrete is an important application. Since current approaches omit thixotropic effects, we aim to develop a simple theoretical model to evaluate or understand the significance of thixotropy on the concrete pumping behaviour. We therefore extended Poiseuille flow for thixotropic concretes and reformulated it in a dimensionless form to gain insights. After a validation, the results and significance are elaborated and concluded.Results showed that for increasing thixotropy and decreasing flow rates, the plug radius, wall shear rate and pumping pressure loss increase. Even though all thixotropy mechanisms may not be covered, a simple model is delivered to interpret or predict the effect of thixotropy on the pumping behaviour of cementitious suspensions. The dimensionless formulations via the Bingham number Bn and related discharge diagrams are sufficiently elegant for computational implementation and very insightful to distinguish a thixotropic flow regime. The model could be extended for more complicated thixotropies, irreversible time-dependent effects or even other pumping related phenomena.

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Section: Thixotropic Poiseuille Flow Extensionmentioning

confidence: 99%

Section: Pumpbability Contributionmentioning

confidence: 99%

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Insights in thixotropic concrete pumping by a Poiseuille flow extension

Schryver

Schutter

2020

Applied Rheology

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“…In some cases, however, bulk control will not be required. As an example, the pumping behaviour to a very large extent depends on the properties of the lubrication layer near the pipe surface [ 118 ]. In that case, an economical question might emerge, related to the cost of adding (probably relatively expensive) functional material to the bulk of the concrete, while only needing them for control purposes in a limited zone of interest.…”

Section: Challenges For Active Control In Concretementioning

confidence: 99%

Active control of properties of concrete: a (p)review

Schutter

Lesage

2018

Mater Struct

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Concrete properties to a large extent depend on mix design and processing, currently leaving only limited options to actively modify concrete properties during or after casting. This paper gives a (p)review on a more advanced active control of properties of concrete, based on the application of external signals to trigger an intended response in the material, either in fresh or hardened state. Current practices in concrete industry that could be considered as active control are briefly summarized. More advanced active control mechanisms as studied in other fields, e.g. based on hydrogels and other functional polymers, are reviewed and some principles are listed. A specific focus is further given on potential methods for active rheology control. Based on the concepts developed in other fields, substantial progress could be made in order to achieve active control of fresh and hardened concrete properties. However, several challenges remain, like the stability and functioning of the responsive material in a cementitious environment, the applicability of the control signal in a cementitious material, and the economy, logistics and safety of a control system on a construction site or in precast industry. Finding solutions to these challenges will lead to marvelous opportunities in general, and for 3D and even 4D printing more particularly.

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“…Another well-known phenomenon that leads to drastic changes in the flow behavior is the segregation of the coarse material during the transport process [14,15]. Especially the segregation near the pipe wall is of great importance for the pumping of fresh concrete.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Pumping of a Model-Concrete through Pipes

2020

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Many practical aspects of processing fresh concrete depend on its rheology, such as the pumping of the material. It is known that a lubricating layer is formed in the process, which significantly reduces the pumping pressure. However, these phenomena can hardly be considered in the usual rheological measurements. A main problem is the optical inaccessibility of the material, which prevents estimations about, e.g., the thickness of the plug flow or particle migration. In this paper, the pneumatic pumping of a transparent model concrete is performed by means of a test plant. The flow profile over the entire pipe cross-section is resolved in time and space via Particle Image Velocimetry (PIV) measurements. This allows the comparison with the analytical flow profile from rheological measurements of the material using the Buckingham–Reiner equation. A reduction of the pressure loss to around 60% induced through segregation of the material is found. These measurements reflect the rheology of the material under realistic pumping conditions including particle migration. This makes it possible for the first time to observe a transparent material with concrete-like rheology under pulsating pumping conditions and to compare the true and calculated time-resolved pressure loss.

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Pumping of Fresh Concrete: Insights and Challenges

Cited by 79 publications

References 21 publications

Insights in thixotropic concrete pumping by a Poiseuille flow extension

Insights in thixotropic concrete pumping by a Poiseuille flow extension

Active control of properties of concrete: a (p)review

Experimental Investigation of the Pumping of a Model-Concrete through Pipes

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