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Open AccessFeature PaperArticle

Estimation of Lubrication Layer Thickness and Composition through Reverse Engineering of Interface Rheometry Tests

Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO 65409, USA
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Materials 2020, 13(8), 1799; https://doi.org/10.3390/ma13081799
Received: 13 March 2020 / Revised: 8 April 2020 / Accepted: 9 April 2020 / Published: 11 April 2020
(This article belongs to the Special Issue Rheology of Reactive, Multiscale, Multiphase Construction Materials)
During concrete pumping, a lubrication layer is formed near the pipe wall. Extensive research has been performed on measuring and modeling the properties of this layer and using these values to predict pumping pressures. However, there are numerous discussions in the literature about the composition and thickness of this layer: can it be considered mortar, a micromortar, or is it cement paste? In this paper, possible solutions for the thickness and composition of the lubrication layer are derived from interface rheometry tests. It is assumed that the lubrication layer is composed of one or more concentric layers of paste or micromortar. To accomplish this determination, the rheological properties of the composing paste, mortars with different maximum particle sizes and concrete need to be known. Challenges arising from using different rheometers and from the sensitivity of the paste rheology to shearing are addressed in this contribution. The results show that, mathematically, a single layer of homogeneous paste or mortar with different maximum particle sizes can be responsible for the formation of the lubrication layer. Physically, however, the composing material should contain sand particles to some extent, as particle migration is proportional to the size squared. If the literature results from pumping are applicable to the results obtained in this paper, it seems that the lubrication layer is composed of a mortar with a maximum particle size of around 1 to 2 mm. View Full-Text
Keywords: lubrication layer; interface rheometer; rheology; concrete; mortar; viscosity; yield stress; pumping lubrication layer; interface rheometer; rheology; concrete; mortar; viscosity; yield stress; pumping
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MDPI and ACS Style

Salinas, A.; Feys, D. Estimation of Lubrication Layer Thickness and Composition through Reverse Engineering of Interface Rheometry Tests. Materials 2020, 13, 1799.

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