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How clay particulates affect flow cessation and the coiling stability of yield stress-matched cementing suspensions

Abstract

The remarkable increase in the flow resistance of dense suspensions can hinder 3D-printing processes on account of flow cessation in the extruder, and filament fragility/rupture following deposition. Understanding the nature of rheological changes that occur is critical to manipulate flow conditions or to dose flow modifiers for 3D-printing. Therefore, this paper elucidates the influences of clay particulates on controlling flow cessation and the shape stability of dense cementing suspensions that typically feature poor printability. A rope coiling method implemented with varying stand-off distances was used to probe the buckling stability and tendency to fracture of dense suspensions that undergo stretching and bending during deposition. The contributions of flocculation and short-term percolation due to the kinetics of structure formation to deformation rate were deconvoluted using a stepped isostress method. It is shown that the shear stress shows a divergence with a power-law scaling when the particle volume fraction approaches the jamming limit; ϕ → ϕJ ≈ϕmax. Such a power-law divergence of the shear stress decreases by a factor of 10 with increasing clay dosage. Such behavior in clay-containing suspensions arises from a decrease in the relative packing fraction (ϕ/ϕmax) and the formation of fractally-architected aggregates with stronger interparticle interactions, whose uniform arrangement controls flow cessation in the extruder and suspension homogeneity, thereby imparting greater buckling stability. The outcomes offer new insights for assessing/improving the extrudability and printability behavior during slurry-based 3D-printing process.

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Supplementary files

Article information


Submitted
07 Dec 2019
Accepted
25 Mar 2020
First published
26 Mar 2020

Soft Matter, 2020, Accepted Manuscript
Article type
Paper

How clay particulates affect flow cessation and the coiling stability of yield stress-matched cementing suspensions

I. Mehdipour, H. Atahan, N. Neithalath, M. Bauchy, E. J. Garboczi and G. Sant, Soft Matter, 2020, Accepted Manuscript , DOI: 10.1039/C9SM02414J

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