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

Iman Mehdipour, Hakan Atahan, Narayanan Neithalath, Mathieu Bauchy, Edward Garboczi, Gaurav Sant*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

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 was implemented with varying stand-off distances 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 indicates 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.

Original languageEnglish
Pages (from-to)3929-3940
Number of pages12
JournalSoft Matter
Volume16
Issue number16
DOIs
Publication statusPublished - 28 Apr 2020

Bibliographical note

Publisher Copyright:
© The Royal Society of Chemistry 2020.

Funding

The authors acknowledge financial support for this research from: the Anthony and Jeanne Pritzker Family Foundation, TRANSCEND: a joint UCLA-NIST consortium that is supported by its industry and agency partners, and the National Science Foundation (DMREF: 1922167). This research was conducted in the Laboratory for the Chemistry of Construction Materials (LC2). As such, the authors gratefully acknowledge the support that has made these laboratories and their operations possible. The contents of this paper reflect the views and opinions of the authors, who are responsible for the accuracy of the datasets presented herein, and do not reflect the views and/or policies of the funding agencies, nor do the contents constitute a specification, standard or regulation.

FundersFunder number
DMREF
National Science Foundation1922167

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