Reducing shear thickening of cement-based suspensions

Toussaint, Fabrice; Roy, Cédric; Jézequel, Pierre-Henri

doi:10.1007/s00397-009-0362-z

Cited by 40 publications

(28 citation statements)

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“…It is important to note that such mixed suspensions cannot be treated simply in terms of polydispersity as the spherical non‐colloidal particles and colloidal particles are separated by more than an order of magnitude in size and three orders of magnitude in mass. Suspensions comprised of mixtures of non‐colloidal and colloidal particles are found in a wide variety of materials such as: concrete, asphalt, coal water slurry fuels, and ice cream, just to name a few. As such, there is a significant engineering interest in understanding the flow behavior of such suspensions and how these properties can be tuned for design purposes.…”

Section: Introductionmentioning

confidence: 99%

Rheology of cubic particles in a concentrated colloidal dispersion suspending medium

2016

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The flow behavior of mixtures of micron‐sized cubic particles suspended in a concentrated colloidal dispersion is investigated across a broad range of cubic particle concentrations. In the semi‐dilute regime, the qualitative shape of the dynamic moduli and flow curves reflect those of the underlying colloidal dispersion medium. These curves are superimposed with the underlying colloidal dispersion using shift factors that are found to be larger than those obtained in a recent study of suspensions of non‐colloidal spherical particles in the same colloidal dispersion medium. At higher concentrations of cubic particles, deviations from this shifting procedure are apparent. Scaling calculations suggest depletion interactions are responsible for the increase in the low shear viscosity and confinement of the underlying colloidal dispersion can be expected to enhance the shear thickening behavior at high shear stresses. The results of this study provide guidance for formulating suspensions through control of particle shape and mixture concentration. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1091–1101, 2017

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Section: Introductionmentioning

confidence: 99%

Rheology of cubic particles in a concentrated colloidal dispersion suspending medium

2016

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“…Hundreds of millions of metric tons of cement are used globally each year, for example, and production engineers are careful to formulate modern high-strength cements and concretes that don't suffer from the effect-at least in a range of shear rates important for processing and construction. 4 In pioneering work in the 1970s, Monsanto's Richard Hoffman developed novel light-scattering experiments to probe the underlying microstructural transitions that accompanied shear thickening in concentrated latex dispersions. 5 The transition was observed to correlate with a loss of Bragg peaks in the scattering measurement.…”

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confidence: 99%

Shear thickening in colloidal dispersions

2009

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The popular interest in cornstarch and water mixtures known as "oobleck" after the complex fluid in one of Dr. Seuss's classic children's books arises from their transition from fluid-like to solid-like behavior when stressed. The viscous liquid that emerges from a roughly 2-to-1 (by volume) combination of starch to water can be poured into one's hand. When squeezed, the liquid morphs into a doughy paste that can be formed into shapes, only to "melt" into a puddle when the applied stress is relieved. Internet videos show people running across a large pool of the stuff, only to sink once they stop in place, and "monsters" that grow out of the mixture when it's acoustically vibrated (for an example, see the online version of this article). Shear-thickening fluids certainly entertain and spark our curiosity, but their effect can also vex industrial processes by fouling pipes and spraying equipment, for instance. And yet, when engineered into composite materials, STFs can be controlled and harnessed for such exotic applications as shockabsorptive skis and the soft body armor discussed in box 1. Engineers and colloid scientists have wrestled with the scientific and practical problems of shear-thickening colloidal dispersions-typically composed of condensed polymers , metals, or oxides suspended in a liquid-for more than a century. More recently, the physics community has explored the highly nonlinear materials in the context of jamming 1 (see the article by Anita Mehta, Gary Barker, and Jean-Marc Luck in PHYSICS TODAY, May 2009, page 40) and the more general study of colloids as model systems for understanding soft condensed matter. Hard-sphere colloids are the "hydrogen atom" of colloidal dispersions. Because of their greater size and interaction times compared with atomic and molecular systems, colloidal dispersions are often well suited for optical microscopy and scattering experiments using light, x rays, and neutrons. That makes the dispersions, beyond their own intrinsic technological importance, ideal models for exploring equilibrium and near-equilibrium phenomena of interest in atomic and molecular physics-for example, phase behavior and "dynamical arrest," in which particles stop moving collectively at the glass transition. The relevance of colloids to atomic and molecular systems breaks down, though, for highly nonequilibrium phenomena. Indeed, shear thickening in strongly flowing colloidal dispersions may be among the most spectacular, and elucidating, examples of the differences between the systems.

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“…The CST-DST transition was then measured by shear rheometry in a helicoidal paddle geometry (Anton Paar 301 rheometer, see [21] Fig.4 for geometry description) with a descending logarithmic stress ramp after pre-shear (from 700 to 0.01 P a in 100s). The viscosity curves are divided into two main parts: at low shear rate, the fluid shows a Newtonian behavior with a viscosity that depends on volume fraction [43] (Fig.3b) but not on the polymer coating (Fig.3c).…”

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Microscopic Mechanism for Shear Thickening of Non-Brownian Suspensions

et al. 2013

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We propose a simple model, supported by contact-dynamics simulations as well as rheology and friction measurements, that links the transition from continuous to discontinuous shear-thickening in dense granular pastes to distinct lubrication regimes in the particle contacts. We identify a local Sommerfeld number that determines the transition from Newtonian to shear-thickening flows, and then show that the suspension's volume fraction and the boundary lubrication friction coefficient control the nature of the shear-thickening transition, both in simulations and experiments.Flow non-linearities attract fundamental interest and have major consequences in a host of practical applications [1,2]. In particular, shear-thickening (ST), a viscosity increase from a constant value (Newtonian flow-Nw) upon increasing shear stress (or rate) at high volume fraction φ, can lead to large-scale processing problems of dense pastes, including cement slurries [3]. Several approaches have been proposed to describe the microscopic origin of shear-thickening [4][5][6][7]. The most common explanation invokes the formation of "hydroclusters", which are responsible for the observed continuous viscosity increase [6,8,9] and which have been observed for Brownian suspensions of moderate volume fractions [10,11]. However, this description no longer holds for bigger particles and denser pastes, where contact networks can develop and transmit positive normal stresses [12]. Moreover, the link between hydroclusters and CST for non-Brownian suspensions is still a matter of debate [13]. Additionally, dense, non-Brownian suspensions can also show sudden viscosity divergence under flow [14][15][16][17] with catastrophic effects, such as pumping failures. In contrast to a continuous viscosity increase at any applied rate, defined as continuous shear-thickening (CST), the appearance of an upper limit of the shear rate defines discontinuous shear-thickening (DST). This CST to DST transition is observed when the volume fraction of the flowing suspension is increased above a critical value, which depends on the system properties, e.g. polydispersity or shape, and on the flow geometry [3,18]. An explanation for its microscopic origin is still lacking [19]. Moreover, experiments have demonstrated that the features of the viscosity increase (slope, critical stress) can be controlled by tuning particle surface properties such as roughness [20] and/or by adsorbing polymers [21,22]. These findings suggest that inter-particle contacts play a crucial role in the macroscopic flow at high volume fractions. A more precise description of these contacts is therefore essential to interpret the rheological behavior.In this paper, we present a unified theoretical framework, supported by both numerical simulations and experimental data, which describes the three flow regimes of rough, frictional, non-Brownian particle suspensions (Nw,CST,DST) and links the Nw-ST (in terms of shear) and the CST-DST transitions (in terms of volume fraction) to the local friction. Our micro...

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Reducing shear thickening of cement-based suspensions

Cited by 40 publications

References 32 publications

Rheology of cubic particles in a concentrated colloidal dispersion suspending medium

Rheology of cubic particles in a concentrated colloidal dispersion suspending medium

Shear thickening in colloidal dispersions

Microscopic Mechanism for Shear Thickening of Non-Brownian Suspensions

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