Distinguishing dynamic and static yield stress of fresh cement mortars through thixotropy

Qian, Ye; Kawashima, Shiho

doi:10.1016/j.cemconcomp.2017.11.019

Cited by 199 publications

(79 citation statements)

References 38 publications

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“…Similar results have been observed for other thixotropic materials. According to previous studies [6,11,13], the difference between static and dynamic yield stresses ranges between 1.5 and 2-fold. It is, of course, believed that the difference is larger when the solid volume concentration is greater.…”

Section: Stress Growth Test: Time Dependencymentioning

confidence: 90%

“…Uncertainties are higher for the rheological properties measured at lower shear rates because the variations in viscosity at low shear rates (less than 1 s −1 ) are significant. In an elastic regime, the structure begins to break down, is subjected to shear localization, and creates partial shear-induced particle migration in the flow curves when the shear strain approaches the critical shear strain [6]. In the transition from the solid-like to liquid-like regime, there is a critical deformation.…”

Section: Methodsmentioning

confidence: 99%

“…2019, 9, 4744 2 of 11 flow stopping, but the static yield stress is associated with flow starting [13]. According to previous studies [6], the dynamic and static yield stresses are related to the state before and after microstructural changes in materials. In addition, the conception of the time depending on the value of the yield stress has been pointed out by numerous studies [14][15][16].…”

mentioning

confidence: 92%

“…The yield stress is a special property associated with non-Newtonian fluids, such as clay suspensions, concrete cements, crude oil, foams, food, paints, pastes, and polymers [1][2][3][4][5][6]. In general, the yield stress is defined as the shear stress at the point where the applied stress exceeds the critical shear rate; in this case, the material starts to flow.…”

Section: Introductionmentioning

confidence: 99%

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Shear Rate-Dependent Rheological Properties of Mine Tailings: Determination of Dynamic and Static Yield Stresses

Jeong¹

2019

Applied Sciences

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In this paper, shear rate-dependent rheological properties of mine tailings taken from abandoned mine deposits prone to mass movements are examined using a commercial ball-measuring rheological system. The yield stresses (i.e., dynamic and static yield stresses) and viscosity of sand-rich materials are examined by the shear rate-controlled flow curve and time-dependent stress growth methods. Before yielding, the shear stress reaches a peak value (i.e., yield stress) observed for all flow curves. In the steady-state condition, the materials have a minimum shear stress (i.e., dynamic yield stress). The static yield stress can be determined under a constant applied shear rate with different initial values ranging from 10−4 to 10−1 s−1. As a result, the Bingham yield stress and viscosity can be used as a first approximation for estimating the debris flow mobility of post-failure materials. However, the Bingham yield stress is competitive with the static yield stress measured from stress growth methods. Upon comparison of the dynamic and static yield stresses, the static yield stress is approximately 35–45 times greater than the dynamic yield stress, and may be strongly related to microstructural changes (i.e., thixotropy). In this context, special attention must be paid to the determination of yield stresses in debris flow mitigation programs.

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Section: Stress Growth Test: Time Dependencymentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Shear Rate-Dependent Rheological Properties of Mine Tailings: Determination of Dynamic and Static Yield Stresses

Jeong¹

2019

Applied Sciences

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“…Further, thixotropic materials with high values of the yield stress are particularly suited to high-resolution direct-write printing. Examples include printing of structures using foams, elastomers, concrete, cell-laden gels, and conductive inks [16][17][18][19][20][21]. To assist in understanding and optimizing yield stress materials for applications, rapid, reliable, and accurate measurements of the material behavior are required.…”

Section: Introductionmentioning

confidence: 99%

Improved rheometry of yield stress fluids using bespoke fractal 3D printed vanes

Owens

Hart

McKinley

2020

Journal of Rheology

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To enable robust rheological measurements of the properties of yield stress fluids, we introduce a class of modified vane fixtures with fractal-like cross-sectional structures. A greater number of outer contact edges leads to increased kinematic homogeneity at the point of yielding and beyond. The vanes are 3D printed using a desktop stereolithography machine, making them inexpensive (disposable), chemically-compatible with a wide range of solvents, and readily adaptable as a base for further design innovations. To complete the tooling set, we introduce a textured 3D printed cup, which attaches to a standard rheometer base. We discuss general design criteria for 3D printed rheometer vanes, including consideration of sample volume displaced by the vanes, stress homogeneity, and secondary flows that constrain the parameter space of potential designs. We also develop a conversion from machine torque to material shear stress for vanes with an arbitrary number of arms. We compare a family of vane designs by measuring the viscosity of Newtonian calibration oils with error <5% relative to reference measurements made with a coneand-plate geometry. We measure the flow curve of a simple Carbopol yield stress fluid, and show that a 24-arm 3D printed fractal vane agrees within 1% of reference measurements made with a roughened cone-and-plate geometry. Last, we demonstrate use of the 24-arm fractal vane to probe the thixo-elasto-visco-plastic (TEVP) response of a Carbopol-based hair gel, a jammed emulsion (mayonnaise), and a strongly alkaline carbon black-based battery slurry.

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Synthesis and study of organo‐modified silica based hydrogels: Rheological properties and drug release kinetics

Parfenyuk,

Dolinina,

Kraev

2024

J Biomed Mater Res

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The method of synthesis of unmodified and organo‐modified silica hydrogels and their composites with orotic acid as a model drug was developed. The hydrogels had a pH of 6.5–7.8. The particulate nature and highly porous structures of the hydrogel materials were revealed using scanning electron and optical microscopy methods. The content of aqueous phase in the hydrogels was 99% or more. In order to evaluate the possibility of their application as a basis for development of novel soft drug formulations and cosmetic compositions, rheological properties of the hydrogels and in vitro release kinetics of the drug were studied. The effects of synthesis conditions (increasing concentration of catalyst of silica sol formation, drug loading) and the silica matrix modification with various organic groups on the indicated properties were investigated. It was found that all synthesized hydrogels exhibited pseudoplasticity, thixotropy and controlled release of the drug, which are important for their potential application. However, in general, the indicated effects led to worsening the properties of the hydrogel materials in comparison with the unmodified silica hydrogels.

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Distinguishing dynamic and static yield stress of fresh cement mortars through thixotropy

Cited by 199 publications

References 38 publications

Shear Rate-Dependent Rheological Properties of Mine Tailings: Determination of Dynamic and Static Yield Stresses

Shear Rate-Dependent Rheological Properties of Mine Tailings: Determination of Dynamic and Static Yield Stresses

Improved rheometry of yield stress fluids using bespoke fractal 3D printed vanes

Synthesis and study of organo‐modified silica based hydrogels: Rheological properties and drug release kinetics

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