The Synergistic Effect of Ester-Ether Copolymerization Thixo-Tropic Superplasticizer and Nano-Clay on the Buildability of 3D Printable Cementitious Materials

The shape retention ability of materials deposited layer by layer is called buildability, which is an indispensable performance parameter for successful 3D printable cementitious materials (3DPC). This study investigated the synergistic effect of nano-clay (NC) and thixotropic superplasticizer (TP) on the buildability of 3DPC. The rheological parameters and static yield stress are characterized by the rheology testing, the green strength is measured by a self-made pressure tester, and the fluidity is tested by flow table. Results indicate that NC significantly increases the growth rate of static yield stress and green strength and TP can improve the initial rheological parameters and fluidity, which ensures the initial stiffness and workability of printed materials. The mixture with 7‰ (by mass of cementitious materials) NC and 3‰ TP obtains excellent extrudability and buildability, due to the synergistic effect of NC and TP. Based on the rheology testing and specific printing experiments, a printable window with 1.0 Pa/s~2.0 Pa/s of the rate of static yield stress evolution over time (RST) or 170 mm~200 mm of fluidity is established. This work provides theorical support for the control and evaluation of rheological properties in 3DPC.

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Effects of Volume Fraction and Surface Area of Aggregates on the Static Yield Stress and Structural Build-Up of Fresh Concrete

10.20944/preprints202003.0007.v1 ◽

2020 ◽

Author(s):

Irina Ivanova ◽

Viktor Mechtcherine

Keyword(s):

Rheological Properties ◽

Yield Stress ◽

Surface Area ◽

Cement Paste ◽

Volume Fraction ◽

Fresh Concrete ◽

Total Surface Area ◽

Rheological Parameters ◽

Static Yield ◽

Static Yield Stress

With increasing interest in the use of additive manufacturing techniques in the construction industry, static rheological properties of fresh concrete have necessarily come into focus. In particular, the knowledge and control of static yield stress (SYS) and its development over time are crucial for mastering formwork-free construction, e.g. by means of layered extrusion. Furthermore, solid understanding of the influences of various concrete constituents on the initial SYS of the mixture and the structural build-up rate is required for purposeful material design. This contribution is concentrated on the effect of aggregates on these rheological parameters. The volume fraction of aggregates was varied in the range of 35 to 55 % by volume under condition of constant total surface area of the particles. The total surface area per unit volume of cement paste was equal to 5.00, 7.25 and 10.00 m²/l, conditioned on the constant volume fraction of aggregates. Both variations were enabled by changing the particle size distributions of the aggregates while holding the cement paste composition constant for all concrete mixtures. To characterise the SYS and the structural build-up, constant shear rate tests with a vane-geometry rotational rheometer were performed. It was found that in the ranges under investigation the variation in volume fraction had a more pronounced effect on the static rheological properties of concrete than did the variation in surface area. An accurate mathematical description of the relationship between the initial SYS of concrete and the relative volume fraction of aggregate based on the Chateau-Ovarlez-Trung model was proposed. Challenges in deriving a similar relationship for the structural build-up rate of concrete were highlighted.

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Effects of Volume Fraction and Surface Area of Aggregates on the Static Yield Stress and Structural Build-Up of Fresh Concrete

Materials ◽

10.3390/ma13071551 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1551 ◽

Cited By ~ 4

Author(s):

Irina Ivanova ◽

Viktor Mechtcherine

Keyword(s):

Rheological Properties ◽

Yield Stress ◽

Surface Area ◽

Cement Paste ◽

Volume Fraction ◽

Fresh Concrete ◽

Total Surface Area ◽

Rheological Parameters ◽

Static Yield ◽

Static Yield Stress

With increasing interest in the use of additive manufacturing techniques in the construction industry, static rheological properties of fresh concrete have necessarily come into focus. In particular, the knowledge and control of static yield stress (SYS) and its development over time are crucial for mastering formwork-free construction, e.g., by means of layered extrusion. Furthermore, solid understanding of the influences of various concrete constituents on the initial SYS of the mixture and the structural build-up rate is required for purposeful material design. This contribution is concentrated on the effect of aggregates on these rheological parameters. The volume fraction of aggregates was varied in the range of 35% to 55% by volume under condition of constant total surface area of the particles. The total surface area per unit volume of cement paste was equal to 5.00, 7.25 and 10.00 m²/L, conditioned on the constant volume fraction of aggregates. Both variations were enabled by changing the particle size distributions of the aggregates while holding the cement paste composition constant for all concrete mixtures. To characterise the SYS and the structural build-up, constant shear rate tests with a vane-geometry rotational rheometer were performed. It was found that in the ranges under investigation the variation in volume fraction had a more pronounced effect on the static rheological properties of concrete than did the variation in surface area. An accurate mathematical description of the relationship between the initial SYS of concrete and the relative volume fraction of aggregate based on the Chateau–Ovarlez–Trung model was proposed. Challenges in deriving a similar relationship for the structural build-up rate of concrete were highlighted.

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THE STATIC YIELD STRESS OF FERROFLUID-BASED MAGNETORHEOLOGICAL SUSPENSIONS

Electrorheological Fluids and Magnetorheological Suspensions ◽

10.1142/9789812771209_0009 ◽

2007 ◽

Author(s):

Y. B. YANG ◽

L. LI ◽

G. CHEN ◽

W. H. LI

Keyword(s):

Yield Stress ◽

Magnetorheological Suspensions ◽

Static Yield ◽

Static Yield Stress

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Static yield stress of a magnetorheological fluid containing pickering emulsion polymerized Fe3O4/polystyrene composite particles

10.1063/1.5121687 ◽

2019 ◽

Author(s):

Sangsok Han ◽

Junsok Choi ◽

Hoyun Kim ◽

Sehyun Kim ◽

Yongsok Seo

Keyword(s):

Yield Stress ◽

Magnetorheological Fluid ◽

Pickering Emulsion ◽

Composite Particles ◽

Static Yield ◽

Static Yield Stress

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LANTHANUM TITANATE NANOPARTICLES ER FLUIDS WITH HIGH PERFORMANCE

Modern Physics Letters B ◽

10.1142/s0217984912500790 ◽

2012 ◽

Vol 26 (13) ◽

pp. 1250079 ◽

Cited By ~ 1

Author(s):

DE WANG ◽

RONG SHEN ◽

SHIQIANG WEI ◽

KUNQUAN LU

Keyword(s):

Yield Stress ◽

Silicone Oil ◽

Heating Temperature ◽

Hydroxyl Group ◽

Lanthanum Titanate ◽

Different Temperatures ◽

Static Yield ◽

Er Fluids ◽

Er Fluid ◽

Static Yield Stress

A new type of electrorheological (ER) fluid consisting of lanthanum titanate (LTO) nanoparticles is developed. The ER fluids were prepared by suspending LTO powder in silicone oil and the particles were fabricated by wet chemical method. This ER fluid shows excellent ER properties: The static yield stress reaches over 150 kPa under 5 kV/mm with linear dependence on the applied DC electric field, and the current density is below 10 μA/cm2. In order to investigate the affect factor on the ER behavior, the LTO powder were heated under different temperatures. The ER performances of two particles treated under different temperatures were compared and the composition changes for those particles were analyzed with TG-FTIR technique. It was found that the static yield stress of the suspensions fell from over 150 kPa to about 40 kPa and the current densities decreased prominently as the rise of the heating temperature. TG-FTIR analysis indicated that polar groups remained in the particles such as alkyl group, hydroxyl group and carbonyl group etc., contribute to the ER effect significantly. The experimental results are helpful to understand the mechanism of the high ER effect and to synthesize better ER materials.

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Many‐body effect in the static yield stress of electrorheological fluid

Journal of Applied Physics ◽

10.1063/1.354834 ◽

1993 ◽

Vol 74 (2) ◽

pp. 938-941 ◽

Cited By ~ 6

Author(s):

Montonori Ota ◽

Tetsuo Miyamoto

Keyword(s):

Yield Stress ◽

Electrorheological Fluid ◽

Many Body ◽

Body Effect ◽

Static Yield ◽

Static Yield Stress

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Influence of Fructose and Sucrose on Small and Large Deformation Rheological Behaviour of Heated Amioca Starch Dispersions

Food Science and Technology International ◽

10.1177/1082013204042073 ◽

2004 ◽

Vol 10 (1) ◽

pp. 51-57 ◽

Cited By ~ 10

Author(s):

D. B. Genovese ◽

V. M. Acquarone ◽

K. -S. Youn ◽

M. A. Rao

Keyword(s):

Yield Stress ◽

Large Deformation ◽

Heating Temperature ◽

Ageing Time ◽

Rheological Behaviour ◽

Angular Frequency ◽

Rheological Parameters ◽

Static Yield ◽

Pasting Temperature ◽

Dynamic Yield

Effect of sucrose or fructose on the rheological behaviour of gelatinized 5% w/w amioca starch dispersions (GSDs), was studied by small and large deformation rheological techniques. Storage (G0) and loss (G00) moduli as a function of angular frequency (o), and shear stress (s) as a function of shear rate (_) data were obtained on GSDs with: 0, 30 and 60% w/w sugars. Magnitudes of Herschel–Bulkley yield stress (0-HB) were determined from – _ data. Using the vane method, the static yield stress (0s), the dynamic yield stress (0d) and the shear modulus (G) were determined. Effect of pasting temperature and ageing time were also studied by the vane method. Addition of sugars produced an increase in all rheological parameters except 0d, suggesting that sugars increased the strength of the internal bonds or cohesiveness of the GSDs; in general, fructose was slightly more effective than sucrose. Equivalent parameters: G0 and G, and 0-HB and 0s showed good agreement. Decreasing the heating temperature increased G. GSDs with fructose showed a clear increase in 0s and G with ageing time.

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