Study on a Method of Evaluating a Yield Value of Fresh Concrete With a Slump Flow Value

Kokado, Takeshi; Hosoda, Takashi; Miyagawa, Toyoaki; Fujii, Minoru

doi:10.2208/jscej.1997.578_19

Cited by 5 publications

(4 citation statements)

References 9 publications

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“…17 Therefore, in this study, mortar rheological constants were investigated as an index to evaluate the viscosity. The rheological constants were obtained using a steel ball pull-up test, [18][19][20] which can be applied to highly viscous mortar.…”

Section: Overviewmentioning

confidence: 99%

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Prediction of effective vibration condition under air void reduction using mortar rheological constant

Kisaku

Yoshida

Muto³

et al. 2022

Engineering Reports

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Air voids remaining on the concrete surface are detrimental to the durability. Surface voids also affect the esthetics of concrete structures. In this study, the method of reducing the surface voids caused by entrapped air of fresh concrete was verified using 122 cases of vibration box tests with different materials, mix proportions, vibration frequencies, and amplitudes. The surface void area ratio (SVAR) decreased when the acceleration of the vibration box was increased regardless of the type of concrete. The relationship between SVAR and acceleration can be expressed through a power function. However, a segregation was observed in medium‐fluidity concrete when the acceleration exceeded 4.0 Gal (hereinafter referred to as G). In addition, the SVAR correlated with the mortar rheological constant was measured using a steel ball pull‐up test. An equation using mortar rheological constants, which can be estimated using a concrete slump, was proposed to predict the SVAR‐acceleration relationship.

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Section: Overviewmentioning

confidence: 99%

“…The steel ball sunk in the viscous fluid was pulled upward, and the rheological constant was estimated from the drag force acting on the steel ball. The test device was manufactured according on References 19, 20. An overview of the device is presented in Figure 24.…”

Section: Measurement Of Rheological Constantsmentioning

confidence: 99%

Prediction of effective vibration condition under air void reduction using mortar rheological constant

Kisaku

Yoshida

Muto³

et al. 2022

Engineering Reports

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“…、Hara ら 5,6) 、Kitamura and Okohira 7) の研究、および、Hara and Ogino 8) のレビューがある。試験転炉および実機転炉でフォーミング高さについても Tatsukawa ら 9) の報告がある。また、フォーミング高さだけでなく、気泡の滞留時間やフォーミングインデックスを対象とした検討については、高温スラグを用いた実験や冷間モデル実験での結果が Ito and Fruehan [10][11][12] を始めとして多数報告されている [13][14][15][16][17][18][19][20][21][22][23][24] 。転炉スラグフォーミングの状態を音響情報から検討する報告 25) もある。また、火山分野では粒子や気泡を含む溶岩やマグマの粘度を高温流体、あるいは、それを模擬する流体を使って検討され 3 ている [26][27][28][29][30][31][32][33] 。土木工学や建築分野でも、モルタルやセメントなどを対象に、粒子が分散した 2 相流体をビンガム流体とした実験および評価、数値計算に関する研究が多数実施されている [34][35][36][37] Roscoe の式(6) 43) 、Yagi and Ototake の式(7) 44) 、Krieger and Dougherty の式(8) は、少量の液体粒子の存在はフォーミングを助長すること、をそれぞれ報告している。…”

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多相融体の流動特性評価とプロセスシミュレーション

Higuchi,

Shimasaki,

Ueda

et al. 2024

Tetsu-to-Hagane

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In the process of steelmaking refining, slag used in the preliminary treatment of molten iron or the converter is a multiphase melt. It contains solid particles that cannot dissolve entirely from the raw materials and gas bubbles generated through reactions, thus making it a multiphase molten material with dispersed components. The flow characteristics of the suspensions, foams, and emulsions significantly affect the separation of iron particles in the slag and the behavior of slag discharge. Multiphase melts typically behave as non-Newtonian fluids, so the evaluation, focusing on viscosity, is crucial to understanding their flow characteristics. This report reviews recent advances in slag visualization techniques for understanding the flow of multiphase molten materials. The results are as follows:Through studies of viscosity measurements of multiphase melts using rotational viscometers, falling-ball methods, and dam break methods in cold experiments with simulated slag and hightemperature experiments with slag compositions close to practical operation, it has been shown that the apparent viscosity increases with an increase in the volume fraction of solid particles and bubbles. The complex behaviors of the viscosity measurement values could have been reproduced with high precision using predictive models based on recent developments in machine learning. In terms of process evaluation, the application of mesh and mesh-free methods is advancing as methods of computational fluid dynamics (CFD) that take non-Newtonian behavior into account, providing valuable insights into evaluating slag discharge properties and more.

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“…Slump flow is closely related to the yield stress [Mur84, CPA96, Dom98] and researchers have attempted to quantify it. [KHMF97] established a relation between yield stress and spread diameter, taking the total volume of concrete into consideration while neglecting the influence of viscosity. This relation is given in (5.1) where D f is measured spread diameter, ρ is the concrete density, g is the acceleration of gravity and V c is total volume of slump cone.…”

Section: Mathematical Models To Establish Relationship Between Test R...mentioning

confidence: 99%

Numerical Modelling of Multiphase Flow With Application to Industrial Processes

Bhokare¹

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Multiphase ﬂows are witnessed often in nature and the industry. Simulating the behaviour of multiphase ﬂows is of importance to scientists and engineers for better prediction of phenomena and design of products. This thesis aims to develop a multiphase ﬂow framework which can be applied to industrial applications such as placement of concrete in construction and proppant transport in oil and gas. Techniques available in literature to model multiphase ﬂows are systematically introduced and each of their merits and demerits are analysed. Their suitability for diﬀerent applications and scenarios are established. The challenges surrounding the placement of fresh concrete in formwork is investigated. Construction defects, the physics behind these defects and existing tests used to monitor fresh concrete quality are evaluated. Methods used to simulate fresh concrete ﬂow as an alternative to experiments are critically analysed. The potential beneﬁts of using numerical modelling and the shortcoming of the existing approaches are established. It is found that the homogeneous Bingham model is currently the most widely used technique to model fresh concrete ﬂow. Determining the Bingham parameters for a given concrete mix remains a challenge and a novel method to obtain values for them is demonstrated in this work. The Bingham model is also applied to a full-scale tremie concrete placement procedure in a pile. Knowledge on the ﬂow pattern followed by concrete being placed using a tremie is extracted. This is used to answer questions which the industry currently demands. The need for a more sophisticated model is emphasised in order to obtain an even greater understanding of fresh concrete ﬂow behaviour. A CFD-DEM framework in which the multiphase nature of concrete is captured is developed. To validate this framework a new benchmark test is proposed in conjunction with the ﬂuidised bed experiment. A comparative study of the drag models used in CFD-DEM approaches is performed to systematically assess each of their performances. CFD-DEM modelling is then applied to model fresh concrete ﬂow and its potential to model defect causing phenomena is demonstrated. A model to capture more complex behaviours of concrete such as thixotropy is introduced and demonstrated.

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Study on a Method of Evaluating a Yield Value of Fresh Concrete With a Slump Flow Value

Cited by 5 publications

References 9 publications

Prediction of effective vibration condition under air void reduction using mortar rheological constant

Prediction of effective vibration condition under air void reduction using mortar rheological constant

多相融体の流動特性評価とプロセスシミュレーション

Numerical Modelling of Multiphase Flow With Application to Industrial Processes

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