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... The devices attempting to use fluid rheology methods to measure the concrete flow by measuring the shear stress at varying shear rates are called rheometers (Hackley and Ferraris, 2001). The resistance to flow with varying shearing rates can be measured in the commercially available rheometers. ...
Geopolymers are under scrutiny as a sustainable alternative to cement in 3D printing for eco-friendly construction. Geopolymer 3D printing (G3DP) holds promise for green construction and advanced manufacturing. This study addresses G3DP's rheological properties, printability, and microstructure analysis. Results indicate the pivotal role of the rheological properties in the printability, encompassing parameters like the pumpability, extrudability, and shape retention. Lower viscosity and appropriate yield stress are crucial. The structural performance of G3DP, given its inherent anisotropic nature and assessment techniques, is scrutinized. Process variables such as nozzle design and print speed and interval affect the printability, buildability, and structural properties. Research on the parameters' optimization is necessary. Additionally, evaluation techniques for the G3DP's rheological and structural behaviors require standardization. Understanding the G3DP's rheology is paramount for the successful 3D printing construction. Findings offer quantitative insights into the importance of the rheological properties for the printability and structural performance. The microstructural analysis uncovers the porosity and density disparities compared to traditional geopolymers. This comprehensive review provides valuable insights for researchers and practitioners to enhance the G3DP's application as a futuristic sustainable construction material.
... Rheology of the SCC in terms of the shear stress (τ), plastic viscosity (µ) and flow resistance were determined using a rotational rheometer, viskomat XL (Schleibinger Geräte, Buchbach, Germany), with a vane probe testing paddle at a constant temperature of 20 • C. The measurement started with the maximum rotational speed of 12 rpm for 80 s and decreased in 14 steps of 20 s each until the end of the measurement [46]. The recorded torque was used to estimate the yield stress (τ 0 ) and plastic viscosity (η) of the SCC according to the Bingham model [47,48] using Equation (3). The flowability retention of the SCC is monitored by calculating flow resistance of the SCC mixtures over time (area under curve) obtained by plotting the torque against the velocity as described previously by [26]. ...
The durability of concrete requires a dense microstructure which can be achieved by using self-compacting concrete (SCC). Both calcined clay (CC) and rice husk ash (RHA) are promising supplementary cementitious materials (SCMs) that can partially replace cement, but their use in SCC is critical due to their higher water demand (WD) and specific surface area (SSA) compared to cement. The effect of partial substitution of cement at 20 vol-% with binary and ternary blends of CC and RHA on flowability retention and durability of SCC was investigated. The empirical method of SCC design was adopted considering the physical properties of both CC and RHA. The deformability of the SCC was evaluated using the slump flow and J-ring tests. The T 500 time and the V-funnel test were used to assess the viscosity of the SCC. The flowability retention was monitored by the plunger method, and flow resistance was determined based on the rheological measurements of SCC. The evolution of the hydrate phases of the binder in SCC was determined by thermogravimetric analysis, while the durability was evaluated by a rapid chloride migration test. Cement partial replacement with 20 vol-% CC has no significant effect on fresh SCC, flowability retention, compressive strength and durability properties. On the other hand, 20 vol-% RHA requires a higher dosage of SP to achieve self-compactability and increase the viscosity of SCC. Its flowability retention is only up to 30 min after mixing and exhibited higher flow resistance. It consumes more calcium hydroxide (CH) and improves the compressive strength and chloride resistance of SCC. The ternary blending with CC and RHA yielded better fresh SCC properties compared to the binary blend with RHA, while an improved chloride penetration resistance could be achieved compared to the binary CC blend.
... these acid gels have a different texture, may be due to differences in the characteristic of EPS produced by this strain. These acid gels fitted to Carreau-Yasuda model (Supplementary Table S2) which describes a pseudoplastic fluid with asymptotic viscosities at zero (η 0 ) and infinite (η ∞ ) shear rates with no yield stress (Hackley and Ferraris, 2001). Moreover, the acid gels obtained by fermentation with CIDCA 83124 were significantly more viscous, compared to those fermented by L. paracasei CIDCA 8339 and CIDCA 83123 ( Figure 2B; Supplementary Table S3). ...
... The measurement started with the maximum rotational speed of 12 rpm for 80 s and decreased in 14 steps of 20 s each until the end of the measurement [40]. The recorded torque were used to estimate the yield stress (τ0) and plastic viscosity (η) of the SCC according to the Bingham model [41,42] using Equation (3). The workability retention of the SCC is monitored by calculating FR of the SCC mixtures over time (area under curve) obtained by plotting the torque against the velocity as described previously by [31]. ...
Durability of concrete requires a dense microstructure which can be achieved by using self-compacting concrete (SCC). Both calcined clay (CC) and rice husk ash (RHA) are promising supplementary cementitious materials (SCMs) that can partially replace cement, but their use in SCC is critical due to their higher water demand and specific surface area (SSA) compared to cement. Empirical method of SCC design was adopted considering the physical properties of both CC and RHA. The influence of partially substituting cement at 20 vol-% with binary and ternary blends of CC and RHA were investigated. The fresh properties of SCC were investigated using a variety of tests. The time dependent workability was monitored by plunger method and flow resistance determined based on the rheological measurements of SCC. The evolution of the hydrate phases of the binder in SCC was determined by thermogravimetric analysis, while the durability was evaluated by rapid chloride migration test. Cement partial replacement with 20 vol-% CC has no significant effect on SCC fresh, time dependent, compressive strength and durability properties. 20 vol-% RHA on the other hand requires higher dosage of SP to achieve self-compactability and increased the viscosity of SCC. Its workability retention is only up to 30 min after mixing and exhibited higher flow resistance. It consumes more CH and improves compressive strength and chloride resistance of SCC. The ternary blending with CC and RHA yielded better fresh SCC properties compared to the binary blend with RHA, while an improved chloride penetration resistance could be achieved compared to binary CC blend.
... On the contrary, if the applied stress is larger than t 0 , it is said that the sample leaves the elastic or pre-yield regime, breaks (also called sample failure) and starts to flow or to strain continuously. 84 However, the previous definition together with its related phenomenology is rarely seen experimentally (e.g. Wang et al. 85 ). ...
Magnetically responsive soft matter is a colloidal model system where interparticle interactions can be tuned through external magnetic fields. Covering the most recent literature in the field, with special emphasis on the physical mechanisms behind their rheological behaviour, this book aims to demonstrate the controllability of soft matter through an external (magnetic) stimulus.
With chapters written by leading experts, fundamental topics are complemented by cutting edge research, in particular, discussions on advances in sedimentation stability, structural characterization using microCT, surface functionalization, bidisperse composites, self-assembly at interfaces and collective dynamics, friction and shear-thickening, dynamics, self-assembly and rheology under unsteady triaxial magnetic fields, theoretical developments and particle level numerical simulations, including contact forces and biomedical and tissue engineering applications.
This complete perspective of the field attempts to bridge the gap between fundamentals and applications and is an excellent addition to any soft matter scientist’s library.
... these acid gels have a different texture, may be due to differences in the characteristic of EPS produced by this strain. These acid gels fitted to Carreau-Yasuda model (Supplementary Table S2) which describes a pseudoplastic fluid with asymptotic viscosities at zero (η 0 ) and infinite (η ∞ ) shear rates with no yield stress (Hackley and Ferraris, 2001). Moreover, the acid gels obtained by fermentation with CIDCA 83124 were significantly more viscous, compared to those fermented by L. paracasei CIDCA 8339 and CIDCA 83123 ( Figure 2B; Supplementary Table S3). ...
Exopolysaccharides (EPS) produced by lactic acid bacteria are molecules of great interest for the dairy food industry. Lacticaseibacillus paracasei CIDCA 8339, CIDCA 83123, and CIDCA 83124 are potentially probiotic strains isolated from kefir grains whose EPS-production on MRS broth is dependent on incubation temperature. The aim of the present work is to evaluate the effect of fermentation temperature on the characteristics of EPS produced in milk by L. paracasei strains and the consequent impact on the rheological properties of the fermented products. Additionally, the protective effect of these EPS against Salmonella infection was evaluated in vitro. Acid gels with each strain were obtained by milk fermentation at 20°C, 30°C, and 37°C evidencing for all the strains a reduction in growth and acidification rate at lower temperature. Lacticaseibacillus paracasei CIDCA 83123 showed low fermentation rate at all temperatures requiring between 3 and 8 days to obtain acids gels, whereas CIDCA 8339 and 83124 needed between 24 and 48 h even when the temperature was 20°C. Fermentation temperature led to changes in crude EPS characteristics of the three strains, observing an increase in the relative amount of the high molecular weight fraction when the fermentation temperature diminished. Additionally, EPS83124 and EPS83123 presented modifications in monosaccharide composition, with a reduction of rhamnose and an increase of amino-sugars as temperature rise. These changes in the structure of EPS83124 resulted in an increase of the apparent viscosity of milks fermented at 20°C (223 mPa.s) and 30°C (217 mPa.s) with respect to acid gels obtained at 37°C (167 mPa.s). In order to deepen the knowledge on EPS characteristics, monosaccharide composition of low and high molecular weight EPS fractions were evaluated. Finally, it was evidenced that the preincubation of intestinal epithelial cells Caco-2/TC-7 with EPS8339 and EPS83124 partially inhibit the association and invasion of Salmonella. In light of these results, it can be concluded that the selection of the EPS-producing strain along with the appropriate fermentation conditions could be an interesting strategy to improve the technological properties of these L. paracasei fermented milks with potential protective effects against intestinal pathogens.
... • with the following program: ten minutes at a rotational speed of 120 min -1 , each two minutes at 80, 40, 20 min -1 . It is analyzed according to Bingham fit, the linear fit between rotational speed and torque resulting in viscosity factor (slope of fit) and yield stress (y-axis intercept of fit) [63,266]. ...
... QP particles exhibit smooth surfaces and conchoidal marks (Fig. 2a) as also published e.g. by Ref. [61][62][63][64]. This resultscombined with a coarse particle size distribution (PSD) -in the lowest SSA and water demand ( Table 3). ...
... This paper uses two methods to describe the relation between rotational speed and torque. On the first hand, rheological parameters are analyzed following the Bingham model [14,63] as it previously revealed good correlations with calcined clay blends [37]. It considers the linear fit of the flow curve between 120 min −1 and 20 min −1 .The y-intercept " " viscosity μ). ...
This thesis debutes a systematic study of the rheological behavior of cements blended with both metaphyllosilicates and calcined common clays. With their addition, the flow resistance, yield stress and viscosity of blended cement pastes increase in parts significantly as shown via rotational viscometer tests. The analysis of single-phase materials reveals the influence of mineralogical composition of raw clays, especially their concentration of kaolinite, different types of 2:1 phyllosilicates, and quartz. The correlation of rheological behavior with physical characteristics of metaphyllosilicates and calcined common clays, such as particle size, zeta potential, water demand, and surface area is evaluated critically.
The dispersion performance of a broad variety of superplasticizer (lignosulfonates, NSF polycondensate, polycarboxylate-based co-polymers (PCEs)) is determined via mini slump tests and rotational viscometer tests. The demand for superplasticizer is directly linked to the flow resistance of the respective reference mixture. It increases to different extents depending on the calcined clay added, its water demand, particle fineness, and negative zeta potential; the latter mainly resulting from kaolinite content. Regardless of their increased demand, the performance of superplasticizers in calcined clay blended cements is as efficient as it is in plain cements. In case of PCEs, a higher anionic charge density enables a better initial dispersion. All conventional macromonomers exhibit an overall good to excellent dispersion performance. Metamuscovite is the only phase that perturbs the performance of superplasticizers and is sensitive towards the type of superplasticizer.
The use of calcined clays can lead to rapid slump loss, which is stronger with the addition of conventional PCEs than with NSF polycondensate as time related mini slump tests and rheological tests show. The addition of lignosulfonates may limit this phenomenon, but often goes along with significant retardation effects. This thesis investigates one possible solution to prevent rapid slump loss, namely the introduction of hydroxyethyl methacrylate into the PCE polymer. Its decomposition into ethylene glycol and carboxyl groups in alkaline media leads to a later adsorption of the latter and can enable a subsequent dispersion. The study reveals the total phyllosilicate content in clay as well as the specific surface area of the calcined clay as decisive parameters for the functionality of this special type of polymer.
Complementing tests study the early hydration of calcined clay blended cements in the presence of superplasticizers via isothermal calorimetry, as well as in situ XRD and ultrasound method on selected samples. The early hydration kinetics depend mainly on the characteristics of the calcined clay as well as on the superplasticizer dosage. Overall, the retardation is minor in calcined clay blended cements. This is related to the increased surface area which favors the formation of early hydration products - despite the adsorption of superplasticizers onto binder particle surfaces. An enhanced ettringite formation of calcined clay blended cements enables an unhindered silicate hydration and transformation of ettringite to hemicarboaluminate, even in the presence of most superplasticizers.
This thesis reveals the suitability of a wide array of calcined common clays and their limitations as future SCM regarding their impact on rheological behavior in combination with the correct choice of superplasticizer. A fair assessment and a careful selection provided, their use can meet the high demand for sustainable cementitious materials and help improving the ecological footprint of modern concrete.
... In the Bingham model, plastic viscosity (A) increased with an increase in microfluidization pressure at both temperatures (20 • C and 40 • C), but decreased with an increase in analysis temperature. The plastic viscosity region exhibits a linear relationship between shear stress and shear rate with a constant differential viscosity equal to the plastic viscosity (Hackley & Ferraris, 2001). Moreover, values of consistency coefficient increased with an increase in microfluidization pressure at both temperatures (20 • C and 40 • C) for the Casson and Herschel-Bulkley models. ...
Aim of this research was to study the effects of microfluidization [103 (MEY1), 138 (MEY2), 172 (MEY3), and 207 (MEY4) MPa] on the rheological characteristics of liquid egg yolk (EY). Apparent viscosity of EY increased as the microfluidization pressure increased. Power law parameter, K increased from 0.29 (MEY0) to 8.56 (MEY4), while n decreased from 1.01 (MEY0) to 0.57 (MEY4), demonstrating shear thinning characteristics. Power law, Bingham, Casson and Herschel–Bulkley models described the experimental data (R² ~ 0.99) well. Thixotropic and anti-thixotropic behavior of microfluidized EY was observed in time-dependent rheology. Furthermore, as microfluidization pressure increased, Weltman model parameters (A and B) increased. In dynamic rheological analysis, MEY0 (control), MEY1, and MEY2 showed elastic solid-like behavior, while EY microfluidized at higher pressure showed liquid-like behavior (MEY3 and MEY4). Furthermore, damping factor (DF) of MEY3 and MEY4 was found to be >1 across the entire applied strain. The Reynolds numbers of the control and microfluidized EYs were computed, for microfluidized EY, a laminar flow has been observed.
Industrial relevance
Food is made up of a variety of biological components with varying rheological properties. Understanding food and its rheological behavior is an important component of the food industry. Food rheological behavior analysis answers important problems like whether a certain food product will easily deform, flow through a pipe, or perform well as a topping. Furthermore, fluid characterization parameters such as flow consistency index and flow behavior index, obtained after modelling rheological data, can be further used to predict flow behavior and velocity profile in a pipe flow. This information is crucial during the development of industrial plant designs that include the selection of pumps and pipes. It provides computations for extruders, mixers, coaters, and homogenizers in process engineering. Moreover, this information is vital to determine operation parameters during mass and heat transfer.
... The devices attempting to use methods of fluid rheology to measure the flow of concrete by measuring shear stress at varying shear rates are called rheometers [58]. The resistance to flow with varying shearing rates can be measured in the commercially available rheometers. ...
The rapid advancement of 3D concrete printing (3DCP) and the development of relevant cementitious material compositions can be seen in the last few decades. The commonly used 3DCP method is to build the structure layer by layer after extruding the material through a nozzle. Initially , the pumping and extrusion of the material should be done with considerable fluidity and workability. The extruded layers should retain their shape immediately after extruding and depositing. While constructing the structure in a layerwise manner, the bottom layers should have enough early age strength to support the layers at the top. Therefore, at different processes in 3DCP, the rheological requirement is contradictory. As the rheology of the material is the deterministic factor which decides the fluidity or workability of the mix, proper rheological characterization should be completed accurately. In some instances, due to the higher stiffness, and higher time and rate-dependent material behavior (thixotropic behavior) compared to the conventional concrete, standard rheology measurement techniques have many limitations when used for 3DCP material. Therefore, non-conventional and novel techniques can be implemented with suitable material models to characterize the rheology of 3DCP material. In this study, a comprehensive review was conducted on conventional and non-conventional methods used for characterizing the rheological parameters for 3DCP material. The previously conducted studies were highlighted with the targeted 3DCP processes in the study (if applicable), and rheological parameters achieved from the test (i.e., yield stress, viscosity, and thixotropy). In addition, some experimental studies were conducted to compare several selected testing methods. The rheological parameters achieved from different test methods were compared to identify the similarities, dissimilarities, pros, and cons between the test methods. Furthermore, the extrudability and buildability studies were conducted for the mixes to demonstrate the usage of the mixes in 3DCP applications and to correlate the achieved rheological parameters with these processes.
... The samples present a critical shear rate at which the viscosity begins to decline, 46 which was due to the change in the structure of molecules upon the application of BSPHs. Then, to evaluate the shear stress behavior with the shear rate, a flow curve was plotted (Figure 3b) by adjusting the experimental data to the Herschel−Bulkley model (eq 2) ...
In this study, hydrocolloids from butternut squash pulp (BSPH) have been employed as stabilizers for the development of acidified milk drinks to evaluate their physicochemical, rheological, and microstructural properties. BSPH was obtained in the alkaline medium (yield of 630 mg of hydrocolloids/100 g of pulp), presenting 79.97 ± 0.240% carbohydrate and non-Newtonian-type shear thinning. Four acidified milk drinks (AMDs) were obtained with 0.25, 0.50, and 1.00% BSPHs and a control sample without BSPHs. The addition of BSPHs did not alter the proximal composition of AMDs with similar proximal values; also, the samples present typical behavior of non-Newtonian-fluid-type shear thinning adjusted to the Carreau-Yasuda model. Storage (G') and loss (G″) moduli values were slightly dependent on the frequency in most of the studied systems. Then, the addition of BSPHs retained their uniform internal structure and contributed to the stabilization of the products.
