scholarly journals MACROMOLECULAR AND AROMATIC CHARACTER INFLUENCE OF SBR ON THE RHEOLOGICAL PROPERTIES OF WELL CEMENT SLURRIES

2018 ◽  
Vol 1 (1) ◽  
pp. 21-27
Author(s):  
Mostafa Aboelkheira ◽  
Celeste Siqueira ◽  
Fernando Souza Jr. ◽  
Romildo Toledo
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Flow Behavior ◽  
Free Water ◽  
Plastic Viscosity ◽  
Hydration Process ◽  
Cement Particle ◽  
Newtonian Flow ◽  
Aromatic Character ◽  
Well Cement

Ensuring the rheological properties of the latex-based cement slurries in steam EOR is indispensable. Ca(OH)2 is produced after cement/water reaction and the macromolecules tend to disturb the hydration process, after the latex demulsification, by covering the cement particle. The free water decreases due to the high hydrophilicity of demulsified SBR, where final gel values increased up to 67%. The slump diameter was decreased exponentially by increasing the latex content limiting the workability. SBR-modified slurries presented a Pseudoplastic non-Newtonian flow behavior and the plastic viscosity decreases gradually, while the yield stress values registered a progressive increment by adding SBR till 10%.

scholarly journals Influence of Nano-SiO2, Nano-CaCO3 and Nano-Al2O3 on Rheological Properties of Cement–Fly Ash Paste

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2598 ◽  
Author(s):  
Yiming Peng ◽  
Kunlin Ma ◽  
Guangcheng Long ◽  
Youjun Xie
Keyword(s):  
Fly Ash ◽  
Rheological Properties ◽  
Yield Stress ◽  
Free Water ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Plastic Viscosity ◽  
Behavior Changes ◽  
Nano Sio2 ◽  
Resting Time

Rheological curves of cement–fly ash (C–FA) paste incorporating nanomaterials including nano-SiO2 (NS), nano-CaCO3 (NC) and nano-Al2O3 (NA) at different resting times (hydration time of 5 min, 60 min, and 120 min) were tested with a rheometer. The rheological behaviors were described by the Herschel–Bulkley (H–B) model, and the influences of these nanomaterials on rheological properties of C–FA paste were compared. Results show that the types, content of nanomaterials and resting time have great influences on the rheological properties of C–FA paste. Incorporating NS and NA increases yield stress and plastic viscosity, and decreases the rheological index of C–FA paste. When the content of NS and NA were 2 wt%, the rheological index of C–FA paste was less than 1, indicating rheological behavior changes from shear thickening to shear thinning. Meanwhile, with rising resting time, yield stress and plastic viscosity increased significantly, but the rheological index decreased evidently, showing paste takes on shear thinning due to the rise of resting time. However, incorporating 3 wt% NC and the rising of resting time did not change the rheological properties of C–FA paste. These differences are mainly that the specific surface area (SSA) of NS (150 m2/g) and NA (120 m2/g) are much larger than that of NC (40 m2/g). The huge SSA of NS and NA consume lots of free water and these tiny particles accelerate the hydration process during resting time.

A Study of Debris Flow Behaviors According to Rheometer Properties: Focused on the Hwangnyeong Mt. and Umyeon Mt.

2020 ◽  
Author(s):  
Hyeong-Jin Kim ◽  
Dae-Ho Yun ◽  
Yun-Tae Kim
Keyword(s):  
Debris Flow ◽  
Rheological Properties ◽  
Yield Stress ◽  
Flow Behavior ◽  
Front Velocity ◽  
Experimental Results ◽  
Small Scale ◽  
Water Mixture ◽  
Runout Distance ◽  
Two Samples

<p>A debris flow, a mass movement of soil and water mixture, is generally occurred by heavy rainfall during the rainy season in Korea. Because of climate change, the amount and frequency of rainfall has continually increased these days. Populated areas located in debris flow-prone mountainous areas are commonly subject to debris flow hazards. For this reason, it is necessary to analyze the characteristics of the debris flow behavior for the hazard mitigation. In this study, for two samples from Hwangnyeong Mt. and Umyeon Mt. in Korea, the vane-type rheometer test were performed to estimate the rheological property such as viscosity and yield stress and small-scale flume experiment was carried out to evaluate the characteristics of debris flow behaviors such as front velocity, runout distance and deposition volume. From the experimental results, rheological properties decrease with decreasing volumetric sediment concentration, and debris flow behavior gradually increased with decreasing rheological properties in the experiment. Additionally, in case of Hwangnyeong Mt. which has a high silt and clay fraction, the experimental results show that the amount of the front velocity, runout distance and deposition volume tend to increase higher than Umyeon Mt. as viscosity and yield stress decreased.</p>

The flow properties of axoplasm in a defined chemical environment: influence of anions and calcium

1979 ◽  
Vol 205 (1160) ◽  
pp. 323-345 ◽  
Keyword(s):  
Protease Inhibitor ◽  
Rheological Properties ◽  
Cellulose Acetate ◽  
Yield Stress ◽  
Plastic Viscosity ◽  
Chemical Environment ◽  
Flow Properties ◽  
Giant Axons ◽  
The Matrix ◽  
Anion Composition

The flow properties of axoplasm have been studied in a defined chemical environment. Axoplasm extruded from squid giant axons was introduced into porous cellulose acetate tubes of diameter roughly equal to that of the original axon. Passage of axoplasm along the tube rapidly coated the tube walls with a layer of protein. By measuring the rate of flow back and forth along the tube, the rheological properties of the axoplasm plug were investigated at a range of pressures and in a variety of media. Axoplasm behaves as a classical Bingham body the motion of which can be characterized by a yield stress ( θ ) and a plastic viscosity ( η p1 ). In a potassium methanesulphonate medium containing 65 nM free Ca 2+ , θ averaged 109 ± 46 dyn/cm 2 and η p1 146 ± 83 P. † These values were little affected by ATP, colchicine, cytocholasin B or by replacing K by Na but were sensitive to the anion composition of the medium. The effectiveness of different anions at reducing θ and η p1 was in the order SCN > I > Br > Cl > methanesul­phonate. θ and η p1 were also drastically reduced by increasing the ionized Ca. This effect required millimolar amounts of Ca, was unaffected by the presence of ATP and was irreversible. It could be blocked by the protease inhibitor TLCK. E. p. r. measurements showed that within the matrix of the axoplasm gel there is a watery space that is largely unaffected by anions or calcium.

scholarly journals Effect of polycarboxylate superplasticizer on fluidity and rheology of cement slurry containing silica fume

2021 ◽  
Vol 237 ◽  
pp. 03008
Author(s):  
Qingen Meng ◽  
Juan He ◽  
Congmi Cheng ◽  
Xiaofen Zhu
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Silica Fume ◽  
Plastic Viscosity ◽  
Cement Slurry ◽  
Pseudoplastic Fluid ◽  
Plasticizer Content ◽  
Polycarboxylate Superplasticizer ◽  
Dispersion Degree ◽  
Fluid Characteristic

The effect of polycarboxylate superplasticizer on the fluidity and rheology of cement - silica fume - water paste was investigated. The changes of dispersion degree, yield stress and plastic viscosity of paste with different superplasticizer content were analyzed. The results show that the rheological properties of paste with different superplasticizer content conform to Herschel-Bulkley model. The shear thinning of the slurry is manifested as a typical yielding pseudoplastic fluid characteristic. When the content of superplasticizer is less than 1.0%, the plastic viscosity and yield stress decrease and the fluidity increase with the increase of plasticizer content. When the content of superplasticizer is more than 1.0%, the yield stress decreases slightly and the plastic viscosity increases with the increase of plasticizer content. The fluidity decreases with the increase of yield stress, and there is a good correlation between them.

scholarly journals Influence of Enzyme Additives on the Rheological Properties of Digester Slurry and on Biomethane Yield

2020 ◽  
Vol 7 (2) ◽  
pp. 51 ◽  
Author(s):  
Liane Müller ◽  
Nils Engler ◽  
Kay Rostalsky ◽  
Ulf Müller ◽  
Christian Krebs ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Large Scale ◽  
Flow Behavior ◽  
Degradation Efficiency ◽  
Observable Effect ◽  
Newtonian Flow ◽  
Biogas Yield ◽  
Enzyme Product ◽  
Substrate Degradation ◽  
Enzyme Application

The use of enzyme additives in anaerobic digestion facilities has increased in recent years. According to the manufacturers, these additives should increase or accelerate the biogas yield and reduce the viscosity of the digester slurry. Such effects were confirmed under laboratory conditions. However, it has not yet been possible to quantify these effects in practice, partly because valid measurements on large-scale plants are expensive and challenging. In this research, a new enzyme product was tested under full-scale conditions. Two digesters were operated at identic process parameters—one digester was treated with an enzyme additive and a second digester was used as reference. A pipe viscometer was designed, constructed and calibrated and the rheological properties of the digester slurry were measured. Non-Newtonian flow behavior was modelled by using the Ostwald–de Baer law. Additionally, the specific biomethane yield of the feedstock was monitored to assess the influence of the enzyme additive on the substrate degradation efficiency. The viscosity measurements revealed a clear effect of the added enzyme product. The consistency factor K was significantly reduced after the enzyme application. There was no observable effect of enzyme application on the substrate degradation efficiency or specific biomethane yield.

scholarly journals Analysis of the Effect of Various Types of Limestone as a Main Constituent of Cement on the Chosen Properties of Cement Pastes and Mortars

2019 ◽  
Vol 65 (3) ◽  
pp. 75-86
Author(s):  
J. Gołaszewski ◽  
G. Cygan ◽  
M. Gołaszewska
Keyword(s):  
Compressive Strength ◽  
Rheological Properties ◽  
Yield Stress ◽  
Drying Shrinkage ◽  
Plastic Viscosity ◽  
Main Constituent ◽  
Cement Pastes ◽  
Mortar Strength ◽  
The Impact

AbstractThe article is an attempt to compare the impact of the use of various types of limestone as the main constituent of cement on selected mortar properties. Four different limestones were added in amount of 15, 30, 40% to CEM I 42.5 R to obtain limestone cemens. Rheological properties (yield stress, plastic viscosity) of fresh mortar, tensile and compressive mortar strength, early shrinkage, and drying shrinkage were tested. Obtained results indicate that both tensile and compressive strength decreases with the increase of the limestone content in cement. Limestone can worsen or improve workability, depending on distribution of limestone grains. The addition of limestone increases the early shrinkage, but reduces the shrinkage after 28 days. Studies show that the granulation of limestone plays an important role in determining the influence of limestone on mortar properties.

scholarly journals Rheological properties of loose sands subjected to upward flow

2017 ◽  
Vol 54 (5) ◽  
pp. 664-673 ◽  
Author(s):  
Hyo Sub Kang ◽  
Yun Tae Kim
Keyword(s):  
Shear Rate ◽  
Debris Flow ◽  
Rheological Properties ◽  
Yield Stress ◽  
Flow Behavior ◽  
Fluid Pressure ◽  
Hydraulic Gradient ◽  
Flow Index ◽  
Loose Sand ◽  
Upward Flow

The objective of this study was to investigate the rheological properties of loose sands subjected to upward flow by using a vane-type rheometer that controlled upward flow in the loose sand specimens. Various hydraulic gradients (i.e., i = 0–2.0) were applied to loose sands. The rheological properties of the loose sands, such as yield stress and viscosity, were determined based on the Bingham and Herschel–Bulkley models. The experimental results showed that the flow behavior of loose sand samples exhibited a shear thickening when the Herschel–Bulkley model was applied (i.e., nondimensional flow index n > 1) and exhibited a Bingham-like within a limited shear rate range (i.e., 1∼30 1/s). The latter is clearly shown for a relatively high shear rate. As the hydraulic gradient was increased, the flow characteristics were close to the Bingham fluid. Yield stress showed a tendency to decrease linearly as hydraulic gradient was increased. However, the viscosity of the loose sands maintained a constant value irrespective of hydraulic gradient. The test results indicated that the pore fluid pressure resulting from upward flow in a soil sample affects yield stress, which contributes to the initiation of debris flow mobilization. As a result, it was possible to estimate the rheological properties of soil at the condition of liquefaction (critical hydraulic gradient), or initial occurrence of debris flow.

scholarly journals Effect of Polyvinyl Alcohol on the Rheological Properties of Cement Mortar

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 754
Author(s):  
Fang Liu ◽  
Baomin Wang ◽  
Yunqing Xing ◽  
Kunkun Zhang ◽  
Wei Jiang
Keyword(s):  
Polyvinyl Alcohol ◽  
Rheological Properties ◽  
Yield Stress ◽  
Cement Mortar ◽  
Chemical Properties ◽  
Degree Of Polymerization ◽  
Plastic Viscosity ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
Hydrolysis Degree

Polyvinyl alcohol (PVA) is a kind of water-soluble polymer, which has been widely used in different industries due to its excellent mechanical and chemical properties. In this paper, the effects of polyvinyl alcohol with different hydrolysis and polymerization degrees on the rheological properties of cement mortar are studied. The results show that the rheological properties of PVA-modified cement mortar can be described by the modified Bingham model. The yield stress of modified cement mortar is less than that of unmodified mortar when the degree of polymerization and the content of PVA are small. With the increase of polyvinyl alcohol content and polymerization degree, the yield stress and plastic viscosity of modified cement mortar increase sharply, which are larger than those of the unmodified cement mortar. However, the effect of hydrolysis degree of PVA on yield stress and plastic viscosity of modified cement mortar is not obvious.

scholarly journals Rheological Properties of Cement Pastes with Multiwalled Carbon Nanotubes

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Gintautas Skripkiunas ◽  
Ekaterina Karpova ◽  
Irmantas Barauskas ◽  
Joana Bendoraitiene ◽  
Grigory Yakovlev
Keyword(s):  
Carbon Nanotubes ◽  
Rheological Properties ◽  
Yield Stress ◽  
Multiwalled Carbon Nanotubes ◽  
High Performance ◽  
High Performance Concrete ◽  
Plastic Viscosity ◽  
Multiwalled Carbon ◽  
Cement Pastes ◽  
Rheological Test

The evaluation of rheological properties of cement systems is getting more relevant with growing interest to self-consolidating concrete (SCC), high-performance concrete (HPC) and ultrahigh-performance concrete (UHPC). The rheology models are a perspective tool to predict and manage the properties of cement systems in the fresh and hardened state. The current research is focused on the rheological test of cement systems modified by multiwalled carbon nanotubes (MWCNT) dispersion with and without polycarboxylate ether (PCE). The content of dispersion with 1% concentration of MWCNT in cement pastes varied from 0.125 to 0.5% by weight of cement. The dosage of PCE was taken as 0.6% by weight of cement. The cement pastes were prepared based on Portland cement without mineral additives. The rheological test was carried out at 5, 30, 60, and 120 min after mixing of cement paste. The rheological test established that modification of cement pastes by MWCNT dispersion in dosage 0.25% leads to the decrease of yield stress by 30.7% and increase of plastic viscosity by 29.6%. The combined modification by PCE and MWCNT dispersion shows the decrease in plastic viscosity of cement pastes by 9.90% in dosage of MWCNT equal to 0.5% by weight of cement, reduction of water demand by 20% for the same workability, and decrease of yield stress till 0 Pa. It gives the ability to obtain the self-compacting mixtures. The cement pastes with and without MWCNT dispersion revealed the shear-thinning behavior during 120 min after mixing. The modification of cement pastes by PCE with and without MWCNT dispersion showed the shear-thickening behavior which remains during 120 min after mixing.

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