scholarly journals Effects of Fly Ash and Chemical Admixtures on the Rheological Properties of High-Concentration Full-Tailing Filling Slurry

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Fulin Wang ◽  
Faguang Yang ◽  
Zhengping Yuan ◽  
Shijiao Yang
Keyword(s):  
Fly Ash ◽  
Rheological Properties ◽  
Yield Stress ◽  
Polyethylene Oxide ◽  
Viscosity Coefficient ◽  
Pipeline Transportation ◽  
High Concentration ◽  
Polycarboxylate Superplasticizer ◽  
Chemical Admixtures

Good fluidity is the precondition to ensure the pipeline transportation of the filling slurry. The admixture in the filling slurry will affect the rheological properties of the slurry. In this paper, yield stress (YS), viscosity coefficient (VC), and expansion (ED) of the filling slurry were measured by the MCR52 rheometer and expansion tester, respectively, and the influence regularities of the three kinds of admixtures including fly ash (FA), polycarboxylate superplasticizer (PS), and polyethylene oxide (PEO) on the rheological properties of the filling slurry were obtained. The results show that when other conditions are fixed, the fluidity of the slurry becomes worse with the increase of the amount of fly ash but improves with the increase of the amount of the polycarboxylate superplasticizer; polyethylene oxide is not suitable for the improvement of the fluidity of the high-concentration full-tailing filling slurry, and the fluidity of the slurry becomes worse rapidly with the increase of the amount of polyethylene oxide.

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 Effect of Polyethylene Oxide on the Rheological Behavior of Bentonite Suspensions

2021 ◽  
Vol 2 (5) ◽  
pp. 352-357
Author(s):  
Azril N ◽  
Gareche M ◽  
Saoudi L ◽  
Zeraibi N
Keyword(s):  
Molecular Weight ◽  
Rheological Properties ◽  
Yield Stress ◽  
Polyethylene Oxide ◽  
Rheological Behavior ◽  
Complex Behaviour ◽  
Clay Particles ◽  
Viscoelastic Modulus ◽  
Bentonite Suspension ◽  
Basic Characteristics

The effect of Polyethylene Oxide (PEO) with a molecular weight 10000g/mol on the rheological behavior of bentonite suspension was examined in terms of viscosity, yield stress and viscoelastic modulus (G’ and G’’); characteristic of complex behaviour of montmorillonite in water. A Physica MCR301 rheometer has been used to measure the rheological properties of samples (6% bentonite) as well as bentonite-PEO mixtures at different concentrations of PEO (0.18%, 0.25%, 0.5% and 1%). The polyethylene oxide adsorbs onto clay particles, which changes their basic characteristics depending on the amount of PEO adsorbed.

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.

scholarly journals Experimental Study and Application of Rheological Properties of Coal Gangue-Fly Ash Backfill Slurry

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 284 ◽  
Author(s):  
Yumin Wang ◽  
Yucheng Huang ◽  
Yuxin Hao
Keyword(s):  
Reynolds Number ◽  
Fly Ash ◽  
Rheological Properties ◽  
Mass Concentration ◽  
Coal Mines ◽  
Coal Gangue ◽  
Rheological Parameters ◽  
Pipeline System ◽  
Flow State ◽  
High Concentration

From the perspective of resource recovery and environmental protection, coal gangue-fly ash cemented backfill coal mining has become an important direction for the green development of coal mines in recent years. Analysis of the rheological parameters of backfill slurry is the basic principle to design a backfill pipeline system. Coal gangue-fly ash backfill slurry has a mass concentration of 76% to 79% and a maximum particle size 20 mm. Therefore, it is difficult to use conventional rheometers for experimental analyses of the rheological parameters of such fluids. We developed a rheometer for high-concentration coal gangue backfill slurry (HCGS rheometer) based on the coal gangue-fly ash backfill practice of Gonggeying Mine, and analyzed the rheological properties of the backfill slurry. The experimental results showed that the Reynolds number of the coal gangue-fly ash backfill slurry was much smaller than the critical Reynolds number, indicating the flow state in the pipeline was laminar. Based on these results, it may be more appropriate to control the mass concentration to 77% to 78%, and the suggested fly ash content is 25%. This work provides a scientific basis to optimize the backfill parameters and pipeline system in coal mines.

scholarly journals Comparison of the Effects of Conching Parameters on the Contents of Three Dominant Flavan3-ols, Rheological Properties and Sensory Quality in Chocolate Milk Mass Based on Liquor from Unroasted Cocoa Beans

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2502
Author(s):  
Bogumiła Urbańska ◽  
Hanna Kowalska ◽  
Karolina Szulc ◽  
Małgorzata Ziarno ◽  
Irina Pochitskaya ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Sensory Quality ◽  
Raw Material ◽  
Antioxidant Compounds ◽  
Chocolate Milk ◽  
Cocoa Beans ◽  
Variable Parameters ◽  
The Relationship ◽  
Manufacturing Parameters

The content of polyphenols in chocolate depends on many factors related to the properties of raw material and manufacturing parameters. The trend toward developing chocolates made from unroasted cocoa beans encourages research in this area. In addition, modern customers attach great importance to how the food they consume benefits their bodies. One such benefit that consumers value is the preservation of natural antioxidant compounds in food products (e.g., polyphenols). Therefore, in our study we attempted to determine the relationship between variable parameters at the conching stage (i.e., temperature and time of) and the content of dominant polyphenols (i.e.,catechins, epicatechins, and procyanidin B2) in chocolate milk mass (CMM) obtained from unroasted cocoa beans. Increasing the conching temperature from 50 to 60 °C decreased the content of three basic flavan-3-ols. The highest number of these compounds was determined when the process was carried out at 50 °C. However, the time that caused the least degradation of these compounds differed. For catechin, it was 2 h; for epicatechin it was 1 h; and for procyanidin it was 3 h. The influence of both the temperature and conching time on the rheological properties of chocolate milk mass was demonstrated. At 50 °C, the viscosity and the yield stress of the conched mass showed its highest value.

Low Cement/High Fly Ash Concretes: Their Properties and Response to Chemical Admixtures

1987 ◽  
Vol 113 ◽  
Author(s):  
V. H. Dodson
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Calcium Hydroxide ◽  
Pozzolanic Reaction ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Fly Ashes ◽  
Chemical Admixtures ◽  
Reaction With Water

ABSTRACTIn practice, the amount of fly ash added to portland cement concrete varies depending upon the desired end properties of the concrete. Generally, when a given portland cement concrete is redesigned to include fly ash, between 10 and 50% of the cement is replaced by a volume of fly ash equal to that of the cement. Sometimes as much as twice the volume of the cement replaced, although 45.4 kg (100 lbs) of cement will only produce enough calcium hydroxide during its reaction with water to react with about 9 kg (20 lbs) of a typical fly ash. The combination of large amounts of certain fly ashes with small amounts of portland cement in concrete has been found to produce surprisingly high compressive strengths, which cannot be accounted for by the conventional “pozzolanic reaction”. Ratios of cement to fly ash as high as 1:15 by weight can produce compressive strengths of 20.7 MPa (3,000 psi) at I day and over 41.4 MPa (6,000 psi) at 28 days. Methods of identifying these “hyperactive” fly ashes along with some of the startling results, with and without chemical admixtures are described.

scholarly journals Effect of Calcareous Fly-ash Processing Methods on Rheological Properties of Mortars

2018 ◽  
Author(s):  
Jacek Gołaszewski ◽  
Zbigniew Giergiczny ◽  
Tomasz Ponikiewski ◽  
Aleksandra Kostrzanowska-Siedlarz ◽  
Patrycja Miera
Keyword(s):  
Fly Ash ◽  
Rheological Properties ◽  
Negative Influence ◽  
Plastic Viscosity ◽  
Processing Methods ◽  
Yield Value ◽  
Selective Collection

The paper presents the results of research into the influence of calcareous fly ash (CFA) processing methods on the rheological properties of mortars. The study consisted of a comparison of changes of the rheological properties (plastic viscosity and yield value) of the mortars during 90 minutes when CFA, unprocessed or processed by grinding, grain separation, or selective collection from the filter, was used as a substitute for a part of the cement. The results show that processing of CFA decreases its negative influence on the rheological properties; the efficient methods are separation or grinding, while the effect of selective collection is almost insignificant.

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