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 Rheological Properties and Flow Behaviour of Cement-Based Materials Modified by Carbon Nanotubes and Plasticising Admixtures

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 169
Author(s):  
Gintautas Skripkiunas ◽  
Ekaterina Karpova ◽  
Joana Bendoraitiene ◽  
Irmantas Barauskas
Keyword(s):  
Carbon Nanotubes ◽  
Rheological Properties ◽  
Yield Stress ◽  
Cement Paste ◽  
Shear Thickening ◽  
Plastic Viscosity ◽  
Flow Behaviour ◽  
Volume Coefficient ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this study, the rheological properties of cement paste modified by a suspension containing both multi-walled carbon nanotubes (MWCNT) and carboxymethyl cellulose (CMC) (MWCNT/CMC suspension) with different types of plasticising admixtures (Pl), such as lignosulphonate (LS), sulfonated naphthalene formaldehyde condensate (NF), and polycarboxylate ether (PCE) were evaluated. The increase in yield stress and plastic viscosity up to 20% was established in the case of the modification of cement-based mixtures by MWCNT in the dosage up to 0.24% by weight of cement (bwoc) without Pl and with LS and NF. The complex modification of cement paste by MWCNT and PCE increases the yield stress and plastic viscosity from the MWCNT dosage of 0.06% and 0.015% bwoc, respectively. The yield stress and plastic viscosity of cement paste with PCE enhanced by 265% and 107%, respectively, in a MWCNT dosage of 0.12% bwoc. MWCNT do not have a significant influence on the flow behaviour index of cement paste; however, in the case of usage of PCE, the shear thickening effect decreased from a MWCNT dosage of 0.03% bwoc. The significant reduction in the volume coefficient of water bleeding by 99, 100, and 83% was obtained with LS, NF, and PCE, respectively, with an increase in MWCNT dosage up to 0.24% bwoc.

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%.

Influence of Glass Powder on Rheological Properties of Ultra-High Performance Concrete Paste

2021 ◽  
Vol 1036 ◽  
pp. 419-431
Author(s):  
Xue Li Nan ◽  
Jian Rui Ji ◽  
Rong Yang Li ◽  
Yi Wang ◽  
Hao Chen ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Silica Fume ◽  
High Performance ◽  
Glass Powder ◽  
High Performance Concrete ◽  
Shear Thickening ◽  
Plastic Viscosity ◽  
Ecological Problem ◽  
Ultra High Performance Concrete

Replacing cement and silica fume with glass powder to prepare ultra-high performance concrete (UHPC) is beneficial to solve the ecological problem in the field of civil engineering, but the technologies of preparation, transportation, pumping, and hardening of UHPC mainly relate to its rheological property. Therefore, this paper studied the influence of glass powder on the rheological properties of UHPC paste by performing the flow and the rheological test. Experimental results showed that when the cement and silica fume partially replaced by glass powder, the UHPC paste appears shear thickening, yield stress, plastic viscosity, and area of hysteresis loop decrease. This means that mixing glass powder can somehow inhibit the problems of segregation and bleeding of UHPC during pumping. In this manner, the dosage of the superplasticizer in UHPC is appropriately reduced, the filling capacity of UHPC during pouring is improved, and the energy required for UHPC in the pumping process is weakened. Compared with replacing cement, replacing silica fume with glass powder significantly increases the shear thickening and fluidity of UHPC paste, and at the same, reduces its yield stress and plastic viscosity. This indicates that the construction performance of UHPC is greatly improved with the replacement of silica fume. The fluidity and yield stress of UHPC paste satisfy the quadratic polynomial function relationship, and the replacement of cement and silica fume with glass powder should be less than 33% and 50%, respectively. Under this condition, the rheological properties of the UHPC paste are greatly improved and result in little negative impact on the mechanical properties of UHPC.

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.

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.

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 Evolution of flow properties, plastic viscosity, and yield stress of alkali-activated fly ash/slag pastes

2020 ◽  
Vol 5 ◽  
pp. 141-149
Author(s):  
Mohammed Fouad Alnahhal ◽  
Taehwan Kim ◽  
Ailar Hajimohammadi
Keyword(s):  
Fly Ash ◽  
Yield Stress ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Time Intervals ◽  
Increasing Trend ◽  
Binder Ratio ◽  
Drastic Effect ◽  
Effect On Yield ◽  
Alkali Activated

The development of cementless concrete is attracting increasing attention in practice and research to reduce both greenhouse gas emissions and energy consumption of concrete. Alkali-activated materials (AAMs) are one of the viable alternatives to replace Portland cement due to their lower CO2 emissions. This study investigated the evolution of rheological parameters of alkali-activated fly ash/slag pastes as a function of time. Flowability and rheological measurements were carried out to determine the fluidity, plastic viscosity, and yield stress at different time intervals. The effects of the slag content, the concentration of SiO2 in the activator, and the solution/binder ratio were considered. Based on the results, the yield stress and plastic viscosity followed an increasing trend over time coinciding with a reduction in the paste fluidity. The plastic viscosity of AAM pastes was in the range of 1.3–9.5 Pa.s and 2.6–28.9 Pa.s after 5 min and 45 min of mixing, respectively. Given the same alkali activator, the higher content of slag the paste had, the higher yield stress the paste showed. In addition, this paper confirmed that the SiO2/Na2O ratio in the activator had no significant effect on yield stress, but a drastic effect of this ratio was found on the plastic viscosity of the paste.

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 Shear thinning and thickening of cemented paste backfill

2019 ◽  
Vol 29 (1) ◽  
pp. 80-93 ◽  
Author(s):  
Liuhua Yang ◽  
Hongjiang Wang ◽  
Aixiang Wu ◽  
Hong Li ◽  
Arlin Bruno Tchamba ◽  
...  
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Yield Stress ◽  
Shear Thinning ◽  
High Shear ◽  
Cemented Paste Backfill ◽  
Concentrated Suspension ◽  
History Effects ◽  
Paste Backfill ◽  
Shear History

Abstract Cemented paste backfill (CPB) is considered to be a concentrated suspension in which tailings are bonded together by the hydraulic binder and water, and it has a high solid volume concentration (≥50 vol.%). Although the shear thinning and thickening of CPB has been extensively reported in literature, the shear history effects have been ignored in previous studies. In this paper, by using rheometer and Focused Beam Reflectance Measurement, the relationship between the rheological properties and microstructure of the paste under different shear histories was studied. The results have shown that at a low shear rate, CPB revealed shear thinning, low yield stress and low index parameters; while exhibited shear thickening, high yield stress and high consistency index when at high shear rates of shear history. This agreed with the general trends shown in the FBRM analysis. It was proposed that the action of shear is beneficial to particle dispersion, whereas a high shear rate history tends to promote the aggregation of particles. It was revealed that both shear thinning and thickening of paste are related to the situation of particles (flocculation, dispersion and aggregation), and shear history effects play an important role in rheological properties of CPB.

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