Energy Consumption of Self-Compacting Concrete during Mixing and Its Impact on the Yield Stress Measured in the Ready-Mix Concrete Plant

To find the energy required during the mixing process of self-compacting concrete in a ready-mixed concrete plant and correlate the results with the yield stress of concrete. Power consumption required during the mixing of concrete is measured with a wattmeter connected to the mixing unit’s power supply. A coaxial cylinder viscometer is used to measure the yield stress of concrete. The clamp meter measures the power when the impeller rotates inside the coaxial cylinder viscometer, which is filled with concrete. When the impeller rotates in a coaxial cylinder filled with concrete, the power is measured by a clamp meter. Torque is obtained through the power relationship, which is an essential factor in determining the yield stress. The cost of a rheometer is so high that all construction industries, research institutions, and researchers cannot measure rheological parameters. Nowadays, all rheometers are automated; hence, the cost is very high. Tattersall’s approach of power requirement in mixing the concrete and calculating the yield stress reduces the complexity in determining the rheological parameter.

Designing of a double-cylinder viscometer for high-pressure liquids

In this work, a double-cylinder viscometer is designed to measure dynamic viscosity over a pressure range from atmospheric pressure up to 150 MPa and a temperature range of 278.15–333.15 K. A high-pressure closed cavity is designed innovatively and the magnetic coupling is adopted to transfer the torque to reduce the friction; the inner cylinder with ruby bearing is designed to reduce the friction torque, thus the accuracy of the viscosity measurement is improved. The experiment of measuring the standard viscosity liquid (N10 and N35) under normal pressure and measuring the viscosity of methylbenzene under the pressure of 0.1–150 MPa were carried out, and considering all the experimental data, the uncertainty of the viscosity measurements is approximately ±3%.

Apparent Viscosity and Rheological Behavior of Aluminum-Alloy Slurry Containing Nano-Sized SiC Particles

The apparent viscosity and rheological behavior of nanoSiCP/Al-5Cu composites were studied by using a high temperature coaxial rotating cylinder viscometer. The results show that mass fraction of nanoSiCP is an important factor for apparent viscosity of the nanoSiCP/Al-5Cu composites, and there is a great enhancement of apparent viscosity of the slurry with the increase of nanoSiCp content. It can attribute to the viscous force between nanoSiCp and matrix alloy melt above the liquidus. The increased amplitude of apparent viscosity in semi-solid state is far less than those in liquid state with the increase of mass fraction of nanoSiCp. The apparent viscosities of the composites reinforced with 0.5%, 1%, 1.5% and 2% nanoSiCp at 700°C were 24.78%, 95.25%, 160.29% and 228.62% higher than that of Al-5Cu alloy, respectively. Besides, the rheological model of nanoSiCP/Al-5Cu composites was established based on the fitting curve, which can precisely describe the relationship between the apparent viscosity of nanocomposites slurry and nanoSiCp mass fraction.

Concentric cylinder viscometer flows of Herschel-Bulkley fluids

Drilling fluids and well cements are example non-Newtonian fluids that are used for geothermal and petroleum well construction. Measurement of the non-Newtonian fluid viscosities are normally performed using a concentric cylinder Couette geometry, where one of the cylinders rotates at a controlled speed or under a controlled torque. In this paper we address Couette flow of yield stress shear thinning fluids in concentric cylinder geometries.We focus on typical oilfield viscometers and discuss effects of yield stress and shear thinning on fluid yielding at low viscometer rotational speeds and errors caused by the Newtonian shear rate assumption. We relate these errors to possible implications for typical wellbore flows.

Study on the Variety of Rheological Properties and Thermal Analysis of Modified Coal Tar Pitch with 1,4-Benzenedimethanol

Coal tar pitch (CTP) as carbon material was studied using 1,4-Benzenedimethanol (PXG) as modifier by p-toluene sulfonic acid (PTS) catalyst and the variety of rheological properties of modified coal tar pitch (MTP) was discussed. The apparent viscosity of CTP and MTP were measured using rotating coaxial-cylinder viscometer, and the relations between the apparent viscosity and temperature were studied. Thermal behaviors of CTP and MTP were analyzed with TG-DSC. The results showed that the viscosity of the MTP gradually decreased with the temperature rising and the viscous activation energy of the MTP is 72.92 kJ·mol-1, which was beneficial to the process for producing carbon materials and the carbon yield was greatly improved. Therefore, coal tar pitch modified with PXG was qualified to be an excellent carbon precursor.

THE EFFECT OF SYNTHETIC ZEOLITE ON THE VISCOSITY OF CEMENT PASTE / SINTETINIO CEOLITO PRIEDO ĮTAKA CEMENTO TEŠLOS KLAMPUMUI

The paper reports the effect of the synthetic zeolite admixture on the viscosity of cement paste. Materials include Portland cement CEM I 42.5 R, synthetic zeolite obtained through low-temperature synthesis under laboratory conditions, polycarboxylate ester based supeplasticizer Muraplast FK 63.30 and tap water. Three compositions of cement paste were made adding 0%, 5%, and 10 wt% of synthetic zeolite. A rotating cylinder viscometer was used for measuring the consistence of the paste; viscosity was measured employing vibrational viscometer SV–10. The consistency test on cement paste showed that spread with no addition of synthetic zeolite made 149 mm, containing 5% of synthetic zeolite the slump was 85 mm and containing 10% of synthetic zeolite spread was 70 mm. The viscosity test also indicated that for the period of 30 minutes, changes in the viscosity of cement paste were as follows: 81.11 mPa s with no addition of synthetic zeolite, 746.5 mPa s containing 5% of synthetic zeolite and 827.1 mPa s containing 10% of synthetic zeolite. Data on the viscosity of cement paste were statistically processed applying software Statistica. Dispersion diagrams demonstrate changes in the viscosity of cement paste adding from 0 to 10 wt% of synthetic zeolite. Taking into account synthetic zeolite, the following correlation coefficients were calculated: 0% – 0.938, 5% – 0.967, 10% – 0.988. The coefficients of determination made 0% – 0,880, 5% – 0,935, 10% – 0,976. Equations for a dependent variable were produced by regression analysis. Santrauka Šio darbo tikslas – nustatyti, kokią įtaką cemento tešlos klampumui turi sintetinio ceolito priedas. Naudotos šios medžiagos: portlandcementis CEM I 42,5 R, sintetinis ceolitas, gautas laboratorijoje atliekant žematemperatūrę sintezę, superplastiklis Muraplast FK 63.30 multikarboksilato esterio pagrindu ir vandentiekio vanduo. Buvo maišomos trijų sudėčių cemento tešlos dedant 0 %, 5 %, 10 % sintetinio ceolito priedo nuo cemento masės. Cemento tešlos konsistencijai nustatyti buvo naudojamas Sutardo viskozimetras, klampumui – vibroviskozimetras SV-10. Atlikus cemento tešlos konsistencijos bandymą nustatyta, kad be sintetinio ceolito priedo cemento tešlos pasklidimas – 149 mm, su 5 % sintetinio ceolito priedu – 85 mm, 10 % – 70 mm. Nustačius cemento tešlos klampumą gauta, kad be sintetinio ceolito priedo cemento tešlos klampumas per 30 minučių kinta 81,11 mPas, su 5 % priedo – 746,5 mPas, 10 % – 827,1 mPas. Cemento tešlos klampumo tyrimo duomenys buvo statistiškai apdorojami kompiuterine programa „Statistica“. Šiame darbe pateikiamos sklaidos diagramos, kuriose pavaizduota, kaip kinta cemento tešlos klampumas laiko atžvilgiu naudojant sintetinio ceolito priedą nuo 0 iki 10 %. Nustatyti korealiacijos koeficinetai: 0 % – 0,9380, 5 % – 0,9669, 10 % – 0,9881, bei determinacijos koeficientai: 0 % – 0,8798, 5 % – 0,9348, 10 % – 0,9763. Atlikus regresinę analizę buvo gautos priklausomybių lygtys.

Rheological Properties of Plastisols Based on Low-Toxicity Plasticizers

The rheological properties of plastisols based on low-toxicity plasticizers have been evaluated using a DV-79+ pro coaxial cylinder viscometer by steady shearing. The effect of plasticizer and temperature on the shearing rate dependence of apparent viscosity, non-Newtonian index ( n ) , as well as apparent activation energy ( Ea ) was investigated. The results indicate that all the plastisols prepared in this experiment show shear thinning pseudoplastic behavior before and after aging process. The plastisols prepared by DOTP shows an obvious shear thinning behavior than that of plastisols prepared by ATBC and DINCH. The dependence of viscosity properties on temperature of plastisols accord with Arrhenius formula except DOTP-based system, and the apparent activation energy of plastisols prepared by DINCH is bigger than that of plastisols prepared by ATBC.

BEHAVIOR OF MR FLUIDS AT HIGH SHEAR RATE

The high shear rate behavior of MR fluids is investigated using a concentric rotational cylinder viscometer fabricated in-house. The rotational cylinder viscometer is designed such that a high shear rate of up to 30,000 s-1 can be applied to the MR fluid in a pure shear flow mode. As a comparison, the maximum shear rate of a commercially available parallel disk type rheometer is only up to 1,000 s-1. To determine the shear rate of the MR fluid in the viscometer, an exact expression between torque and angular velocity is established. The yield stress and viscosity of the MR fluid is determined by fitting the expression into the measured torque and angular velocities, and the shear stress as a function of the shear rate is further derived. The magnetic filed strength across the fluid gap is determined based on an electromagnetic field analysis, and the yield stress and viscosity of the fluid as a function of the magnetic filed is established. Specifically, the stability of the MR fluid at high shear rate is also evaluated. Two commercially available MR fluids, i.e., Lord's MRF-132DG and MRF-140CG, are investigated using the rotational cylinder viscometer, and the testing results are compared to the manufacturer's data.