scholarly journals Estimation of Lubrication Layer Thickness and Composition through Reverse Engineering of Interface Rheometry Tests

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1799
Author(s):  
Alexis Salinas ◽  
Dimitri Feys
Keyword(s):  
Particle Size ◽  
Pipe Wall ◽  
Single Layer ◽  
Particle Migration ◽  
Particle Sizes ◽  
Maximum Particle Size ◽  
Lubrication Layer ◽  
Concrete Pumping ◽  
Maximum Particle ◽  
Sand Particles

During concrete pumping, a lubrication layer is formed near the pipe wall. Extensive research has been performed on measuring and modeling the properties of this layer and using these values to predict pumping pressures. However, there are numerous discussions in the literature about the composition and thickness of this layer: can it be considered mortar, a micromortar, or is it cement paste? In this paper, possible solutions for the thickness and composition of the lubrication layer are derived from interface rheometry tests. It is assumed that the lubrication layer is composed of one or more concentric layers of paste or micromortar. To accomplish this determination, the rheological properties of the composing paste, mortars with different maximum particle sizes and concrete need to be known. Challenges arising from using different rheometers and from the sensitivity of the paste rheology to shearing are addressed in this contribution. The results show that, mathematically, a single layer of homogeneous paste or mortar with different maximum particle sizes can be responsible for the formation of the lubrication layer. Physically, however, the composing material should contain sand particles to some extent, as particle migration is proportional to the size squared. If the literature results from pumping are applicable to the results obtained in this paper, it seems that the lubrication layer is composed of a mortar with a maximum particle size of around 1 to 2 mm.

Effects of maximum particle size of coarse aggregates and steel fiber contents on the mechanical properties and impact resistance of recycled aggregate concrete

2021 ◽  
pp. 136943322110179
Author(s):  
DongTao Xia ◽  
ShaoJun Xie ◽  
Min Fu ◽  
Feng Zhu
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Steel Fiber ◽  
Impact Resistance ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Maximum Particle Size ◽  
Maximum Particle

Fiber reinforced recycled aggregate concrete has become a new type of green concrete material. The maximum particle size of coarse aggregates and steel fiber contents affect the mechanical properties and impact resistance of recycled aggregate concrete. However, such studies are rare in literature. The present paper shortens the gap through experimental study. A total of 144 specimens of 12 kinds of concrete mixtures were tested, which adopted different steel fiber volume admixtures (0%, 0.8%, 1.0%, 1.2%) and recycled coarse aggregates in different maximum particle sizes (9.5, 19, 31.5 mm) replacing 30% natural coarse aggregate. The compressive strength, splitting tensile strength, and impact resistance of the 12 concrete mixtures were tested. The results showed that the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete increased first and then decreased with the increase of the maximum particle size. The recycled aggregate concrete with the maximum particle size of 19 mm had the highest mechanical properties and impact resistance. Besides, with the increase of steel fiber content, the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete showed an increasing trend. Considering a large amount of experimental data and the coupling effect of steel fiber contents and the maximum particle size of coarse aggregates, the Weibull distribution function was introduced to analyze the impact test results and predict the number of resistance to impact under different failure probabilities. The results showed that the number of blows of the recycled aggregate concrete followed a two-parameter Weibull distribution, and the estimated value of the number of resistance to impact for failure increased with the increase of the failure probability.

A study on the behaviour of soil–geotextile systems in filtration tests

1996 ◽  
Vol 33 (6) ◽  
pp. 899-912 ◽  
Author(s):  
E M Palmeira ◽  
R J Fannin ◽  
Y P Vaid
Keyword(s):  
Particle Size ◽  
Soil Characteristics ◽  
Retention Capacity ◽  
Unidirectional Flow ◽  
Maximum Particle Size ◽  
Theoretical Predictions ◽  
New Apparatus ◽  
Maximum Particle ◽  
Gradient Ratio ◽  
Different Soils

The behaviour of soil–geotextile systems in filtration tests is reported for nonwoven geotextiles under unidirectional flow. A new apparatus was developed to preform filtration tests under an applied vertical stress, and tests were then conducted with different soils and nonwoven geotextiles in order to evaluate the clogging potential and retention capacity of these materials under rather severe combinations of geotextile and soil characteristics. Results show that the geotextiles perfomed well and that observed permeability losses were acceptable even for gradient ratios close to 3. No progressive piping was observed, and it is believed that the retention capacity of the geotextiles may be influenced by their manufacturing process. In general, theoretical predictions for the maximum particle size passing through the geotextile compared well with measurements. Key words: geotextiles, filtration, gradient ratio, permeability, soil retention, clogging.

Performance Evaluation of Al2O3 Powder Dispersion by Bead and Ball Mills

2014 ◽  
Vol 682 ◽  
pp. 32-34 ◽  
Author(s):  
N.S. Belousova ◽  
O.A. Goryaynova ◽  
E.V. Melnikova
Keyword(s):  
Particle Size ◽  
Performance Evaluation ◽  
Ball Mill ◽  
Aqueous Suspension ◽  
Ball Mills ◽  
Powder Dispersion ◽  
Maximum Particle Size ◽  
Bead Mill ◽  
Maximum Particle

In this paper the results of alumina aqueous suspension disaggregation with the help of bead and ball mills are shown. The changing of maximum particle size for50 wt. % and 90 wt. % of powder (from lowest to highest size) in suspension dispersed by a bead mill for one hour and ball mill for 48 hours was fixed. In order to achieve powder parameters given by the manufacturer disaggregating process sets was defined.

scholarly journals Modelling of Metallic Particle Binders for Increased Part Density in Binder Jet Printed Components

2019 ◽  
Author(s):  
Joseph Roberts ◽  
Peter Green ◽  
Kate Black ◽  
Christopher Sutcliffe
Keyword(s):  
Particle Size ◽  
Critical Radius ◽  
Detailed Knowledge ◽  
Particle Sizes ◽  
Powder Bed ◽  
Beneficial Effects ◽  
Drop Tests ◽  
Maximum Particle ◽  
Packing Efficiency ◽  
Selection Of

Binder jet printed components typically have low overall density in the green state and high shrinkage and deformation after heat treatment. It has previously been demonstrated that, by including nanoparticles of the same material in the binder, these properties can be improved as the nanoparticles can fill the interstices and pore throats between the bed particles. The beneficial effects from using these additive binder particles can be improved by maximising the binder particle size, enabling the space within the powder bed to be filled with a higher packing efficiency. The selection of maximum particle size for a binder requires detailed knowledge of the pores and pore throats between the powder bed particles. In this paper, a raindrop model is developed to determine the critical radius at which binder particles can pass between pores and penetrate the bed. The model is validated against helium pycnometry measurements and binder particle drop tests. It is found that the critical radius can be predicted, with acceptable accuracy, using a linear function of the mean and standard deviation of the particle radii. Percolation theory concepts have been employed in order to generalise the results for powder beds that have different mean particle sizes and size distributions. The results of this work can be employed to inform the selection of particle sizes required for binder formulations, to optimise density and reduce shrinkage in printed binder jet components.

Subsea Slurry Lift Pump for Deepsea Mining

2010 ◽  
Author(s):  
Robert A. Judge ◽  
Alan Yu
Keyword(s):  
Particle Sizes ◽  
Flow Conditions ◽  
Positive Displacement ◽  
Maximum Particle Size ◽  
Pumping Efficiency ◽  
Recent Developments ◽  
Maximum Particle ◽  
Vertical Lift ◽  
Transport Problems ◽  
Slurry Transport

Recent developments in subsea mining as well as oil & gas exploration and development drilling will require the use of a subsea pumping solution capable of handling slurries. These slurries are characterized by relatively large particle sizes and non-uniform flow conditions including fluctuating solids concentrations, densities, viscosities, and maximum particle size in both the mining and drilling applications. While challenging enough in surface applications, slurry transport problems are exacerbated by the vertical lift required in subsea use. This paper will first present the effect of each varying parameter on the overall horsepower required. Additionally, the pumping efficiency of some different pump types when responding to these changing conditions will be shown. From a control perspective, altering a pump’s speed in response to changing flow conditions presents some unique challenges. As an alternative to adjusting a rotary pump’s speed, an algorithm to control a positive displacement pumping solution to automatically adjust its output in this application is presented.

Determination of maximum particle size in magnetic fluids

2016 ◽  
Vol 78 (2) ◽  
pp. 269-272 ◽  
Author(s):  
I. M. Aref’ev ◽  
A. V. Lebedev
Keyword(s):  
Particle Size ◽  
Magnetic Fluids ◽  
Maximum Particle Size ◽  
Maximum Particle

Influence of Maximum Particle Size, Fines Content, and Dust Ratio on the Behavior of Base and Subbase Coarse Aggregates

2017 ◽  
Vol 2655 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Rabindra Chaulagai ◽  
Abdolreza Osouli ◽  
Sajjad Salam ◽  
Erol Tutumluer ◽  
Sheila Beshears ◽  
...  
Keyword(s):  
Particle Size ◽  
High Strength ◽  
Maximum Size ◽  
Fines Content ◽  
Coarse Aggregates ◽  
Maximum Particle Size ◽  
Maximum Particle ◽  
Improved Performance ◽  
Aggregate Base

Unbound aggregate base and subbase layers are the main load-bearing layers in a pavement structure. Size and shape properties of these aggregate materials should be controlled to ensure proper workability during construction and improved performance for pavement longevity. The effects of gradation, maximum particle size, fines content (percentage passing the No. 200 sieve), and dust ratio on the quality of aggregates were investigated by performing many soaked California bearing ratio tests on a crushed limestone material. The dust ratio represents the amount of fines content divided by the amount of minus No. 40 sieve material. The dust ratios studied were 0.4, 0.6, and 1.0. Two gradations commonly used in Illinois, with maximum particle sizes of 1 in. and 2 in., were studied to analyze the effect of fines content with respect to maximum particle size in the gradation. A typical range of fines contents (i.e., 5%, 8%, and 12%) was also considered. The results show that the gradation, dust ratio, and fines content should be taken into account in the selection of aggregate properties for stability requirements. Aggregates with larger maximum size particles provide high strength, and they are not affected as much as aggregates with smaller maximum size particles by an increase in fines content. The aggregates with smaller maximum size particles provide lower strength. It was also concluded that samples with a dust ratio of 1.0 do not necessarily result in an aggregate material with low strength.

Influence of Aggregate on Workability of Self-Compacting Concrete

2012 ◽  
Vol 482-484 ◽  
pp. 1101-1104
Author(s):  
Huan Qiang Liu ◽  
Xi Chen
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Particle Shape ◽  
Shape Index ◽  
Self Compacting Concrete ◽  
Aggregate Gradation ◽  
Self Consolidating Concrete ◽  
Maximum Particle Size ◽  
Maximum Particle

The workability of self-compacting concrete is influenced greatly by aggregate. In this study, the effects of aggregate gradation, maximum particle size, sand percentage and particle shape on the workability of self-consolidating concrete were investigated. The results showed that the compressive strength and workability of self-compacting concrete were increased by increasing the particle size of aggregate, optimizing gradation, choosing proper sand percentage and increasing shape index in a certain range.

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