scholarly journals Rheological analysis of mud from Port of Hamburg, Germany

2019 ◽  
Vol 20 (6) ◽  
pp. 2553-2562 ◽  
Author(s):  
Ahmad Shakeel ◽  
Alex Kirichek ◽  
Claire Chassagne
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Measurement Techniques ◽  
Organic Matter Content ◽  
Matter Content ◽  
Rheological Parameters ◽  
Fluid Mud ◽  
Frequency Sweep ◽  
Rheological Analysis ◽  
Stress Dependent

Abstract Purpose An innovative way to define navigable fluid mud layers is to make use of their rheological properties, in particular their yield stress. In order to help the development of in situ measurement techniques, it is essential that the key rheological parameters are estimated beforehand. Is there only one yield stress? In which shear rate/shear stress range is yield expected to occur? How is yield stress dependent on depths and locations in the harbor? In order to answer these questions, we investigated the changes in the rheological properties of mud from along the river stream in the Port of Hamburg, Germany, using a recently developed laboratory protocol. Materials and methods In this study, a detailed rheological analysis was carried out on the mud samples collected from different locations and depths of the Port of Hamburg. A variety of rheological tests was performed including: stress sweep tests, flow curves, thixotropic tests, oscillatory amplitude, and frequency sweep tests. Results and discussion The yield stresses of sediments from different locations were significantly dissimilar from each other due to differences in densities and organic matter content. Two yield stresses (termed static and fluidic) were observed for every sample and linearly correlated to each other. The thixotropic studies showed that all mud samples, except from one location, displayed a combination of thixotropic and anti-thixotropic behaviors. The results of frequency sweep tests showed the solid-like character of the sediments within the linear viscoelastic limit. The yield stresses, thixotropy, and moduli of the mud samples increased by going deeper into the sediment bed due to the increase in density of the sediments. Conclusions This study confirmed the applicability of the recently developed protocol as a fast and reliable tool to measure the yield stresses of sediments from different locations and depths in the Port of Hamburg. The fluid mud layer, in all the locations it was observed, exhibited relatively small yield stress values and weak thixotropic behavior. This confirms that despite the fact that rheology of fluid mud is complex, this layer can be navigable.

scholarly journals Rheology of Mud: An Overview for Ports and Waterways Applications

2021 ◽  
Author(s):  
Ahmad Shakeel ◽  
Alex Kirichek ◽  
Claire Chassagne
Keyword(s):  
Organic Matter ◽  
Rheological Properties ◽  
Organic Matter Content ◽  
Matter Content ◽  
Point Of View ◽  
Sampling Location ◽  
Fluid Mud ◽  
Systematic Analysis ◽  
Semi Empirical ◽  
Cohesive Material

Mud, a cohesive material, consists of water, clay minerals, sand, silt and small quantities of organic matter (i.e., biopolymers). Amongst the different mud layers formed by human or natural activities, the fluid mud layer found on top of all the others is quite important from navigational point of view in ports and waterways. Rheological properties of fluid mud layers play an important role in navigation through fluid mud and in fluid mud transport. However, the rheological properties of mud are known to vary as a function of sampling location within a port, sampling depth and sampling location across the globe. Therefore, this variability in rheological fingerprint of mud requires a detailed and systematic analysis. This chapter presents two different sampling techniques and the measured rheological properties of mud, obtained from laboratory experiments. The six protocols used to measure the yield stresses are detailed and compared. Furthermore, the empirical or semi-empirical models that are commonly used to fit rheological experimental data of such systems are presented. The influence of different factors such as density and organic matter content on the rheological behavior of mud is discussed. The fluidic yield stress of mud samples was observed to vary from 0.2 Pa to 500 Pa as a function of density and organic matter content.

scholarly journals Is density enough to predict the rheology of natural sediments?

2019 ◽  
Vol 39 (5) ◽  
pp. 427-434 ◽  
Author(s):  
Ahmad Shakeel ◽  
Alex Kirichek ◽  
Claire Chassagne
Keyword(s):  
Organic Matter ◽  
Yield Stress ◽  
Complex Modulus ◽  
Organic Matter Content ◽  
Rheological Behaviour ◽  
Matter Content ◽  
Frequency Sweep ◽  
Content Change ◽  
Two Samples ◽  
Static Yield

Abstract Mud is a cohesive material which contains predominantly clay minerals, water, organic matter and some amounts of silt and sand. Mud samples can have complex rheological behaviour, displaying viscoelasticity, shear-thinning, thixotropy and yield stress. In this study, influence of organic matter on the rheological behaviour of different mud samples having similar densities is investigated. Four samples, collected from different locations and depths of Port of Hamburg (Germany) were selected. Two samples with the density of about 1210 kg/m3 and two samples with the density of about 1090 kg/m3 were analysed by different rheological tests, including stress ramp-up tests, flow curves, thixotropic tests, oscillatory amplitude and frequency sweep tests. Two yield stress regions (with two yield stress values stated as “static” and “fluidic” yield stresses) were identified for all the samples, and these regions, corresponding to a structural change of the samples were significantly different from sample to sample due to the differences in organic matter content. For lower density samples, the ratio of fluidic to static yield stress increased from 3 to 4.4 while it increased from 4.4 to 5.2 in case of higher density samples, by increasing the organic matter content. The thixotropic studies showed that the mud samples having lowest organic matter content (VH and KBZ) exhibit a combination of thixotropic and anti-thixotropic behaviours. The results of frequency sweep tests revealed the solid-like character of the mud within the linear viscoelastic regime. Mud samples having higher organic matter content (RV and RT) had a higher complex modulus (417 Pa and 7909 Pa) than the ones with lower organic matter content (13 Pa and 1774 Pa), for a given density. This study demonstrated that the density only is not a sufficient criterion to predict the rheology of different mud. Furthermore, even small amounts of organic matter content change significantly the mud rheological behaviour.

scholarly journals Effects of Volume Fraction and Surface Area of Aggregates on the Static Yield Stress and Structural Build-Up of Fresh Concrete

2020 ◽  
Author(s):  
Irina Ivanova ◽  
Viktor Mechtcherine
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Surface Area ◽  
Cement Paste ◽  
Volume Fraction ◽  
Fresh Concrete ◽  
Total Surface Area ◽  
Rheological Parameters ◽  
Static Yield ◽  
Static Yield Stress

With increasing interest in the use of additive manufacturing techniques in the construction industry, static rheological properties of fresh concrete have necessarily come into focus. In particular, the knowledge and control of static yield stress (SYS) and its development over time are crucial for mastering formwork-free construction, e.g. by means of layered extrusion. Furthermore, solid understanding of the influences of various concrete constituents on the initial SYS of the mixture and the structural build-up rate is required for purposeful material design. This contribution is concentrated on the effect of aggregates on these rheological parameters. The volume fraction of aggregates was varied in the range of 35 to 55 % by volume under condition of constant total surface area of the particles. The total surface area per unit volume of cement paste was equal to 5.00, 7.25 and 10.00 m²/l, conditioned on the constant volume fraction of aggregates. Both variations were enabled by changing the particle size distributions of the aggregates while holding the cement paste composition constant for all concrete mixtures. To characterise the SYS and the structural build-up, constant shear rate tests with a vane-geometry rotational rheometer were performed. It was found that in the ranges under investigation the variation in volume fraction had a more pronounced effect on the static rheological properties of concrete than did the variation in surface area. An accurate mathematical description of the relationship between the initial SYS of concrete and the relative volume fraction of aggregate based on the Chateau-Ovarlez-Trung model was proposed. Challenges in deriving a similar relationship for the structural build-up rate of concrete were highlighted.

scholarly journals Effects of Volume Fraction and Surface Area of Aggregates on the Static Yield Stress and Structural Build-Up of Fresh Concrete

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1551 ◽  
Author(s):  
Irina Ivanova ◽  
Viktor Mechtcherine
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Surface Area ◽  
Cement Paste ◽  
Volume Fraction ◽  
Fresh Concrete ◽  
Total Surface Area ◽  
Rheological Parameters ◽  
Static Yield ◽  
Static Yield Stress

With increasing interest in the use of additive manufacturing techniques in the construction industry, static rheological properties of fresh concrete have necessarily come into focus. In particular, the knowledge and control of static yield stress (SYS) and its development over time are crucial for mastering formwork-free construction, e.g., by means of layered extrusion. Furthermore, solid understanding of the influences of various concrete constituents on the initial SYS of the mixture and the structural build-up rate is required for purposeful material design. This contribution is concentrated on the effect of aggregates on these rheological parameters. The volume fraction of aggregates was varied in the range of 35% to 55% by volume under condition of constant total surface area of the particles. The total surface area per unit volume of cement paste was equal to 5.00, 7.25 and 10.00 m²/L, conditioned on the constant volume fraction of aggregates. Both variations were enabled by changing the particle size distributions of the aggregates while holding the cement paste composition constant for all concrete mixtures. To characterise the SYS and the structural build-up, constant shear rate tests with a vane-geometry rotational rheometer were performed. It was found that in the ranges under investigation the variation in volume fraction had a more pronounced effect on the static rheological properties of concrete than did the variation in surface area. An accurate mathematical description of the relationship between the initial SYS of concrete and the relative volume fraction of aggregate based on the Chateau–Ovarlez–Trung model was proposed. Challenges in deriving a similar relationship for the structural build-up rate of concrete were highlighted.

Sediment sampling and soil properties of sediments in the Hamburg port and the river Elbe in comparison with hydro-acoustic measurements

2020 ◽  
Author(s):  
Nino Ohle ◽  
Thomas Thies ◽  
Rolf Lüschow ◽  
Ulrich Schmekel
Keyword(s):  
Boundary Conditions ◽  
Soil Properties ◽  
Rheological Properties ◽  
In Situ Monitoring ◽  
Rheological Parameters ◽  
Fluid Mud ◽  
Acoustic Measurements ◽  
Port Authority ◽  
River Elbe

<p>For future strategies in water depth maintenance in the Port of Hamburg, determining the navigability limit (i.e. the nautical safe depth) is of major importance. For this purpose, a project "Nautical Depth" was set up at the Hamburg Port Authority (HPA), which is dedicated to dealing with this issue. The aim is to measure a nautical safe depth under various boundary conditions and to identify limits for a safe passage of high concentrated soil suspensions. Among other things, the project cooperates with the Antwerp Port Authority, the Port of Rotterdam and the TU Delft. The project is also embedded in a research platform or network called MUDNET (www.tudelft.nl/mudnet).</p><p>In order to achieve the required acceptance for a reassessment of the nautical depth, it is necessary to determine the rheological properties of soil suspensions in-situ. The rheological parameters - which will be used to describe the nautical depth - have still to be determined. For a permanent identification of nautical relevant rheological properties of the soil suspensions, existing in-situ measuring devices have been tested and, under certain circumstances, new equipment has to be developed. However, these devices cannot be used for the spatial determination of the rheological properties but will reproduce these on cross-sections and depth profiles. Therefore, new evaluation algorithms should be developed in echo-sounding technology - which have to be correlated with the in-situ rheological properties - in order to ensure spatial representations of a safe nautical depth.</p><p>In a first step, measurements of nature conditions in the water column and at the riverbed were carried out in 9 areas and in 12 measuring campaigns in 2018 and 2019 in the Hamburg Port. Therefore, different sediment profiler devices (Rheotune, Graviprobe, Admodus USP) have been tested. Sediment samples were taken with a modified Frahm-Lot. All investigations were combined with hydro-acoustic measurements which includes multibeam echo-sounders and sub-bottom profilers with Silas processing software.</p><p>The presentation will give a closer look to the sampling strategies and results of the different soil properties within the Hamburg port and the river Elbe, which serves as fairway to the port. The investigations show that the soil properties are dependent from local and regional boundary conditions, as flow velocity, grain size distribution and especially in Hamburg from the organic matters and nutrients within the suspended and the soil material. Moreover, the laboratory data will be compared with hydro-acoustical and in-situ monitoring devices. Advantages and disadvantages of the different systems will be discussed.</p><p>Kamphuis et al. (2013) Fluid Mud and Determining, Nautical Dept Hydro International, 22-25;</p><p>Malcherek, A. et al. (2011) Zur Rheologie von Flüssigschlicken: Experimentelle Untersuchungen und theoretische Ansätze, Mitteilungen des Instituts für Wasserwessen der Universität der Bundeswehr, München 111:1-191;</p><p>Metha et al. (2013) Fluid Mud Properties in Nautical Depth Estimation, Journal of Waterway, Port, Coastal & Ocean Engineering, 140:210-222;</p><p>Ohle, N. et al (2019) Introduction and first results within the project “Nautical Depth” in Hamburg, 11<sup>th</sup> International SedNet conference, 3-5 April 2019, Dubrovnik;</p>

scholarly journals Effect of Silica Fume on the Rheological Properties of Cement Paste with Ultra-Low Water Binder Ratio

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 554
Author(s):  
Juan He ◽  
Congmi Cheng ◽  
Xiaofen Zhu ◽  
Xiaosen Li
Keyword(s):  
Hysteresis Loop ◽  
Rheological Properties ◽  
Yield Stress ◽  
Silica Fume ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Loop Area ◽  
Binder Ratio ◽  
Hysteresis Loop Area ◽  
Water Binder Ratio

The effect of silica fume on the rheological properties of a cement–silica fume–high range water reducer–water mixture with ultra-low water binder ratio (CSHWM) was studied. The results indicate that the W/B ratio and silica fume content have different effects on the rheological parameters, including the yield stress, plastic viscosity, and hysteresis loop area. The shear-thickening influence of CSHWM decreased with the increased silica fume content. When the silica fume content increased from 0% to 35%, the mixture with W/B ratio of 0.19 and 0.23 changed from a dilatant fluid to a Newtonian fluid, and then to a pseudoplastic fluid. When the silica fume content was less than 15%, the yield stress was close to 0. With the increase of silica fume content, the yield stress increased rapidly. The plastic viscosity and hysteresis loop area decreased slightly with the addition of a small amount of silica fume, but increased significantly with the continuous increase of silica fume. Compared with the Bingham and modified Bingham models, the Herschel–Buckley model is more applicable for this CSHWM.

scholarly journals OPTIMIZATION OF LITHIUM SOAP-BASED GREASE TESTING METHODOLOGY BASED ON MEASUREMENTS REPEATABILITY

2017 ◽  
Author(s):  
A.V. Radulescu ◽  
I. Radulescu
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Rheological Parameters ◽  
Testing Time ◽  
Thermal Variation ◽  
Testing Methodology ◽  
Temperature Range ◽  
Lithium Soap

The purpose of the paper is to investigate the rheological properties of a lithium soap-based grease, using a Brookfield viscometer. An optimized methodology was proposed, applicable to the tested grease, which takes into account the possibility of reducing the testing time by analyzing the degree of measurements repeatability. Finally, the thermal variation of the rheological parameters (yield stress and viscosity) was obtained, in the temperature range 10...75 oC. The main result of the paper is the reducing of the testing time from 6 hours to 3 hours for one temperature, with the same precision of measurements, according to economical effects.

Experimental Research on Rheological Properties of Cemented Mortar in Tail Void Grouting of Shield Tunnel

2011 ◽  
Vol 261-263 ◽  
pp. 1201-1205 ◽  
Author(s):  
Xiao Hui Yuan ◽  
Yue Wang Han
Keyword(s):  
Rheological Properties ◽  
Flow Pattern ◽  
Yield Stress ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Shear Yield Stress ◽  
Shear Yield ◽  
Binder Ratio ◽  
Water Ratio ◽  
Water Binder Ratio

Grout flow pattern and rheological parameters determine grouting pressure transfer process in annular tail void and filling rate for shield tail void. However, cemented mortar is a mixture of cement, fly ash, sand, bentonite and water, which lead to grout rheological properties and rheological parameters are difficultly determined. Based on orthogonal experimental design method, grout rheological properties were tested by rotational viscometer. Utilizing variance and poly-nonlinear regression analysis, the qualitative and quantitative relationships between mix ratios and rheological parameters were obtained respectively. It is shown that cemented mortar flow pattern commonly agree with Bingham fluid type, and plastic viscosity varies between 1 and 4Pa•s, and shear yield stress varies between 10 to 40Pa respectively. Water-binder ratio and bentonite-water ratio are key influencing factors for grout rheological parameters. With the water-binder ratio increasing and bentonite-water ratio decreasing, plastic viscosity and shear yield stress present reducing tendency.

scholarly journals Physicochemical, pasting, and rheological properties of pearl millet starches from different cultivars and their relations

2020 ◽  
Vol 49 (1) ◽  
pp. 49-59 ◽  
Author(s):  
A.K. Siroha ◽  
S. Punía ◽  
K.S. Sandhu ◽  
B.L. Karwasra
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Pearl Millet ◽  
Starch Granule ◽  
Amylose Content ◽  
Granule Size ◽  
Elastic Behaviour ◽  
Frequency Sweep ◽  
Flow Behaviour Index ◽  
Behaviour Index

Physicochemical, pasting, and rheological properties of pearl millet starches were studied and correlations among these properties were calculated. Amylose content, swelling power, and solubility of starches varied from 11.57 to 21.93%, 11.11 to 17.91 g g−1 and 12.20 to 15.20%, respectively. Volume% of starch granule size less than 10 µm varied from 36.23 to 48.34%, and 12.16 to 18.75% for above 20 µm size of granule. Peak viscosity of starches varied from 1291 to 1853 mPa·s, cv. RHB-173 had the highest value. Frequency sweep measurement of starch pastes revealed higher magnitude of G′ as compared to G″ with increase in to, indicating visco-elastic behaviour. Yield stress (σo), consistency index (K), and flow behaviour index (n) were observed as 40.73 to 115.72 Pa, 0.729 to 3.998 Pa·s, and 0.604 to 0.964, respectively. Starch pastes from cultivars studied showed shear thinning behaviour.

The Rheological Properties and Yield Stress Model of High-Density Slurry Added with Coarse Sands

2014 ◽  
Vol 580-583 ◽  
pp. 231-237 ◽  
Author(s):  
Xiu Xiang Zhang ◽  
Deng Pan Qiao
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Mass Concentration ◽  
Cement Content ◽  
Coarse Sand ◽  
High Density ◽  
Rheological Parameters ◽  
Suitable Model ◽  
Bingham Plastic ◽  
The Stability

In order to determine the concentration range of high-density slurry with coarse sands for suiting pipeline transportation in Jinchuan mine, at the same time find a suitable model to predict yield stress. In this paper, based on the coarse sand of Jinchuan mine as material to prepare high-density slurry, studied on the rheological properties. Through two-factor variance analysis, qualitative and ration analysis of the effect was conducted on the cement content and mass concentration to rheological parameters. The results show that the rheological model of the coarse sand is similar to that of Bingham plastic fluid, the mass concentration has a significant effect on viscosity and yield stress, and the viscosity is significantly affected by the cement content. The mass concentration of 82%-84% is suitable gravity transportation in pipeline. Meanwhile the relation model is established between yield stress and water-cement ratio, aggregate volume concentration, the model has high precision. These provide technical basis for designing filling system and ensuring the stability of slurry transportation, and a new idea for the research of rheological properties.

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