Experimental and theoretical investigations on the viscosity of heterogeneous asphalt binders

2017 ◽  
Vol 50 (4) ◽  
pp. 354-371 ◽  
Author(s):  
Aboelkasim Diab
Keyword(s):  
Flow Behavior ◽  
Ethylene Vinyl Acetate ◽  
Hydrated Lime ◽  
Crumb Rubber ◽  
Asphalt Binders ◽  
Zero Shear Viscosity ◽  
Shear Rates ◽  
Wide Range ◽  
Theoretical Investigations ◽  
Pavement Construction

The inherent multiphase structure of heterogeneous asphalt binders (additives containing binders) may complicate viscosity understanding and predictions in the Newtonian or non-Newtonian response. The objective of this article is to understand the viscosity characteristics of heterogeneous asphalt binders based on experimental and theoretical investigations over a wide range of conditions the matter may encounter in the field (temperatures and oxidative aging). Selected materials representing the generic additives commonly used for pavement construction including styrene–butadiene–styrene block copolymer and ethylene–vinyl acetate copolymer, crumb rubber, and two mineral fillers, namely hydrated lime and fly ash, were utilized separately at different concentrations to produce the heterogeneous materials under study. The effects of varied temperatures as well as short- and long-term aging processes were studied for the materials over a wide range of shear rates. A further theoretical investigation was carried out by addressing the capability of Tscheuschner model to predict the flow behavior under the aforementioned conditions. In addition, the zero shear viscosity said to be an intrinsic characteristic of asphalt binders was evaluated using the regression analysis of data predicted from Tscheuschner model. Overall, the shear thinning behavior of heterogeneous asphalt binders occurred at low shear rates as compared to the base binder, especially at low temperatures. Emphasis was placed on the repeatability of the model predictions under different conditions, which could be an initiative to provide a simple but accurate representation of the viscosity of heterogeneous asphalt binders.

Rheology of Plastisols of Poly(Vinyl Chloride)

1979 ◽  
Vol 52 (3) ◽  
pp. 676-691 ◽  
Author(s):  
E. A. Collins ◽  
D. J. Hoffmann ◽  
P. L. Soni
Keyword(s):  
Flow Behavior ◽  
Basic Mechanism ◽  
Particle Sizes ◽  
Solvent Interaction ◽  
Factors Affecting ◽  
Shear Rates ◽  
Wide Range ◽  
Size Of Particles ◽  
Increasing Temperature ◽  
Future Work

Abstract The viscosity of PVC plastisols is seen to be affected by numerous variables. Increase in concentration of the resin causes the viscosity to rise, with the increase being more abrupt at the higher concentrations. Deviation from Newtonian behavior also increases with concentration. Decrease in the size of particles results in an increase in viscosity, the effect being more pronounced at low shear rates. Broadening the distribution of particle sizes results in a decrease in viscosity. Porous particles yield plastisols with higher viscosity as compared to nonporous compact particles. The type of plasticizer also affects the viscosity. A plasticizer which is a better solvent for PVC (low value of polymer-solvent interaction parameter, χ) results in a higher viscosity due to an increase in the amount of dissolved polymer. Additives such as alcohols and soaps affect the viscosity in an, as yet, unknown way. Fillers, heat stabilizers, and pigments also increase the viscosity. With increasing temperature, the viscosity first decreases, passes through a minimum and then increases until gelation. With further rise in temperature the viscosity again decreases and then levels out before degradation occurs. In future work, particular emphasis needs to be given to the understanding of the basic mechanism involved in the effect of additives on the flow behavior. Systematic experiments with a range of well-defined particle sizes and over a wide range of shear rates are also needed. A better understanding of the factors affecting the behavior of plastisols will go a long way in changing the art of plastisol formulation to a science.

scholarly journals Non-Newtonian Behaviors of Crumb Rubber-Modified Bituminous Binders

2018 ◽  
Vol 8 (10) ◽  
pp. 1760 ◽  
Author(s):  
Haopeng Wang ◽  
Xueyan Liu ◽  
Panos Apostolidis ◽  
Tom Scarpas
Keyword(s):  
Shear Thinning ◽  
Crumb Rubber ◽  
Shear Loading ◽  
Modified Bitumen ◽  
Zero Shear Viscosity ◽  
Shear Rates ◽  
Rate Dependent ◽  
Correlation Degree ◽  
Warm Mix Additives ◽  
Bituminous Binders

Crumb rubber-modified bitumen (CRMB) has been utilized in the asphalt paving industry for decades due to its various benefits. The complex interaction between bitumen and crumb rubber as well as the addition of warm-mix additives makes the typical laws of Newtonian fluids insufficient to describe the behaviors of highly modified bituminous binders. To systematically explore the non-Newtonian behaviors of CRMB, a dynamic shear rheometer was utilized to apply shear loading on the samples at various temperatures and shear rates. Results show that the viscosity of different binders are highly temperature- and shear rate-dependent, while highly modified binders exhibit more obvious shear-thinning behaviors at certain temperatures. With the help of zero shear viscosity and yield stress, the shear-thinning behaviors of non-Newtonian binders can be sufficiently characterized. The Arrhenius equation is invalid to describe viscosity-temperature characteristics of bitumen in the non-Newtonian region. A second-order polynomial function was proposed to characterize the viscosity-temperature dependence with a high correlation degree.

Nonnewtonian Flow of Poly(Dimethyl Siloxane)

1967 ◽  
Vol 40 (5) ◽  
pp. 1483-1491
Author(s):  
Yoshio Ito
Keyword(s):  
Shear Rate ◽  
Polymer Solutions ◽  
Flow Behavior ◽  
Degree Of Polymerization ◽  
High Shear ◽  
Newtonian Viscosity ◽  
Shear Rates ◽  
Molecular Weights ◽  
Dimethyl Siloxane ◽  
Wide Range

Abstract Nonnewtonian flow of poly(dimethyl siloxanes) of various molecular weights has been studied with a short capillary viscosimeter. The experiment covered a wide range of shear rate, from 10−1 to 3×106sec−1. Results were as follows: (1) Flow behavior of the sample changes with the degree of polymerization. For siloxanes with degrees of polymerization less than 1.55×102, flow of the fluid is newtonian throughout the whole range of shear rates; for siloxanes with degrees of polymerization from 3.22×102 to 2.63×103, flow is nonnewtonian at moderate shear rates; it again becomes newtonian at high shear rates. With degrees of polymerization more than 3.31×103, the spiral flow rises to a high shear rate. (2) Plow behavior of the samples is expressed by modifying Shishido's equation proposed for nonnewtonian polymer solutions. (3) When the observed flow curve contains its inflection point, the upper newtonian viscosity can be estimated by a new method proposed here. (4) The relations among the end correction of capillary, the pressure loss, and the shear stress proposed by Shishido for polymer solutions are applicable to poly(dimethy! siloxane) also.

Studying viscosity of asphalt binders and effect of varied production temperatures on engineering properties of hot mix asphalt mixtures

2017 ◽  
Vol 44 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Aboelkasim Diab
Keyword(s):  
Ethylene Vinyl Acetate ◽  
Hydrated Lime ◽  
Asphalt Mixtures ◽  
Engineering Properties ◽  
Asphalt Binders ◽  
Void Content ◽  
Damage Evaluation ◽  
Indirect Tensile ◽  
Air Void ◽  
Newtonian Behavior

The objectives of this paper are studying the viscosity characteristics of asphalt binders containing different additives, ethylene vinyl acetate, polypropylene, and hydrated lime, and the influence of varying mixing and compaction temperatures on the engineering properties of the corresponding mixtures. The engineering properties of the asphalt mixtures were investigated using the indirect tensile strength, moisture damage evaluation, and volumetric properties (in terms of the air void content). Based on the viscosity results, the non-Newtonian behavior of the asphalt binders prevails with the increase in the concentration of polymers and hydrated lime, thus the setting of the production temperatures using the equiviscous principle would be expected to be rather inaccurate. The variation in the production temperatures affected the engineering properties of the asphalt mixtures. It is recommended that a revision of the production temperatures from different methods be undertaken to satisfy the desired engineering properties for different conditions.

scholarly journals Laboratory Evaluation of the Residue of Rubber-Modified Emulsified Asphalt

2020 ◽  
Vol 12 (20) ◽  
pp. 8383
Author(s):  
Dongdong Ge ◽  
Xiaodong Zhou ◽  
Siyu Chen ◽  
Dongzhao Jin ◽  
Zhanping You
Keyword(s):  
Chemical Change ◽  
Asphalt Binder ◽  
High Volume ◽  
Crumb Rubber ◽  
Asphalt Binders ◽  
Laboratory Evaluation ◽  
Chip Seal ◽  
Improvement Effect ◽  
Pavement Construction ◽  
Emulsified Asphalt

Emulsified asphalt has been widely used in various surface treatment methods such as chip seal for low-volume road preservation. Using modified emulsified asphalt made it possible to use chip seal technology on medium- and even high-volume traffic pavements. The main objective of the study is to quantify the residue characteristics of rubber-modified emulsified asphalt and to assess the effectiveness of using crumb rubber to modify emulsified asphalt binder. The four emulsified asphalt residues used the distillation procedure. Then, the rheology characteristics of emulsified asphalt residue were evaluated. The Fourier transform infrared spectroscopy (FTIR) test analyzed the chemical change of emulsified asphalt during the aging procedure. The results indicate that the evaporation method cannot remove all the water in emulsified asphalt. The mass change during the rolling thin film oven (RTFO) process only represented the component change of emulsified asphalt binder residue. Both the high-temperature and low-temperature performance grade of the two emulsified asphalt binders with rubber were lower. The original asphalt binder adopted to emulsification had a crucial influence on the performance of emulsified asphalt. The rubber modification enhanced the property of the emulsified asphalt binder at low temperatures, and the improvement effect was enhanced as the rubber content in the emulsified asphalt was raised. The C=O band was more effective in quantifying the aging condition of the residue. The findings of this study may further advance the emulsified asphalt technology in pavement construction and maintenance.

Challenges Associated with Optimisation of Blending, Mixing and Compaction Temperature for Asphalt Mixture Modified with Crumb Rubber Modifier (CRM)

2012 ◽  
Vol 256-259 ◽  
pp. 1837-1844 ◽  
Author(s):  
Iman Mohammadi ◽  
Hadi Khabbaz
Keyword(s):  
Asphalt Mixture ◽  
Crumb Rubber ◽  
Test Methods ◽  
Asphalt Binders ◽  
Asphalt Pavements ◽  
Compaction Temperature ◽  
Modified Asphalt ◽  
Wide Range ◽  
Modified Binder ◽  
Very High

The use of modified asphalt binders has become much more common over the past two decades. Many types of modifier have been used in paving asphalts to enhance the performance of asphalt pavements in a wide range of climates and loading conditions. Among various asphalts binder modifiers, the recycled crumb rubber has been used very successfully for many years. Generally in production of CRM binder, mixing and compaction temperature is determined by measuring of binder viscosity. The ordinary method used for viscosity measurement of unmodified binder leads to a very high Mixing and Compaction Temperature (MCT) for CRM binder. The aims of this paper are to identify, develop and give some recommendations on a reliable laboratory approach for blending of CRM with binder, as well as introducing appropriate laboratory test methods for optimisation of MCT of crumb rubber modified binder asphalt.

scholarly journals Non-Newtonian Patient-specific Simulations of Left Atrial Hemodynamics

2021 ◽  
Author(s):  
Alejandro Gonzalo ◽  
Manuel Garcia-Villalba ◽  
Lorenzo Rossini ◽  
Eduardo Duran ◽  
David Vigneault ◽  
...  
Keyword(s):  
Blood Flow ◽  
Left Atrial ◽  
Flow Behavior ◽  
Blood Rheology ◽  
Patient Specific ◽  
Shear Rates ◽  
Wide Range ◽  
History Of ◽  
Slow Blood Flow ◽  
Cell Aggregations

Atrial fibrillation (AF) is the most common arrhythmia, affecting ~35M people worldwide. The irregular beating of the left atrial (LA) caused by AF impacts the LA hemodynamics increasing the risk of thrombosis and ischemic stroke. Most LA thrombi appear in its appendage (LAA), a narrow sac of varied morphology where blood is prone to stagnate. In the LAA, the combination of slow blood flow and low shear rates (<100 [1/s]) promotes the formation of red blood cell aggregations called rouleaux. Blood experiences a non-Newtonian behavior when rouleaux formed that has not been considered in previous CFD analysis of the LA. We model the anatomy and motion of the LA from 4D-CT images and solve the blood flow inside the LA geometry with our CFD in-house code, which models Non-Newtonian rheology with the shear-hematocrit-dependent Carreau-Yasuda equation. We cover a wide range of non-Newtonian effects considering a small and a large hematocrit, including an additional constitutive relation to account for themrouleaux formation time, and we compare our results with Newtonian simulations. Blood rheology influence in LAA hemostasis is studied in 6 patient-specific anatomies. Two subjects had an LAA thrombus (digitally removed before running the simulations), another had a history of TIAs, and the remaining three had normal atrial function. In our simulations, the shear rate remains below 50 [1/s] in the LAA for all non-Newtonian models considered. This triggers an increase of viscosity that alters the flow behavior in that site, which exhibits different flow patterns than Newtonian simulations. These hemodynamic changes translate into differences in the LAA hemostasis, calculated with the residence time.

URBAN FACADE GEOMETRY ON OUTDOOR COMFORT CONDITIONS: A REVIEW

2020 ◽  
Vol 4 (1) ◽  
pp. 45
Author(s):  
Elahe Mirabi ◽  
Nasrollahi Nazanin
Keyword(s):  
Thermal Comfort ◽  
Urban Areas ◽  
Natural Ventilation ◽  
Flow Behavior ◽  
Air Flow ◽  
Urban Geometry ◽  
Wide Range ◽  
Low Energy Buildings ◽  
Outdoor Comfort ◽  
Solar Access

<p>Designing urban facades is considered as a major factor influencing issues<br />such as natural ventilation of buildings and urban areas, radiations in the<br />urban canyon for designing low-energy buildings, cooling demand for<br />buildings in urban area, and thermal comfort in urban streets. However, so<br />far, most studies on urban topics have been focused on flat facades<br />without details of urban layouts. Hence, the effect of urban facades with<br />details such as the balcony and corbelling on thermal comfort conditions<br />and air flow behavior are discussed in this literature review. <strong>Aim</strong>: This<br />study was carried out to investigate the effective factors of urban facades,<br />including the effects of building configuration, geometry and urban<br />canyon’s orientation. <strong>Methodology and Results</strong>: According to the results,<br />the air flow behavior is affected by a wide range of factors such as wind<br />conditions, urban geometry and wind direction. Urban façade geometry<br />can change outdoor air flow pattern, thermal comfort and solar access.<br /><strong>Conclusion, significance and impact study</strong>: In particular, the geometry of<br />the facade, such as indentation and protrusion, has a significant effect on<br />the air flow and thermal behavior in urban facades and can enhance<br />outdoor comfort conditions. Also, Alternation in façade geometry can<br />affect pedestrians' comfort and buildings energy demands.</p>

scholarly journals Material Properties and Environmental Benefits of Hot-Mix Asphalt Mixes Including Local Crumb Rubber Obtained from Scrap Tires

Environments ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 47
Author(s):  
Lim Min Khiong ◽  
Md. Safiuddin ◽  
Mohammad Abdul Mannan ◽  
Resdiansyah
Keyword(s):  
Asphalt Binder ◽  
Crumb Rubber ◽  
Environmental Benefits ◽  
Asphalt Binders ◽  
Rubber Content ◽  
Scrap Tires ◽  
Asphalt Mixes ◽  
Temperature Resistance ◽  
Modified Asphalt ◽  
Marshall Stability

This paper presents the results of a laboratory-based experimental investigation on the properties of asphalt binder and hot-mix asphalt (HMA) mixes modified by locally available crumb rubber, which was used as a partial replacement of asphalt by weight. In this study, fine crumb rubber with a particle size in the range of 0.3–0.6 mm, obtained from scrap tires, was added to the asphalt binder through the wet process. Crumb rubber contents of 5%, 10%, 15%, and 19% by weight of asphalt were added to the virgin binder in order to prepare the modified asphalt binder samples, while the unmodified asphalt binder was used as the control sample. The crumb rubber modified binder samples were examined for measuring viscosity indirectly using the penetration test, and temperature resistance using the softening point test. Later, both the modified and unmodified asphalt binders were used to produce HMA mixes. Two categories of HMA mix commonly used in Malaysia—namely, AC 14 (dense-graded) and SMA 14 (gap-graded)—were produced using the modified asphalt binders containing 5%, 10%, 15%, and 19% crumb rubber. Two AC 14 and SMA 14 control mixes were also produced, incorporating the unmodified asphalt binder (0% crumb rubber). All of the AC 14 and SMA 14 asphalt mixes were examined in order to determine their volumetric properties, such as bulk density, voids in total mix (VTM), voids in mineral aggregate (VMA), and voids filled with asphalt (VFA). In addition, the Marshall stability, Marshall flow, and stiffness of all of the AC 14 and SMA 14 mixes were determined. Test results indicated that the modified asphalt binders possessed higher viscosity and temperature resistance than the unmodified asphalt binder. The viscosity and temperature resistance of the asphalt binders increased with the increase in their crumb rubber content. The increased crumb rubber content also led to improvements in the volumetric properties (bulk density, VTM, VMA, and VFA) of the AC 14 and SMA 14 mixes. In addition, the performance characteristics of the AC 14 and SMA 14 mixes—such as Marshall stability, Marshall flow, and stiffness—increased with the increase in crumb rubber content. However, the AC 14 mixes performed much better than the SMA 14 mixes. The overall research findings suggest that crumb rubber can be used to produce durable and sustainable HMA mixes, with manifold environmental benefits, for use in flexible pavements carrying the heavy traffic load of highways.

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