Impact of viscosity modifier on asphalt properties used for bus rapid transit lane in Chengdu (original) (raw)
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ASCE: T & DI Congress 2011, 2011
The Superpave asphalt binder specifications are intended to improve pavement performance by limiting the potentials for plastic deformation and cracking. Hot-mix asphalt (HMA) behavior depends on the binder’s—temperature susceptibility, and the rate of loading. The binder viscosity temperature susceptibility (VTS) characterization plays a major role in determining the HMA dynamic modulus (E*) master curve, especially when input Level 3 is used in the M-E PDG. For input Levels 2 and 3, E* could be predicted by the Witczak equation, whereas, three test methods are specified to determine the asphalt binder VTS. These tests are (i) dynamic shear rheometer (DSR) for determining shear modulus (Gb*) and phase angle (δ); (ii) conventional tests such as penetration, kinematic and absolute viscosities, and ring and ball softening point; and (iii) rotational viscosity. All test methods can be utilized to determine the ASTM “A-VTS” parameters. In this paper, the A-VTS parameters for twenty two (22) neat and polymer modified binders were obtained from the three test methods and compared. The results show that A-VTS parameters from the three tests could be significantly different. Further, the impact of the VTS parameters’ variations on the E* master curve and on the predicted flexible pavement performance are discussed.
Determination of Zero Shear Viscosity of Warm Asphalt Binders
With the increasing awareness of the warm asphalt technology, it is imperative to study the properties of the binders containing the warm asphalt additives thoroughly, especially since not much research has been conducted on warm asphalt binder properties to date. Also, in the recent years, researchers have observed that the SHRP rutting parameter G*/sin δ is not very effective in predicting the rutting performance of binders, especially in case of modified binders. Zero shear viscosity (ZSV) has been evaluated to determine its effectiveness in predicting the rutting behavior of asphalt binders. Thus, in this paper, the ZSV of five asphalt binders with and without the warm asphalt additives, Asphamin® and Sasobit®, were calculated using the different models and test methods available in literature. From the test results, it was observed that the addition of the warm asphalt additives increased the ZSV of all the five binders used in this study. It was also observed that the different test methods gave different ZSV values, and that the selection of the test methods and the testing parameters are crucial parameters.
THE EFFECT OF COMMERCIAL WAX ON VISCOSITY CHARACTERISTICS OF MODIFIED ASPHALT
The study was carried out to determine the effect of a commercial wax Sasobit (additive) on the bitumen viscosity. The binder consistency and hence ability to sustain and hold its fundamental cementing mechanism changes depending on its viscosity. In this study bitumen with penetration grade 60/70 was modified with a commercial wax sasobit to improve its performance. The binders mixed with various percentage of the additive 0.5%, 1%, 1.5%, 2%, 2.5% and 3% were investigated and the trend was the viscosity of the binder decreases at higher temperatures while at midrange temperatures the viscosity increases with an increase in the additive. This could be attributed to the presence of additive in the binder, which is expected to improve workability and enhance the resistance to deformation of the asphalt concrete mixture. The results from the study also indicated increase in softening point and the decrease in the binder penetration as the additive hardens the binder.
A STUDY ON THE VARIATION OF VISCOSITY AND FILM THICKNESS OF MODIFIED BINDERS AT VARIOUS TEMPERATURES
The government of India has setup an investment plan of Rs.3,23,000 crores in the 12 th five-year plan for road construction and infrastructure industry. In addition, more than twice this amount is likely to be contributed by the private investors engaged in road sector industry. Taking into account this considerable investment in road construction, it is required that robust design methods are followed during the initial phase of construction, as maintenance cost of these structures are likely to be higher than the initial expenditure for construction. Hence considerable research and development work in terms of material characterization is urgently required.
Zero Shear Viscosity of Hybrid Modified Asphalts and Its Gray Correlation with Other Properties
Materials
The viscosity of modified asphalt binders is the most important property to ensure the durability of open-graded friction course (OGFC). Zero shear viscosity (ZSV) is considered to be the optimum result to reflect the rutting characterization of high viscosity modified asphalt binders, compared with conventional vacuum capillary viscosity. However, there are few reports on using ZSV to evaluate the material characteristics of hybrid modified asphalt binders and to establish the relationship between ZSV and other properties. In this paper, a high viscosity hybrid modified asphalt binder was prepared with Sty-rene-butadiene-styrene (SBS) and Crumb rubber modifier (CRM). ZSV, three major indicators, 60 °C dynamic viscosity, 135 °C Brookfield viscosity, and a dynamic rheological test were used to determine the properties of the hybrid modified asphalt binders. The relationship between ZSV and other properties was studied by the gray correlation analysis method. Results indicated that: (...
RANKING ASPHALT BINDERS BY ACTIVATION ENERGY FOR FLOW
The viscosity of neat and modified asphalt binders were measured at temperatures between 110 o C and 160 o C by rotational viscometry. The Arrhenius relationship was used to analyze the data and obtain the activation energy for flow of the asphalt binders. Activation energies for flow ranged from 44 kJ/mol to 90 kJ/mol. The effects of film thickness, asphalt type, aging, polymer content, and polymer type on the activation energy for flow were studied. A preliminary analysis was conducted to explain these effects. The results indicate that the activation energy for flow can be used to differentiate asphalt binders and rank their temperature susceptibility in a quantitative manner. It is suggested that this asphalt binder ranking can be used to predict the relative compaction effort for these binders in mixes.
New Predictive Models for Viscosity and Complex Shear Modulus of Asphalt Binders
Transportation Research Record: Journal of the Transportation Research Board, 2007
The main purpose of this paper is to present the development of a set of predictive models for the viscosity and complex shear modulus of asphalt binders. The model development was aimed at overcoming the limitations of current models used in the Mechanistic-Empirical Pavement Design Guide (MEPDG), which has been developed under NCHRP Project 1-37A and refined under NCHRP Project 1-40D. A comprehensive study was completed at Arizona State University to conduct a number of asphalt binder tests and to finalize a large binder characterization database containing 8,940 data points from 41 different virgin and modified binders. This database was used to develop the new models. The first of the models developed in this study is a fully revised version of the widely known ASTM Ai-VTSi viscosity model. This new, revised model takes into account the loading frequency applied on the binder while accurately predicting the viscosity at a specific temperature and loading frequency from the Ai an...
Construction and Building Materials, 2014
This study presents three bitumen modifiers which may find successful application in the fabrication of binders for warm mix asphalt in the paving industry. In that sense, two non-polymeric additives, thiourea and thiourea dioxide, along with a reactive isocyanate-terminated prepolymer have been evaluated. Viscous flow and linear viscoelasticity tests, at 60 ºC, reveal bituminous modified binders which evolve towards highly viscous materials when subjected to ambient curing. However, at 135 ºC, they show lower viscosity than a typical 3 wt.% SBS binder used as reference. These results suggest modified binders with low viscosity which may contribute to reduce the mix asphalt temperature. On the contrary, they are expected to undergo an important increase in viscosity when the asphalt is in service, which would contribute to improve further their performance. Low temperature performance and effects of short-term and long-term aging were not considered in this study.
International Journal of Engineering and Technology, 2015
The complex moduli relationship related mixture moduli to temperature and time rate of loading has been an integral part of several mechanistic-empirical (M-E) design procedures used throughout of the world. Seven asphalt concrete mixtures of different types of polymer modified binders (PMB) were produced in a laboratory to modify performance of asphalt mixture. The main role of this research is to evaluate the influence of these polymer modifiers on the pavement performance of asphalt mixture with the dynamic modulus, |E*| of hot-mix asphalt (HMA) mixture indicator in a laboratory test for Mainroad Western Australia and Fulton Hogan. In this study, the influence of temperature, loading frequency, and confining pressure on the dynamic characteristic of asphalt mixture were analysis, master curves of dynamic modulus of HMA mixtures were developed and data's were interpreted. Results showed that AC10 5.7% A35P (EVA) M7 B5, AC10 5.7% C450 M10 B5 and AC10 Multi 600/700 M5 B4 mixes method were the more efficient and effective in all categories of asphalt performance measures for strength and durability of HMA as compared to others polymer modifiers. A very good correlation (R 2 = 1) was found for each polymer modifier. This suggested that laboratory test using a various temperatures and loading frequencies can improve pavement mix design, lab and field control and assurance. A strong correlation between binder viscosity and temperature [R 2 = 1] for polymer modified asphalt mixture.
Transportation Research Record, 2005
Rotational viscosities of different asphalt binders were determined at temperatures between 80°C and 185°C. Viscosity-temperature dependence of asphalt binders was described with the use of the Vogel-Tammann-Fulcher (VTF) and the William-Landel-Ferry (WLF) equations. The Vogel temperature (T v) and the glass transition temperature (T g) for different asphalt binders were determined by fitting experimental values of viscosity at different temperatures with these two equations. For asphalt binders, the difference between T v and T g was about 40K. Effects of asphaltenes, aging, chemical modification, and polymer content on these temperatures were evaluated. As asphaltene content increased, both temperatures, T v and T g , increased. Different polymers showed different effects on these temperatures. The values of T v and T g were correlated with the critical cracking temperature (T cr) determined through use of a bending beam rheometer and a direct tension tester. The results suggested that the correlations between T v , T g , and T cr could be used to determine T cr from the rotational viscosity results tested at high temperature. With simple rotational measurements, a quick estimation of T cr of asphalt binders could be obtained. Liquid fragility theory was also used to study T g of asphalt binders. Parameters determined with the VTF and WLF equations indicated that asphalt binders behaved as fragile liquids because of their non-Arrhenius behavior in the temperature range studied.