Engineering Properties of Asphalt Binders from Different Sources and Their Influence on Stiffness of Asphalt Concrete Mixtures

Author(s):  
Alexandra Torres

The quality and quantity of asphalt binder are crucial for proper adhesion, cohesion, and performance of asphalt concrete (AC) mixtures. The current Superpave grading system for asphalt binders provides engineers with the high and low temperature ranges at which the asphalt binder should perform satisfactorily. The objectives of this study are to document the differences in the performance of different asphalt binders with the same nominal performance grade (PG) acquired from different refineries and to investigate the impact that binder properties may have on the stiffness of the AC mixes. To that end, five PG 64-22 and five PG 70-22 binders were studied. Each binder was graded twice, in the original state and extracted from the mix conditions. The conventional performance grading tests such as the bending beam rheometer, dynamic shear rheometer, pressure aging vessel, and rolling thin-film oven were conducted on all asphalt binders. Alternative binder parameters (e.g., parameter ΔTc, viscosity) that can potentially supplement the current PG system were measured and documented. The stiffness properties of the ten mixes as measured with the dynamic modulus tests were correlated with the measured binder properties. The asphalt binders with the same performance grades yielded different cracking, rutting, and stiffness properties, which may explain the differences in their performance when used to design AC mixes.

Author(s):  
Jhony Habbouche ◽  
Elie Y. Hajj ◽  
Peter E. Sebaaly ◽  
Adam J. Hand

Florida Department of Transportation uses the 1993 AASHTO guide to conduct new and rehabilitation designs for all the state’s flexible pavements. Based on previous experience, a structural layer coefficient of 0.44 was found to be well representative of the department’s conventional polymer-modified (PMA) asphalt concrete (AC) mixtures. If the positive impact of the polymer on the layer is assumed to be maintained at higher contents, then the use of high polymer-modified (HP) asphalt binder may lead to a higher AC structural layer coefficient and a reduced AC layer thickness for the same design traffic and serviceability design loss. The objective of this paper was to determine a fatigue-based structural layer coefficient for asphalt mixtures that contain HP binder using comprehensive mechanistic analyses. This approach relied on combining measured engineering properties and performance characteristics of AC mixtures with advanced flexible pavement modeling (3D-Move). A total of eight PMA and eight HP AC mixtures were designed and evaluated in the laboratory. Overall, the HP AC mixtures showed similar or lower dynamic modulus and better fatigue performance models when compared with those of their respective PMA AC mixtures. However, the fatigue-based structural layer coefficients, determined via mechanistic analysis using the service life approach, ranged between 0.33 (lower than 0.44) and 1.32 (greater than 0.44). Using advanced statistical analyses, a fatigue-based structural layer coefficient of 0.54 was determined for HP AC mixtures. This coefficient should still be verified for other modes of distress.


Author(s):  
Gerald A. Huber ◽  
Xishun Zhang ◽  
Robin Fontaine

The Strategic Highway Research Program (SHRP) spent $50 million researching asphalt binders and asphalt mixtures and provided three main products: an asphalt binder specification, an asphalt mixture specification, and Superpave, an asphalt mixture design system that encompasses both the binder and mixture specification. SHRP researchers have provided tools that promise more robust asphalt mixtures with reduced risk of premature failure. Implementation of the specifications and mix design system will require overcoming several obstacles. Superpave must be demonstrated to be practical and easy to use. The impact of Superpave aggregate requirements on aggregate availability must be determined. The Superpave gyratory compaction procedure has been uniquely defined and then calibrated to traffic volume. The reasonableness of this approach must be tested in widespread application. Perhaps the largest implementation hurdle exists in the performance models. Expensive test equipment is necessary to do the performance-based tests. The performance predictions must be established as reasonable to justify the cost. A highway reconstruction project containing three Superpave Level 1 mix designs is documented including quality control done with the Superpave gyratory compactor. Superpave Level 2 performance-based tests were carried out to predict permanent deformation of the design and the mixture as constructed. The performance-based engineering properties obtained from the tests are evaluated, and the reasonableness of the performance prediction models is discussed.


Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1067 ◽  
Author(s):  
Hechuan Li ◽  
Jianying Yu ◽  
Shaopeng Wu ◽  
Quantao Liu ◽  
Yuanyuan Li ◽  
...  

Induction heating is a valuable technology to repair asphalt concrete damage inside. However, in the process of induction heating, induced particles will release a large amount of heat to act on asphalt binder in a short time. The purpose of this paper was to study the effect of induction heating on asphalt binder aging in steel fibers modified asphalt concrete. The experiments were divided into two parts: induction heating of Dramix steel fibers coated with asphalt binder (DA) and steel wool fibers modified asphalt concrete. After induction heating, the asphalt binders in the samples were extracted for testing aging indices with Fourier Transform Infrared (FTIR), Dynamic Shear Rheometer (DSR), and Four-Components Analysis (FCA) tests. The aging of asphalt binder was analyzed identifying the change of chemical structure, the diversification of rheological properties, and the difference of component. The experiments showed that the binder inside asphalt concrete began aging during induction heating due to thermal oxygen reaction and volatilization of light components. However, there was no peak value of the carbonyl index after induction heating of ten cycles, and the carbonyl index of DA was equivalent to that of binder in asphalt concrete after three induction heating cycles, which indicated the relatively closed environment inside asphalt concrete can inhibit the occurrence of the aging reaction.


Author(s):  
Nura Bala ◽  
Amirhossein Ghasemirad ◽  
Leila Hashemian

In this study, high, intermediate and low temperature properties of two crude oil asphalts and three asphalts derived from Alberta oil sands bitumen distilled at temperatures of 400 °C, 430 °C and 460 °C were evaluated. High and intermediate temperature properties of the asphalt binders at different distillation temperatures were studied using a dynamic shear rheometer (DSR) through the performance grading (PG) tests. Low-temperature properties and performance grading were evaluated using a bending beam rheometer (BBR). The DSR high-temperature analysis indicated that oil sand bitumens distilled at high temperatures have significantly higher stiffness and more resistant to permanent deformation. BBR test results showed that irrespective of the asphalt source, oil sand bitumens distilled at lower temperatures are more resistant to cracking at low temperatures. The overall results indicate that oil sand bitumens are thus suitable to be used for both asphalt pavements requiring low and high-temperature resistance.


2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Asif Ali ◽  
Naveed Ahmad ◽  
Muhammad Adeel ◽  
Syed Bilal Ahmed Zaidi ◽  
Muhammad Sohail Jameel ◽  
...  

Asphalt is one of the primary materials that are extensively used by the pavement industry throughout the world. Its behaviour is highly dependent on the amount of loading and the level of temperature it is exposed to. Asphalt has been modified in the past with different additives to improve its high- or low-temperature properties. In Pakistan, temperature remains high for most of the time of the year; hence, asphalt binders with less susceptibility to higher temperatures are preferred for flexible pavements. Acids, polymers, fibers, and extenders have been used by the researchers to improve high-temperature performance of asphalt mixture. In the present study, a bio material derived from the animal waste, named as bone glue (BG), has been used with the 60/70 penetration grade binder in dosages of 3%, 6%, 9%, and 12% by weight of asphalt binder. The bone glue is produced from a sustainable source. It is a cost-effective and eco-friendly material. Moreover, it produces a durable and nonhazardous asphalt composite. The influence of addition of bone glue on asphalt binder was evaluated using different testing techniques which include consistency tests, rheological analysis, and adhesion tests. Furthermore, different performance tests were conducted on bone glue-modified asphalt mixtures. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis were carried out to ensure the homogeneity and proper mixing of bone glue in asphalt binder. The results from the tests reveal that bone glue stiffens the asphalt binder hence enhancing its high temperature performance. Bone glue dosage of 9% by weight of the binder was found to be the optimum dosage based on the rheological and performance analysis.


Author(s):  
Alekh S. Bhurke ◽  
E. Eugene Shin ◽  
Lawrence T. Drzal

Pavement distress occurs through a variety of mechanisms, but it is always controlled by the adhesive and cohesive performance of the asphalt binder. Although the causes of pavement failures are known, the precise mechanisms by which they occur remain to be understood. Observation of the fracture morphology of asphalt concrete can provide some information in this respect. The fracture morphology of asphalt concrete is dependent on the morphology of the binder. A network structure was observed in thin asphalt binder films and the fracture morphology and engineering properties of asphalt concrete were found to be dependent on the network morphology of the asphalt binder. Addition of polymers to asphalt binders causes changes in the nature of the network structure, and its effect can be qualitatively determined by characterizing the fracture morphology. Styrene butadiene styrene (SBS), styrene ethylene butylene styrene (SEBS), styrene butadiene rubber (SBR) latex and an epoxy-terminated reacting polyolefin (Elvaloy AM) were used in this study. A quantitative method to determine the effect of polymer modification on the fracture properties of asphalt concrete is the J-contour integral fracture toughness measurement. An experimental protocol to measure the critical J-integral fracture toughness ( J1 c) was developed and the low temperature (-10°C) J1 c values were determined for SEBS and Elvaloy AM-modified asphalt concrete at three different concentrations.


Author(s):  
Geoffrey M. Rowe

ABSTRACTThe Vialit Cohesion Pendulum has been used for many years in Europe as a tool for assessing modified asphalt binders with a particular emphasis on chip seal/surfacing dressing applications. The cohesion measured in this device has been considered as an indicator of quality of the base asphalt binder and subsequent polymer formulation. This test demonstrates a transition between brittle and ductile failure of binder systems. When a test of this kind is compared to other binder tests, it is possible to deduce the impact that the high rate of loading in the Vialit Cohesion Pendulum test has on the test results. Data have been developed on a series of SHRP core asphalt binders and these are compared to master curves developed with the same binders. A discussion will follow on how the fracture of asphalt binder and mixture is both rate and temperature dependent and that this parameter always needs that consideration to truly evaluate the meaning of test data. A test of this nature, while founded partly on an empirical data base of use, can be better explained and understood with consideration of the speed of loading and temperature effects that allows the translation of fracture temperatures at one condition to those at another. The results from this type of evaluation offer better understanding of criteria such as fatigue, fracture and bond of asphalt binders and mixtures.


2020 ◽  
Vol 30 (1) ◽  
pp. 103-122
Author(s):  
Mana Motamedi ◽  
Gholamali Shafabakhsh ◽  
Mohammad Azadi

Asphalt concrete is composed of stone, sand, filler, and asphalt binder. Fatigue can be considered as a phenomenon affecting both the binder (asphalt binder or mastic) and the mixture. The purpose of this study was to investigate the fatigue damage response in asphalt binders, mastics, and asphalt concrete mixtures modified with nano-silica and synthesized polyurethane. The continuum damage mechanics method and phenomenological approaches in this study were used to investigate the fatigue performance. Obtained results indicated that the effect of the synthesized polyurethane on improving the fatigue life was far greater than that of nano-silica. The damage process in asphalt binders differed from that in the mastic and asphalt concrete mixture. Damage intensity parameter is an appropriate criterion for evaluating fatigue performance of asphalt binders and mastics. Concerning the fatigue of asphalt concrete mixture, the results of this study indicated a better convergence between the fatigue parameters of mastics and asphalt concrete mixture compared to asphalt binders, especially with increasing aging. Also, there was greater convergence between the fatigue life of the asphalt concrete mixture and asphalt binder and mastics in the method of continuum damage mechanics as compared to the phenomenological approach.


Author(s):  
Raj Dongré ◽  
Mark G. Bouldin ◽  
Dean A. Maurer

A new specification procedure was proposed recently to determine the low-temperature performance grade of asphalt binders. This new procedure uses bending beam rheometer (BBR) and direct tension test (DTT) data at two temperatures to determine the low-temperature grade of an asphalt binder. A study was conducted to validate this procedure by using asphalt binder retained samples from the widely published test road in Pennsylvania. This road was constructed in 1976 in Elk County, and performance—including low-temperature transverse cracking index—was monitored over 6 years. In this study, the retained binder samples from test sections T-1 to T-6 were tested with the BBR and the new Superpave® DTT. The data from these two tests were analyzed to obtain critical cracking temperatures and low-temperature performance grades. Results indicate that the new procedure correctly predicts the temperature at which cracking was observed in the field.


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