Asphalt Binder Source Research Articles

Implementation considerations of Balanced Mix Design in practice: recent experience in Vermont

This paper discusses the implementation considerations of Balanced Mix Design (BMD) in both design and production phases according to the recent experience from the agency and a contractor in Vermont since BMD was implemented by Vermont Agency of Transportation (VTrans) in 2019. In the design, the sensitivity of selected performance tests to mix design factors and the impact of asphalt binder source are two important aspects to consider as both agency and contractor need to understand the implications on the potential change of mix compositions. There are also several critical things to consider if BMD is implemented in production, including but not limited to the impact of production variation, the difference between design and production, and so forth. A case study through a VTrans pilot project constructed in 2020 season is discussed to demonstrate the importance of these considerations.

Recycled Polyethylene Modified Asphalt Binders and Mixtures: Performance Characteristics and Environmental Impact

This study addresses the effects of recycled polyethylene (RPE) on the performances of both asphalt binders and asphalt mixtures. Whether using RPE in an asphalt mixture might leach harmful chemicals into rainwater or melted snow was also determined. Two processes, wet and dry, were used to formulate the RPE modified asphalt binders and mixtures. In the wet process, RPE was added to asphalt binder. In the dry process, it was added to heated aggregates. RPE from two sources and PG 64-22 virgin asphalt binders from two sources were used in this study. In conclusion, RPE improved the rutting resistance of the asphalt binders and asphalt mixtures. However, it had adverse effects on their resistance to intermediate-temperature and non-load associated cracking. The dry process could produce a mixture with a higher RPE dosage compared with the wet process using one virgin asphalt binder but not the other; thus, the virgin asphalt binder source was a significant factor for the dry process. Based on an embryotoxicity test, it was found that RPE can be used by the asphalt paving industry without creating any significant environmental risks.

Influence of Production Considerations on Balanced Mixture Designs

Measuring or predicting mixture performance prior to placement has become essential for many state transportation agencies due to incorporation of more recycled materials into mixtures, utilization of binders formulated with various modifiers, and utilization of new and unproven technologies. Mixtures designed incorporating these elements in accordance with the current Superpave mixture design method have unknown performance as Superpave was never designed to compensate for them. Thus, agencies have interest in implementing the balanced mixture concept that requires testing for acceptable mixture performance during the design phase. The effect of production considerations on a balanced mixture design is not known. It is unknown if a mixture remains performance balanced during production due to factors like asphalt content, gradation and binder source variations. This study was undertaken to understand the influence of these production considerations on a balanced mixture design. Two Superpave mixtures, a 9.5 mm and 12.5 mm, were developed using the balanced mixture design approach using volumetric properties, one rutting test and one cracking test. These mixtures were then modified to represent production variations in asphalt binder content, gradation passing the No. 200 sieve, and asphalt binder source. All mixtures remained performance balanced when examining the production considerations in terms of rutting and cracking using the selected tests. Examination of other performance results, like moisture susceptibility, suggest it is possible to effectively unbalance the mixture design during production. This underscores the importance of proper selection of performance tests to address the performance needs of the agency.

Significance of pH Variance in Predicting Chemical Reaction in Hot Mix Asphalt

AbstractHot mix asphalt (HMA) is a combination of siliceous, calcareous, or intermediate aggregate materials from selected sources, blended with formulated asphalt binders from various asphalt binder producers. These components are modified by additional additives to enhance the bonding of the binders and aggregates. Concern over moisture damage (stripping), defined as the loss of strength and durability in asphalt mixtures when the binder separates from the aggregate, has prompted years of research into a variety of failure mechanisms. Prominent in these failure mechanisms is the pH at the binder–aggregate interface. This technical paper addresses the pH variance of individual components and loose blended HMA mixes from 17 selected material sources and 2 asphalt binder sources to assess the pH of any chemical reactivity. The main objective of the paper is to determine whether pH variances of individual components or mixed HMA materials (asphalt binder, aggregate, and additives) point to suspect component...

Rheology evaluations of WMA binders using ultraviolet and PAV aging procedures

Oxidation of an asphalt binder affects the long term performance of an asphalt pavement, especially under thermal and/or ultraviolet (UV) radiation conditions. The objective of this study is to investigate the rheological behaviors of various WMA binders after long term UV aging and conventional PAV aging procedures. The following rheological properties were tested and evaluated in this study: complex shear modulus, phase angle, elastic modulus, viscous modulus at an intermediate service temperature, and deflection, stiffness, and m-value at a low temperature. The experimental design included four asphalt binder sources (two grades); four WMA additives and control. Two aging methods of UV and PAV aging were utilized and a total of 40binders were tested and evaluated. The test results indicated that UV and PAV aging procedures are significantly affected by asphalt binder source and grade. In addition, WMA additives generally have no influences on rheological properties of UV and PAV aged binders. Moreover, the differences in deflection, creep stiffness, and m-values of UV and PAV aged binders are generally not affected by their grade, source and WMA additives. Therefore, UV aging procedure used in this study may be an effective method in investigating rheological characteristics of WMA binder after a long term aging process.

Evaluation of the Rheological Properties and Activation Energy of Virgin and Recovered Asphalt Binder Blends

AbstractIn this study, the rheological properties and activation energy (AE) of unaged and aged asphalts blended with different percentages of binder, recovered from three reclaimed asphalt pavement (RAP) sources, were investigated. Superpave asphalt binder tests were used to evaluate the effects of the recovered asphalt binder source and content. The results indicated that the addition of recovered binder from each source increased the viscosity, G*/sinδ, and G*sinδ. The increase in viscosity per 1% recovered binder was evaluated using non-dimensional viscosity index (∇ηRAP). In addition, the increase in G*/sinδ and G*sinδ per 1% recovered binder were investigated using relative Superpave rutting gradient (RSRG) and relative G*sinδ gradient (RG) factors, respectively. The results indicated that the ∇ηRAP, RSRG, and RG depended on recovered binder source, content, aging, and test temperature. The interpretation of the AE results depended on the physical phase of the asphalt blends, irrespective of the rec...

A long-term ultraviolet aging effect on rheology of WMA binders

Asphalt binder is generally easy to age in the field, especially under thermal and/or ultraviolet (UV) radiation conditions. Current asphalt performance evaluation system gives limited consideration to UV aging, especially, as using warm mix asphalt (WMA) technologies. The objective of this study is to investigate the influence of long-term UV aging on rheology of various WMA binders. The following rheological properties were tested and evaluated in this study: viscous flow, performance grade, creep and creep recovery, amplitude and frequency sweep tests. The experimental design included four asphalt binder sources and two grades; four WMA additives (Cecabase-RT, Evotherm, Rediset, and Sasobit) and control. A total of 20 binders were tested. The test results indicated that a UV aging procedure generally had obvious effect on the complex modulus and phase angle values of various UV aged WMA binders. Their viscosity values were generally different since the WMA additive or binder source played a key role. Moreover, creep and creep recovery generally showed a similar trend for various WMA binders. Similarly, the amplitude and frequency sweep values exhibited a similar trend for various WMA binders but these values were different for various binder sources and grades. Therefore, it is necessary to explore the rheological properties of WMA binders after a long term UV aging procedure in the lab.

Significance of Mixture Parameters on Binder Aging in Hot-Mix Asphalt Mixtures

Traditionally, aging studies of asphalt materials have been conducted primarily on asphalt binders only and have omitted any potential influence of the aggregate. These results are commonly extrapolated to the mixture behavior without a comprehensive understanding of how the mixture characteristics may potentially influence the aging of the binder within the mixture. This study was initiated by FHWA to evaluate the effects of mixture parameters—namely, different aggregate and asphalt binder sources, air voids, and binder contents—on the aging characteristics of asphalt binders aged in mixtures. Those same binders were also aged in pressure aging vessel (PAV) pans in laboratory ovens to determine the aging characteristics of the asphalt binders, as is the current state of practice. These characteristics were determined by the binder kinetics, with respect to the carbonyl area measured from the Fourier transform infrared spectroscopy spectra as a function of aging time and temperature. The hardening susceptibility (HS) of the asphalt binders, as defined by the relationship between the low shear viscosity and the carbonyl area, was also determined. The HS of the asphalt binders aged in the mixtures was compared with the HS of the binders aged in the PAV pans and was found to be statistically dissimilar for some mixtures and statistically similar for others. The analysis revealed that the effective binder content of the mixtures provided the strongest indicator of whether the evaluated mixture parameters would have a significant influence on the aging characteristics of the asphalt binder in the mix.

Long-term ageing influence on rheological characteristics of asphalt binders containing carbon nanoparticles

Nano-sized particles have been used in numerous applications to improve properties of various materials. The utilisation of nanotechnology in civil engineering area is relatively new and its use and applications are expected to increase rapidly. The objective of this study was to investigate and evaluate the rheological properties of binders containing various percentages of carbon nanoparticles after a long-term ageing process. The experimental design for this study included the utilisations of five binder sources (three grades of PG 64-22, PG 64-16 and PG 52-28) and four nano percentages (0.0, 0.5, 1.0 and 1.5% by weight of the virgin binder). The rheological characteristics of these pressurised aged vessel (PAV) binders were tested including G* value, creep and creep recovery, and frequency and amplitude sweep at an intermediate temperature and deflection, stiffness and m-value at a low temperature as well. The results of the experiments indicated that the addition of nanoparticles does not increase the G* values and does have an obvious effect on complex modulus, phase angle under a frequency sweep test. However, nanoparticles have a slight effect on creep angle and compliance of a binder. Moreover, at a low tested temperature, the experimental results indicate that the nanoparticles have no effect on deflection, stiffness and m-value of PAV residue. Furthermore, statistical analysis indicates that the asphalt binder source and grade rather than nanoparticles play a key role in determining the rheological properties

Viscosity prediction of CRM binders using artificial neural network approach

The primary objective of this study was to develop a series of artificial neural network (ANN) models to predict the viscosity values of crumb rubber-modified (CRM) binders using four input variables: asphalt binder source, rubber size, mixing duration and rubber content. The results indicated that ANN-based models are effective in predicting the viscosity values of CRM binders regardless of rubber type and can easily be implemented in a spreadsheet. In addition, the developed ANN model can be used to predict viscosity values of other types of CRM binders. Furthermore, the results also show that asphalt binder source, rubber size and rubber content are the most important factors in the developed ANN models while the mixing duration is relatively unimportant. The sensitivity analysis of input variables indicated that the viscosity changes significantly with changes in asphalt binder source, rubber size and rubber content.

Characterization of Unaged Asphalt Binder Modified with Carbon Nano Particles

In recent years, nanotechnology has been utilized in many engineering applications. In this technology, nano-sized particles are used in improving the properties of various materials. The construction industry, in general, has not embraced this technology; however, these particles could be used to enhance the physical and chemical properties of the materials such as asphalt binders. The objective of this study was to investigate and evaluate the rheological properties of three asphalt binder sources containing various percentages of carbon nano particles. The experimental design for this study included the utilizations of three binder sources (PG 64-22), one type of nano particle, and four nano dosage percentages (0.2%, 0.5%, 1.0%, and 1.5% by weight of the binder). The following rheological properties were tested and evaluated: viscosity, performance grade, creep and creep recovery, and frequency sweep. The results of the experiments indicated that the addition of nano particles was helpful in increasing the viscosity, failure temperature, complex modulus, and elastic modulus values as well as in improving rutting resistance of the binder. On the other hand, the content analysis of nano particles showed that a relatively low percentage (＜0.2%) of nano particles did not have a significant effect on improving the binder properties while a relative high percentage (＞1.0%) of nano particles is recommended for the modification of an asphalt binder.

Influence of Carbon Nanoparticles on the Rheological Characteristics of Short-Term Aged Asphalt Binders

Nanotechnology has the potential to create many new materials and devices with wide-ranging purposes. Nano-sized particles have been used in numerous applications to improve the properties of various materials. The utilization of nanotechnology in civil engineering is expected to increase and may become an attractive alternative for asphalt binder modification. The objective of this study was to investigate and evaluate the rheological properties of binders containing various percentages of carbon nanoparticles after a short-term aging process. The experimental design for this study included five binder sources (three grades including PG 64-22, PG 64-16, and PG 52-28), three nano percentages (0.5, 1.0, and 1.5% by weight of the virgin binder), and control binders. The rheological characteristics of the rolling thin film oven (RTFO) binders, including failure temperature, performance grade, creep and creep recovery, viscous flow, and frequency and amplitude sweep, were tested. The results of the experiments indicated that the addition of nanoparticles was helpful in increasing the failure temperature, complex modulus, and elastic modulus values and in improving rutting resistance of the RTFO binder. The phase angle of the binders generally decreased with an increase in nano content and RTFO aging procedure. In addition, statistical analysis indicated that the asphalt binder source plays a key role in determining the rheological properties because of significant evaluations.

Midrange Temperature Rheological Properties of Warm Asphalt Binders

With increasing concerns of global warming and increasing emissions, the asphalt industry is making a constant effort to lower its emissions by reducing the mixing and compaction temperatures of the asphalt mixture without affecting the properties of the mix. Several proprietary chemicals are available in the industry that can help reduce the mixing and compaction temperatures. A significant reduction of required heat can be achieved in most cases. Several studies have been conducted evaluating the properties of the warm mix asphalt; however, properties of the binders containing these chemicals have not been studied in great detail. Warm asphalts were produced using two of the available processes utilizing five different asphalt binder sources, and some rheological tests were conducted (dynamic shear rheometer and viscosity). The results indicated that binders containing the inorganic additive Aspha-Min (Eurovia, France) underwent minor or no changes compared to the base binders in terms of flow properties, stiffness, and response to creep. However, the flow of binders with the additive Sasobit (Sasol Wax, Germany), which consists of aliphatic hydrocarbons, changed from Newtonian to shear thinning at 60°C, and the viscosity of the binder at 60°C increased. Sasobit also improved the stiffness and penetration resistance of the base binders, and binders with Sasobit had significantly lower permanent deformations after repeated creep-recovery tests compared to the base binders.

Estimating Indirect Tensile Strength of Mixtures Containing Anti-Stripping Agents Using an Artificial Neural Network Approach

The objective of this study was to develop a series of artificial neural network (ANN) models to predict the indirect tensile strength (ITS) and tensile strength ratio (TSR) of various mixtures considering five input variables such as asphalt binder source, aggregate source, anti-striping agents (ASA), conditioning duration, and asphalt binder content. The results indicate that ANN-based models are effective in predicting the ITS and TSR values of mixtures regardless of the test conditions and can easily be implemented in a spreadsheet, thus making it easy to apply. In addition, the developed ANN models can be used to predict (or estimate) the ITS values of the mixtures used in other research projects. Furthermore, the results also show that the asphalt binder source, aggregate source, and asphalt binder content are the most important factors in the developed ANN models while the conditioning duration is relatively unimportant (i.e., it has less effect on the ITS values in comparison with other variables). In addition, the sensitivity analysis of input variables indicated that the changes of ITS values are significant as the changes of the most important independent variables.