Polymer Modified Asphalt Binders Research Articles

Initial Field Validation of Poroelastic Pavement Made with Crumb Rubber, Mineral Aggregate and Highly Polymer-Modified Bitumen.

Tire/road noise in most driving conditions dominates other sources of traffic noise. One of the most efficient ways of reducing tire/road noise is to use the so-called “low noise pavement”. According to numerous studies, at present, poroelastic road pavement that is composed of rubber and mineral aggregate and polyurethane or bituminous binder gives the best noise reduction up to 12 dB. Unfortunately, there are many problems with making durable poroelastic pavements. This article presents the first results of a project that is executed in Poland and aims at the development of a durable, low noise poroelastic pavement based on polymer-modified asphalt binder called Safe, Eco-friendly POroelastic Road Surface (SEPOR). Two test sections were built in 2019 to test the production technology and performance of the SEPOR pavement. It is observed that some of the problems with previous poroelastic materials were mainly eliminated (especially delamination from the base layer and raveling) but noise reduction is a little less than expected (up to 9 dB). Rolling resistance for car tires is acceptable and fire properties (damping of spill fuel fires, toxic gas emission) are very good.

Investigation on self-healing of neat and polymer modified asphalt binders

The paving asphalts have long been recognized to be capable of self-healing. The objective of this study was to evaluate the healing potential of asphalt binders and investigate its relationship with molecular characteristics in terms of composition and structures. Five neat and styrene–butadiene–styrene (SBS) modified asphalt binders were characterized using the recently developed linear amplitude sweep-based healing test. The data were analyzed based on the viscoelastic continuum damage theory to establish healing master curves and determine the healing rate HR. Chemical evaluation methods included saturates, aromatics, resins, and asphaltenes fractionation, gel permeation chromatography, and nuclear magnetic resonance spectroscopy. Results indicated that the presence of more light/low-polarity fractions of saturates and aromatics or higher concentrations of small molecules promoted healing, as these molecules were expected to have higher mobility facilitating molecular diffusion across crack interfaces. Lower percentages of aromatic ring structures and more aliphatic chains corresponded to higher healing rates. The SBS-modified asphalt binders contained higher concentrations of aromatic rings, but still provided comparable healing potential with the neat asphalts.

Fatigue-Based Structural Layer Coefficient of High Polymer-Modified Asphalt Mixtures

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.

Nonlinear Viscoelastic Response of Crumb Rubber Modified Asphalt Binder Under Large Strains

Agencies have been increasing their use of polymer modified asphalt binders in recent years to address performance issues and lengthen the useful life of their pavements. When deployed these materials likely experience strain levels exceeding their linear viscoelastic (LVE) limits. The same situation exists in non-polymer modified asphalt binders as well, but the effect may be more pronounced in polymer modified systems because of their bi-phasic nature. In this study, terminally blended crumb rubber (CR-TB) modified asphalt is studied to understand and quantify the nonlinear viscoelastic response under large strains. The CR-TB binders are extensively used in pavements subjected to high vehicular loads and extreme climatic conditions; thereby, their response under large strains becomes more critical. The current standard characterization techniques are based on LVE response using small amplitude oscillatory shear rheology only and do not consider the behavior of binders under large strains. In this study, large amplitude oscillatory shear (LAOS) rheology is used as a framework to more thoroughly investigate the complete response of the CR-TB modified asphalt binder under large strains at 30°C, 40°C, 50°C, and 60°C and at the frequencies of 0.5, 1, and 5 Hz. The LAOS response is analyzed using Fourier-transform rheology and the orthogonal stress decomposition method involving Chebyshev polynomial representation. It is found that nonlinearity manifests greatly in this study material as strain levels increase and frequencies decrease. The relative nonlinearity increases with increasing strain amplitude and is more significant towards lower end of the tested temperature range. The CR-TB binder shows strain-stiffening/softening and shear-thinning/thickening behavior depending upon a specific temperature, strain level, and frequency.

Evaluation of moisture-induced damage of stone matrix asphalt mixture with polymer modified binder

Moisture – induced damage is one of the most common reasons for the premature deterioration of Hot Mix Asphalt (HMA) pavements. Over the years, extensive research has been carried out by scientists and engineers on this subject; however, pavements still succumb to early failure from infiltrating moisture. The purpose of this research is to study the moisture induced damage performance of Stone Matrix Asphalt (SMA) asphalt pavements using Styrene Butadiene Styrene (SBS) polymer modified asphalt binder. To achieve the objective of this research the Superpave gyratory compactor was used for preparing the asphaltic samples and determining the volumetric properties of mixtures. The physical properties of aggregate, bitumen and other mix materials were assessed and evaluated with the laboratory tests. The mixtures were prepared using penetration Graded (40-50) bitumen and a chemical named Polypropylene Fiber was used as a stabilizing additive. Volumetric properties, Marshall Stability, behaviour to moisture action etc. were determined in laboratory. From the results it is seen that addition of SBS to the asphalt binder has significantly improved the cohesion as well as adhesion properties of the asphalt binder, and hence the stripping performance. Therefore, it can be concluded that the SBS is suitable to be used as a modifier in order to enhance the properties of the asphalt binder and thus improving the performance of asphalt in and SMA mixes.

Evaluation of the performance of highly modified asphalt binder using accelerated pavement testing

ABSTRACT A full-scale experiment was conducted at the Florida Department of Transportation (FDOT)’s accelerated pavement testing (APT) facility to evaluate the performance of a newly formulated asphalt binder commonly referred to as Highly Modified Asphalt (HiMA) binder. Test sections were constructed using three dense-graded Superpave asphalt mixtures consisting of the same aggregate components and gradation. One mixture included a polymer-modified asphalt (PMA) binder meeting PG 76-22 requirements, another contained HiMA binder at the same effective binder content, and the third one also used HiMA binder but at an additional 0.5% binder content. The subsequent accelerated testing showed that, under similarly controlled conditions, test sections using HiMA binder exhibited better rutting and fatigue cracking performance than those with PG 76-22 PMA binder. The 0.5% additional HiMA binder content resulted in negligible improved performance compared to the sections using HiMA binder at the design content. Furthermore, supplementary laboratory tests including Dynamic Shear Rheometer (DSR), Multiple Stress Creep Recovery (MSCR), softening point, and Indirect Tensile strength confirmed the improved properties of the HiMA binder and HiMA mixtures.

Asphalt mixture reinforced with banana fibres

Stone Matrix Asphalt (SMA) is a gap-graded mixture which requires high contents of asphalt binder. To prevent draindown, natural or synthetic fibres and polymer-modified asphalt binders are conventionally used in SMA. Banana agribusiness is one of the major sources of post-harvest residue in Brazil. Amongst those residues, fibres extracted from the pseudostem of the banana plant are resistant and used in diverse purposes. The present study assesses the incorporation of fibres from the pseudostem of the banana plant in an SMA mixture. The fibre contents and lengths capable to prevent binder draindown were evaluated from draindown tests. Mechanical properties of an SMA mixture stabilised with different banana fibre lengths were analysed through the tests of Marshall stability, modified Lottman, Indirect Tensile Strength and Cantabro. The results indicated that the fibres studied are a viable alternative for SMA, stabilising draindown and improving its mechanical performance, especially at the length of 20 mm.

Evaluation of polyphosphoric acid on the performance of polymer modified asphalt binders

AbstractThe aim of this research is to evaluate the effect of polyphosphoric acid (PPA) on the mechanical performance of styrene–butadiene–styrene (SBS) and styrene–butadiene–rubber (SBR) modified asphalt. Conventional properties, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS) tests were conducted to evaluate the performance characteristics of asphalt at different PPA inclusions. Gel‐permeation chromatography (GPC), saturates, aromatics, resins, and asphaltenes (SARA), and Fourier transform infrared (FTIR) were carried to reveal the molecular weight, component and infrared spectra of asphalt. Results showed that PPA hardened the asphalt, improved the rutting and fatigue performances of polymer modified asphalt (PMA) binder, but weakened the anti‐cracking performances. Besides, storage stability had a significant improvement as the addition of PPA. The addition of PPA brought more macromolecules into asphalt and led to more high‐average molecular weight compounds. Furthermore, PPA changed four component ratios of asphalt. Both PMA with or without PPA have similar absorption peaks. This may be due to absorption peak of PMA covered the changes in PPA modification process as the low content of PPA. 0.8% dosage of PPA may be considered optimum for composite modified binder combining the above experimental results for this binder source.

Laboratory Evaluation of SBS Modified Asphalt Binder Containing GTR, SIS, and PE

Performance properties of polymer modified asphalt (PMA) binders with Styrene‐isoprene‐styrene (SIS), petroleum resin (PE), and ground tire rubber (GTR) were evaluated at high, intermediate, and low temperatures. Styrene‐butadiene‐styrene (SBS) PMA binder of PG 76‐22 was used as a base binder. The PG76 SBS PMA binders were blended with SIS, PE, and three different GTR contents (0, 5, and 10%). The binders were artificially short‐term and long‐term aged using rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. Superpave binder tests were conducted on the binders through rotational viscometer (RV), dynamic shear rheometer (DSR), and bending beam rheometer (BBR). Multiple stress creep recovery (MSCR) test was also performed to evaluate the rutting property. The results of this study indicated that (1) the addition of PE can decrease the binder viscosity, (2) although the incorporation of GTR and SIS significantly improve the rutting resistance of the binders, the effect of PE is found to be insignificant, (3) PE is observed to have positive effect on the cracking properties of control PG76 SBS PMA binder blended with SIS and GTR, and (4) incorporation of PE might be an useful option to improve the workability of high performance PMA binder in lieu with maintaining good rutting and cracking resistance.

Waste bio-oil as a compatibilizer for high content SBS modified asphalt

Use of waste bio-oil as a polymer modified asphalt (PMA) component is an effective approach to solve the related pollution problem because of tremendous consumption of asphalt binders. In this article, a bio-oil is used as softening and compatibility agent for high content SBS modified asphalt. The effect is given and is compared with that of aromatic oil. The results in this work reveal bio-oil is more advantageous to the PMA binder to exhibit better elasticity and flexibility, which are necessary to PMA. The anti-aging behaviors have also clearly been improved.

Ocena wpływu zawartości elastomeru styren-butadien-styren na właściwości funkcjonalne lepiszczy asfaltowych

This paper discusses the issue of improving the functional properties of road asphalt pavements by modifying bituminous binder with SBS copolymer. The main purpose of the paper is to assess the resistance to permanent deformations and the temperature susceptibility of polymer-modified road asphalt binders, which are most commonly used in the upper layers of road and airport pavements. The bitumens subject to the study originate from various crude oil deposits (Russian and Venezuelan). They were modified in laboratory conditions with a concentrated additive with the known content of the SBS copolymer of 9%. The result was a asphalt binder containing the known percentage of the SBS copolymer of 1.5%, 3.0%, 4.5% and 6%. The rheological properties of the tested bitumens were determined by use of a dynamic shear rheometer (DSR), and with the application of the sinusoidal variable load, in the broad test temperature spectrum (from 40°C to 100°C). The analysis of the values of the dynamic shear modulus |G*| of all the studied bitumens shows that the increase in the content of SBS copolymer in the tested binder increases the value of |G*|, which may result in higher resistance to permanent deformations of road pavements caused by repeated traffic loads, especially in the case of pavements operated at high temperatures. The asphalt mixtures resistance to rutting is one of the basic parameters related to road pavement service-life, affecting both the safety and driving comfort of users.

A Novel Method for Polymer Content Determination in Asphalt Binder and Emulsion

Modification of asphalt binder is a must to enhance the performance of asphalt binder. The objectives of this study are to develop an extensional deformation test method using a Sentmanat Extensional Rheometer (SER) fixture inside a Dynamic Shear Rheometer (DSR) and to investigate the relationship between different percentages of latex polymer and force ductility in polymer (latex) modified asphalt emulsion (PMAE) and polymer modified asphalt binder (PMAB). The sample geometry used in this study is 3 mm × 0.72 mm. Total twenty-four samples are tested by the SER where twelve samples are PMAE and twelve samples are PMAB. One neat binder PG 64-22 and one PMAE are used. 2%, 4% and 6% latex are mixed with PG 64-22 by a mechanical mixer and a high shear mixer for making PMAB. PMAEs are collected from the manufacture with 0%, 2.5%, 4% and 5.5% latex in it. Second peak elongation force, F2 is only obtained from the latex modified binders and emulsions. First peak elongation force, F1 has no linear correlation in case of PMAE and PMAB where F2 has a linear correlation with the percent of the polymer in the PMAE and PMAB with R2 values equal to 0.9934 and 0.9535 respectively indicating extensional deformation test with SER is very promising. Additionally, DSR temperature sweep test results and multiple stress creep recovery (MSCR) test results indicate that F2 is a better indicator of polymer content than rutting factor G*/sinδ and non-recoverable creep compliance, Jnr.

Evaluation of Mixing and Compaction Temperatures (MCT) for modified asphalt binders using zero shear viscosity and Cross-Williamson model

The current study was conducted to examine the rheological properties and the performance characteristics of polymer-modified asphalt binders at various temperatures. Different types and concentrations of polymers were used; including Styrene Butadiene Styrene (SBS) with or without a cross linker, Honeywell (HW) and polyphosphoric acid (PPA) which were added based on the total weight of different Performance Grade bitumen contents. Two methodologies (traditional Superpave and zero shear rate viscosity (ZSV)) were used for comparing binder viscosity and mixing and compaction temperatures. Theory of ZSV measurement was used to assess the rheological characteristics of the asphalt binder while a rotational viscometer device was used to measure the relation of viscosity changes with shear rate for neat and modified Iraqi asphalt binders. The Cross Williamson model was used for the simulation of the viscosity–shear rate dependency for each of the studied temperatures. From the results, there were changes in the rheological properties of the bituminous binders after the modification process. The neat bitumen showed improved rheological properties after mixing with the modifiers. It was noticed that increases in the percentage of polymer had no effect on the calculated mixing and compaction temperatures by ZSV; however, an increase of about 8% was observed with the traditional system. Furthermore, the two methods were observed to provide slightly different values for the viscosity when applied over a considerable range of test temperature. For the modified binders, they showed different mixing and compaction temperatures when ranked according to their Superpave grading protocol or their ZSV. The ZSV for mixing temperature was lower by about 42–54 °C compared to the Superpave method.

Investigation of thermal degradation of asphalt binders during storage and transportation

A disadvantage of current asphalt performance evaluation systems is that thermal degradation during storage and transportation is rarely considered, especially for polymer modified asphalt binders. The thermal degradation test in thin air (TDTTA) was designed to simulate the aging during storage and transportation. The aim of this study is to evaluate the change in properties of polymer modified asphalt binders during storage and transportation by the convention tests, gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). Based on the above analysis, the main factors affecting the performance of polymer modified asphalt binders were obtained. The results showed that storage time, oxygen concentration and polymer type have a greater impact on the properties erosion, while type of base asphalt binders has a lesser effect. For TFOT or TDTTA, the asphalt binders exhibit performance erosion with aging time increases. Compared with the change in the properties of base asphalt binders after TDTTA, the TDTTA caused a large change in the properties of polymer modified asphalt binders. The degradation in polymer also can be clearly occurred as gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR) results showed. In addition, the chemical structure and physical properties also showed the deterioration after TDTTA aging and different polymer modifiers have different influences. The performance degradation is more obvious when the air/oxygen is present. But the performance degradation needs to pay attention in thin air/oxygen in practical applications.

Evaluation of solvents for asphalt extraction

The laboratory evaluation of the performance of a number of asphalt extraction solvents was conducted. The performance testing was conducted on unmodified and polymer modified asphalt binder with the Bitumen Degradation Test (BDT) and on polymer modified and RAP mixtures with centrifuge extraction. The chemical interaction between the binder and the solvent was analysed by Fourier Transform Infrared (FTIR) Spectrometry. Several commonly used extraction solvents were tested including trichloroethylene, dichloromethane, toluene and xylene along with a number of alternative agents. The alternative agents included chlorinated, petroleum-based and bio-sourced solvents. The chlorinated solvents (trichloroethylene-TCE, dichloromethane and two higher exposure limit candidate agents) were found to be the best solvents to dissolve the binder in the BDT. These solvents were tested in the final round with centrifuge extraction, where they were evaluated based on the ability to dissolve the binder and evaporate after the extraction. While TCE had the best performance, some candidates were found to perform almost as effectively as the trichloroethylene, making them viable alternatives to the latter.

Effect of recycled asphalt binder on high and intermediate temperature performance of polymer modified asphalt binder

The present study aimed at investigating the effect of Recycled Asphalt Pavement (RAP) binder on high and intermediate temperature performance of Polymer Modified Binders (PMB) through advance laboratory characterization techniques. Different RAP binder proportions (0%, 15%, 25% and 40% by the weight of PMB) were initially blended with PMB. Different characterization techniques such as Superpave rutting parameter (G*/Sinδ), Shenoy parameter, Multiple Stress Creep Recovery (MSCR) and Zero Shear Viscosity (ZSV) tests were used for evaluating high temperature performance. Based on the different rheological parameters, improvement in rutting performance was observed with the addition of RAP binder. Likewise, intermediate temperature performance was evaluated using Linear Amplitude Sweep (LAS), Double Edge Notch Tension (DENT) and Elastic Recovery (ER) test. The improvement in high temperature performance and degradation in intermediate temperature performance shows that care must be taken while selecting the appropriate amount of RAP based on prevalent failure type in the field.

Microcapsule and polymer reinforcement techniques developed asphalt for use of pothole repairs in winter and rainy seasons

This paper proposes a new Polymer Modified Asphalt (PMA) for cold mixtures used to patch potholes in the adverse weather conditions of low temperature and rain. The new PMA is based on the microcapsules and polymer reinforcement techniques. Test results of the PMA binder found that the PMA improved the performance of the asphalt in low temperature and improved the adhesion of the cold mixtures by importing corresponding foundational groups. For example, the conjugated olefinic bond was used in the microcapsule formation and polybutadiene was used to improve the performance in low temperature as compared with the matrix asphalt and terpene resin cutback asphalt (TRCA). The modifier and adhesive stored in the microcapsules were distributed evenly in the asphalt. Test results of the cold mixtures verified that the PMA mixtures had a better performance than the TRCA mixtures, involving cohesion, stability and freeze-thaw resistance. Field surveys taken over 12 months indicated that the pothole patches filled with the PMA patching materials met the requirement for ride-ability and traffic safety standards. Therefore, it is concluded that the PMA is an adequate asphalt binder for pothole repairs in cold temperature and wet conditions.

Effect of long-term laboratory aging on rheological properties and cracking resistance of polymer-modified asphalt binders at intermediate and low temperature range

Aging of modified asphalt binder has a great influence on its rheological property and paving performance, and decreases the quality of asphalt pavements. The primary objectives of this study were to investigate the effect of long-term laboratory aging on rheological properties and cracking resistance of polymer-modified asphalt binders at intermediate and low temperature range, and to analyze different evaluation indexes. SBS modified asphalt and two kinds of SBS/crumb rubber compound modified asphalt were subjected to Rolling Thin Film Oven (RTFO) test and 20 h, 40 h, 60 h Pressure Aging Vessel (PAV) test. Two rheological methods (frequency sweep test and Bending Beam Rheometer test) and a conventional test (Fraass breaking point test) were applied. Experimental results indicate that the studied binders tend to be more viscous at relatively low loading frequencies and harder after aging, and the ability to relax internal stress declines. Master curves and aging sensitivity analysis show that after 40 h PAV test, the effect of aging on polymer-modified asphalt binders rheological properties and cracking resistance becomes insignificant. The phase angle master curve can well reflect the effect of aging on asphalt binders rheological properties since the shape of phase angle master curve is obviously different before and after aging. Besides, critical temperature from BBR and Fraass breaking point tests can only be regarded as a reference of the minimum service temperature of asphalt pavements, and it can hardly reflect the impact of aging on materials property. While Glover-Rowe (G-R) parameter and ΔTc are well-related to asphalt binders rheological and physical properties when used to evaluate the age-related cracking resistance of asphalt binders. Besides, SR2 compound modified asphalt binder exhibits a better cracking resistance compared with the other two binders. Its G-R values range from 5.09 to 19.24 kPa among the whole aging conditions, besides, both of the minimum critical and Fraass breaking temperatures are under –23.41 °C.

Assessment of existing micro-mechanical models for asphalt mastic considering inter-particle and physico-chemical interaction

Micromechanical models have been used since the 1990s to predict the properties of asphalt mastic. However, most of these models are found to be unsatisfactory in predicting the mastic’s properties because the models were derived from the research of particle-filled composites that did not take into account the asphalt-filler physico-chemical interactions and particle interactions. In this paper, three micro-mechanical models for predicting the complex shear modulus master curve of asphalt mastic are evaluated: the generalized self-consistent scheme model, the four-phase micro-mechanical model, and the particle interaction model. All three micro-mechanical models are based on the mechanical properties of their constituent materials as well as the filler-asphalt physiochemical interactions and the particle interactions. Two virgin asphalt binders and two polymer modified asphalt binders were selected to fabricate 16 mastics of four different filler volume fractions. The accuracy of prediction was evaluated by comparing the relative differences between the experimental complex shear modulus master curves and that predicted by the models. The results suggest that (1) the generalized self-consistent scheme model have a satisfactory prediction at a low filler volume fraction, but their accuracy is significantly affected by frequency; (2) the particle interaction model cannot calculate the complex shear modulus of mastic with a filler volume fraction of more than 0.53; (3) the four-phase model shows a precise forecast of complex shear modulus for mastic with moderate and high filler volume fractions; and (4) for all of the three models, the deviations increase severely with the increase of the filler volume fraction.

Impact of Ultraviolet Radiation on the Aging Properties of SBS-Modified Asphalt Binders.

Styrene Butadiene Styrene (SBS) polymer-modified asphalt binders have become widely used in asphalt pavement because of their advantages in high- and low-temperature performance and fatigue resistance. Asphalt pavement is inevitably exposed to sunlight and ultraviolet (UV) radiation during its construction and service life. However, consideration of the aging effect of UV radiation is still limited in current pavement design and evaluation systems. In order to evaluate the impact of UV radiation on the aging properties of SBS-modified asphalt binders, UV aging tests were performed on Rolling Thin Film Oven Test (RTFOT)-aged samples with different UV radiation intensities and aging times. Sixteen different groups of tests were conducted to compare the rheological properties and functional group characteristics of SBS-modified asphalt binders. Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), FTIR, and SEM tests were conducted to evaluate the aging mechanisms in various UV aging conditions. The results found that UV radiation seriously destroys the network structure formed by the cross-linking effect in SBS-modified asphalt binders, which aggravates the degradation of SBS and results in a great change of rheological properties after UV aging. The nature of SBS-modified asphalt binder aging resulted from the degradation of SBS and the changes of asphalt binder base composition, which lead to the transformation of colloidal structure and the deterioration of asphalt binder performance. The tests also found that continuous UV radiation can increase shrinkage stress in the asphalt binder surface and leads to surface cracking of the asphalt binder.