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Asphalt modified by microwave-treatment crumb rubber (CR-microwave) and that of deodorant-addition crumb rubber (CR-deodorant) have low unfavorable or detrimental emissions, but their high- and low-temperature performances have been insufficiently researched, potentially limiting their application and promotion. In order to investigate high-temperature performances of the two low-emissions crumb rubber modified asphalt (CRMA), viscosity, temperature ramp, creep and creep recovery and amplitude sweep tests were conducted using Brookfield Viscometer and dynamic shear rheometer (DSR). Also, low-temperature performances of CMRA were characterised by bending beam rheometer (BBR) tests. Results showed that deodorant-addition CR with a high dosage is not allowed considering asphalt workability, but microwave-treatment CR with various dosages can still meet workability requirements. Moreover, the introduction of microwave-treatment CR or deodorant-addition CR into asphalt improved high-temperature performances of asphalt, while the former had lower positive effects on high-temperature performance grades, elastic recovery and deformation resistance of asphalt. Furthermore, like common CRMA, the two low-emissions CRMA had different viscoelastic behaviour from styrene–butadiene-styrene copolymer (SBS) modified asphalt. Additionally, 18% CR-microwave or CR-deodorant can basically improve the low-temperature performance grades of asphalt. Comprehensively considering the workability and high- and low-temperature performances of the two low-emissions CRMA, 18% CR-microwave is recommended for low-emissions CRMA manufacture. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop artificial neural networks to predict the viscosity of rubberized asphalt rejuvenated reclaimed asphalt pavement binders. Eight variables were selected as input factors, namely, viscosity measuring temperature, rubber blending time, reclaimed asphalt pavement blending time, original binder blending time, rubber content, reclaimed asphalt pavement content, blending temperature for aged binder, and asphalt type. Two viscosity analysis models, backpropagation artificial neural networks and genetic algorithm modified artificial neural networks, were developed in this study. It was found that both artificial neural network models were effective in predicting the viscosity of rubberized asphalt rejuvenated reclaimed asphalt pavement binders. Through sensitivity analysis, blending temperature for aged binder, viscosity measuring temperature, original binder blending time, and reclaimed asphalt pavement blending time were found to be important variables that contributed to the binder viscosity. On the contrary, the asphalt type and rubber blending time were found to be less important. As a result, the viscosity of rubberized asphalt rejuvenated reclaimed asphalt pavement binders changed significantly with the blending temperature, blending time of the aged binder, and blending time of the original binder. Both backpropagation artificial neural networks and genetic algorithm modified artificial neural networks viscosity models were validated using data collected from prior studies, and the results were barely acceptable. [ABSTRACT FROM AUTHOR]

Due to its nature of large surface area and small size, nano-material shows specific characteristics compared to the common material and exhibits some novel properties and incredible features which make it possible to be applied in the field of asphalt pavement as an additive. This review focuses on introducing the main nano materials and related techniques used for nano-modified asphalts and major performance characteristics at various states. Some conventional test results including viscosity, dynamic modulus, stiffness, rut depth, indirect tensile strength and so on were employed to characterize the rheological and engineering performances of nano-modified asphalts and some innovative technologies such as atomic force microscopy, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were effectively utilized to explore their micro structures and molecular components. It can be found that the addition of nanomaterials could dramatically enhance the properties of an asphalt material such as visco-elasticity, high temperature properties, and the resistances to aging, fatigue and moisture. In addition, nano-particle type, content and production process were mainly studied and other factors such as binder type and particle size also need to be considered to explore the modification mechanism and effect. The properties of both nano-material and original binder played the key roles in determining optimal production process parameters. In addition, the degree of dispersion was governed by some factors such as the mixing temperature, duration and speed. [ABSTRACT FROM AUTHOR]

In this study, the objective was to conduct an investigation of Superpave mix design characteristics of WMA technologies in terms of various high percentages of reclaimed asphalt pavements (RAPs). One PG 58-28 binder, two PG 64-22 binders, and two RAP sources were selected from South Carolina. In addition, three mix technologies (e.g. hot mix asphalt (HMA), foaming technology, and Evotherm additive) were employed to produce the mixtures. Meanwhile, four RAP contents of 20%, 30%, 40%, and 50% (by weight of total mixture) were utilized to blend with virgin materials. 36 Superpave mix designs were conducted to explore the volumetric characteristics of various mixtures. In this study, the results indicated that, all mixtures have an optimum asphalt content (OAC) less than 5.0%, and most of these values are close to a minimum OAC value of 4.5% set by South Carolina Department of Transportation (SCDOT). No noticeable increases at the mixing and compaction temperatures for these mixtures containing a higher percentage of RAP (i.e., over 40%) were found in this study. In addition, the voids in mineral aggregate (VMA), voids filled with asphalt (VFA), dust/asphalt ratios, and moisture susceptibility meet the requirements of SCDOT’s specifications. Therefore, these specific mix designs could be used as the guidelines for developing a set of specifications for a higher percentage of RAP in terms of warm mix asphalt technology. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the rheological properties of the modified asphalt binders based on the effects of base binder type and other five polymers or acid combined with 7% dosage ground tire rubber (GTR) at the high temperature. The test results included viscosity, fail temperature, G ∗ /sin δ , phase angle, viscometry, amplitude sweep, frequency sweep, creep and creep recovery, and stress relaxation in this study. The results indicated that two of alternative polymers modified binders had noticeably lower viscosity values compared to SBS modified binders. Additionally, the addition of polyphosphoric acid could remarkably decrease the polymer dosage to produce PG76 binder. Meanwhile, asphalt source played a key role in determining the characteristics of all modified binders. The terminally and laboratory blended binders generally had approaching rheological properties in this study. [ABSTRACT FROM AUTHOR]

Highlights: [•] Rheology on SBS and three alternative binders with/without PPA was studied. [•] Two base asphalt binders, four polymers, and one PPA were used to produce binders. [•] Viscosity, G */sin δ, amplitude and frequency sweep, creep recovery, etc. were tested. [•] 0.5% PPA could reduce by 1.0% the polymer needed to produce the PG 76-22 binder. [•] Rheology of binders is dependent on polymer type, asphalt source and test temperature. [Copyright &y& Elsevier]

Highlights: [•] Rejuvenator, waste cooking and cotton seed oils were employed for rejuvenation of RAP. [•] High temperature characteristics of rejuvenated asphalt binder were tested. [•] The used rejuvenated additives can reduce the viscosity value and fail temperature. [•] Rejuvenator, cotton seed oil or waste cooking oil result in an increase of phase angle. [ABSTRACT FROM AUTHOR]

Abstract: Due to many reasons including the energy reductions and environmental benefits, warm asphalt has been gaining increasing popularity in recent years around the world. In the present study, the objective was to conduct a laboratory investigation of rheological properties of non-foaming WMA additives at high performance temperatures. The conventional testing procedures such as viscosity, performance grade, creep and creep recovery, amplitude sweep and frequency sweep as well as specific Fourier Transform Infrared Spectroscopy (FTIR) were performed to determine the influences of non-foaming additives on asphalt binders. The experimental design included eight binders and four non-foaming WMA additives. The test results indicated that, the non-foaming WMA additive can slightly reduce the viscosity value of asphalt binder and thus decrease the mixing and compaction temperatures of the mixture. The binders containing non-foam additive have a slight increase in high failure temperatures compared to control binder and thus improving the rutting resistance of the mixtures. In addition, creep recovery, amplitude and frequency sweep tests show that the binders with Sasobit has a slightly higher complex modulus but exhibits lower creep compliance and phase angle than the binder containing other WMA additives regardless of asphalt type and grade. Furthermore, FTIR analysis results indicate that the binder type plays a key role in determining the rheological properties of WMA binders. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

In recent years, nano technology, a relatively new field in science dealing with structures that are on the nano scale, have been used in numerous applications to improve properties of various materials. However, the use of this technology has not been explored in detail in the area of asphalt binder materials. The objective of this study was to investigate and evaluate the high temperature rheological properties of the binders containing various percentages of carbon nano particles. The experimental design for this study included the utilization of five binder sources, three binder grades (PG 64-22, PG 64-16, and PG 52-28), one type of nano particle, and four percentages of nano particles (0.0 %, 0.5 %, 1.0 %, and 1.5 % by weight of the virgin binder). Some of the rheological characteristics of these binders were obtained, including rotational viscometer (four testing temperatures of 120, 135, 150 ,and 165°C) and dynamic shear rheometer. The results of the experiments indicated that the addition of nano particles was helpful in increasing the viscosity, failure temperature, phase angle, and viscous and elastic modulus values and in improving the rutting resistance of the binders. On the other hand, the binder sources and grades generally influenced their rheological properties as the nano particles were added to the asphalt binder. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, warm mix asphalt (WMA) is widely used for reducing energy requirements and emissions in hot mix asphalt (HMA) industry. In addition, the use of rubberized asphalt in the past has proven to be economical, environmentally sound and effective in improving the performance of pavements across the US and the world. The objective of this research was to investigate the mixture performance characteristics of rubberized warm asphalt mixtures, and their correlation with binder properties, through a series of laboratory tests (e.g., viscosity, dynamic shear rheometer (DSR), and bending beam rheometer (BBR)) conducted on the binders, and obtaining the indirect tensile strength, rutting resistance, and resilient modulus of various mixtures. The results of the experiments indicated that the use of crumb rubber and WMA additive in HMA can effectively improve the engineering properties of these mixes at lower mixing and compacting temperatures and some statistical correlations between rheological and/or engineering properties were developed successfully. [ABSTRACT FROM AUTHOR]

Abstract: Warm mix asphalt (WMA) has been gaining increasing popularity in recent years around the world. Rising energy prices, global warming, and more stringent environmental regulations have resulted in an interest in WMA technologies as a mean to decrease the energy consumption and emissions. However, the water absorption and release process caused by water bearing WMA additive (Asphamin) makes the charge re-distribution complex and thus may result in the moisture induced damage of asphalt mixtures. Especially, the liquid antistrip additives (ASAs) blended with the binder and then mixed with aggregate and Asphamin make the issue more complicated. The objective of this study was to investigate and evaluate the rheological properties and moisture susceptibility of the binder and mixture containing ASAs and Asphamin additive. The experimental design for this study included rheological property tests of binders and moisture susceptibility of mixtures. The materials included one binder (PG 64-16), two liquid ASAs and hydrated lime, one water bearing additive, and three aggregate sources. The performed testing included viscosity, performance grade, creep and creep recovery, amplitude sweep, frequency sweep, boiling test, and indirect tensile strength (ITS). The results indicated that the addition of Asphamin can slightly increase the viscosity, failure temperature and G */sin δ values. The mixture containing Asphamin has a lower ITS value than others. Statistical analysis illustrates that there is not significant difference in ITS value between any mixtures containing Asphamin additive and control mixtures. However, significant differences can be found between mixtures containing Asphamin and without any Asphamin additive. [Copyright &y& Elsevier]

In many parts of the world, highway officials are utilising crumb rubber and reclaimed asphalt pavement (RAP) in order to save money, protect the environment, and improve the life of asphalt pavement. However, due to the use of these materials, the effects of moisture damage should be investigated for rubberised asphalt concrete (RAC) mixtures containing RAP. The objective of this research involved investigating the moisture susceptibility of RAC containing RAP. The testing conducted included the determination of binder viscosity, toughness and indirect tensile strength (ITS) analysis. Several mixtures containing different crumb rubber types, two different RAP sources and various percentages of rubber and RAP were evaluated. The results indicated that, in general, the additional of RAP was beneficial in improving the ITS values and reducing the moisture susceptibility of the mixture although the addition of crumb rubber had a slightly negative effect. [ABSTRACT FROM AUTHOR]

In general, crumb rubber modifier-modified binders (CRM binders) have better performance properties than base binders and thus, are becoming more widely used in pavements in a few states. However, the mechanism by which the interaction between the asphalt base binder and the CRM blends added takes place has not been fully characterised. In this study, the surface areas of CRM were at first measured using the Brunauer, Emmett and Teller (BET) tester. Second, 108 CRM binders were produced using different combinations of CRM blend variables and mixing conditions and consequently tested for their viscosity at 135°C. The influence of the surface area and the average size of the CRM blends on the viscosity of the CRM binders was statistically investigated. Results from this study indicated that: (1) the surface area of the ambient CRM is almost twice as large as that of the cryogenic CRM, leading to an increase in the viscosity up to 16-58% over cryogenic CRM binders and (2) the viscosity of the CRM binders has a moderate correlation with both the surface area and the average size of the CRM blends, but is prevailingly influenced by the average size of the CRM blends. [ABSTRACT FROM AUTHOR]

Abstract: Accurately predicting the viscous properties of crumb rubber modified (CRM) binders has proven difficult, especially as these properties tend to vary with changing crumb rubber concentrations and temperatures. This study explores the utilization of the statistical regression and neural network (NN) approaches in predicting the viscosity values of CRM binder at various temperatures (135°C and greater). A total of 53 CRM binder combinations were prepared from two different rubber types (ambient and cryogenic), three different binder sources, four rubber concentrations (0%, 5%, 10%, and 15%), and five crumb rubber gradations (ADOT, SCDOT, 0.18mm, 0.425mm, and 0.85mm). The results indicated that the regression model is easy to use and can be used for viscosity prediction, similarly NN-based models also provided accurate for predictions for the viscosity values of CRM binders regardless of rubber type and can easily be implemented in a spreadsheet. In addition, the developed NN model can be used to predict viscosity values of other types of CRM binders efficiently. Furthermore, the sensitivity analysis of input variables indicated that the changes of viscosity are significant as the changes of asphalt binder grade, test temperature, and rubber content. The results also show that these three independent variables are the most important factors in the developed NN models in comparison with other variables. [Copyright &y& Elsevier]

Waste cooking oil residues (WCOR) based bio-asphalt is a potential substitute for petroleum asphalt. This study aims to prepare a bio-asphalt with high percentage of WCOR derived from esterification reaction for biodiesel. According to the uniform design results, the optimum mass ratios of materials were determined as WCOR of 33.3%, resin (RE-1) of 30.3%, hard asphalt particles (HAP) of 31.8%, low density polyethylene particles (LDPE) of 4.6% and linear SBS (L-SBS) of 4%. Based on the orthogonal design results, the WCOR based bio-asphalt would have the best performance when stirred for 40 min and sheared for 50 min (4000 rpm) under the condition of 170 °C with the optimum mass ratios. Rotational viscosity (RV) test results indicated that the viscosity of optimal bio-asphalt (OBA) was between PEN 70 base asphalt (PEN 70) and SBS modified asphalt (SBS-MA). Dynamic shear rheometer (DSR) test and bending beam rheometer (BBR) test results proved that OBA exhibited excellent high-temperature performance similar with SBS-MA, and it had superior low-temperature performance to SBS-MA and PEN 70. Furthermore, the effect of thermo-oxidative aging on the properties of OBA was studied. DSR test results revealed that the complex modulus and phase angle of thin film oven (TFO)-aged OBA both increased with the elevated aging level, indicating an increase in viscosity during aging process. Fourier transform infrared spectroscopy (FTIR) test results showed that there was no obvious variation on the functional groups of OBA after 15 h TFOT aging process. It was confirmed that less aging susceptibility of OBA was found compared with PEN 70, which demonstrated that OBA had a better aging resistance performance. [ABSTRACT FROM AUTHOR]

The self-healing capability of asphalt materials has been known for many years. Related studies have focused mostly on the healing mechanism or self-healing behavior during load repetitions. Limited work has been accomplished to fully understand the healing performance of different modified asphalt. In this paper, the effects of various contents of different modifiers on the healing capability of binders were investigated by a simple self-healing test procedure to give suggestions to ensure better choice of asphalt materials with good healing properties. Results from the Binder Bond Strength (BBS) test indicate that the modifier significantly affected the healing potential of asphalt binder depending on both the type and content of modifier that was used. Interestingly, increased modifier content deteriorated the healing capability of the base binder regardless of the type of additive employed, thereby suggesting that soft binders are more desirable for healing. Furthermore, methylene plus methyl hydrogen to carbon (MMHC) ratio was verified to be useful for predicting the healing potential of base asphalt binder but was found to be unsuitable for characterizing the healing potential of modified asphalt. By contrast, rotational viscosity @135 °C can predict the healing property in the case of base and modified asphalt. Finally, the Four-Point Beam Fatigue (4PB) test further confirmed that the BBS test can help to determine the healing potential of asphalt binders in an efficient and simple manner. [ABSTRACT FROM AUTHOR]

Polymer modified asphalt binders have been commonly used to improve the resistance of the airfield pavements to distresses, especially wheel rutting. The objective of this study was to investigate the rheological and chemical properties of the modified binders containing anti-rutting agent (ARA), polyethylene (PE) and styrene-butadiene-styrene copolymer (SBS) before and after a short-term aging procedure. Rotational viscosity, penetration degree, softening point as well as performance grade, multi-stress creep recovery (MSCR), frequency and amplitude sweep were performed to determine the effects of ARA and PE on rut depths at high temperatures. In addition, Fourier Transform Infrared Spectroscopy (FTIR) was conducted to determine the chemical properties of various polymerized binders. The test results showed that, as expected, the addition of PE and ARA polymer increased the rotational viscosity, softening point and rutting factor values and reduced the penetration degree. However, ARA could only increase complex modulus while PE had the influences on both the complex modulus and phase angle of the modified binders. In addition, the rising tendency of phase angle during frequency sweep test was totally different in terms of the binders with or without PE. Furthermore, the FTIR test results showed that the ARA has no significant effects on aging resistance, while the modified binders with PE have better resistance to aging. [ABSTRACT FROM AUTHOR]

Effects of different anti-stripping agents (ASAs) (M5000, M1 and LOF-6500) with various dosages (0.25%, 0.50% and 0.75% by weight of asphalt binder) on the rheological properties of asphalt binder before and after rolling thin film oven test (RTFO) at high temperature were investigated. The tested rheological properties included rotational viscosity, complex modulus (G ∗ ), phase angle (δ), rutting resistance factor (G ∗ /sinδ), failure temperature, non-recoverable creep compliance ( J nr ) and amplitude sweep. The results indicated that the rheological properties such as viscosity, G ∗ , δ, G ∗ /sinδ and failure temperature of ASA modified asphalt binders before aging depended on the ASA types and its dosages. After RTFO, all ASA modified asphalt binders showed the lower high temperature stability compared with blank sample, however, the high temperature performance grade maintained 64 °C unchanged. Besides, the J nr susceptibility for stress level was weakened evidently by adding ASAs. As a result of the amplitude sweep test, compared with blank sample, all ASA modified asphalt binders after RTFO had the higher δ and G ∗ values. Additionally, the introduction of ASAs could effectively improve the ability of asphalt binder to resist RTFO. Moreover, compared with M5000 and LOF-6500, the improvement degree of M1 was more apparent. [ABSTRACT FROM AUTHOR]

The ground tire rubber (GTR) modified binder has been affirmed to improve resistance to rutting, moisture susceptibility, low temperature cracking and durability of asphalt pavement. However, the liable phase separation of GTR modified asphalt binders results in a big issue at construction site. Therefore, an alternative crumb rubber, devulcanized ground tire rubber (DGTR), is manufactured with devulcanization process and as an additive to substitute for GTR or styrene-butadiene-styrene (SBS) in PG76 binders preparation process. The objective of this study was to compare the rheological properties and hot storage characteristics of PG76 asphalt binders produced with DGTR and two alternative polymers for future applications. The Brookfield Rotational Viscometer, Dynamic Shear Rheometer, and hot storage test were performed with all modified asphalt binders. The results indicated that PG76 binders modified with DGTR had approaching apparent viscosity values compared to GTR or SBS modified binders. In addition, the application of DGTR could reach the similar modification effect on the High PG critical temperature as well as GTR modified binders with same concentration. While those binders modified with DGTR exhibited remarkable lower tendency of phase separation than other modified binders regardless of base binder source. Moreover, similar trends were observed from the characteristics of creep and creep recovery, and Multiple Stress Creep and Recovery (MSCR) of all modified binders. [ABSTRACT FROM AUTHOR]