Rheological and chemical characteristics of warm mix asphalt binders at intermediate and low performance temperatures (original) (raw)

Thermo-rheological analysis of WMA-additive modified binders

Materials and Structures

Thermo-rheological characteristics of unmodified and modified bitumen have significant impacts on the mechanical response of asphalt. This study investigates the impacts of an organic and a chemical Warm Mix Asphalt additive on bitumen thermo-rheological and mechanical characteristics. Modified binders with different concentrations of each additive were studied and analysed comparatively to a 40/60 penetration grade bitumen. Frequency sweep tests were performed at different ageing levels to characterise the Linear Viscoelastic properties. The multiple stress creep and recovery, linear amplitude sweep (LAS) and low temperature creep stiffness tests, together with the Glover–Rowe (G–R) fatigue parameter (determined from fitting of the 2S2P1D model to the complex shear modulus and phase angle master curves) were used to analyse the performance of the binders at critical operating temperatures. The results demonstrated the necessity to analyse the behavior of the studied binders beyond ...

Effects of non-foaming WMA additives on asphalt binders at high performance temperatures

Fuel, 2012

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.

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 sour...

Laboratory Investigation of Rheological and Moisture Susceptibility of WMA Mixtures

2010

Warm mix asphalt (WMA) technology is showing an increasingly potential in decreasing the energy consumption and emissions associated with conventional hot mix asphalt (HMA) production. The objective of this study was to investigate and evaluate the moisture susceptibility of the WMA mixtures. The experimental design for this study included the utilizations of one binder source (PG 64-22), two aggregate sources, and three WMA additives and control. The performed properties include viscosity, dynamic shear rheometer, beam bending rheometer of WMA binders as well as indirect tensile strength (ITS), tensile strength ratio (TSR), and flow of WMA mixtures. The results indicated that the WMA additive can result in a slight decrease in viscosity and an increase in failure temperature. In addition, the moisture susceptibility results illustrate that the mixtures containing WMA additives generally have a slightly lower ITS values than conventional HMA mixtures.

Rheological Investigation of Non-Foaming WMA Additives at Mid-Temperature

Emerging Technologies for Material, Design, Rehabilitation, and Inspection of Roadway Pavements, 2011

In this study, the objective was to conduct a laboratory investigation of rheological properties of non-foaming WMA additives at a mid-temperature. The conventional testing procedures such as viscosity, performance grade, creep and creep recovery, and frequency sweep were performed to determine the influences of nonfoaming additives on asphalt binders. The experimental design included four binders and four non-foaming WMA additives. The test results indicated that, as expected, the non-foaming WMA additive can reduce the viscosity value of asphalt binder and thus decrease the mixing and compaction temperatures of mixture. The failure temperature of binders containing non-foam additive has a slight increase compared to the virgin binder and thus, improve the rut resistance of the mixtures. In addition, creep recovery and frequency sweep tests show that the binder with Sasobit has a slightly higher complex modulus but exhibits lower creep compliance and phase angle than the binder containing other WMA additives.

Rheological quantification of bitumen aging: Definition of a new sensitive parameter

Applied Rheology, 2010

Bitumen is undoubtedly the most important material in the construction and rehabilitation of flexible road pavements. By increasing the temperature, bitumen changes from brittle solid, to viscoelastic solid and finally to Newtonian fluid. The rheological characteristics of bitumen also vary greatly due to aging, which is a phenomenon initiated in the phases of production and application of bituminous (asphalt) mixtures and continued during the life of road pavements. The aim of this work is to study several rheological parameters in order to evaluate if they are able to quantify the aging of various types of bitumens. Four bitumens from the same distillation column in the refinery, but with different penetration grades, were aged by using the RTFOT method, which simulates the aging of the bitumen during the asphalt mixture production and pavement construction. The original (base) and aged bitumens were characterized with conventional tests used in the paving industry, and the results were compared with the rheological characteristics obtained with small amplitude oscillatory shear tests. Aging was assessed at high temperatures (110 to 180°C) through the activation energy computed from the temperature dependence of the Newtonian viscosity. However, the comparison of the characteristic relaxation times extracted from master curves measured at medium/low temperatures (between 25 to 80ºC), proved to be the most sensitive indicator of bitumen aging. Zusammenfassung: Asphalt ist unzweifelhaft das wichtigste Material bei der Konstruktion und Ausbesserung von flexiblen Straßenbelag. Durch Temperaturerhöhung geht Asphalt von einem spröden Festkörper, zu einem viskoelastischen Festkörper und schließlich zu einer Newtonschen Flüssigkeit über. Darüber hinaus verändern sich die rheologischen Eigenschaften von Aphalt durch Alterung. Dieses Phänomen wird während der Herstellung und Anwendung der Asphaltmischungen initiiert und setzt sich danach fort. Das Ziel dieser Arbeit ist, verschiedene rheologische Parameter zu untersuchen und ihre Eignung zur Charakterisierung des Alterungsverhalten von Asphalt zu evaluieren. Vier Asphaltmischungen aus derselben Destillationskolonne einer Raffinerie mit unterschiedlichen Eindringwerten wurden mit Hilfe der RTFOT-Methode gealtert. Diese Methode simuliert die Alterung von Aphalt während der Herstellung der Asphaltmischungen und des Straßenbelags. Der Ausgangs-und der gealterte Asphalt wurden mit den üblichen industriellen Versuchen getestet und ihre Resultate mit den Ergebnissen von linear-viskoelastischen Scheroszillationen verglichen. Das Alterungsverhalten wurde bei hohen Temperaturen (110°C bis 180°C) durch die Aktivierungsenergie ermittelt, die aus der Temperaturabhängigkeit der Newtonschen Viskosität bestimmt wurde. Es zeigte sich jedoch, dass der Vergleich der charakteristischen Relaxationszeiten, die aus den gemessenen Masterkurven bei niedrigen und mittleren Temperaturen (zwischen 25°C und 80°C) erhalten wurden, der beste Indikator für die Alterung von Asphalt ist. Résumé: Le bitume est sans aucun doute le matériau le plus important pour la réhabilitation et la construction de revêtements routiers flexibles. En chauffant, le bitume passe d'un comportement de solide cassant, à celui d'un solide viscoélastique et finalement à celui d'un fluide Newtonien. Les caractéristiques rhéologiques du bitume varient grandement avec le vieillissement, qui est un phénomène initié dans les phases de production et d'application des mélanges bitumineux (asphalte), et qui continue durant la vie du revêtement routier. Le but de ce travail est d'étudier les paramètres rhéologiques du bitume qui sont les plus sensibles au vieillissement. Quatre bitumes provenant de la même colonne de distillation mais possédant des grades différents, ont été vieillis au moyen de la méthode RTFOT qui simule le vieillissement du bitume lors de la production du mélange d'asphalte et lors de la construction du revêtement. Les bitumes originaux (base) et âgés ont été caractérisés à l'aide de tests conventionnels utilisés dans l'industrie, et les résultats ont été comparés avec les caractéristiques rhéolo

Using thermal analysis methods to better understand asphalt rheology

Thermochimica Acta, 1998

The Strategic Highway Research Program allowed to de®ne some parameters that characterize the rheological properties of asphalt cement(s) (ACs). Those parameters implied that ACs follow the time and temperature superposition principle. However, highly asphaltic or waxy ACs deviate from this rule since their structure changes as a function of time and temperature. Some of these transitions clearly appear on differential scanning calorimetry curves.

Rheological Evaluation of Short- and Long-Term Performance for Warm Mix Asphalt (WMA) Binders

8th RILEM International Symposium on Testing and Characterization of Sustainable and Innovative Bituminous Materials

Warm-mix asphalt (WMA) additives are environmentally friendly and cost-effective products that lower the viscosity of bituminous binders to allow reduction of mixing and compaction temperatures in asphalt mix production. In this study, two WMA additives were used; Sasobit® and Advera®. Both were mixed in the lab with unmodified 60/70 Pen and modified PG 76-22 binders. Strain oscil- lation and viscosity measurement tests were performed to determine the rheological properties of the binder with and without WMA additives. Different ageing pro- cesses were performed in this study; half and full short-term ageing using the Rolling Thin Film Oven (RTFO) procedure, and long-term ageing using the Pressurized Ageing Vessel (PAV) procedure. Test results have shown that the addition of Sasobit® increased the stiffness of both binders and changed PG grade by one unit up (6 °C PG grade). Also, Sasobit® presented better rutting resistance in modified and unmodified binders than Advera®, while both WMA additives decreased the fatigue cracking resistance. Multiple Stress Creep Recovery (MSCR) test was also conducted on both unaged and RTFO aged binders. Modified binder with Sasobit® and Advera® exhibited the same performance of the original binder after complete short-term ageing. However, Sasobit® increased the potential of rutting resistance in the unmodified binder more than Advera® did. The viscosity measurements revealed that adding Sasobit® to modified or unmodified binders lowered the viscosity more than Advera® did. These measures were considered as preliminary data required for further studies on the effect of WMA additives on the resistance of bituminous binders to fatigue cracking.

Evaluation of the rheological behaviour of Warm Mix Asphalt (WMA) modified binders

Advanced Testing and Characterization of Bituminous Materials, 2009

Several processes and products are available to produce warm mix asphalt (WMA). The use of those may reduce the mixing and compaction temperatures in relation to hot mix asphalt (HMA), ensuring a good performance of the pavement. Lower plant mixing temperatures mean reduction in fuel consumption and lower emissions, what may contribute to diminish odours and health problems. A laboratory study on the properties of the modified binders (using two commercial WMA additives-Sasobit ® and Cecabase ®) was carried out through conventional (penetration, softening point), dynamic viscosity and rheology (DSR) tests, in order to establish the optimum additive content. Stripping of binder from the aggregates is a reported problem in WMA. Thus, the affinity of the modified binders was assessed without encountering significant problems. It was also observed that only Sasobit ® alters the viscosity of the binder. A maximum temperature reduction of 15°C was achieved using 4% of Sasobit ® with a softer binder.

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 40 binders 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.