The colloidal structure of bitumen: Consequences on the rheology and on the mechanisms of bitumen modification

http://www.diva-portal.org/smash/get/diva2:711917/FULLTEXT01

Polymer modification of bitumen : Advances and challenges

https://arpi.unipi.it/bitstream/11568/798598/2/polacco%20798598.pdf

A review of the fundamentals of polymer-modified asphalts: Asphalt/polymer interactions and principles of compatibility

Morphology, rheology, and physical properties of polymer-modified asphalt binders

This paper investigates the effect of the processes on fatigue fracture and fracture healing during controlled-strain, dynamic mechanical analysis (DMA) testing. Sand asphalt samples were fabricated with two SHRP-classified binders: AAD-1 and AAM-1. DMA testing was performed at 25°C and at 10 Hz. The mechanical response during DMA testing was monitored using three different damage indicators: (1) change in dynamic modulus; (2) change in pseudo stiffness; and (3) change in dissipated strain energy. When either of these parameters are plotted versus the number of load cycles, two inflection points are apparent that define a significant change in sample behavior due to damage. The second inflection point is a reasonable definition of failure, as it is strongly correlated with the peak of the plot of phase angle versus load repetitions. Furthermore, the phase angle drops precipitously at the second inflection point. By performing controlled-strain torsional fatigue tests at three different strain levels, each great enough to induce damage, a reproducible fatigue relationship (number of load cycles as a function of stress level) is developed. The introduction of several rest periods during testing lengthened fatigue life. Successful development of this testing method is suggested as a potential specification-type test method because of its efficiency, reproducibility, and reliability.

Fatigue and healing characterization of asphalt mixtures

Viscoelastic properties of paving grade asphalt cements (AC) were measured on a Rheometrics RDA II. Thermal properties were studied with a Mettler TA 2000 B differential scanning calorimeter. A review of the literature showed that most authors proposed that the time‐temperature superposition principle applies to asphalt over the whole temperature range. However, the results presented herein demonstrate that it indeed fails at high temperature, especially for high asphaltene content and high crystalline content materials. This paper focuses on the role of asphaltenes, which are, by definition, insoluble in n‐heptane. Asphaltenes are suspended in a colloidal manner within the AC matrix and are peptizided by the species called resins. Thus, a temperature dependent solid fraction exists within a liquid (or glassy) matrix. This paper shows that the viscoelastic properties of asphalt are bimodal: they are governed by both solid and continuous phases.

A structure‐related model to describe asphalt linear viscoelasticity

The original SuperPave asphalt binder specification criterion for fatigue, G* sin δ, has received considerable criticism. Recently, a time sweep using the dynamic shear rheometer (DSR) has been proposed as an alternative test method for developing load-associated fatigue information for asphalt binders. This proposed test method is examined with respect to a phenomenon called edge fracture. Edge fracture is reported in the literature for steady state and oscillatory flow in DSR, but it has not been reported for asphalt binders. The modulus, when plotted versus number of cycles generated in a time sweep test, has the appearance typical of fatigue behavior; however, the actual response of the material depends markedly on the initial modulus of the material. The development of the modulus with repeated shearing is described with respect to flow of the asphalt binder at its circumference. The data are examined with respect to their validity as a measure of fatigue, and recommendations with respect to the use ...

Evaluation of fatigue criteria for asphalt binders

Recently there has been considerable interest, especially in Europe, in the use of zero shear viscosity (ZSV) as a specification criterion for asphalt binders. This interest is precipitated by the apparent inability of the current Superpave® criterion, G*/sin(δ), to capture the contribution to rutting resistance afforded by polymer modification. ZSV can be determined directly from long-term creep tests, but such tests are timeconsuming and are often very difficult to perform. Several alternative methods for determining the ZSV have been proposed in the literature, including extrapolating the dynamic viscosity to zero frequency; applying the Cross model to dynamic data; and superimposing multiple short-term, non-steady-state creep tests. A number of methods for determining the ZSV from both creep and dynamic data were evaluated. Laboratory test data for 10 unmodified and modified binders were obtained through a series of creep and dynamic experiments. ZSV values obtained from two of the more promising meth...

Zero Shear Viscosity of Asphalt Binders

In this paper the thermal cracking temperatures are presented for 42 plain and modified asphalt binders. Thermal cracking temperatures determined by the original and recently proposed alternative Superpave specification are compared. In addition, fracture properties obtained for ten asphalt binders are compared to the thermal cracking temperatures as determined by the original and recently proposed alternative Superpave specification. The set of ten binders were produced from a common base material but modified bY different means. For the set of ten binders there is little difference iN their ranking according to both the original and recently proposed alterNative Superpave low temperature criteria. However, their ranking is quite different based on the fracture properties as measured by Kic. Kic appears to provide a much more definitive ranking of the binders than either of the Superpave specification criteria. For the covering abstract see ITRD E107185.

Low-temperature thermal cracking of asphalt binders as ranked by strength and fracture properties

The original Superpave low-temperature specification for asphalt binders placed limits on the low-temperature stiffness and m-value. A recently approved alternative to the original Superpave asphalt binder low-temperature specification makes use of the measured stiffness and tensile strength of the binder to determine a critical cracking temperature. Thermal cracking temperatures are presented for 42 plain and modified asphalt binders. Thermal cracking temperatures determined by the original and recently approved alternative Superpave specification are compared. The fracture toughness, KIC, can also be used to evaluate low-temperature cracking properties of asphalt binders. Fracture properties obtained for 14 asphalt binders are compared with the thermal cracking temperatures determined by the original and recently adopted alternative Superpave specifications. The set of 14 binders was produced from a common base material but modified by different means. For the set of 14 binders, there is little differen...

Didier Martin

Papers

A structure‐related model to describe asphalt linear viscoelasticity

Evaluation of fatigue criteria for asphalt binders

Zero Shear Viscosity of Asphalt Binders

Low-temperature thermal cracking of asphalt binders as ranked by strength and fracture properties

Low-Temperature Thermal Cracking of Asphalt Binders as Ranked by Strength and Fracture Properties: