Designing a toolbox for bitumen to answer the need for tomorrow's pavement

The asphalt industry is facing some key challenges. There is a need to move towards more sustainable and environmental friendly solutions to construct the pavements for tomorrow. This has to answer the market needs for greater performance with improved warranties, increased safety and less impact on environment, all in required budget constraints. At the same time, there is an even greater diversity in binders, petroleum based binders from different sources or processes for which bitumen quality may be affected. Up to now, specifications and characterisation for asphalt binders have been designed for known petroleum-based bitumen. With complex binders, more fundamental understanding and properties have to be considered to really capture the long-term benefits in road and airport engineering. And finally, beyond the technical requirements, sustainable aspects need to be part of the design including circularity, environmental impacts, health and safety amongst others. This is an important paradigm where new technologies are needed and adjustment of designing materials. Thus, the need for new solutions are becoming increasingly common practice. Designing the exact solution may depend on various parameters such as the nature of the modifier, the dosage level, or the expected effects on the binder, on the asphalt mix and finally on the pavement. It can be viewed as a toolbox where different options can be selected and combined together to adjust the properties of the binders that fits the need for pavement applications. Through some examples with the specific use of polymers and bio-based additives, an example of general framework will be discussed to be served as a toolbox to design materials to bring the frontiers of road and airport engineering a step further to the future

Evaluation of chemical composition and physical properties of bituminous binders and fractions

Bituminous binders are foreseen as colloidal dispersed systems characterised by high chemical complexity containing a plethora of molecules classified into maltenes and asphaltenes. The effect of these fractions on the overall response of bituminous binders remains elusive. This research selected two binders from the same refinery but with different paving grades. First, Dynamic Shear and Bending Beam Rheometers were employed to assess their rheological properties, and results were consistent with the physical measurements conducted on binders to address low to high temperature rheological response. Then, the binders and their fractions were individually analysed in a Fourier transform infrared spectroscopy and differential scanning calorimetry to elucidate their chemistry associated with the structural changes. No significant difference could be noticed in the infrared spectra of binders, even if they displayed diverse physical properties. Differences may be identified in asphaltenes, an observation which is also supported by calorimetric measurements where steric hindrance occurred upon heating. Maltenes contributed significantly to the glass transition of both binders, while the impact of asphaltenes on the heat capacity changes in glass transition was limited. The findings from this research could be used to establish a new analytical approach for bituminous binders to understand the differences in the physical properties of binders based on their chemistry.Pavement Engineerin

RILEM TC272 PIM: phase morphology of bituminous binders with liquid additives

In the past years, the use of liquid additives as bitumen modifiers has increased to tailor the rheology of bitumen for a wide range of applications. Their chemical composition and mutual interaction result in specific phase morphologies in the binders. Hence, there is a need to evaluate the phase morphology of complex binders and the impact of additives on their physical properties. The RILEM Technical Committee 272-PIM ‘Phase and Interphase behaviour of innovative bituminous Materials’, Task Group TG1 assessed the phase and interphase properties of bituminous binders. Some preliminary results are presented on blends using three liquid additives and a neat 35/50 bitumen. The goal of formulating the blends was to achieve similar consistency of a pen grade 70/100 bitumen at the original state and to evaluate the binders at both original and after aging. Physical properties were evaluated through rheological characterisation using a dynamic shear rheometer (DSR) in a wide range of conditions. The phase morphology was assessed using atomic force microscopy (AFM). Differential scanning calorimetry (DSC) was also used for the characterisation of the thermal behaviour of the binders. While conventional properties, as obtained from the routine binder testing methods, hardly distinguish between blends, the cross-over temperature, derived from DSR measurements, enabled to dictate the impact of liquid additives on the physical properties of bituminous binders at intermediate temperature. AFM confirmed a difference in phase morphology between the blends, whereas some binders displayed new phases at original and aged conditions. Glass transition, as determined by DSC, also showed a difference in the low-temperature domain that may be explained with the difference in phase morphology. Overall, an in-depth understanding of microstructure morphology and glass transition behaviour of complex binders can assist in designing future specifications to distinguish durable bituminous materials better.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Pavement Engineerin

Rheological and Microstructural Assessment of Complex Bituminous Binders

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Glass transitions in bituminous binders

The RILEM TC 272 PIM (Phase and Interphase behavior of innovative bituminous Materials)—TG1 Binder has initiated an inter-laboratory program investigating the phase and interphase behaviour of bituminous binders. Within the scope, four laboratories evaluated the low temperature properties of seven binders with differential scanning calorimetry (DSC). DSC has been accepted as a powerful tool to evaluate, among others, the glass transitions, Tg, monitoring the endothermic or exothermic heat flow of a material under controlled temperature conditions. There are different ways to run the test, conventional temperature linear-DSC (TL-DSC), and temperature modulation-DSC (TM-DSC). The latter has been proven as an efficient method differentiating the structural relaxation phenomena from the heat capacity. In this study, emphasis was placed on comparing the Tg measured by TL- and TM-DSC to improve the interpretation of binder glass transitions. In this study, the scope was restrained to two Polymer modified Binders (PmBs): a commercially available modified binder named PmB1 and a highly modified binder (7.5 wt% high vinyl SBS) named PmB2, were evaluated and compared with two neat bituminous binders. Based on the thermographs of the PmB2 obtained through this inter-laboratory program, it was observed that the modification by 7.5% SBS resulted in a decrease of the Tg. This reduction of Tg reflects the positive influence of SBS at low temperatures.Pavement Engineerin

Glass Transitions in Complex Bituminous Binders

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Fourier-transform infrared analysis and interpretation for bituminous binders

InfraRed spectrometry is a powerful technique to characterise bituminous binders. The methodology is not fully harmonised and may lead to vari-ability. The RILEM-272-PIM-TG1, evaluated seven complex bituminous, for which eleven laboratories performed FTIR. While, the spectra showed sim-ilar trends, further analysis was needed to improve comparison. A specific approach was applied on two binders, unmodified and polymer modified bitumen, and two ageing conditioning. Combining a Gaussian distributionand derivative analysis confirmed a good alignments of laboratory results. A two-step model was developed improving further interpretation. It con-sists of a baseline adjustment with eight points and normalisation over the maximum aliphatic peak. Furthermore, a specific fingerprint model was determined with the main absorption peaks defined by their location and shape. Only the intensity varies from laboratory to laboratory and binders. This general approach can be used as a platform to characterise aging or binder complexityGreen Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Pavement Engineerin

Complex bituminous binders, are current test methods suitable for?

The asphalt industry is constantly working to enhance the performances of asphalt materials, introducing innovative and more sustainable solutions. In this context, the incorporation of materials, such as additives, polymers, is more and more used to improve the properties of neat bitumen. This leads to even more complex bituminous binders, raising the question, are the current specifications and test methods appropriate for complex materials? To deal with this, the RILEM Technical Committee 272-PIM ‘Phase and Interphase behaviour of innovative bi-tuminous Materials’ with its Task Group TG1 is looking at the efficiency of vari-ous test methods for complex binders with an extensive inter-laboratory program with 17 laboratories. It includes seven different binders, two neat bitumen, two polymer modified bitumen and three binders with liquid additives, emphasising on compositional and physical changes at different conditions. The focus is low temperature; while a complementary experimental program encompasses as well as testing at intermediate and high temperatures. The outcomes of the work will provide indications on how robust the current binder characterisation techniques are and establish technical recommendations for future test methods specially de-signed for complex binders. Some first results are presented hereby.Accepted Author ManuscriptPavement Engineerin

RILEM TC 279 WMR round robin study on waste polyethylene modified bituminous binders: advantages and challenges

Inter-laboratory experiments were designed to evaluate the impact of plastic waste blended directly in bitumen and to assess the properties, using conventional and advanced bituminous binder testing. The blends targeted 5% of plastic waste in 95% bitumen, using two types of polyethylene (PE) primary (pellets) and secondary (shreds) waste. The experiments showed that the addition of PE waste to bitumen does not alter the chemistry of the bitumen, the blending is physical. The DSR results indicate a strong dependency on the testing temperature as at low temperatures the composite material bitumen and PE behave both elastically whereas, at higher temperatures, the bitumen becomes viscoelastic. The MSCR tests indicated that the neat binder is more sensitive to permanent deformation compared to the blends with PE. The fatigue performance using the Linear Amplitude Sweep test showed a better performance in terms of stress and fatigue life for the PE blends.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Pavement Engineerin