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Life Cycle Assessment of low temperature asphalt mixtures for road pavement surfaces: a comparative analysis. Resources, Conservation and Recycling, Elsevier, 2018, pp.

Davide (2016) Bitumen stabilized ballast: a potential solution for railway track-bed. Construction and Building Materials, 124 . pp. 118-126. ISSN 1879-0526 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/36984/1/Accepted%20Manuscript%20-%20Bitumen %20stabilized%20ballast%20-%20A%20potential%20solution%20for%20railway%20track-bed.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the Creative Commons Attribution Non-commercial No Derivatives licence and may be reused according to the conditions of the licence. For more details see: http://creativecommons.org/licenses/by-nc-nd/2.5/ A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. U N C O R R E C T E D P R O O F ARTICLE INFO ABSTRACTRailway ballast degradation under dynamic loads progressively leads to loss of mechanical performance and geometry of the track, so that maintenance interventions are frequently needed. In order to systematically avoid this issue, recently solutions have been proposed to reinforce track-bed by using polyurethane and/or resins as well as asphalt layers among others. Nonetheless, their main limitations are related to the high initial cost and low productivity.To cope with these limitations, in this study, bitumen stabilized ballast (BSB) is proposed as a new solution for ballast stabilization. This method aims at improving durability and reducing settlement by modifying both stiffness and the ability of energy dissipation of the layer. The paper introduces the potential of this technology as material to be used in railway track-beds by presenting the results of a laboratory-based investigation using the Precision Unbound Material Analyser (PUMA). Different variables such as ballast grading, bitumen emulsion dosage, compaction method and stress levels are considered. Results showed a significant decrease in permanent deformation and deformation rate associated with modified stiffness and energy dissipation properties of BSB, which suggest the potential for improving long-term performance and sustainability of ballasted track.

On the Degree of binder Activity of reclaimed asphalt and Degree of Blending with recycling agents It's common practice to assume full blending of the aged binder of reclaimed asphalt (RA) within the design of new asphalt mixtures. Although being practical, this assumption has often led designers to asphalt mixtures lacking binder. Hence, going towards recycled asphalt mixtures (RAM) there is a need to have a better understanding of the blending phenomena, to have a general agreement on terminology and finally adapting RA classification and mix design procedures accordingly. This manuscript aims at being both a reference and stimulus for the scientific community to work in this direction and on this basis provides a nomenclature and a theoretical framework of the blending phenomena. The study is built upon a literature review on definitions, methods and influencing factors related with the blending phenomena and as a result an intrinsic property of RA, the degree of binder activity (DoA), is introduced for the sake of improving RA classification. Furthermore, the two well-known concepts of degree of Blending (DoB) and degree of Availability (DoAv) are redefined, within the proposed framework, together with practical suggestions to introduce them in mix design procedures. Keywords: degree of activity; degree of blending; degree of availability; recycled asphalt; recycling agent, blending phenomena Black Aggregate White Aggregate Softer RA binder: The layer of aged binder that does not move from the RA particles, but becomes softer and acts as a glue. Total RA binder: amount of binder potentially available as binding agent and composed of the RA binder and, when present, recycling agents. Unavailable RA binder: the amount of aged binder that cannot be considered available in a new formulation: This quantity is made of two components: Black Rock RA binder and Absorbed RA binder. 7. References AASTHO M323-12: Standard Specification for Superpave Volumetric Mix Design.

(2016) Towards 100 % recycling of reclaimed asphalt in road surface courses: binder design methodology and case studies.

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Polymer additives are used to improve the properties of road bitumens including their oxidative resistance. However, their usage as anti-oxidative materials remains relatively unclear. This study aims to investigate the changes in the morphology and the rheological response of polymer modified bitumens used in road pavement construction caused by ageing. An elastomer (radial styrene butadiene styrene, SBS) and a plastomer (ethyl vinyl acetate, EVA) polymer were mixed with one base bitumen at three polymer concentrations. The bitumens were RTFO and PAV aged. The morphology of the bitumens was captured by fluorescence microscopy while the rheological properties were measured by means of the multiple stress creep and recovery (MSCR) test. The results show that the morphology of the SBS modified bitumen degrades with ageing as a function of polymer concentration and dispersion, with higher dispersion being more resistant. The morphology of the EVA modified bitumen has a low ageing susceptibility irrespective of polymer concentration. The MSCR response of EVA modified bitumens does not differ from that found for unmodified bitumen, where the hardening produces a decrease in the non-recoverable compliance. In the case of SBS modified bitumen, the degradation of the polymer backbone affects the bitumen hardening as much as the polymer phase dispersed and networked in the bitumen phase. Furthermore, in the case of the elastomer, the average percent recovery is in agreement with the variation of the morphology with ageing. Therefore, the use of the average percent recovery as a valuable rheological index of the integrity of the polymer network can be advocated.

Abstract. The aim of this paper is to propose a fractional viscoelastic and viscoplastic model of asphalt mixtures using experimental data of several tests such as creep and creep recovery performed at different temperatures and at different stress levels. From a best fitting procedure it is shown that both the creep one and recovery curve follow a power law model. It is shown that the suitable model for asphalt mixtures is a dashpot and a fractional element arranged in series. The proposed model is also available outside of the linear domain but in this case the parameters of the model depend on the stress level.