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The current need to move towards more sustainable technologies in the construction sector has promoted the investigation of using alternative materials in asphalt mixtures for pavements. Biomaterials, used as biobinders, have shown their potential as partial replacement of bitumen in asphalt mixtures as solution to decreasing the demand for fossil-fuel-based binders as well as CO2 emissions. However, more research is needed to increase the replacement of bitumen in asphalt mixtures. In this investigation,biobinders are used as full replacement of virgin bitumen and as recycling agent within asphalt mixtures with high Reclaimed Asphalt (RA) content. Blends of biobinders and RA binders, and bio-recycled asphalt mixtures, were produced, subjected to ageing and rheologically characterised. The results show that the rheological properties of binders' blends seem adequate for their use, while the bio-recycled asphalt mixtures seem to have a faster ageing than conventional ones, hence their full-scale application still remains a concern. [ABSTRACT FROM AUTHOR]

Bituminous sub-ballast in railway track-bed can mitigate the variation of the moisture content in the subgrade and reduce vertical stiffness variations of the track leading to a more durable infrastructure. Nevertheless, durability is only one of the aspects that affects the sustainability of an infrastructure. Other relevant aspects are related to the environmental and economic issues. This research work joins the worldwide effort towards a paradigm shift in civil engineering devoted to assess the sustainability of infrastructures at the design stage. With this in mind, in this study different alternative bituminous sub-ballast mixtures containing recycled materials, namely crumb rubber (CR) and reclaimed asphalt pavements (RAP) were compared by means of the results of a Life-Cycle Assessment (LCA). In comparison with a traditional bituminous sub-ballast the Crumb Rubber Modified (CRM) mixtures showed higher impacts due to the treatment of the rubber as well as the higher amount of bitumen employed in the mixture. In turn, when RAP is used, the LCA results report an improvement of all the indicators considered. The reduction of the impacts is even higher when full blending between the aged and the virgin binder is assumed because it allows reducing the amount of virgin bitumen employed. The results are intended to be used by engineering experts and practitioners to make more assertive judgments on the advantages and disadvantages associated with the use of emerging and commonly called sustainable strategies and practices for railway track-bed. [ABSTRACT FROM AUTHOR]

Pavements are engineered systems present in every modern society, and they have significant environmental, economic and social impacts. In an effort to promote more sustainable decisions regarding pavement design, construction and management, several pavement sustainability assessment tools have been developed. This research reviewed some of these tools and found that many of them do not treat the pavement as a system; instead, they seek to optimize individual aspects of the pavement in an effort to increase its sustainability. Therefore, a framework for analytically assessing the system outcomes towards sustainable objectives is presented and applied for modern pavement sustainability assessment. The results suggest that this framework provides a way to systematically include data in the evaluation of the outcomes of pavement management decisions towards achieving sustainable objectives. [ABSTRACT FROM AUTHOR]