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Part of this research was funded by the project RTI2018-096224-J-I00 that has been cofounded by the Spanish Ministry of Science and Innovation, inside the National Program for Fostering Excellence in Scientific and Technical Research, National Subprogram of Knowledge Generation, 2018 call, in the framework of the Spanish National Plan for Scientific and Technical Research and Innovation 2017-2020, and by the European Union, through the European Regional Development Fund, with the main objective of Promoting technological development, innovation and quality research. Part of this work was financially supported by the Italian Ministry of University and Research with the research Grant PRIN 2017 USR342 Urban Safety, Sustainability and Resilience., This paper describes the development of novel/state-of-art computational framework to accurately predict the degree of binder activity of a reclaimed asphalt pavement sample as a percentage of the indirect tensile strength (ITS) using a reduced number of input variables that are relatively easy to obtain, namely compaction temperature, air voids and ITS. Different machine learning (ML) techniques were applied to obtain the most accurate data representation model. Specifically, three ML techniques were applied: 6th-degree multivariate polynomial regression with regularization, artificial neural network and random forest regression. The three techniques produced models with very similar precision, reporting a mean absolute error ranging from 12.2 to 12.8% of maximum ITS on the test data set. The work presented in this paper is an evolution in terms of data analysis of the results obtained within the interlaboratory tests conducted by Task Group 5 of the RILEM Technical Committee 264 on Reclaimed Asphalt Pavement. Hence, despite it has strong bonds with this framework, this work was developed independently and can be considered as a natural follow-up, Spanish Government RTI2018-096224-J-I00, European Commission, Ministry of Education, Universities and Research (MIUR) PRIN 2017 USR342

The addition of crumb rubber particles as bitumen modifier can be currently considered as a well-established alternative to conventional polymers for bitumen modification. However, Recycle Tyre Rubber (RTR) modified binders still present drawbacks such as poor mix workability and hot storage stability. Within this study the authors try unlocking the full potential of devulcanised tyre rubber-heavy oils blend, named Liquid Rubber (LR), by exploring the possibility of tailoring recycled polymer modified bitumen with unconventional high-content of RTR and designed to overcome the above mentioned technological problems of RTR modified bitumen while keeping its advantages. Results show that LR-bitumen blends incorporating up to 30% RTR in weight of total binder clearly improves useful temperature interval of base bitumen by maintaining solubility values allowing them to be considered stable at hot-storage temperature. Furthermore, the LR modifier allows reducing usual manufacture temperatures up to 30 °C by providing superior low and intermediate temperature rheology, however high service temperature properties are improved only at low strain.

The recent drive to find ways to increase sustainability and decrease costs in asphalt paving has led researchers to find innovative ways to incorporate more recycled materials and bio-derived binders into mixes with varying success. A new novel bio-derived binder made from refined pine chemistry stabilised with a polymer can increase the sustainability of asphalt mixes while maintaining pavement performance. Laboratory performance testing was conducted on asphalt mixes containing 50% Reclaimed Asphalt Pavement (RAP) by mix weight and the novel bio-derived binder. Results show that the bio-derived binder outperforms the conventional 50/70 pen grade binder mixes with respect to resistance to thermal cracking and adequately passes all requirements for pavements with 20-year design loadings of less than 30 million ESALs. This research shows that asphalt mixes containing 50% RAP and a bio-derived binder can be designed to pass performance criteria at low, intermediate, and high temperatures without the need of neat bitumen.

The pavement engineering industry, having realized the significance of the impacts that it imposes on the environment through the production, construction and management of its products and assets, has been driven towards a more sustainable and circular way of operating. This has partly been through asphalt recycling, which is an area that many road authorities have prioritized. However, not all the National Road Authorities (NRAs) and/or sector stakeholders seem to be adequately familiar with the Circular Economy (CE) concept. This paper attempts to assist the transition of NRAs to a more circular way of doing business, by analyzing the current situation of CE within national/regional authorities and NRAs. To do so, a questionnaire was sent to di erent NRAs and an online search was conducted to identify the ways that NRAs communicate their CE practices. Findings indicate that, although the majority of the NRAs are familiar with CE as a concept, not many actions have been taken so far towards its holistic implementation. Finally, there is a significant lack of CE expertise and communication within these bodies., European Union's Horizon 2020 Program under the Marie Curie-Sklodowska actions for research, technological development, and demonstration 721493, CEDR Transnational Research Programme

As part of an effort by agencies and industry to move towards performance-based design to evaluate mixtures in the laboratory at a smaller scale before moving to full scale operation, laboratory protocols exist to simulate the aging that occurs as a material is produced. However, recent research has shown that these existing protocols may not accurately represent the changes a material experiences in a plant. Moreover, due to the focus of previous studies on the ability of the current method to replicate mixture characteristics and performance in an undamaged state, there is a lack of information as it relates to the damaged state. This paper presents a concise description of a study undertaken on a particular mixture to evaluate the differences in the behaviour of a standard asphalt concrete mixture produced in the laboratory and in the plant to assess the anticipated field performance at the mixture design stage. The results, in terms of the rheological properties of binders extracted and recovered from laboratory and plant produced mixtures as well as rheological, repeated cyclic fatigue, and cracking performance evaluation of the asphalt mixtures, have shown the ability of a short-term oven aging protocol to replicate plant produced material in the laboratory.

Alternative binders not derived from fossil fuels, known as biobinders, are opening new paths for multiple applications in road infrastructure. Biobinders, usually produced from bio-oils obtained from the processing of biomass and industry by-products, are tuneable materials whose properties can be adjusted to meet specific targets. For this reason, an interesting approach is to couple biobinders with Reclaimed Asphalt (RA) by taking advantage of their rejuvenating properties to design bio-asphalt mixtures with high-content RA and no additional virgin bitumen. Recent research has proven the feasibility of this approach through validation at full-scale (BioRePavation project). However certain aspects related to the durability of bio-asphalt mixtures still require further research, one of these being their resistance to moisture damage. This study aims at filling some of these current gaps by conducting an initial investigation of the moisture sensitivity of selected biobinders and bio-rejuvenated asphalt binders. In order to do this, the intrinsic adhesion and cohesion properties of an extracted RA binder, two biobinders, their blends and two types of aggregates were characterised by means of Surface Free Energy (SFE), individually and as a system. The binders/blends-aggregate systems were further tested by means of the Pneumatic Adhesion Tensile Test Instrument (PATTI) to determine their pull-off tensile strength (POTS). The results show that the bio-rejuvenated asphalt binders present equivalent cohesive and adhesive properties to a conventional bitumen and superior performance when compared to the RA binder. Hence, the combination of biobinders and RA has great potential to guarantee resistance to moisture damage of bio-recycled asphalt mixtures with high-content RA and no additional bitumen.

The massive exploitation of non-renewable natural resources which has taken place in the last decade has led to significant global environmental concerns. In such a context, the use of non-petroleum-based binders for the construction of bound layers of flexible pavements can represent an effective solution to limit crude oil depletion. The research work presented in this paper focused on the effects of ageing on the rheological and chemical characteristics of a non-bituminous binder, indicated in the study as a “biobinder”, and a traditional neat bitumen selected as a reference material. Binders were analyzed in four ageing conditions obtained by making use of the Rolling Thin Film Oven and of the Pressure Ageing Vessel. Rheological behaviour of binders was investigated by means of oscillatory tests carried out in a wide range of temperatures and frequencies with a dynamic shear rheometer. Chemical structure was explored via Thin Layer Chromatographic analyses and Fourier Transform Infrared Spectroscopy. The experimental work demonstrated that mechanisms of ageing which are involved in biobinders completely differ from those experienced by petroleum-based binders. Concerns were expressed with respect to the applicability to non-conventional binders of currently available ageing techniques and of chemical characterization methods.

The aged properties of Reclaimed Asphalt (RA) binders are one of the main factors working against their utilisation in high-RA content (&gt, 30%) mixes for surface courses. Fatigue cracking is the main distress of surface courses that are manufactured with a high percentage of RA. This investigation presents results of the rheological and fatigue results of different asphalt mixtures and their recovered binders. The binders were recovered from asphalt mixtures that had been manufactured in asphalt plants using different amounts of RA with contents up to 60% with and without rejuvenators. Two different sources of RA were used, representing a moderately aged RA and an extremely aged RA. The Dynamic Shear Rheometer (DSR) was used to assess the fatigue-characteristics of the binders using time sweep tests while the fatigue characteristics of their mixtures were assessed using the Indirect Tensile Fatigue Test (ITFT). The fatigue data was analysed based on the cumulative dissipated energy approach in addition to traditional fatigue analysis. Results have shown that the ageing condition of RA significantly affects the fatigue properties of recovered binders. Binder and asphalt mixture fatigue results showed that RA contents up to 60% can produce comparable fatigue performance compared to lower percentages of RA in road surface course if the aged RA binder is sufficiently rejuvenated.

Reclaimed Asphalt Pavement (RAP) has shown great potential for being used in the construction or maintenance of roads. However, RAP is usually downgraded to lower pavement layers and the percentage of RAP used in wearing courses is still moderate (≤30%). The research and results contained in this paper focus on the definition of binder recipes aimed at increasing the percentage of RAP in hot and warm mix asphalt wearing courses. A review of current internationally used blend design methodologies is presented followed by case studies aimed at defining binder recipes for high RAP content asphalt mixture wearing courses to be further used for mix design and production in asphalt plants. Binder design has been carried out by means of rotational viscosity, Dynamic Shear Rheometer, Bending Beam Rheometer and conventional experimental tests with results showing that the amount of RAP used in a mix can be increased through the development of an accurate binder design and the selection of an appropriate rejuvenator. As a result, laboratory design showed that using up to 90% of RAP is a feasible option. However, the percentage of RAP to be used is highly dependent on the properties of the initial RAP binder, so every case has to be independently and carefully studied. The research presented is carried out as part of the CEDR Transnational Road research Programme Call 2012 (http://allback2pave.fehrl.org) and the Marie Curie Initial Training Network action, FP7-PEOPLE-2013-ITN (http://www.superitn.eu).

Reclaimed Asphalt (RA) has shown great potential to be reused in new asphalt mixtures, however its incorporation in top asphalt pavement layers is still very limited (10e30%). In fact, despite the advan- tages that its use implies, RA content in road pavement surface courses is still restricted in most countries due to mainly legislation limitations, but also some technical issues. This paper aims at being a step further to improve the latter by providing a methodology that allows producing fundamental inputs for confidently performing mix design of asphalt mixtures incorporating up to 100% RA. The methodology consists in an advanced preliminary binder's blend design that can be used with any type of RA and also in presence of rejuvenators. This procedure includes in the production of blending charts and laws that considers the uncertainties on accounting the extent of final binder content, Degree of Blending and Replaced Virgin Binder. The description of the methodology is accompanied with results of two extreme case studies consisting in the preliminary design of binders for asphalt mixtures with high content of two types of RA corresponding to extreme cases: the short-term aged RA (STA-RA), having a very soft residual binder (Pen > 20 dmm) and the long-term aged RA, having a much harder residual binder (Pen < 10 dmm). As a result, the proposed methodology allowed assessing the feasibility of using up to 90% of RA and determining whether the use of rejuvenating agents was needed.

This paper presents the results from a laboratory investigation on the effects of aging on the properties of two binders recovered from two different sources of Reclaimed Asphalt (RA) and additivated with a biorejuvenator derived from pine trees. It has been already proven that the rejuvenators are able to restore some of the properties of the aged binder present in the RA, but nowadays their effects into the long-term period are not well known. In this regard, the rejuvenated asphalt binders and a virgin binder, defined as a target, have been aged artificially to simulate short-and long-term aging. All binders have been studied conducting physical, chemical, rheological, and performance-related tests at three different aging levels. Results show that physical and rheological properties can be fully restored by the addition of the proper dose of rejuvenator, while the chemical composition should be investigated in more detail. Rejuvenated binders exhibit great long-term performance especially at high and low temperatures, but also show significant resistance against fatigue at intermediate temperatures.

El interés en la utilización de bio-materiales en ingeniería de pavimentos ha crecido significantemente en las últimas décadas debido a la conciencia ambiental sobre el uso de recursos naturales no renovables. En este artículo, se utilizan bio-materiales para recuperar las propiedades iniciales del betún envejecido presente en mezclas con alto contenido de asfalto reciclado (RA). Para ello, se ha estudiado y comparado el comportamiento de dos bio-materiales con betunes convencionales y betunes modificados con polímeros. Con este objetivo, se fabricaron mezclas de bio-materiales y betún reciclado simulando mezclas asfálticas con 50% de contenido de reciclado. El efecto rejuvenecedor de los bio-materiales se ha evaluado y comparado con el efecto rejuvenecedor de ligantes convencionales mediante el cálculo de las distribuciones de peso molecular aparente y diferentes parámetro reológicos. Los resultados muestran el poder rejuvenecedor de los bio-materiales, poniendo de manifiesto su potencial para usarse como ligantes vírgenes en mezclas asfálticas con alto contenido de reciclado.

The use of Half Warm Mixes with high Reclaimed Asphalt content (HWMRA) has the potential to generate significant environmental advantages such as the reduction in consumption of natural resources and the emission of gases into the atmosphere. This paper therefore focuses on demonstrating the viability of using these types of mixes in wearing courses. For this purpose, an HWMRA with 70 % and 100 % Reclaimed Asphalt Pavement (RAP) and emulsion were designed in the laboratory. The performance of the mixes was then assessed and compared with that of conventional Hot Mix Asphalt. In a second stage, the mixes were manufactured in-plant, and laid and compacted in an Accelerated Pavement Test track. The cores were then extracted and tested for stiffness modulus and resistance to fatigue. The results from the tests conducted with both the laboratory specimens and the cores showed that the performance of HWMRA is comparable to that of HMA. These findings encourage greater confidence in promoting the use of these types of sustainable asphalt mixes., La utilización de mezclas asfálticas templadas con alto contenido de asfalto reciclado (HWMRA) conlleva ventajas medioambientales como la reducción del consumo de recursos naturales y la emisión de gases a la atmósfera. Este artículo se centra en mostrar la viabilidad de este tipo de mezclas para capas de rodadura. Para ello, se diseñaron mezclas HWMRA con 70 % y 100 % de asfalto reciclado en el laboratorio y se evaluó y comparó su comportamiento con una mezcla caliente convencional. En una segunda etapa, las mezclas fueron fabricadas en planta, extendidas y compactadas en una pista de ensayo acelerado de pavimentos. A continuación, se extrajeron testigos y se ensayaron para conocer su módulo de rigidez y resistencia a fatiga. Tanto los resultados de laboratorio como tras la fabricación en planta y puesta en obra mostraron que el comportamiento de mezclas HWMRA es comparable al de mezclas calientes convencionales. Dicha conclusión puede aportar confianza a este tipo de mezclas sostenibles promoviendo su mayor utilización.

Resumen.-La mayoría de las investigaciones sobre el diseño de firmes de mezclas bituminosas se basan en ensayos de laboratorio que determinan las propiedades mecánicas de las mismas intentando reproducir las condiciones de fabricación de la mezcla en planta, su puesta en obra y las acciones que sufrirá durante su vida de servicio. Son muchas las variables que intervienen en el diseño de una mezcla bituminosa: tipo de árido, tamaño, tipo de ligante, contenido de huecos, etc., por lo que la realización de ensayos de laboratorio que abarquen todas ellas supone un consumo de material y tiempo muy elevados. Además, los materiales que componen las mezclas, áridos (provenientes de cantera) y betún (subproducto del petróleo), son recursos agotables que conllevan el deterioro del medio ambiente y un alto gasto económico. La posibilidad de predecir propiedades fundamentales de las mezclas bituminosas mediante modelos micro-mecánicos es esencial para suplir o reducir la necesidad de realizar ensayos de laboratorio. Asimismo, la simulación de las mezclas mediante estos modelos proporciona un mejor conocimiento del funcionamiento de la estructura interna de la mezcla. El Trabajo Fin de Máster que se presenta ensaya teóricamente el Método de los Elementos Discretos para modelizar el comportamiento mecánico de mezclas bituminosas y relacionar las propiedades del modelo con las variables que intervienen en el diseño de mezclas. En particular, esta investigación se centra en el tamaño de árido, la naturaleza del mismo y el tiempo de aplicación de la carga. Con este propósito, se ha generado un modelo 3D en el que se reproducen las propiedades volumétricas de las mezclas y se simula un ensayo de compresión uniaxial. Mediante la variación de las propiedades del modelo se obtienen resultados que se correlacionan con los datos de laboratorio. Dentro del rango de estudio del presente trabajo, se ha encontrado que el aumento del tamaño de árido no influye significativamente en las propiedades de las mezclas, pero sí en la rigidez de los contactos del modelo. Por el contrario, la naturaleza del árido y el tiempo de aplicación de la carga afectan tanto al comportamiento de la mezcla en laboratorio como a la rigidez de los contactos del modelo., Universidad de Granada. Departamento de Mecánica de Estructuras e Ingeniería Hidráulica. Máster Universitario en Estructuras, curso 2012-2013

The interest in using bio-materials in pavement engineering has grown significantly over the last decades due to environmental concerns about the use of non-recoverable natural resources. In this paper, bio-materials are used together with Reclaimed Asphalt (RA) to restore some of the properties of the aged bitumen present in mixtures with high RA content. For this purpose, two bio-materials are studied and compared to conventional and polymer modified bitumens. Blends of these materials with RA bitumen were produced and studied to simulate a 50% RA mixture. The rejuvenating effect of the two bio-materials on RA has been assessed and compared with the effect of the conventional binders. Apparent Molecular Weight Distribution of the samples (obtained by the ?-method) and different rheological parameters were used for this purpose. Results revealed the power of bio-materials to rejuvenate RA bitumen, showing their capability to be used as fresh binders in high-RA content mixtures., El interés en la utilización de bio-materiales en ingeniería de pavimentos ha crecido significantemente en las últimas décadas debido a la conciencia ambiental sobre el uso de recursos naturales no renovables. En este artículo, se utilizan bio-materiales para recuperar las propiedades iniciales del betún envejecido presente en mezclas con alto contenido de asfalto reciclado (RA). Para ello, se ha estudiado y comparado el comportamiento de dos bio-materiales con betunes convencionales y betunes modificados con polímeros. Con este objetivo, se fabricaron mezclas de bio-materiales y betún reciclado simulando mezclas asfálticas con 50% de contenido de reciclado. El efecto rejuvenecedor de los bio-materiales se ha evaluado y comparado con el efecto rejuvenecedor de ligantes convencionales mediante el cálculo de las distribuciones de peso molecular aparente y diferentes parámetro reológicos. Los resultados muestran el poder rejuvenecedor de los bio-materiales, poniendo de manifiesto su potencial para usarse como ligantes vírgenes en mezclas asfálticas con alto contenido de reciclado.