Consequences of long-term infrastructure decisions—the case of self-healing roads and their CO2 emissions

What could be the reduction in greenhouse gas emissions if the conventional way of maintaining roads is changed? Emissions of greenhouse gases must be reduced if global warming is to be avoided, and urgent political and technological decisions should be taken. However, there is a lock-in in built infrastructures that is limiting the rate at which emissions can be reduced. Self-healing asphalt is a new type of technology that will reduce the need for fossil fuels over the lifetime of a road pavement, at the same time as prolonging the road lifespan. In this study we have assessed the benefits of using self-healing asphalt as an alternative material for road pavements employing a hybrid input–output-assisted Life-Cycle Assessment, as only by determining the plausible scenarios of future emissions will policy makers identify pathways that might achieve climate change mitigation goals. We have concluded that self-healing roads could prevent a considerable amount of emissions and costs over the global road network: 16% lower emissions and 32% lower costs compared to a conventional road over the lifecycle

Study of the effect of four warm mix asphalt additives on bitumen modified with 15% crumb rubber

Due to a growing concern over global warming, the bituminous mixture industry is making a constant effort to diminish its emissions by reducing manufacturing and installation temperatures without compromising the mechanical properties of the bituminous mixtures. The use of mixtures with tyre rubber has demonstrated that these mixtures can be economical and ecological and that they improve the behaviour of the pavements. However, bituminous mixtures with a high rubber content present one major drawback: they require higher mixing and installation temperatures due to the elevated viscosity caused by the high rubber content and thus they produce larger amounts of greenhouse gas emissions than conventional bituminous mixtures. This article presents a study of the effect of four viscosity-reducing additives (Sasobit®, Asphaltan A®, Asphaltan B® and Licomont BS 100®) on a bitumen modified with 15% rubber. The results of this study indicate that these additives successfully reduce viscosity, increase the softening temperature and reduce penetration. However, they do not have a clear effect on the test for elastic recovery and ductility at 25 °C

Proyecto LCweb. Respaldo documental para prácticas de laboratorio [LCweb Project. Documental support for laboratory practices]

Las prácticas de laboratorio en enseñanza universitaria están siendo sustituidas en muchos casos por laboratorios virtuales o entornos Web que permiten trabajar a distancia. Sin embargo, parece ser que el mejor modelo docente en este ámbito está constituido por una combinación de las tradicionales prácticas presenciales en el laboratorio y laboratorios virtuales o entornos Web que complementen las prácticas reales. Esta comunicación técnica presenta el Proyecto LCweb. Se trata de un entorno Web que no sustituye sino complementa las prácticas de laboratorio de materiales de construcción de la asignatura de Firmes y Pavimentos de la Universidad Politécnica de Madrid. Su contenido está compuesto por los diferentes ensayos de laboratorio de materiales para carreteras, casos prácticos a partir de datos del laboratorio, tests de autoevaluación y normativa técnica actualizada que se utiliza en la resolución de los casos prácticos. Aunque su implantación es muy reciente, en el curso 2016/2017, todo parece indicar que los alumnos efectivamente la utilizan como complemento de las visitas al laboratorio. Proyectos de este tipo suponen un fuerte trabajo inicial, pero una vez en marcha precisan poco esfuerzo por parte del profesor y suponen un recurso importante para el alumno. [Laboratory practices in the university education are being replaced for virtual laboratories or web-based applications which allow the students to work offsite. Nevertheless, it appears that the best model for this purpose is a combination of traditional hands-up laboratory work and virtual or web-based applications. This technical communication presents the LCweb Project. It is a web-based application which does not replace the hands-up work in the laboratory but complements it for the students of Pavements in the Universidad Politécnica de Madrid. The web site offers several road materials standard trials, practical examples, self-evaluation tests and the in force specifications for materials, useful to solve the practical examples. Although it has been implemented during 2016/2017 it appears that the students make use of this resource as a complement of the hands-up laboratory work rather than a substitute. This kind of projects demands a strong initial effort by the professor but when it is ongoing a small effort is required even though it gives an important support to the student.

Challenge B: Human sciences in transition scenarios

Coordinators: Josep Martí Pérez (IMF, CSIC), Idoia Murga Castro (IH, CSIC).This challenge is formulated in terms of “humanities in transition,” that is, their approach and articulation in the face of the changes they must undergo to achieve the social weight that, due to their intrinsic relevance, should correspond to them. Faced with these situations that would demand a reinforcement in research and dissemination in diverse aspects of the humanities, from multiple perspectives, paradoxically an adverse panorama is drawn for the development and dissemination of humanistic knowledge, which concerns different factors. Some are related to the consideration of the area of knowledge itself, its organization within the scientific system, the questioning of its own limits, and the interaction with another knowledge. Considering current transition scenarios does not mean having to abandon old objectives, but it adds to the work conducted new objects of study closely related to current reality, such as: the informational revolution; the relations with the ecosystem and the environmental crisis; globalization; the intensification of human mobility and migration flows; the growing economic and social inequality; the frictions derived from the articulation of collective identities; the decolonization of discourses; demographic dynamics; integration of technological advances; and viability and support for alternative models of society.Peer reviewe

Asphalt rubber mixtures with warm mix asphalt additives

En los últimos años, debido a la creciente preocupación por el calentamiento global y el cambio climático, uno de los retos más importantes a los que se enfrenta nuestra sociedad es el uso eficiente y económico de energía así como la necesidad correspondiente de reducir los gases de efecto invernadero (GEI). Las tecnologías de mezclas semicalientes se han convertido en un nuevo e importante tema de investigación en el campo de los materiales para pavimentos ya que ofrece una solución potencial para la reducción del consumo energético y las emisiones de GEI durante la producción y puesta en obra de las mezclas bituminosas. Por otro lado, los pavimentos que contienen polvo de caucho procedente de neumático fuera de uso, al hacer uso productos de desecho, ahorran energía y recursos naturales. Estos pavimentos ofrecen una resistencia mejorada a la formación de roderas, a la fatiga y a la fisuración térmica, reducen los costes de mantenimiento y el ruido del tráfico así como prolongan la vida útil del pavimento. Sin embargo, estas mezclas presentan un importante inconveniente: la temperatura de fabricación se debe aumentar en comparación con las mezclas asfálticas convencionales, ya que la incorporación de caucho aumenta la viscosidad del ligante y, por lo tanto, se producen mayores cantidades de emisiones de GEI. En la presente Tesis, la tecnología de mezclas semicalientes con aditivos orgánicos (Sasobit, Asphaltan A, Asphaltan B, Licomont) se incorporó a la de betunes de alta viscosidad modificados con caucho (15% y 20% de caucho) con la finalidad de dar una solución a los inconvenientes de mezclas con caucho gracias a la utilización de aditivos reductores de la viscosidad. Para este fin, se estudió si sería posible obtener una producción más sostenible de mezclas con betunes de alto contenido en caucho sin afectar significativamente su nivel de rendimiento mecánico. La metodología aplicada para evaluar y comparar las características de las mezclas consistió en la realización de una serie de ensayos de laboratorio para betunes y mezclas con caucho y con aditivos de mezclas semicalientes y de un análisis del ciclo de vida híbrido de la producción de mezclas semicalientes teniendo en cuenta la papel del aditivo en la cadena de suministro con el fin de cuantificar con precisión los beneficios de esta tecnología. Los resultados del estudio indicaron que la incorporación de los aditivos permite reducir la viscosidad de los ligantes y, en consecuencia, las temperaturas de producción y de compactación de las mezclas. Por otro lado, aunque la adición de caucho mejoró significativamente el comportamiento mecánico de los ligantes a baja temperatura reduciendo la susceptibilidad al fenómeno de fisuración térmica, la adición de las ceras aumentó ligeramente la rigidez. Los resultados del estudio reológico mostraron que la adición de porcentajes crecientes de caucho mejoraban la resistencia del pavimento con respecto a la resistencia a la deformación permanente a altas temperaturas y a la fisuración térmica a bajas temperaturas. Además, se observó que los aditivos mejoran la resistencia a roderas y la elasticidad del pavimento al aumentar el módulo complejo a altas temperaturas y al disminuir del ángulo de fase. Por otra parte, el estudio reológico confirmó que los aditivos estudiados aumentan ligeramente la rigidez a bajas temperaturas. Los ensayos de fluencia llevados a cabo con el reómetro demostraron una vez más la mejora en la elasticidad y en la resistencia a la deformación permanente dada por la adición de las ceras. El estudio de mezclas con caucho y aditivos de mezclas semicalientes llevado a cabo demostró que las temperaturas de producción/compactación se pueden disminuir, que las mezclas no experimentarían escurrimiento, que los aditivos no cambian significativamente la resistencia conservada y que cumplen la sensibilidad al agua exigida. Además, los aditivos aumentaron el módulo de rigidez en algunos casos y mejoraron significativamente la resistencia a la deformación permanente. Asimismo, a excepción de uno de los aditivos, las mezclas con ceras tenían la misma o mayor resistencia a la fatiga en comparación con la mezcla control. Los resultados del análisis de ciclo de vida híbrido mostraron que la tecnología de mezclas semicalientes es capaz de ahorrar significativamente energía y reducir las emisiones de GEI, hasta un 18% y 20% respectivamente, en comparación con las mezclas de control. Sin embargo, en algunos de los casos estudiados, debido a la presencia de la cera, la temperatura de fabricación debe reducirse en un promedio de 8 ºC antes de que los beneficios de la reducción de emisiones y el consumo de combustible puedan ser obtenidos. Los principales sectores contribuyentes a los impactos ambientales generados en la fabricación de mezclas semicalientes fueron el sector de los combustibles, el de la minería y el de la construcción. Due to growing concerns over global warming and climate change in recent years, one of the most important challenges facing our society is the efficient and economic use of energy, and with it, the corresponding need to reduce greenhouse gas (GHG) emissions. The Warm Mix Asphalt (WMA) technology has become an important new research topic in the field of pavement materials as it offers a potential solution for the reduction of energy consumption and GHG emissions during the production and placement of asphalt mixtures. On the other hand, pavements containing crumb-rubber modified (CRM) binders save energy and natural resources by making use of waste products. These pavements offer an improved resistance to rutting, fatigue and thermal cracking; reduce traffic noise and maintenance costs and prolong pavement life. These mixtures, however, present one major drawback: the manufacturing temperature is higher compared to conventional asphalt mixtures as the rubber lends greater viscosity to the binder and, therefore, larger amounts of GHG emissions are produced. In this dissertation the WMA technology with organic additives (Sasobit, Asphaltan A, Asphaltan B and Licomont) was applied to CRM binders (15% and 20% of rubber) in order to offer a solution to the drawbacks of asphalt rubber (AR) mixtures thanks to the use of fluidifying additives. For this purpose, this study sought to determine if a more sustainable production of AR mixtures could be obtained without significantly affecting their level of mechanical performance. The methodology applied in order to evaluate and compare the performance of the mixtures consisted of carrying out several laboratory tests for the CRM binders and AR mixtures with WMA additives (AR-WMA mixtures) and a hybrid input-output-based life cycle assessment (hLCA) of the production of WMA. The results of the study indicated that the incorporation of the organic additives were able to reduce the viscosity of the binders and, consequently, the production and compaction temperatures. On the other hand, although the addition of rubber significantly improved the mechanical behaviour of the binders at low temperatures reducing the susceptibility to thermal cracking phenomena, the addition of the waxes slightly increased the stiffness. Master curves showed that the addition of increasing percentages of rubber improved the resistance of the pavement regarding both resistance to permanent deformation at high temperatures and thermal cracking at low temperatures. In addition, the waxes improved the rutting resistance and the elasticity as they increased the complex modulus at high temperatures and decreased the phase angle. Moreover, master curves also attest that the WMA additives studied increase the stiffness at low temperatures. The creep tests carried out proved once again the improvement in the elasticity and in the resistance to permanent deformation given by the addition of the waxes. The AR-WMA mixtures studied have shown that the production/compaction temperatures can be decreased, that the mixtures would not experience binder drainage, that the additives did not significantly change the retained resistance and fulfilled the water sensitivity required. Furthermore, the additives increased the stiffness modulus in some cases and significantly improved the permanent deformation resistance. Except for one of the additives, the waxes had the same or higher fatigue resistance compared to the control mixture. The results of the hLCA demonstrated that the WMA technology is able to significantly save energy and reduce GHG emissions, up to 18% and 20%, respectively, compared to the control mixtures. However, in some of the case studies, due to the presence of wax, the manufacturing temperature at the asphalt plant must be reduced by an average of 8ºC before the benefits of reduced emissions and fuel usage can be obtained. The results regarding the overall impacts generated using a detailed production layer decomposition indicated that fuel, mining and construction sectors are the main contributors to the environmental impacts of manufacturing WMA mixtures

Evaluation of Warm Rubberized Stone Mastic Asphalt Mixtures through the Marshall and Gyratory Compactors

Stone mastic asphalt (SMA) mixtures exhibit excellent behaviour; they are highly resistant to reflective cracking and permanent deformation, as well as providing the wearing surface with an optimal texture. However, the production and compaction temperatures are similar to conventional mixtures, which means that there is a significant consumption of energy, as well as greenhouse gas emissions. Warm mix asphalt (WMA) technology, which has been developed over the last few years, might allow lower temperatures without compromising the mechanical behaviour of the mixtures. Also, over the last few decades, rubberized asphalt has proved to be effective in improving the performance and being environmentally suitable, but it requires higher production temperatures than conventional mixtures. In this study, several tests were performed to evaluate the effect of a chemical WMA additive on the compactability and water sensitivity of rubberized SMA mixtures with both the Marshall and the gyratory compactor. The investigation has shown that the gyratory compactor is more suitable for studying compactability and the water sensitivity of rubberized SMA with WMA additives

Trabajo Fin de Máster Modalidad A

Se incluyen las reflexiones sobre los conocimientos adquiridos en todas las asignaturas en el Máster en Profesorado. Además, se incluye una unidad didáctica puesta en práctica durante el Practicum II y un proyecto de investigación docente llevado a cabo en el Practicum III

Reuse of plastic waste in asphalt mixtures with residual porous aggregates

The reuse of plastic and poor-quality residual aggregates in the manufacture of bituminous mixtures for paving could contribute to reclaim significant quantities in the pavement construction industry since certain polymers can enhance the mixture properties. This study investigates the potential use of waste from recycled polyethylene terephthalate (PET) in asphalt mixtures with extremely-vesiculated residual aggregates, which are also rejected in quarry production. In this research, the physical, compaction, and mechanical properties of asphalt mixtures with these marginal aggregates, different binder consistencies and PET contents replacing part of the aggregate are studied. The results indicate that limited proportions of waste PET (up to 1 %) are compatible with extremely porous aggregates and can improve certain mixture engineering properties, such as the resistance to water action and to rutting. These mixtures meet specifications for base courses and even for pavement surfaces under limited heavy-truck traffic, while contributing to the sustainability of asphalt pavements by reducing the extractive demand of natural resources and replacing them with waste materials

Identification of the optimal implementation of the microwave self-healing technology for pavements based on sustainability assessment and technical parameters

Self-healing is a preventive maintenance technique developed to extend the service life of road pavements, accordingly, increasing their sustainability: energy consumption savings, lower emissions, and a decrease in the use of non-renewable resources. Microwave (MW) self-healing technology consists of heating the binder so it can flow and fill the cracks in the pavement. To promote and enhance this asphalt self-healing capacity, electrically conductive susceptible particles like steel slag can be added as aggregates in the asphalt mixture, and a combination of heat and re-compaction energy (thermomechanical treatment) can be applied to improve healing rates. However, one of the key issues is determining how to take full advantage of asphalt mixtures self-healing capacity to maximize the extended life span of asphalt pavements in order to avoid the use of a great number of non-renewable resources and energy in the rehabilitation of deteriorated pavements. Although some different factors that affect self-healing effectiveness are being studied, the optimal implementation conditions and moment to apply the MW treatment have yet to be determined. Hence, this paper aims to identify variables and establish an optimal implementation of the MW self-healing technology including steel slags and a thermomechanical treatment (MW heating and re-compaction). For this purpose, the influence of the implementation conditions, the moment of application, and the mixture design have been assessed by Life-Cycle Greenhouse Gas emissions, Cumulative Energy Demand, and cost evaluation. Results have shown that the optimal moment to apply the MW treatment would be around the half-life span of the asphalt pavement, being the most beneficial solution when applied over asphalt mixtures using steel slag as this allows reducing energy requirement during the MW application process and minimise costs

Black curves and creep behaviour of crumb rubber modified binders containing warm mix asphalt additives

Warm mix asphalt (WMA) is a new research topic in the field of road pavement materials. This technology allows lower energy consumption and greenhouse gas (GHG) emissions by reducing compaction and placement temperatures of the asphalt mixtures. However, this technology is still under study, and the influence of the WMA additives has yet to be investigated thoroughly and clearly identified, especially in the case of crumb rubber modified (CRM) binders. In order to study the effect that different types and quantities of organic waxes have on the high and intermediate temperature properties of 15 % and 20 % CRM binders, a dynamic shear rheometer (DSR) was used. Using Black diagrams, the rheological behaviour of the binders for the defined range of test temperature and frequency are summarised in a single diagram. In this way, a preliminary evaluation of the rheological behaviour in the extended domain of time and temperature can be attained as well as the effectiveness of the time–temperature superposition principle (TTSP) on the materials under study. Creep tests were also performed in order to evaluate the differences regarding mechanical response due to the addition of rubber and WMA additives, and particularly the ability to recover the strain at high temperatures. The results of this study reveal that these binders do not conform to the Time Temperature Superposition Principle (TTSP) and their rheological behaviour is strongly affected by the interaction of waxes and bituminous matrix and thus generally exhibited a higher elasticity compared to the corresponding control binder. The creep test results carried out proved the enhancement of elasticity and the resistance to permanent deformation produced by the addition of waxes. The WMA additives significantly lower the maximum deformation when compared to the control binders and slightly increased their elastic recovery