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En el nuevo paradigma de electrificación del transporte, los vehículos eléctricos ligeros representan una vía de bajo coste prometedora para la movilidad urbana inteligente. A pesar de ello, su penetración en el mercado es relativamente baja en comparación con la de otros vehículos eléctricos, como las bicicletas o los coches eléctricos. Uno de los obstáculos para su despliegue masivo es el escaso conocimiento de su existencia por parte de los usuarios. La tesis doctoral explora la actitud previa de la población hacia los vehículos eléctricos ligeros a través de la recogida de datos en seis ciudades piloto, un cuestionario online y entrevistas in situ. El modelo matemático utilizado ha contemplado ocho percepciones y actitudes a priori: predisposición a su uso según el motivo de viaje, predisposición a su utilización como parte de un viaje multimodal, facilidad de aparcamiento, comodidad, seguridad, capacidad de carga, comodidad en la recarga eléctrica y precio., With the paradigm shift towards transport electrification, Electric Light Vehicles (EL-Vs) represent a low-cost, promising pathway to smart urban mobility. Despite this, the current market penetration of EL-Vs is relatively low compared to that of other e-powered vehicles such us e-bikes or e-cars. A major hindrance in wide market deployment of EL-Vs is the users’ low awareness of their existence. The doctoral thesis pursues a beter understanding of the prior attitude of the population towards EL-Vs through data collection in six demonstration cities, an online questionnaire survey and on-site interviews. A mathematical model also explores eight a-priori perceptions and attitudes (indicators) towards EL-V usage: Willingness to use per trip purpose, Willingness to use as a part of a multimodal trip, Ease of parking, Comfort, Safety, Luggage capacity, Charging convenience and Affordability.

La influencia de la vocación en el éxito se puede estudiar a través de diversas encuestas, pero se necesita un modelo para validar los resultados de dichos estudios con una alta probabilidad de representar con precisión la realidad estudiada. Las redes bayesianas cumplen este requisito. Los estudiantes que se matriculan en un grado de ingeniería pueden tener que elegir las disciplinas de ingeniería que difieren de su elección inicial. En algunos casos, estas diferencias pueden perjudicar su compromiso profesional y dejarlos con la sensación de que su elección final era incorrecta. Este estudio pretende cuantificar las percepciones de éxito de los estudiantes de ingeniería en términos de vocación y deficiencias ue puedan aparecer en sus actitudes. En cuanto a la metodología utilizada, las redes bayesianas nos han dado la opción de un modelo probabilístico a través de una serie de variables que validarán este modelo considerando parámetros, como la curva ROC (Receiver Operating Characteristic) que puede calcular las probabilidades de éxito en términos de vocación de nuestros estudiantes de ingeniería. Respecto a las principales conclusiones de este estudio, las relativas a las expectativas profesionales y al aprendizaje tienen más influencia sobre los alumnos, ya sean o no en el campo específico de la ingeniería que refleja su vocación. Las tasas de éxito aumentan considerablemente cuando los estudiantes perciben las variables como "encontrar trabajo útil", "encontrar un trabajo fácil" o "disfrutar del aprendizaje". En pocas palabras, ayudar a los estudiantes a no sentirse frustrados, piensan que encontrarán empleo y que sus trabajos les ayudarán a sentirse útiles en el futuro. Por lo tanto, es esencial hablar desde el nivel universitario sobre la vida profesional desde el primer año hasta la graduación., The influence of vocation in success can be studied through various surveys, but a model to validate the results of such studies with a high probability of accurately represent the reality studied is needed. Bayesian networks meet this requirement. Students who enroll in an engineering degree may have to choose engineering disciplines that differ from their initial choice. In some cases, these differences may impair their professional commitment and leave them with the feeling that his final choice was wrong. This study is intended to quantify the perceptions of success of engineering students in terms of vocation and remedy deficiencies that may appear in their attitudes. As for the methodology used have been the Bayesian networks which have given us the choice of a probabilistic model through a series of variables that will validate this model considering parameters such as the ROC (Receiver Operating Characteristic) curve, can calculate probabilities of success in terms of vocation of our engineering students. As for the main conclusions of this study, it was those relating to professional expectations and learning, having more influence on students whether they are or are not in the specific field of engineering that reflects his vocation. Success rates increase considerably when students perceive variables as "find useful work", "find an easy job" or "enjoy learning". In short, helping students to not get frustrated, you think they will find employment and that their jobs will help them feel useful in the future. Therefore, it is essential to speak from the university level on professional life from the first year until graduation and the students consider their choice of college.

Due to the presence of various traffic calming measures (TCM) and traffic lights in urban areas, the speed of vehicles is maintained low. Nevertheless, a problem arises in the frontier between urban and non-urban areas because drivers must adapt their speed and behavior to new conditions. This risk becomes even greater in rural roads that penetrate small villages without a bypass and with a short urban segment, since drivers do not normally speed down in these segments. Various measures can be installed, but traffic lights that turn red if the speed limit is exceeded is not usually considered as a TCM in the literature. Therefore, this paper aims to analyze the efficiency of traffic lights turning red in case of exceeding speed limit. The village of Abalos in Spain was selected for this research, with an urban area of 630 m and this type of traffic lights in both directions. Results showed that drivers do not respect the speed limit - and hence, the red light - when they are placed separately. However, if they are placed next to a crosswalk, their effect is increased. Consequently, it is recommended to place these traffic lights with a crosswalk to reinforce the efficiency of both TCMs., Debido a la presencia de varias medidas de calmado de tráfico (MCT) y semáforos en zonas urbanas, la velocidad de los vehículos semantiene baja. No obstante, un problema aparece en la frontera entre áreas urbanas y no urbanas porque los conductores debenadaptar su velocidad y comportamiento a nuevas condiciones. Este riesgo se vuelve incluso mayor en las carreteras interurbanas quepenetran en pequeñas poblaciones sin circunvalación y con un corto tramo urbano, pues normalmente los conductores no reducensu velocidad en estos tramos. Varias medidas pueden ser instaladas, pero los semáforos que se ponen rojos si se sobrepasa el límitede velocidad no suelen considerarse como MCT en la literatura. Por lo tanto, el objetivo de este artículo es analizar la eficacia delos semáforos que se ponen rojos en caso de exceder el límite de velocidad. La población de Abalos en España fue seleccionadapara esta investigación, con un área urbana de 630 m y con este tipo de semáforos en ambas direcciones. Los resultados muestranque los conductores no respetan el límite de velocidad - y por tanto, el semáforo en rojo - cuando son colocados por separado. Sinembargo, si son colocados junto a un paso de peatones, se aumenta su efecto. En consecuencia, se recomienda disponer este tipo desemáforos junto con un paso de peatones para reforzar la eficacia de ambas MCT.

Traffic calming measures (TCMs) are implemented in urban areas to reduce vehicles’ speed and, generally speaking, results are obtained. However, speed is still a problem in rural roads crossing small villages without a bypass and with short-length urban areas, since drivers do not normally reduce their speed for that short segment. Hence, various TCM can be installed. It is necessary to maintain a calm area in these short segments to improve road safety, especially for pedestrian aiming to cross the road, and to save combustible by avoiding a constant increase-decrease of speed. Four villages were selected to evaluate the efficiency of radar speed cameras and panels indicating vehicle’s speed. Results showed that the presence of radar speed cameras reduces the speed in the direction they can fine, but with a lower effect in the non-fining direction. Additionally, a positive effect was observed in the fining direction in other points, such as pedestrian crossings. Nevertheless, the effect does not last long and speed cameras may be considered as punctual measures. If the TCMs are placed far from the start of the village they are not respected. Hence, it is recommended to place them near the real start of the build-up area. Lastly, it was verified that longer urban areas make overall speed decrease. However, when drivers feel that they are arriving to the end of the urban area, due to the inexistence of buildings, they start speeding up.

Due to the presence of various traffic calming measures (TCM) and traffic lights in urban areas, the speed of vehicles is maintained low. Nevertheless, a problem arises in the frontier between urban and non-urban areas because drivers must adapt their speed and behavior to new conditions. This risk becomes even greater in rural roads that penetrate small villages without a bypass and with a short urban segment, since drivers do not normally speed down in these segments. Various measures can be installed, but traffic lights that turn red if the speed limit is exceeded is not usually considered as a TCM in the literature. Therefore, this paper aims to analyze the efficiency of traffic lights turning red in case of exceeding speed limit. The village of Ábalos in Spain was selected for this research, with an urban area of 630 m and this type of traffic lights in both directions. Results showed that drivers do not respect the speed limit - and hence, the red light - when they are placed separately. However, if they are placed next to a crosswalk, their effect is increased. Consequently, it is recommended to place these traffic lights with a crosswalk to reinforce the efficiency of both TCMs., Debido a la presencia de varias medidas de calmado de tráfico (MCT) y semáforos en zonas urbanas, la velocidad de los vehículos se mantiene baja. No obstante, un problema aparece en la frontera entre áreas urbanas y no urbanas porque los conductores deben adaptar su velocidad y comportamiento a nuevas condiciones. Este riesgo se vuelve incluso mayor en las carreteras interurbanas que penetran en pequeñas poblaciones sin circunvalación y con un corto tramo urbano, pues normalmente los conductores no reducen su velocidad en estos tramos. Varias medidas pueden ser instaladas, pero los semáforos que se ponen rojos si se sobrepasa el límite de velocidad no suelen considerarse como MCT en la literatura. Por lo tanto, el objetivo de este artículo es analizar la eficacia de los semáforos que se ponen rojos en caso de exceder el límite de velocidad. La población de Ábalos en España fue seleccionada para esta investigación, con un área urbana de 630 m y con este tipo de semáforos en ambas direcciones. Los resultados muestran que los conductores no respetan el límite de velocidad - y por tanto, el semáforo en rojo - cuando son colocados por separado. Sin embargo, si son colocados junto a un paso de peatones, se aumenta su efecto. En consecuencia, se recomienda disponer este tipo de semáforos junto con un paso de peatones para reforzar la eficacia de ambas MCT.

Due to the presence of various traffic calming measures (TCM) and traffic lights in urban areas, the speed of vehicles is maintained low. Nevertheless, a problem arises in the frontier between urban and non-urban areas because drivers must adapt their speed and behavior to new conditions. This risk becomes even greater in rural roads that penetrate small villages without a bypass and with a short urban segment, since drivers do not normally speed down in these segments. Various measures can be installed, but traffic lights that turn red if the speed limit is exceeded is not usually considered as a TCM in the literature. Therefore, this paper aims to analyze the efficiency of traffic lights turning red in case of exceeding speed limit. The village of Ábalos in Spain was selected for this research, with an urban area of 630 m and this type of traffic lights in both directions. Results showed that drivers do not respect the speed limit - and hence, the red light - when they are placed separately. However, if they are placed next to a crosswalk, their effect is increased. Consequently, it is recommended to place these traffic lights with a crosswalk to reinforce the efficiency of both TCMs., Debido a la presencia de varias medidas de calmado de tráfico (MCT) y semáforos en zonas urbanas, la velocidad de los vehículos se mantiene baja. No obstante, un problema aparece en la frontera entre áreas urbanas y no urbanas porque los conductores deben adaptar su velocidad y comportamiento a nuevas condiciones. Este riesgo se vuelve incluso mayor en las carreteras interurbanas que penetran en pequeñas poblaciones sin circunvalación y con un corto tramo urbano, pues normalmente los conductores no reducen su velocidad en estos tramos. Varias medidas pueden ser instaladas, pero los semáforos que se ponen rojos si se sobrepasa el límite de velocidad no suelen considerarse como MCT en la literatura. Por lo tanto, el objetivo de este artículo es analizar la eficacia de los semáforos que se ponen rojos en caso de exceder el límite de velocidad. La población de Ábalos en España fue seleccionada para esta investigación, con un área urbana de 630 m y con este tipo de semáforos en ambas direcciones. Los resultados muestran que los conductores no respetan el límite de velocidad - y por tanto, el semáforo en rojo - cuando son colocados por separado. Sin embargo, si son colocados junto a un paso de peatones, se aumenta su efecto. En consecuencia, se recomienda disponer este tipo de semáforos junto con un paso de peatones para reforzar la eficacia de ambas MCT.

El suelocemento es una mezcla de material granular, agua y cemento que se compacta para su empleo como base o subbase en firmes de carreteras. Esta adición de cemento confiere a la mezcla una mejora en sus propiedades a la vez que aumenta su durabilidad. Para la determinación de su vida útil, el Ministerio de Fomento adopta criterios derivados de los estudios realizados por el Instituto Eduardo Torroja en los años 80. El objetivo principal de esta Tesis Doctoral consiste en optimizar el dimensionamiento de los firmes que presentan como subbase una capa de suelocemento mediante la aportación de una solución más refinada del modelo de comportamiento a fatiga, permitiendo a 7 días corroborar o modificar las propuestas del catálogo de secciones tipo recogido en la norma 6.1-IC de la instrucción de carreteras en función de las características reales del suelocemento ejecutado., The soil cement is a mixture of granular material, water and cement, which is compacted to be used as a base or subbase of a pavement. This addition of cement gives an improvement to the mixture in its properties and increases its durability. To determine the lifetime, the Ministry of Public Works provides design criteria derived from studies conducted by the Eduardo Torroja Institute in the 80s. This thesis attempts to optimize the design of pavement with a soil cement as a base layer providing a new fatigue behavior model. This allows checking and modifying in 7 days the adopted section if its duration is less than expected.

Due to the considerable amount of waste plastics and polymers that are produced annually, the introduction of these waste products in construction materials is becoming a recurrent solution to recycle them. Among polymers, polyamide represents an important proportion of polymer waste. In this study, sustainable and lightweight mortars were designed and elaborated, substituting the aggregates by polyamide powder waste. Mortars were produced with various dosages of cement/aggregates, and the polyamide substitutions were 25, 50, 75, and 100% of the aggregates. The aim of this paper is to determine the density and the compressive strength of the manufactured mortars to observe the feasibility for being employed as masonry or rendering and plastering mortars. Results showed that with increasing polymer substitution, lower densities were achieved, ranging from 1850 to 790 kg/m3 in modified mortars. Mortars with densities below 1300 kg/m3 are cataloged as lightweight mortars. Furthermore, compressive strength also decreased with more polyamide substitution. Obtained values in recycled mortars were between 15.77 and 2.10 MPa, but the majority of the values (eight out of 12) were over 5 MPa. Additionally, an economic evaluation was performed, and it was observed that the use of waste polyamide implies an important cost reduction, apart from the advantage of not having to manage this waste material. Consequently, not only the mechanical properties of the new recycled materials were verified as well as its economic viability.

Pavement performance models play a vital role in any pavement management system. The Regional Government of Biscay (RGB) (Spain) manages a 1200 km road network and conducts pavement data collections, including the International Roughness Index (IRI) values. The aim of the paper is to develop an IRI performance model for two-lane roads with flexible pavement until the first maintenance and/or rehabilitation activity is performed. Due to the huge amount of available information, a deterministic model was selected. A literature review of deterministic models showed that, apart from age and traffic volumes, the pavement structure is a key factor. Therefore, it was decided to analyze the only road stretches whose entire pavement section was known (surface layer + base + subbase). Various variables related to age, traffic volumes and employed materials were introduced as possible factors. The multiple linear regression model with the highest coefficient of determination and all the variables significant included the real pavement age, the cumulated heavy traffic and the total thickness of bituminous layers. As the material employed in the surface layer could affect roughness progression, a qualitative variable was introduced to consider various surface materials. The model improved its accuracy, indicating that the surface layer material is also an influencing factor on IRI evolution.

Traffic calming measures (TCM) are placed in urban areas to improve road safety, and among them, vertical TCMs are widely employed. Many researches are focused on the influence of the geometry of each measure on speed reduction, but it is demonstrated that drivers forget its effect and speed up after it. Therefore, placing consecutive TCMs can help to maintain a safe area. However, scarce literature can be found about the adequate spacing between them. Hence, the aim of this paper is to analyze the adequate distance between TCMs. Various streets with variable distances and different vertical TCMs were evaluated in Poland and Spain, including raised crosswalks, raised intersections, speed humps and speed cushions. The intermediate point between two TCMs was selected as the place where the maximum speed is achieved. Results showed that there was a good correlation between the speeds at intermediate points and the distance between TCMs, with a determination coefficient around 0.80. For an 85th percentile of the speed under 50 km/h, a maximum distance of 200 m between TCMs is recommended, and for a value of 40 km/h, 75 m.

[EN]This article predicts the available minimum skid resistance in the road network of Biscay (Spain) with data collected in the summer season when friction values are at a minimum. Firstly, it was observed that pavement structure does not influence skid resistance. Therefore, roadway segments with available data about the surface layer of single or double carriageway roads were analyzed. Two models were developed: 1) short model with only the surface material, average annual daily traffic, and number of lanes (no pavement history required) and 2) a long model which adds the required Polished Stone Value to improve the prediction. These models can help road agencies to identify the roads where lower skid resistance values are more probable to be obtained to focus their attention and efforts.

Road maintenance and rehabilitation are expected to meet modern society's demands for sustainable development. Full-depth reclamation with cement as a binder is closely linked to the concept of sustainability. In addition to the environmental benefits of reusing the existing pavement as aggregate, this practice entails significant technical and economic advantages. In Spain, in the absence of tests specifically designed to determine the behavior of recycled pavements stabilized with cement, these materials are treated as soil-cement or cement-bound granular material. This assumption is not entirely accurate, because this recycled pavement contains some bituminous elements that reduce its stiffness. This study aimed to obtain the relationships between flexural strength (FS) and the parameters that describe the pavement behavior (long-term unconfined compressive strength (UCS) and indirect tensile strength (ITS)) and compare the findings with the relationships between these parameters in soil-cement and cement-bound granular materials. The results showed that the similar behavior hypothesis is not entirely accurate for recycled pavements stabilized with cement, because they have lower strength values-although, this is not necessarily an indication of poorer performance.

Soil⁻cement is an environmentally friendly road construction technique for base and subbase materials, which allows employing soils placed in the right-of-way of the road or in the surroundings, by improving its engineering properties. With this technique, it is possible to reduce the over-exploitation of quarries, the necessity of landfills and the pollutant gas emission due to the reduction of aggregate fabrication and transport. The manufacturing of soil⁻cement is generally controlled by means of the Uniaxial Compressive Strength (UCS) test at seven days, according to the regulations of each country. Nonetheless, one of the properties that best defines the performance of soil⁻cement is the Flexural Strength (FS) at long term, usually at 90 days. The aim of this paper is to develop new equations to correlate the UCS and the FS at long term and the UCS at seven days and at 90 days. Obtained results validate the proposed models and, hence, the flexural strength can be predicted from the Uniaxial Compressive Strength at seven days, allowing, if necessary, correcting measures (recalculation or rejection) in early stages of the curing time to be taken.

[EN]Skid resistance is a vital issue in pavement management, mainly in relation to road safety; hence, road agencies must assure a minimum friction level of their road networks. The regional government of Biscay (Spain) uses a sideways force coefficient routine investigation machine to assess the present pavement surface condition and to allocate the available funding better. The aim of this paper is to develop a deterioration model to predict the minimum skid resistance in the rural two-lane bituminous roads of Biscay by means of the factors that affect it. In an attempt to include all possible variables that could influence the friction, 23 sections of new roads in Biscay, constructed over the last 25 years, were selected, with different pavement structures (flexible and semi-rigid pavements), ages, surface layers and traffic volumes; a multiple linear regression was then performed. It was concluded that only the average annual daily traffic of heavy vehicles and the required minimum polished stone value of aggregates reflect their importance and, consequently, they are the only variables introduced in the model. The age of pavement, total thickness of bituminous layers and average annual daily traffic of all vehicles showed no influence and were discarded. The proposed model can forecast future skid resistance.

797 p., Due to the competition of funding among different sectors of the economy and society, Pavement Management Systems (PMS) have become necessary for road agencies to design more cost-effective and longer lasting pavements and to better allocate available funds. Within the PMS, the performance models are a key factor, as they are able to predict the future condition of the pavements.The Regional Government of Biscay (RGB) manages and is responsible of almost the entire interurban road network in the territory of Biscay, making a total of more than 1.300 km under its control. Aiming to efficiently manage its resources, the RGB has developed a PMS, where all the information about roads is stored.The aim of this PhD thesis is to develop performance models for the International Roughness Index (IRI) and the Side-force coefficient to predict the future condition of the road network of Biscay. IRI models are developed for new two-lane roads with flexible and semi-rigid pavements. The proposed models for forecasting skid resistance can be deployed in any type of road, two-lane roads or double carriageway roads and for all the usual materials in surface layers., Debido a la competencia por la obtención de fondos de los diferentes sectores de la economía y de la sociedad, los Sistemas de Gestión de Firmes (SGF) se han convertido en necesarios para las administraciones viarias para conseguir unos pavimentos más eficientes con respecto a su coste y con mayor duración y asignar mejor los fondos disponibles en actuaciones. Dentro de los SGF, los modelos de comportamiento son un factor clave, dado que son capaces de predecir el estado futuro de los pavimentos. La Diputación Foral de Bizkaia (DFB) gestiona y es responsable de la mayoría de las carreteras interurbanas que discurren por el territorio histórico de Bizkaia, teniendo bajo su control directo más de 1.300 km de carreteras. Para una más eficiente gestión de sus recursos, la DFB ha desarrollado un SGF, donde se encuentra almacenada toda la información relativa a las carreteras.El objetivo de esta tesis es desarrollar unos modelos de comportamiento para el International Roughness Index (IRI) y el Coeficiente de Rozamiento Transversal (CRT) para predecir el estado futuro de la red viaria de Bizkaia. Los modelos de IRI se desarrollan para nuevas carreteras convencionales de dos carriles con firmes flexibles y semirrígidos. El modelo desarrollado para el CRT puede ser utilizado en cualquier tipo de carretera, convencional o de calzadas separadas y todos los materiales habituales en la capa de rodadura., Ekonomiaren eta gizartearen hainbat sektoreren arteko finantzaketa lortzeko lehia dela eta, Bide-zoruak Kudeatzeko Sistemak (BKS) beharrezko bihurtu dira bide-administraziorako luzeago irauten duten eta kostu eraginkorragoko bide-zoruak diseinatzeko eta dauden funtsak hobeto esleitzeko. BKSen barruan, portaera modeloak oinarrizko faktore bat dira, bide-zoruaren etorkizuneko egoera iragartzeko gai direlako.Bizkaiko Foru Aldundiak (BFA) Bizkaiko lurraldeko hiri arteko ia errepide-sarea osoa kudeatzen du eta horren arduraduna da. Beraz, 1.300 km baino gehiago daude bere kontrolpean. Bere baliabideak hobeto kudeatu nahian, BFAk garatu du BKS bat, non errepideei buruzko datu guztiak biltzen diren.Tesi honen helburua International Roughness Index (IRI) eta zeharkako marruskadura koefizienterako portaera-modeloak garatzea da. IRI modeloak garatu dira errepide konbentzional (bi erreiko errepideak) berrietarako, bide-zoru malgu eta erdi-zurrunekin. Labainketarekiko erresistentziarako proposatutako modeloa edozein errepide motarako erabil daiteke, errepide konbentzionaletan edo galtzada bananduko errepideetan eta normalean erabiltzen diren errodadura geruzako materialerako.

A wide variety of modifiers have been applied to bitumen in order to enhance their properties and performance. Among them, polymers have been mainly used. The aim of this paper is to assess the use of polyurethane foam waste as a bitumen modifier for hot mix asphalts. The polyurethane foam is a by-product of the manufacturing of polyurethane for thermal insulation. From a bitumen with a penetration grade of 50/70, various samples with percentages of waste material in weight ranging from 1% to 5% were produced and tested. Samples with 5% of waste material or more became rough arid were refused due to their poor workability. A bituminous mixture with modified bitumen with a 4% of polyurethane was manufactured arid compared with a sample with the same aggregates and original bitumen. Results in Marshall test showed that a mix with polymer modified bitumen yielded improvements in stability and a lower deformability. This result suggests that the employment of polyurethane foam waste is a promising bitumen modifier, contributing also to recycle waste materials.

Understanding the long-term behaviour of cement-treated base materials is a key factor to improve its design and obtain environmentally friendly pavement base materials. Their characterization requires manufacturing prismatic specimens. However, various authors highlight the absence of standardized test methods for fabricating beams in the field and laboratory, which is not an easy task because it depends on the qualification and experience of the testing team. The aim of this paper is to present a new device and procedure for compacting prismatic specimens of cement-treated base materials. In this research, it was used for compacting soil-cement to simulate its performance as a road base material. This device employs elements that are generally available in a concrete laboratory test, such as a vibrating table or prismatic moulds. Once the procedure was established, and in order to verify its suitability, flexural and compressive strength tests were carried out. Results showed that the values obtained were consistent with this material and, despite the heterogeneity of the material, specimens from the same batch provided similar results and, hence, validated the compaction process. This new compacting procedure can improve understanding of the long-term performance of cement-treated materials from flexural and fatigue tests.

A wide variety of modifiers have been applied to bitumen in order to enhance their properties and performance. Among them, polymers have been mainly used. The aim of this paper is to assess the use of polyurethane foam waste as a bitumen modifier for hot mix asphalts. The polyurethane foam is a by-product of the manufacturing of polyurethane for thermal insulation. From a bitumen with a penetration grade of 50/70, various samples with percentages of waste material in weight ranging from 1% to 5% were produced and tested. Samples with 5% of waste material or more became rough and were refused due to their poor workability. A bituminous mixture with modified bitumen with a 4% of polyurethane was manufactured and compared with a sample with the same aggregates and original bitumen. Results in Marshall test showed that a mix with polymer modified bitumen yielded improvements in stability and a lower deformability. This result suggests that the employment of polyurethane foam waste is a promising bitumen modifier, contributing also to recycle waste materials., Una gran variedad de modificadores se han aplicado al betún para mejorar sus propiedades y rendimiento. Entre ellos, los polímeros han sido principalmente utilizados. El objetivo de este artículo es evaluar el uso del residuo de espuma de poliuretano como modificador de betún en mezclas bituminosas en caliente. La espuma de poliuretano es un residuo que se obtiene durante la fabricación del poliuretano para aislamiento térmico. A partir de un betún de penetración 50/70, se fabricaron y analizaron varias muestras con porcentajes de residuo en peso entre el 1 y el 5 %. Las muestras con porcentajes del 5 % de residuo o superiores produjeron un material áspero y se descartaron debido a su poca trabajabilidad. Se fabricó una mezcla bituminosa con un 4 % de porcentaje de betún modificado con residuo de poliuretano y fue comparado con una muestra con los mismos áridos y el betún original. Los resultados en el test de Marshall mostraron que la mezcla con betún modificado provocaba un aumento en la estabilidad y una menor deformación. Estos resultados sugieren que el empleo de residuo de espuma de poliuretano es un prometedor modificador de betún, contribuyendo además al reciclado de materiales de desecho.