APRÈN. Portal de la producció docent del professorat de la UPC

El hormigón reforzado con fibras (HRF) se distingue por ofrecer una mayor resistencia residual a tracción, así como por contribuir a la reducción de costes y tiempos de ejecución en procesos constructivos. Sin embargo, para garantizar el adecuado desempeño del HRF y promover su uso en aplicaciones estructurales, resulta fundamental realizar una adecuada caracterización del material conforme a las normativas vigentes, así como implementar un adecuado control de calidad en obra. El presente trabajo tiene como objetivo caracterizar el comportamiento mecánico de paneles prefabricados para fachadas de hormigón reforzado con fibras de acero (HRFA). Para ello, se desarrolló una campaña experimental dividida en dos fases: (fase 1) caracterización del HRFA mediante ensayos sobre probetas —evaluación de la resistencia a tracción por f lexión (UNE-EN 14651), clasificación del material según su clase resistente (EN 1992-11:2023) e implementación de ensayos alternativos para el control de calidad, tales como el ensayo Inductivo (UNE 83518) para determinar el contenido real de fibras y el ensayo Barcelona (UNE 83520)— y (fase 2) realización de ensayos de flexión a cuatro puntos a escala real en los paneles prefabricados de HRFA con el objetivo de estudiar su comportamiento post-fisuración y ductilidad —en uno de los paneles tipo sándwich se simuló la acción del viento para evaluar su respuesta estructural—. Los resultados obtenidos muestran (1) una buena correlación entre los métodos de ensayo para la caracterización del material y (2) un comportamiento dúctil adecuado en los elementos a escala real evaluados, lo que respalda el potencial del HRFA en paneles prefabricados para fachadas.

In recent years, the search for alternatives for producing more sustainable cement has gained greater relevance due to the environmental impact of the construction industry, resulting from high CO2 emissions from clinker. In this context, the use of calcined clay in cement manufacturing represents a viable solution for reducing clinker content without directly affecting concrete strength. This study aims to analyze the initial and delayed mechanical properties of concrete made with cement incorporating 7% calcined clay, and to study the effect of incorporating polypropylene fibers in two different dosages. The experimental campaign was conducted in collaboration with Cementos Molins. Four mixtures (HA-25, HA-40, HF-3.5-3 kg, and HF-3.5-6 kg) were manufactured, and tests were conducted at 7, 28, and 90 days. Compressive strength, modulus of elasticity, indirect tensile strength, flexural tensile strength, and shrinkage were analyzed. The HA-25 and HA-40 mixtures exhibited good mechanical performance, while the mixtures with fibers increased post-cracking strength. It is concluded that cements with calcined clay allow the development of structural concretes with satisfactory mechanical performance, providing an effective solution for moving toward more sustainable construction.

El hormigón reforzado con fibra de acero ha ganado popularidad en estructuras civiles, como túneles y pavimentos, en diferentes lugares del mundo gracias a la capacidad de las fibras para mejorar la durabilidad y el comportamiento estructural del hormigón. Es imprescindible asegurar un buen control de control de calidad ya que una correcta dosificación de las fibras es una variable esencial para garantizar la seguridad estructural. El proyecto se desarrolló a lo largo de varios meses, durante los cuales se fabricaron 105 probetas con tres diferentes dosificaciones de fibras, y se llevaron a cabo los ensayos completos. Cada probeta se sometió al método inductivo para medir la inductancia generada por las fibras y, de esta manera, calcular su cantidad. Se realizaron mediciones en los tres ejes de cada probeta, repitiendo el método tres veces con tres distintos procesos para determinar cuál era el más preciso. Posteriormente, se aplicó el ensayo Barcelona para evaluar la resistencia de las probetas reforzadas con fibras, para dejar pie a elaborar una correlación entre los resultados del ensayo con los del método inductivo. Además, se trituraron algunas probetas para determinar el contenido real de fibras. Los resultados obtenidos muestran que los diferentes procesos de medición utilizados en el método inductivo dieron resultados similares, lo que indica que el procedimiento de medición no afecta significativamente el cálculo de la inductancia en las probetas. Se observó que, a mayor cantidad de fibras, el cálculo de la dosificación es más preciso entre los tres procesos empleados, ya que la inductancia generada dentro del aparato inductivo es mayor. Al comparar la dosificación teórica con la calculada en las tres dosificaciones iniciales, se concluyó que, a mayor dosificación de fibras, mayor es la dispersión. Esto se debe que la distribución no es homogénea en las fibras durante el vertido y la fabricación de las probetas. Este proyecto ha permitido proporcionar los datos necesarios para establecer una correlación entre el contenido de fibras calculado mediante el método inductivo y la resistencia residual de las probetas de hormigón reforzado con fibras de acero. Esto facilita la simplificación y mejora del control de calidad del hormigón en obra. Además, se ha conocido cómo varía la distribución de las fibras en las probetas en función de la dosificación. Sin embargo, no se ha realizado la correlación como parte de este estudio.

La impresión 3D se está utilizando cada vez más en el sector de la construcción debido a la cantidad de ventajas que presenta. En este trabajo se referencia su capacidad para disminuir el tiempo requerido para la construcción de estructuras complejas en comparación con los métodos de construcción tradicionales, que además permite una gran libertad de diseño, y un ahorro sustancial de material ya que éste se coloca donde es estructuralmente necesario, lo que conlleva a una menor generación de residuos, afectando de manera positiva al factor medioambiental. Estas ventajas se podrían potenciar si se implementa la optimización topológica, ya que plantea una distribución de los materiales donde sean estructuralmente requeridos, aunque se enfrenta a un reto a causa de la escasez soluciones existentes de referencia en el sector. Muchas de las investigaciones enfocadas al estudio de las estructuras impresas pretenden establecer un nivel de fiabilidad en cuanto a sus propiedades mecánicas, de manera que pueda extenderse su uso a más aplicaciones estructurales. Por ello, en este trabajo final de máster se estudia el comportamiento mecánico de tres tipos de componentes estructurales fabricados con material estándar para impresiones de hormigón. Se trata de tres vigas, la primera es una bóveda tabicada, que se definiría como geometría inicial a partir de la cual se llevaría a cabo dos optimizaciones topológicas de la volta catalana estudiada. La geometría resultante se sustentará gracias a un análisis de referencia establecido para la interpretación de las formas obtenidas. La caracterización mecánica se basa en los resultados de una campaña experimental compuesta por un ensayo a flexión para los especímenes, donde se le aplica una carga uniformemente distribuida a un modelo de viga biapoyada.

The project for the Quimís Colón bridge and the expansion to four lanes of its approach sections is based on three main pillars. Firstly, it aims to improve the E482 collector road to enhance access to Portoviejo and other key cities in Manabí. Secondly, a new structure must be built over the Quimís River due to the deterioration of the current one. Thirdly, it involves upgrading the road category from a two-lane unidirectional carriageway to two separate carriageways, each with two lanes in opposite directions. The project focuses on establishing the foundations of the construction project and centers on the linear works (LOT 1), leaving the structure over the Quimís River and drainage works for LOT 2 (not part of this current project). The project spans 2,646 km and is located at the cantonal boundary of Jipijapa with Montecristi, in Manabí, Ecuador. This segment crosses undulating terrain of clayey loam type with arid climate and water scarcity. In 2017, the Montecristi-Jipijapa stretch recorded an Average Annual Daily Traffic (AADT) of 8,631. By the year of service commencement, AADT is estimated to reach 11,583 (2027), and for the horizon year, 25,069 (2046). With the traffic update, the road is classified as AV1 or multi-lane. The design includes two parallel carriageways separated by a 2 m median, each with lanes of 3.65 m width. Additionally, it features outer shoulders of 2.5 m and inner shoulders of 1.5 m. Embankment berms have a width of 1.0 m, as does the cut slope foot batter. It includes a traversable ditch with a width of 1.60 m. The designed speed for the road is 90 km/h. The execution budget is 9,331,529.59 €, with an additional budget allocated for expropriations and compensations totaling 883,543.96 $.

Este estudio técnico-económico compara el refuerzo tradicional de losas de concreto con varillas corrugadas de acero frente a la implementación de concreto reforzado con fibras de acero, analizando costos y rendimientos laborales en Monterrey, México. Se diseñaron y evaluaron económicamente cuatro alternativas: solo varillas, solo fibras, y dos híbridas, destacando que las opciones con fibras incrementan el costo directo pero reducen el tiempo y costos indirectos de construcción. Los resultados indican que, aunque el refuerzo con fibras es más caro inicialmente, la eficiencia en la ejecución podría compensar estos costos adicionales mediante la disminución de tiempos y gastos operativos.

FRC has gained prominence in the construction industry worldwide in recent decades, being used in a wide range of applications including industrial floors and pavements, shotcrete for tunnels, slopes, and pool construction, precast concrete, as well as structural elements in building construction. However, its use faces challenges in terms of characterization and evaluation of its mechanical properties. The main objective of this thesis is to correlate two widely used tests for FRC characterization: the three-point bending test (3PBT) and the Barcelona test (BCN). The BCN, being simpler to execute and requiring lighter samples, offers significant practical advantages compared to the 3PBT. However, its application is limited by the lack of established correlations with the 3PBT. Throughout the research, a very strong linear correlation has been observed between the results of both tests. This has allowed for the establishment of a direct relationship between a parameter of each test, yielding promising results in terms of FRC characterization. The proposed correlation between the 3PBT and the BCN is based on the comparison of results obtained from samples of reinforced concrete with different types and contents of fibers. In conclusion, this work provides a significant contribution to the field of FRC characterization by proposing an effective correlation between two important tests. This correlation opens up new possibilities for the use of the BCN as a complementary method to evaluate the properties of FRC, which may have a positive impact on the efficiency and accuracy of design and construction processes in the industry.

The construction sector has experienced significant growth in recent years, leading to an increase in the generation of Construction and Demolition Waste (CDW), representing more than one-third of the total waste in Europe. Spain ranks fifth among the countries with the highest CDW generation on the continent. The valorization and recycling of these wastes have gained relevance as a solution, although they still face deficiencies in research and execution. Fiber-reinforced concrete is widely used in construction due to its structural, durability, and cost benefits. However, there is limited research on its post-service phase and strategies for treatment or reuse. This thesis proposes to analyze the effect of using recycled aggregates and fibers in the manufacture of new fiber-reinforced concrete. Tests were carried out with three types of concrete: one with natural aggregates and new fibers, another with recycled aggregates with adhered fibers and new fibers, and another with natural aggregates and recycled fibers, using a fiber content of 3 and 9 kg/m3 for each type. The results indicate that the use of recycled aggregates with adhered fibers leads to a slight decrease in compressive strength but may result in concrete with a strength greater than 30 MPa. The incorporation of recycled fibers does not significantly influence compressive strength. Regarding the modulus of elasticity, the use of recycled aggregates leads to a reduction of up to 22%, while recycled fibers have no significant impact. Regarding residual strength, the fibers adhered to the recycled aggregates contribute during the post-cracking phase of the concrete, while recycled fibers show wear and inferior performance in the stitching stage after cracking.

The 3D concrete printing is an alternative that has great potential, due to the numerous constructive advantages it provides. This construction method allows complex geometries of great difficulty to be made, by dispensing with the use of formwork. It also reduces overall cost and time on a jobsite by automating the construction process. On one hand, the optimization of natural resources reduces the consumption of raw materials and significantly minimizes greenhouse gas emissions. On the other hand, it is expected that the use of this technique will generate more qualified employment. From the point of view of sustainability, additive manufacturing of concrete could offer very interesting contributions to improve current construction with conventional concrete. Even though in conventional concrete the study of the sustainability of the mixes is very extensive, in 3D concrete printing the knowledge about the sustainability of the mixes is still limited. This thesis evaluates the sustainability of five different mixtures of 3D concrete printing intended to be used in facades, through a method based on the Integrated Value Model for the evaluation of Sustainability (MIVES). In order to determine which of them is more appropriate from the point of view of sustainability.

In the present work, a recapitulation of the relevant aspects of digital printing or 3D printing in the construction sector is provided. It explores how this technology has not only revolutionized the construction process but also generated a positive impact on environmental sustainability. Not only reduces construction times and offers design flexibility but also diminishes the use of materials like cement, leading directly to lower emissions and energy consumption. To comprehend the effects of this technology in a sustainable environment, an evaluation of twelve mortar mixtures composed of different materials and compositions was conducted for the fabrication of a one-square-meter printed wall piece. The MIVES multicriteria methodology is used to calculate the sustainability index of these alternatives, which is summarized in a decision tree composed of four requirements: environmental, economic, social, and technological; five criteria; and nine indicators. With the latter, satisfaction is calculated through value functions to ultimately obtain the value index of each alternative. In the main scenario, where environmental aspects are prioritized, the mixture that results in a higher value index is composed of binders such as cement, micro-silica, and fly ash, and it also incorporates the use of coarse recycled aggregates (particle size from 5 mm to 10 mm). Additionally, a sensitivity analysis is carried out where the weight percentages of the requirements are varied in three new scenarios, prioritizing economic, technological, and social aspects, respectively. Finally, an analysis of the results obtained in all scenarios is conducted.

This thesis represents an unconventional approach by fusing modern 3D printing technologies with the untapped potential of recycled aggregates since sustainability in construction starts to be an imperative rather than an aspiration In this thesis, the potential of integrating both approaches—fine Recycled Aggregates (fRAs) from Construction and Demolition Waste (CDW) with 3D Printing Technologies (3DPT)—is evaluated from an experimental and analytical angle. A prototype urban chair made of a concrete mix containing 100% fRA was developed using a 3D gantry printer. High Strength Concrete (HSC) and Normal Strength Concrete (NSC) mixes were designed, with HSC showing superior strength but facing extrusion challenges due to Viscosity Modifying Admixture (VMA) content. Consequently, NSC was utilized for printing the prototype. A sustainability analysis was carried out using the MIVES model, which is a multi-criteria decision-making method, comparing the 3D printed chair to a traditional reinforced concrete urban chair. The results revealed that the 3D printed chair achieved a sustainability index of 75.7%, while the traditional chair attained 42%. However, this study faced limitations including focusing solely on the manufacturing phase and considering only two alternatives. Additionally, the mechanical properties of the traditional chair were not analysed, as a result, it is unknown whether they have higher mechanical aspects, which could produce a subjective result. It's crucial for future research to expand the scope of alternatives, consider the entire product life cycle, find solutions for extrusion challenges faced by mixes with VMA, and evaluate the mechanical properties of all alternatives to provide a more comprehensive and accurate assessment of the sustainability of materials and manufacturing techniques used in creating urban chairs.

This study consists of the mechanical characterization of the fiber-reinforced shotcrete and fiber-reinforced cast concrete in the molds by compression tests, secant modulus of elasticity in compression, Barcelona test, flexural test on beams and square panels. It compares the results, analyzes the residual resistance of both concretes and through the inductive test determines a 37% rebound of steel fibers. It follows the guidelines of the UNE-EN 14651 standard, proposed to the prEN 14488-3 method B standard and the Model Code for Concrete Structures, it is determined that the type of steel fibers and the dosage used meet the requirements to be considered structural and power replace the use of electro-welded mesh. The proposal to the prEN 14488-3 standard refers to shotcrete tests using square panels, while the UNE-EN 14651 standard refers to fiber-reinforced concrete using beams with a cross section of 150 x 150 mm. Within the mechanical characterization used in this study, after testing the square panels, these elements are cut into beams with a cross section of 100 x 100 mm and are tested following the configurations of the UNE-EN 14651 standard to compare the results of panels - steel beams. 100 x 100 mm and 150 x 150 mm beams – 100 x 100 mm beams.

The present experimental campaign is mainly focused on investigating the feasibility of concrete produced with recycled materials, specifically with aggregate from recycled concrete elements and recycled fiber. For this purpose, a first generation of concrete produced with natural aggregates and virgin fiber in different proportions will be used. Once produced and characterized, this concrete will serve as a reference point for the comparison between conventional concrete and concrete produced with recycled materials. Properties in the fresh and hardened state will be evaluated in order to investigate the change in concrete's behavior that can be produced by the use of recycled materials. This campaign is carried out in the context that the construction industry produces millions of tons per year from construction processes, demolition, and remodeling of structures in civil engineering, and there is a need to move towards a more sustainable and efficient industry. This requires the creation of new technologies that help manage waste and, create new materials that are more efficient and can be reused for several cycles

Digital fabrication with concrete (DFC) is generating a great deal of interest in the construction sector thanks to its advantages in terms of sustainability. Lower material consumption and lower emissions of greenhouse gases into the atmosphere highlight among others compared to traditional concrete solutions. Since its first application in footbridges in 2016, six units have been built and four more are currently being assembled, thus demonstrating the viability of the technique and the desire to extend its use. This paper describes these 3D printed concrete footbridges (3DPC) as a State of the Art. On the other hand, in order to quantify the value of sustainability of 3DPC footbridges and to compare this value with other concrete solutions, it is necessary to develop a comprehensive methodology aimed at the evaluation and objective quantification of the economic, environmental and social requirements related to concrete footbridge technology. Currently, there are no regulations that allow such an analysis. The proposed methodology is based on the MIVES method applied for multi-criteria decision-making. The most representative criteria and indicators of sustainability identified are measured and integrated with certain weights in a decision-making tree, specially designed for footbridges. Their overall assessment is given by the Sustainability Index. The methodology described is applied to the 3DPC footbridge in Alcobendas and to four alternative concrete footbridges. These new footbridges, which are specially designed and modelled for this analysis with the same boundary conditions as the Alcobendas footbridge, are two traditional solutions and two technologically innovative solutions. The results of the analysis lead to the conclusion that the 3DPC footbridges have positive impacts on environmental and social indicators, but it is clear that the economic indicators need to be improved in order to attain a competitive solution.

In a context of rapid growth of the global population it is becoming essential to think about how to use the space in an efficient way. Indeed, it is no longer possible to let the cities eat progressively agricultural lands vital to feed this increasing population. And while the cities extend, we observe in urban areas number of old industrial sites, brownfields, left abandoned by the delocalization of productive activities out of the cities. The objective of the present study is to evaluate the sustainability of brownfields rehabilitation projects. The idea is to compare the economic, environmental and social impact of the demolition of the old structure to install a new activity with the valorisation of the industrial building to propose new uses. The study aims at showing the benefits of an emerging vision of urbanisms, sparing resources and developing a circular urbanism. To achieve this objective, a comparison model was build following the MIVES method, to support decision-making by public institutions that attribute subsidies to rehabilitation projects. The model was used and tested in a real case study to evaluate different projects of rehabilitation of an old industrial slaughterhouse abandoned in the city of Marseille in France. The results show that, whatever economic or environmental arguments are considered more important, projects of reutilisation of the old industrial building are the most sustainable alternatives. Since they limit the energy and resources consumption and waste production during the construction period, they also reduce a lot construction costs. The future projects that the site can welcome are of course limited by the size of the existing structure, but the affordable price of these abandoned sites also allows the installation of innovative projects, with cultural and social purposes.

Nowadays, the use of fibre-reinforced concrete is becoming a common solution. Due to the studies conducted, the good structural response it offers, the ease of installation and the economic savings compared to concretes reinforced with traditional reinforcement, make fibre-reinforced concretes a more efficient and common solution. Despite the numerous studies carried out in recent years on fibre-reinforced concretes highlighting their structural advantages, the issues related to the demolition and subsequent recycling of fibre-reinforced concretes have not been addressed and, therefore, the aspects related to their recyclability and reusability are unknown. To answer the questions raised about the recyclability and reusability of fibre-reinforced concretes, this thesis proposes a 3-generation experimental campaign to characterise the recycled aggregates and subsequently characterise the concretes manufactured with the recycled aggregates.

Projecte que combina excavacions en terres i roca amb estabilitzacions variades (murs ancorats, micropilots, talussos en roca...) així com la interacció de l'estructura de l'edificació amb l'estabilitat del terreny.