Estudio de la contaminación de aguas por lixiviación de residuos industriales y minimización mediante la inmovilización en materiales base cemento

Premio extraordinario de Trabajo Fin de Máster curso 2014-2015. Tecnología del Agua en Ingeniería Civi

Promotion of Circular Economy: Steelwork Dusts as Secondary Raw Material in Conventional Mortars

Among the actions proposed by the European Union for the implementation of Circular Economy is the use of waste as a secondary raw material (SRM). During the fusion of the scrap, a steel dust is generated, named Electric Arc Furnace Dust (EAFD). The EAFD is composed mainly of potentially leachable heavy metals, so is classified as “hazardous” waste. Around the world, approximately 70% of this waste is deposited in landfills, with a previous treatment through cement-based materials to prevent the metals’ mobility. However, this action is not in accordance with the Circular Economy concept due to the greater use of resources and the loss of deposited metals. The present investigation analyses the use of EAFD as SRM in conventional mortar production for its use as a construction material. Different substitution percentages (25%, 50% and 100%) were used replacing siliceous filler by EAFD. The investigation analysed the behaviour of conventional mortars by tests of workability, compressive strength, water absorption by capillarity and leaching behaviour in granular and monolithic state. The results obtained indicate a slight improvement in mechanical behaviour with the incorporation of EAFD, the reason why its use as SRM in conventional mortars would benefit the construction industry and would encourage the Circular Economy. From an environmental point of view, the mechanisms of Pb fixation should be improved in granular state

Pollutant Potential of Reinforced Concrete Made with Recycled Plastic Fibres from Food Packaging Waste

In our modern, fast-paced life, plastic is a versatile material essential to our economy; daily life is unthinkable without it. However, there are serious downsides for the environment and health, which are becoming more and more stark in our society, and the recycling of plastic offers a partial solution to these widespread problems. The present work delves into the environmental assessment of fibre-reinforced concrete specimens, made with recycled plastic fibres from food packaging waste. Leaching tank tests for the evaluation of the long-term release of pollutant elements, identification of leaching mechanisms, and the diffusion process of contaminants into the environment were conducted on fibre reinforced concrete. The results showed that the incorporation of the recycled plastic fibres, classified as non-hazardous, did not release relevant levels of any potential harmful element incorporated in concrete. Moreover, low mobility was detected in the studied elements and different release mechanisms were identified through long-term diffusion leaching tests. Hence, the environmental feasibility of the incorporation of recycled plastic fibre in concrete was proven. This study strengthens the objectives set out by the Circular Economy Action Plan, which includes the European Strategy for Plastics and aims to, among other things, boost the market for recycled plastics

Photocatalytic Recycled Mortars: Circular Economy as a Solution for Decontamination

The circular economy is an economic model of production and consumption that involves reusing, repairing, refurbishing, and recycling materials after their service life. The use of waste as secondary raw materials is one of the actions to establish this model. Construction and demolition waste (CDW) constitute one of the most important waste streams in Europe due to its high production rate per capita. Aggregates from these recycling operations are usually used in products with low mechanical requirements in the construction sector. In addition, the incorporation of photocatalytic materials in construction has emerged as a promising technology to develop products with special properties such as air decontamination. This research aims to study the decontaminating behavior of mortars manufactured with the maximum amount of mixed recycled sand without affecting their mechanical properties or durability. For this, two families of mortars were produced, one consisting of traditional Portland cement and the other of photocatalytic cement, each with four replacement rates of natural sand by mixed recycled sand from CDW. Mechanical and durability properties, as well as decontaminating capacity, were evaluated for these mortars. The results show adequate mechanical behavior, despite the incorporation of mixed recycled sand, and improved decontaminating capacity by means of NOx reduction capacity

Optimisation of mortar with Mg-Al-Hydrotalcite as sustainable management strategy lead waste

This study analyses how a Mg-Al-Hydrotalcite with carbonate in the interlayer influences the hydration of mortar allowing the management of lead waste (solid or liquid) in a cement-based material. First, the compatibility of hydrotalcite with the cementitious matrix was studied through heat of hydration, workability, consistency, compressive strength and mineralogical phase formation. The changes produced by the incorporation of hydrotalcite were not drastic and the compatibility with the cement was verified. Lead was added in oxide and nitrate form to mortar with or without hydrotalcite and the same properties were evaluated, including a leaching test. The incorporation of lead delayed the hydration, this effect being increased by the hydrotalcite, which happened in the first instants of hydration. The addition of hydrotalcite counteracted the negative effect of lead in compressive strength values. The interaction between the hydrotalcite and the lead waste was favoured by the formation of plumbites under the pH conditions of cement hydration. Consequently, this interaction would seem to be superficial. The lead leaching decreased to values included in the “Non-Hazardous” limit of the environmental classification, very close to “Inert”. All mortars were produced by two mixing procedures to establish differences. When hydrotalcite was included, the compressive strength was higher in the second procedure and lead leaching showed better behaviour in the first procedure. This research expands the possibilities of the management of solid and liquid waste contaminated with lead by using a Mg-Al-Hydrotalcite in cement-based matrices

The Study of Soil Temperature Distribution for Very Low-Temperature Geothermal Energy Applications in Selected Locations of Temperate and Subtropical Climate

The publication presents the results of research on soil temperature distribution at a depth of 0.25–3 m in three measurement locations. Two boreholes were located in Białystok in the temperate climatic zone and one measuring well was installed in Belmez in the subtropical climatic zone. Measurements were made in homogeneous soil layers in sand (Białystok) and in clay (Białystok and Belmez). Based on the results of the measurements, a simplified model of temperature distributions as a function of depth and the number of days in a year was developed. The presented model can be used as a boundary condition to determine heat losses of district heating pipes located in the ground and to estimate the thermal efficiency of horizontal heat exchangers in very low-temperature geothermal energy applications

Preliminary Study of Recycled Aggregate Mortar for Electric Arc Furnace Dust Encapsulation

This article shows the preliminary results of a study carried out to determine the technical feasibility of encapsulating a high percentage of EAFD in cement-based mortars manufactured with the fine fraction of recycled concrete aggregates (RCA). Two families of mortars, with natural aggregate as a reference and with RCA, were studied. An incorporation rate by weight of two parts mortar to one part EAFD was tested. The mechanical strengths (compressive strength and tensile strength) before and after immersion in water, the rate of delitescence and the leaching behavior were studied. Mortars made with RCA showed similar mechanical strengths to the reference mortars made with natural aggregates; however, the incorporation of EAFD decreased the mechanical strengths. Encapsulation considerably reduced the leaching of heavy metals, although the Pb concentration remained above the hazardous waste limit. With this preliminary study, two wastes are managed together, and the results have shown that the use of RCA instead of natural aggregate is a viable alternative since it does not significantly impair the mechanical or leaching properties of the cement-based matrices used to encapsulate EAFD

Motivation of student learning through the gamification technique in Engineering Degrees, evaluation of performance-fatigue variables

Este trabajo pretende mejorar el proceso de enseñanza-aprendizaje de diferentes asignaturas del Grado en Ingeniería Civil y del Grado en Ingeniería de Recursos Energéticos y Minería de la Universidad de Córdoba (España), con el uso de prácticas docentes innovadoras que mejoren el rendimiento académico resultados de los estudiantes. La introducción de la técnica de gamificación ha permitido una participación más activa de los estudiantes y ha fomentado la adquisición de habilidades, así como el aprendizaje en un ambiente más relajado. El clima de trabajo se ha mantenido más activo. Además, esta técnica ha permitido detectar el punto de fatiga de los alumnos durante las clases. La herramienta utilizada para implementar la técnica de gamificación y evaluar el nivel académico de los alumnos durante las clases ha sido el acceso gratuito a la plataforma web "Kahoot", que es un sistema de respuestas en el aula basado en juegos para escuelas, universidades y empresas. Puede descargarlo en sus dispositivos electrónicos y / o acceder a él a través de su sitio web (https://kahoot.it/#/). Con esto, los estudiantes han utilizado sus teléfonos móviles o dispositivos electrónicos para contribuir a su aprendizaje en el Aula, y dejar de lado su uso inapropiado (redes sociales, noticias deportivas, etc.), evitando uno de los principales problemas que los profesores tienen actualmente en clase. Para cada conferencia, los cuestionarios en línea se llevaron a cabo utilizando la plataforma de aprendizaje Kahoot compuesta de preguntas asociadas con los conceptos teóricos / prácticos dados. Este procedimiento ha permitido una evaluación continua del alumno, e indirectamente del profesor, ya que se verifica en tiempo real si hay algún concepto que deba reforzarse. Mientras se llevaban a cabo los cuestionarios, se ha observado que los mismos estudiantes han participado en la aclaración de posibles preguntas de sus compañeros e incluso han hecho que el profesor reconsidere la forma de explicar y presentar la lección, lo que demuestra que esta técnica ha promovido la retroalimentación entre alumno-maestro y estudiante-alumno, fomentando un buen clima de trabajo y terminando las sesiones de una manera divertida, lo que ha permitido aumentar el rendimiento del alumno. Los resultados obtenidos han reflejado una evaluación final positiva de la asignatura para la mayoría de los alumnos que han participado en las clases. Con respecto a los cursos anteriores, los estudiantes han tenido menos dificultades para aprobar el tema y en la adquisición de habilidades. Es importante resaltar el grado de satisfacción de los alumnos, y en especial de los alumnos que repiten la asignatura, que han logrado aprobar el tema de una manera más fácil gracias al uso de técnicas de gamificación.This work hopes to improve the teaching-learning process of different subjects of the Degree in Civil Engineering and of the Degree in Engineering of Energy Resources and Mining at the University of Córdoba (Spain), with the use of innovative teaching practices that improve the academic results of the students. The introduction of the gamification technique has allowed a more active participation of students and has encouraged the acquisition of skills, as well as learning in a more relaxed environment. The work climate has remained more active. In addition, this technique has made it possible to detect the point of fatigue of the students during the lectures. The tool used to implement the gamification technique and evaluate the academic level of the students during the classes has been free access to the web platform "Kahoot, which is a system of answers in the classroom based on games for schools, universities and companies. Students can download it on their electronic devices and/or access it through its website (https://kahoot.it/#/). With this, the students have made use of their mobile phones or electronic devices to contribute to their learning in the classroom, and put aside their inappropriate use (social networks, sports news, etc.), avoiding one of the main problems that teachers have in class currently. For each lecture, the online questionnaires were carried out using the Kahoot learning platform composed of questions associated with the theoretical/practical concepts given. This procedure has allowed a continuous evaluation of the student, and indirectly of the teacher, since it is verified in real time if there is any concept that needs to be reinforced. While the questionnaires were carried out, it has been observed that the students themselves have participated in the clarification of possible questions from their classmates, and have even made the teacher reconsider the way of explaining and presenting the lesson, which shows that this technique has promoted the feedback between student-teacher and student-student, encouraging a good working climate and ending the sessions in a fun way, which has allowed to increase the student's performance. The results obtained have reflected a final positive evaluation of the subject for the most of students who have participated in the lectures. With respect to past courses, students have had less difficulty in passing the subject and in the acquisition of skills. It is important to highlight the degree of satisfaction of the students, and especially of the repeating the subject students, who have achieved to pass the subject in an easier way thanks to the use of gamification techniques

Optimisation of immobilisation technology of hazardous steelworks waste using plastic and self-compacting mortars

La gestión de residuos mediante técnicas de inmovilización es un campo de especial atención frente a los compromisos ambientales adquiridos por el conjunto de la sociedad. Todos los sectores productivos deben abordar nuevas soluciones que permitan una menor generación de residuos y una gestión más eficiente y sostenible de los mismos. El acero es indispensable en nuestras vidas. Este material es reciclable prácticamente en su totalidad, siendo la chatarra una de las principales materias primas utilizada. Durante la fusión de la chatarra se produce un residuo en forma de polvo que es recogido en los filtros del sistema de extracción de humos. Este residuo es denominado Polvo de Horno de Arco Eléctrico, o polvo de acería, y es catalogado como “Residuo Peligroso” por su elevado contenido en metales pesados potencialmente contaminantes. A fin de evitar la contaminación y minimizar su impacto ambiental, resulta necesario llevar a cabo una gestión eficiente de este residuo de acería que permita aislar mecánica y químicamente los elementos contaminantes. La técnica tradicionalmente empleada ha sido la Estabilización/Solidificación a través de sistemas cementosos. Sin embargo, esta técnica ha demostrado ciertas carencias debido a la complejidad física y química de este tipo de residuos. La presente Tesis Doctoral explora diferentes alternativas de gestión de dos muestras de polvo de acería a través de morteros convencionales, morteros autocompactantes y morteros modificados con adsorbentes, a fin de lograr la optimización de la técnica de inmovilización y evaluar su incorporación como materia prima en estos materiales, promoviendo de esta manera el nuevo paradigma de Economía Circular. Para ello, en primer lugar, se realizó una minuciosa caracterización de todos los componentes utilizados, prestando especial atención a las propiedades físicas, químicas, estructurales y ambientales de ambos residuos. Seguidamente, se abordó la inmovilización a través de morteros convencionales evidenciando la dificultad de encapsular estos materiales. A continuación, se exploró la optimización de la técnica mediante morteros autocompactantes, ya que la estructura interna de estos materiales, más densa y compacta que los morteros convencionales, le otorga buenas propiedades para ser una matriz de inmovilización para este tipo de residuos, tal y como fue confirmado en el desarrollo de la presente investigación. Finalmente, se llevó a cabo una etapa donde los morteros convencionales fueron modificados mediante el empleo de absorbentes tipo hidrotalcitas. Siendo la absorción una de las principales técnicas utilizadas en la captura de metales pesados, su combinación con matrices cementosas ofreció alternativas viables de inmovilización de los elementos contaminantes contenidos en los polvos de acería Esta investigación ha permitido contribuir al conocimiento de la gestión de los polvos residuales de acería desarrollando matrices de inmovilización eficaces desde el punto de vista mecánico y medioambiental. Además, desde la perspectiva de la implantación de la Economía Circular, esta investigación facilita el cierre del ciclo de producción del acero.Waste management using immobilisation techniques is a field of special attention to target the environmental challenges acquired by society as a whole. All productive sectors must address new solutions to produce less waste and a more efficient and sustainable management of them. Steel is indispensable in our lives. This material is recyclable, scrap being one of the main raw materials used. During the melting of the scrap a dust waste is produced that is collected in the filters of the fume extraction system. This waste is named Electric Arc Furnace Dust or steelwork waste and is classified as "Hazardous Waste" due to its high content of potentially polluting heavy metals. In order to avoid pollution and minimise its environmental impact, it is necessary to carry out an efficient management of this steelmaking waste that allows the mechanical and chemical isolation of the polluting elements. Stabilisation/Solidification through cementitious systems has been the traditional technique used. However, this technique has shown certain shortcomings due to the physical and chemical complexity of the waste. This Doctoral Thesis explores different alternatives for the management of two steelwork waste samples through conventional mortars, selfcompacting mortars and mortars modified with adsorbents, in order to achieve immobilisation technique optimisation and evaluate their incorporation as raw material promoting the new paradigm of Circular Economy. To that purpose, first of all a thorough characterisation of all the components used was carried out, paying special attention to the physical, chemical, structural and environmental properties of both wastes. Next, immobilisation through conventional mortars was addressed evidencing the difficulty of encapsulating these wastes. Subsequently, the optimisation of the technique using self-compacting mortars was explored since its internal structure, denser and more compact than conventional ones lends it advantageous properties to be an immobilisation matrix such and as confirmed in the present investigation. Finally, a stage was carried out where conventional mortars were modified by using hydrotalcite-type absorbents. Absorption is one of the main techniques used in the capture of heavy metals. Therefore its combination with cementitious matrices offered viable alternatives to immobilise the polluting elements contained in the steelwork waste. This research has made it possible to contribute to the knowledge of steelwork waste management by producing effective immobilisation matrices from a mechanical and environmental point of view. Furthermore, from the perspective of the Circular Economy implementation, this investigation facilitates the closure of the steel production cycle

Promotion of Circular Economy: Steelwork Dusts as Secondary Raw Material in Conventional Mortars

Among the actions proposed by the European Union for the implementation of Circular Economy is the use of waste as a secondary raw material (SRM). During the fusion of the scrap, a steel dust is generated, named Electric Arc Furnace Dust (EAFD). The EAFD is composed mainly of potentially leachable heavy metals, so is classified as “hazardous” waste. Around the world, approximately 70% of this waste is deposited in landfills, with a previous treatment through cement-based materials to prevent the metals’ mobility. However, this action is not in accordance with the Circular Economy concept due to the greater use of resources and the loss of deposited metals. The present investigation analyses the use of EAFD as SRM in conventional mortar production for its use as a construction material. Different substitution percentages (25%, 50% and 100%) were used replacing siliceous filler by EAFD. The investigation analysed the behaviour of conventional mortars by tests of workability, compressive strength, water absorption by capillarity and leaching behaviour in granular and monolithic state. The results obtained indicate a slight improvement in mechanical behaviour with the incorporation of EAFD, the reason why its use as SRM in conventional mortars would benefit the construction industry and would encourage the Circular Economy. From an environmental point of view, the mechanisms of Pb fixation should be improved in granular state