Search

Several gold deposits in the eastern region of Cuba are genetically related to the island arc- and the ophiolitic complex formation. These have been studied and exploited since the time of the Spanish colonization in the mid-sixteenth century. These deposits belong to the Aguas Claras-Guajabales mineral field in the Holguín Province (Cuba) and lie in an elongated zone approximately 15 km in length. The object of this work is to make a methodical, detailed, and chronological review of the geological and mining work carried out in this region, as well as highlight the degree of the previously achieved studies. To realize this, an extensive bibliographic review of all available data, including published reports and articles, as well as unpublished material, was carried out. Moreover, ore mineralogy and petrography were reviewed by thin section analyses from samples from these deposits by petrographic and scanning electron microscopy. The results obtained from this study highlight that the gold mineralization in that area is closely linked to metasomatic processes produced by the circulation of hydrothermal fluids that affected the different volcanic and ultramafic rocks. This study shows that the highest gold contents observed are controlled by the contacts between the different host lithologies with high rheological contrasts. The presence of different alteration styles such as serpentinization, listvenitization, rodingitization, and propylitization have played a primary role in the deposition of gold during mineralization processes. This work could be a very useful exploration guide for future research in this region, as it provides a useful and practical compilation of the characteristics of the mineralization and alteration styles, as well as a precise indication of the spatial position, thicknesses, and contents of the gold-rich horizons.

The eruption of the Cumbre Vieja volcano on 19 September 2021, resulted in the deposition of large quantities of volcanic ash (VA), causing a great impact on the citizens. This work aims to study the properties of this volcanic ash as pozzolanic raw materials to establish their potential use in the development of sustainable cement. Results of chemical and technical characterization are presented. To achieve this goal, Ordinary Portland Cement (OPC) was replaced with standardized percentages of OPC/VA: 10, 25, and 40%. Characterization studies were carried out using chemical analysis of X-ray fluorescence (XRF), chemical quality analysis (QCA), pozzolanicity test (PT) at 8 and 15 days, as well as determining the mechanical strength (MS) at 7, 28, and 90 days. The results obtained by XRF and QCA established that the chemical composition of the VA corresponds to that of the natural pozzolan typical of pyroclastic genesis. The PT test showed that the analyzed samples have a marked pozzolanic nature, both at 8 and 15 days, showing a significant increase in their hydraulic reactivity. Likewise, the MS tests confirmed a continuous increase in mechanical compressive strength, which increased significantly from 7 to 90 days of curing, reaching more than 58 MPa. On the other hand, mechanical tests showed that the three types of dosages used OPC/VA:10, 25, and 40% were equally effective, with OPC/VA formulations: 10–25% being the most effective. The results obtained in this research could be used by local industries as a guide for the correct use of the volcanic materials of this island, both for the manufacture of construction materials, such as aggregates, and to produce pozzolanic cement with low CO2 emissions, thus having a positive impact on the environment. Finally, the great natural availability of natural VAs in the surrounding areas of La Palma could cover part of the needs for materials used in the construction and restoration of houses and infrastructures damaged d

The speed at which climate change is happening is leading to a demand for new pozzolanic materials that improve the quality of cements and, at the same time, limit the emission of greenhouse gases into the atmosphere. The main objective of this work is the detailed characterization of an ignimbrite sample (IGNS) to demonstrate its effectiveness as a natural pozzolan. To meet this objective, a series of tests were carried out. In the first stage, mineral and chemical analyses were performed, such as petrographic analysis by thin section (TSP), X-ray diffraction (XRD), oriented aggregate (OA), scanning electron microscopy (SEM) and X-ray fluorescence (XRF). In the second stage, the following technical tests were carried out: chemical quality analysis (QCA), pozzolanicity test (PT) and mechanical compressive strength (MS) at 7, 28 and 90 days, using mortar specimens with ignimbrite/cement formulation (IGNS/PC): 10, 25 and 40% to establish the pozzolanic nature of the ignimbrite. The results of the mineral and chemical analyses showed that the sample has a complex mineralogical constitution, consisting of biotite mica, potassium feldspar, plagioclase, smectite (montmorillonite), quartz, volcanic glass, iron, titanium and manganese oxides, chlorite and chlorapatite. On the other hand, the technological tests revealed the pozzolanic nature of the sample, as well as visible increases in the mechanical compressive strengths in the three proportions, the most effective being IGNS/PC:10% and IGNS/PC:25% at 7, 28 and 90 days of setting. The results obtained could be applied in the formulation of new pozzolanic cements with ignimbrite as a natural pozzolanic aggregate.

The object of this work is to study and characterize diatomites from the southeast of the Iberian Peninsula to establish their character and quality as natural pozzolans. This research carried out a morphological and chemical characterization study of the samples using SEM and XRF. Subsequently, the physical properties of the samples were determined, including thermic treatment, Blaine particle finesse, real density and apparent density, porosity, volume stability, and the initial and final setting times. Finally, a detailed study was conducted to establish the technical properties of the samples through chemical analysis of technological quality, chemical analysis of pozzolanicity, mechanical compressive strength tests at 7, 28, and 90 days, and a non-destructive ultrasonic pulse test. The results using SEM and XRF show that the samples are composed entirely of colonies of diatoms whose bodies are formed by silica between 83.8 and 89.99% and CaO between 5.2 and 5.8%. Likewise, this indicates a remarkable reactivity of the SiO2 present in both natural diatomite (~99.4%) and calcined diatomite (~99.2%), respectively. Sulfates and chlorides are absent, while the insoluble residue portion for natural diatomite is 1.54% and 1.92% for calcined diatomite, values comparatively lower than the standardized 3%. On the other hand, the results of the chemical analysis of pozzolanicity show that the samples studied behave efficiently as natural pozzolans, both in a natural and calcined state. The mechanical tests establish that the mechanical strength of the mixed Portland cement and natural diatomite specimens (52.5 MPa) with 10% PC substitution exceeds the reference specimen (51.9 MPa) after 28 days of curing. In the case of the specimens made with Portland cement and calcined diatomite (10%), the compressive strength values increase even more and exceed the reference specimen at both 28 days (54 MPa) and 90 days (64.5 MPa) of curing. The results obtained in this research conf

Climate change is already an undeniable reality, and it is a direct consequence of our society’s lifestyle and the indiscriminate use of certain materials, such as Portland cement, which causes the emission of gases and waste that contributes to the greenhouse effect. The object of this work is to present the results obtained from research on pyroxenic andesites that have become altered to zeolite and their use as alternative, eco-efficient materials that improve the quality of cement through a standardized partial substitution. In this work, four samples of pyroxenic andesites altered to zeolites (PAAZ) and two samples of unaltered andesites (UPA) were analyzed. The methods used in this study are as follows: petrography of thin section (PTS), chemical analysis of X-ray fluorescence (XRF) and phase determination by X-ray diffraction (XRD). Other tests were carried out to determine the quality of the PAAZ from a technical and practical application point of view, such as chemical analysis of pozzolanicity (CPT) at 8 and 15 days, as well as mechanical compression tests at 2, 7, 28 and 90 days. Petrographic and phase analyses show that the original mineral components of the samples such as pyroxene, amphibole, plagioclase and mica were leached and replaced by more than 90% with mordenite and smectite. XRF analyses indicates an anomalous rise in SiO2, a drastic reduction in alumina Al2O3 and a significant increase in alkaline compounds over alkaline-earth compounds in samples of altered pyroxenic andesites (PAAZ) with respect to samples of unaltered andesites (UPA). The pozzolanicity test establishes that the samples of unaltered andesites do not behave like pozzolans at 8 or 15 days; however, altered andesites experienced remarkable pozzolanic reactivity in the same periods. The mechanical compression tests carried out on specimens made with PAAZ and Portland cement showed a growing increase in mechanical resistance from 2 days (15.2 MPa) to 90 days (72.1 MPa). These re

El TFG (Trabajo Final de Grado) realizado se centra en la fabricación de ladrillos y cerámicas, con énfasis en los ladrillos Clinker, un tipo de pieza cerámica vista. El proyecto abarca desde el análisis del proceso de fabricación, el estudio de las pastas cerámicas, el cumplimiento de la normativa española, y el abordaje del problema energético hasta el establecimiento de los métodos de ensayo para evaluar sus propiedades. Además, se explicará la metodología utilizada en cada uno de los ensayos, así como los resultados y un breve análisis de los mismos, determinando de esta manera la validez de los ladrillos para poder ser comercializados fuera de la comunidad europea. ABSTRACT The FDP (Final Degree Project) carried out focuses on the manufacture of bricks and ceramics, with emphasis on Clinker bricks, a type of exposed ceramic piece. The project ranges go from analyzing the manufacturing process, studying ceramic pastes, examining Spanish regulations, addressing the energy problem to establishing test methods to assess their properties. The methodology of each test will be shown, as well as the results and a brief analysis of them. In this way, determining the validity of the bricks to be able to be commercialized out of the European community.

Este proyecto de fin de grado busca conectar la tecnología con la sostenibilidad al desarrollar un prototipo que monitorice el proceso de fraguado del hormigón mediante sensores de temperatura de bajo costo. La monitorización en tiempo real permitiría asegurar la calidad del hormigón y corregir cualquier problema de resistencia a la compresión de manera rápida y económica. Además, se espera que esta monitorización contribuya a reducir las emisiones, optimizar la logística y gestión de los recursos naturales, y fomentar la innovación en la gestión sostenible de las canteras. La transformación digital industrial se considera clave para una construcción más sostenible. Abstract This undergraduate final project aims to bridge technology and sustainability by developing a prototype that monitors the concrete curing process using low-cost temperature sensors. Real-time monitoring would ensure concrete quality and enable prompt and cost-effective correction of compression strength issues. Additionally, it is expected that this monitoring will contribute to emissions reduction, optimize logistics and resource management, and foster innovation in sustainable quarry management. Industrial digital transformation is considered crucial for achieving more sustainable construction practices.

En este trabajo se presentan los resultados de la sustitución parcial de cemento Portland (REF) por caolín de baja densidad (DIA), caolín de baja alúmina (CAO-BA) y caolín de alta alúmina (CAO-AA) para el ensayo en morteros en proporciones de 10, 25 y 40%. Para lograr dichos objetivos se prepararon las muestras y en una primera etapa, se realizaron análisis químicos y ensayos de puzolanicidad a 8 y 15 días con tal de poder ver si cumplen las propiedades puzolánicas. Por último, se realizaron ensayos de resistencia mecánica a compresión a las edades de 7, 28 y 90 días en probetas con las diferentes proporciones, tanto en forma natural, como activada. Los ensayos químicos fueron satisfactorios, mostrando valores óptimos de la sílice reactiva, algunas muestras, aunque no cumplieron los ensayos de puzolanicidad, tras su tratamiento térmico, lograron cumplirla y obtener unas propiedades puzolánicas. Los ensayos mostraron un aumento de las resistencias a compresión desde los 7 a los 90 días, la muestra DIA, tanto natural como activado, tiene un comportamiento que supera los valores del cemento de referencia para sustituciones del 10%, por otro lado, aunque las muestras de CAO-BA y CAO-AA no tengan propiedades puzolánicas, al activarse, logran cumplir los ensayos, y llegando a adquirir unas resistencias muy superiores a los de referencia, llegando a mejorarlas hasta en un 14,88%. Es por ello que las muestras de CAO-BA y CAO-AA podrán ser usadas para la fabricación de cementos con adición puzolánica tras un proceso de calcinación, logrando reducir costes energéticos en su producción, así como en la reducción de las emisiones de CO2, y aunque dichas muestras tengan mejores comportamientos a compresión, se deberá tener en cuenta la muestra de DIA-N, la cual, al no tener la necesidad de tener un proceso térmico, podría reducir aún más las emisiones de carbono y los costes energéticos, el cual se podrá hacer un estudio de viabilidad económico-financiera para saber qué muestra p

La llegada de los Borbones a España supuso el pistoletazo de inicio para el desarrollo de una serie de proyectos encaminados a buscar una racionalización de la administración y la gestión. La base de todo el proceso estaba en la correcta gestión del territorio. Y es que, el peso de lo espacial cobra gran importancia en la centuria de las Luces convirtiéndose en una pieza clave de las reformas que se quería introducir. Un ejemplo de ello es el impulso que cobran las intendencias como una nueva, o no tanto, división administrativa. Pese a la clara necesidad de contar con este tipo de instituciones, su implementación y desarrollo no fue un camino fácil. A lo largo del siglo XVIII se produjeron importantes cambios y transformaciones, pudiéndose establecer claramente dos grandes momentos que dividen casi a la mitad este período cronológico. A partir de 1749 y mientras dure el desarrollo del Catastro de Ensenada tendrán su mayor período de estabilidad solo roto por la lucha entre intendentes y corregidores. A través de esta comunicación buscamos mostrar todos estos hitos, descubriendo los motivos que los fueron ocasionando y las implicaciones que tuvieron. Pese al enfoque global del trabajo, abarcando toda la corona de Castilla, tomaremos dos zonas como espacios piloto, la intendencia de Salamanca y las intendencias que operaron en el territorio burgalés.

The geological nature of the territory of the Republic of Cuba has favoured the formation of large and varied deposits of volcanic tuffs enriched by various species of zeolites. Today, new zeolite deposits continue to be discovered in the country. This work aims to present the results of a study carried out in an unexplored area that is located approximately 1.2 km east of the Loma Blanca deposit, outside the mining operation limits. To carry out this research and to establish a qualitative comparison between both sample populations, four samples were taken from the study area, and another four were taken from the Loma Blanca deposit. The characterisation of the samples was performed by XRD, SEM, and XRF. The pozzolan quality was determined by the pozzolanicity test (PT) and quality chemical analysis (QCA). Finally, a study of the mechanical strength (MST) was performed at 7, 28, and 90 days, using mortar specimens made with PC/ZT: 75–25% and PC/ZT: 70–30%, respectively. The results of the studies using XRD, SEM, and XRF indicated that both groups of samples had a similar complex mineralogical composition, consisting mainly of mordenite and clinoptilolite accompanied by secondary phases such as quartz and amorphous materials in the form of altered glass. The pozzolanicity test showed that both the samples from the study area and those from the Loma Blanca deposit behaved like typical pozzolans, which is a trend that can be seen in the high values of mechanical strength to compression up to 72 MPa for the PC/ZT: 75–25% formulation and 66 MPa for the PC/ZT: 70–30%. The results obtained establish that the zeolite varieties detected in the study area are similar to those of the Loma Blanca deposit, which could have a positive impact on the increase in current reserves, especially for manufacturing pozzolanic cements with properties that contribute to the preservation of the environment.

Metropolitan construction and demolition waste (CDW) is currently an important source of recycled materials that, despite having completed their useful life cycle, can be reincorporated into the circular economy process (CEP); however, the recycling process is very selective, and waste material is not always fully satisfactory due to the intrinsic nature of the waste. This work aims to demonstrate and establish how to increase the effectiveness of the construction and demolition waste in more resistant mortars, by mixing it with zeolitised cinerite tuff (ZCT) at varying normalised proportions. To attain the objectives of this research, a series of tests were done: First, a chemical, physical and mineralogical characterisation of the CDW and the ZCT through XRF, XRD, SEM and granulometric methods. Second, a technological test was made to determine the mechanical strength at 7, 28 and 90 days of specimens made with Portland cement (PC) and mixtures of PC/CDW, PC/ZCT, and PC/CDW-ZCT. The results obtained through the characterisation methods showed that the sample of construction and demolition waste consisted of the main phase made of portlandite and tobermorite, and by a secondary phase consisting of quartz, ettringite and calcite; whereas the ZCT has a main phase of mordenite and a secondary phase of smectite (montmorillonite), amorphous materials consisting of devitrified volcanic glass, quartz and plagioclase. Mechanical strength tests established that specimens made with PC/CDW mixtures have very discreet compressive strength values up to 44 MPa at 90 days, whereas specimens made with PC/ZCT mixtures achieved a remarkably high mechanical strength consisting of 68.5 MPa. However, the most interesting conclusion in this research is the good result obtained in mechanical strength of the specimens made up of mixtures of PC/CDW-ZCT, which increased from 52.5 to 62 MPa at 90 days of curing; this fact establishes the positive influence of ZCT on waste in the mortar mixtu

University students face situations throughout their careers that are sometimes difficult to overcome due to their lack of experience or preparation. Mentoring programs in university education have been proven to be a great accompaniment tool to solve these difficulties in addition to helping students’ personal and professional development. Our study aimed to show the complete mentoring process that accompanies students in the most crucial stages of their university education at the School of Mines and Energy of Universidad Politécnica de Madrid. Three stages of interest were identified in which mentoring projects have been implemented through training activities at the Unit of Social Entrepreneurship, Ethics and Values in Engineering (UESEVI). At the beginning of their studies, two welcome actions are offered: Mentor and Monitor projects that provide administrative and academic support; during the development of their studies, the Mentoring with Energy project offers professional tutoring that helps students in their incorporation into the labor market and provides them with tools to select a specialty; and in the last stage, professional accompaniment is provided by the Gray Angels project that helps students to develop their future careers. The activities of UESEVI are a strategy in our School to guarantee the development of soft skills and compliance with quality education processes. The usefulness of these programs can be measured through the participation and interest of the students. A positive evolution of these projects has been observed over the years. They have been growing according to the demand and needs detected in the successive evaluations of the programs.

In recent decades, large amounts of construction and demolition waste (CDW) have been generated and accumulated throughout Europe, which is a challenge to manage and control nowadays. This work shows the results of a study carried out with samples of ceramic recycled aggregates (CRAs) and recycled concrete aggregates (RCAs) mixed with cement (C) in mortars. The main objective of this research is to demonstrate how, by adding CRAs and RCAs to a mixture of cement and natural aggregate (NA), it is possible to develop a high-strength mortar and achieve the best mixing ratio. To achieve these objectives, the characterization of the samples was initially carried out such as XRF, XRD and SEM. Next, tests were carried out on the products obtained, such as the consistency of the fresh mortar and the density of the specimens. Finally, a study of mechanical compressive strength was performed at 7, 28 and 200 days. The results show that although both CRAs and RCAs negatively affect the curing process of the specimens, it is possible to develop mortars with compressive strengths greater than 20 MPa. An obvious increase in mechanical compressive strengths was seen between 7 and 200 days of analysis. The results achieved in this research could be an important guide for the management of CDWs by local industries, thus favouring the development of the circular economy.

Este trabajo presenta los resultados de la sustitución parcial de cemento Portland (CREF) por fluorita natural (FN) y fluorita calcinada (FC) en morteros, al 10%, 25% y 40%. Para alcanzar estos objetivos, inicialmente se estudió una muestra de fluorita mediante difracción de rayos X, microscopía electrónica de barrido y espectroscopía Raman. En una segunda etapa se realizó un análisis químico y un ensayo de puzolanicidad a 8 y 15 días para establecer las propiedades puzolánicas de la muestra investigada. Finalmente, se realizó un ensayo de resistencia mecánica a compresión a 7, 28 y 90 días en probetas preparadas con mezclas CREF/FN y CREF/FC, en una proporción de 10%, 25% y 40%. Los resultados de difracción de rayos X, microscopía electrónica de barrido y espectroscopía Raman indicaron que la fluorita es la fase mineralógica principal. El ensayo de puzolanicidad y el análisis químico mostraron un aumento en la puzolanicidad de las muestras de 8 a 15 días. El ensayo de resistencia mecánica a compresión mostró un aumento en la resistencia a la compresión de 7 a 90 días para las muestras CREF/FN y CREF/FC. Los resultados obtenidos establecen que la fluorita produce efectos positivos en el mortero y contribuye a la ganancia de resistencia mecánica en el tiempo, siendo un material adecuado para la fabricación de cementos con adición puzolánica con reducción de emisiones de CO2, y reduciendo los costes energéticos de producción. Abstract This work presents the results of the partial substitution of Portland cement (CREF) by natural fluorite (FN) and calcined fluorite (FC) in mortars, at 10%, 25% and 40%. To meet these objectives, a sample of fluorite was initially studied by X-Ray Diffraction, Scanning Electron Microscopy and Raman Spectroscopy. A chemical quality analysis and a chemical pozzolanicity test at 8 and 15 days were carried out in a second stage to establish the pozzolanic properties of the investigated sample. Finally, a mechanical compressive strength test