Optimización de la producción de áridos procedentes de canteras con frentes complejos: cantera de Touro, A Coruña (España)

La cantera de Touro (A Coruña) es una explotación a cielo abierto de la que se extraen anfibolitas y esquistos para su uso como árido de machaqueo. Estos materiales geológicos han sufrido una evolución metamórfica compleja, lo que dificulta su identificación y posterior separación en cantera. Por este motivo, es necesario buscar técnicas analíticas sencillas de campo y laboratorio que permitan identificar y caracterizar el material en los frentes y evaluar su calidad en relación a sus posteriores usos en obra. Con este objetivo, se identificaron las variedades litológicas presentes en los frentes de extracción y se estudió su dureza superficial, porosidad, expresada como la capacidad de absorción del agua, y velocidad de propagación de ondas P. A partir de los resultados obtenidos, se concluyó que la textura, tamaño de grano, porosidad y dureza superficial, son los mejores indicadores de la calidad de los materiales y se propone un sistema de sectorización de los frentes de explotación para un mejor aprovechamiento de los recursos geológicos y un control adecuado de la calidad del producto final en cantera

Crushing effects on the durability of rocky aggregates used on road surfaces subjected to winter maintenance and extreme climate conditions

The internal structure of a rock is determined by its empty spaces (pores and cracks), which can evolve over time by chemical, physical, or biological processes. In construction, these chemical and physical processes, and their effects in the final products, known as aggregates, are well known, and controlled to estimate their quality and durability. However, the intrinsic properties of the raw material, the rock, and the processes that can affect its quality and durability during the production of the aggregates are poorly studied and considered in construction. For this reason, the evolution of the internal structure of two different types of aggregates used in Spanish roads were analyzed. The aggregates will be also studied in their raw form, rock, by measuring their water absorption coefficient and using mercury porosimetry and fluorescence microscopy. To estimate the influence of the internal structure in the durability of the aggregates, both forms, rocks, and aggregates, will be subjected to the combined effect of temperature variations and the salt used during winter maintenance operations on Spanish roads. The results obtained show that crushing processes in the quarry increase the water absorption coefficient of both materials and generate new micro-porosity caused by the microcracking of weak areas of the rock such as its schistosity or the presence of previous cracks. Thus, this increasing of the porosity produced by crushing processes in the quarry has a negative impact on the durability of the aggregates when they are subjected to winter maintenance operations and extreme climate conditions

Importancia de las clases de laboratorio en la motivación de los alumnos de la asignatura Materiales Construcción

Durante el curso 2020/2021 se han retomado las clases de laboratorio de la asignatura de Materiales de Construcción I del grado de Ingeniería Civil y Territorial de la ETSI de Caminos, Canales y Puertos de la Universidad Politécnica de Madrid. Estas clases, de carácter voluntario, se han impartido en los tres grupos de la asignatura. Los resultados de la experiencia han sido contrastados con los datos del curso 2018/2019, debido a la excepcionalidad del curso 2019/2020, afectado por la pandemia del COVID 19. Además, se ha realizado una encuesta voluntaria a los participantes de las clases de laboratorio para conocer su motivación para asistir a estas clases y sus impresiones sobre ellas. El 70 % de los estudiantes matriculados en la asignatura durante el curso 2020/2021 han asistido voluntariamente a las clases de laboratorio y realizado los trabajos exigidos con la intención de mejorar la nota de la asignatura. Sin embargo, durante el desarrollo de las clases, su interés aumentó, lo que se ha traducido en el aumento de la participación de los estudiantes en la modalidad de evaluación continua de la asignatura, disminuyendo, igualmente, el abandono de esta modalidad durante este curso con relación al curso 2018/2019

Variabilidad en la composición y procedencia de las areniscas turbidíticas del Grupo Hecho (Pirineo Sur-Central)

The Eocene turbidite systems of the Hecho Croup (tectosedimentary units, TSU-2, 3, 4 and 5) of the Ainsa-Jaca foreland basin (South-Central Pyrenees) are characterised by spectacular outcrops and good preservation of the original field relationships between the fluvio-deltaic, shelf deposits and turbidites. The aim of this work is the petrographic characterisation of turbiditic carbonate are- nites in order to unravel provenance signatures and their evolution. Ternary compositional diagrams based on carbonate grains types, allow us the recognition of a maturity trend in the Hecho Croup turbidites. The lowermost turbidite system, TSU-2, presents the highest abundance in quartz grains and the lowest quantity in carbonate grains, both extra- and intra-basinal. Toward the top, in TSU- 5, quartz abundance decrease and conversely carbonate grains increase. Non-carbonate rock fragments indicate the dominance of low- and medium-rank metamorphic source rocks toward the uppermost TSU-5. In addition, back scattering electron imaging on feldspar grains, confirm the presence of granites, gneisses and metamorphic rocks in the source area. Thus, the obtained results reflects the exposition and erosion of the Pyrenean crystalline basement (granites, gneisses and metamorphic rocks) and its progressive replacement as source rock by carbonate rocks from the thrust-folds belt, due to tectonism evolution and sea-level variations

Implementación de Laboratorios Virtuales aplicados a los Materiales de Construcción para la resolución de cuestionarios en Moodle

Durante el curso 2022/23 se ha implementado un Laboratorio Virtual, utilizando la plataforma Moodle, para la resolución de un cuestionario asociado a las clases de laboratorio de la asignatura Materiales de Construcción de grado de Ingeniería Civil. Dicho recurso, reproduce los experimentos realizados, de tal forma que los estudiantes tienen que volver a manipular virtualmente los equipos empleados en el laboratorio para obtener los datos necesarios para resolver el cuestionario propuesto. Los resultados obtenidos de esta experiencia han sido muy positivos. El 100 % de los estudiantes superaron el cuestionario, siendo la nota media de 9,23. Además, se realizó una encuesta de satisfacción donde más del 90 % de participantes opina que el Laboratorio Virtual es un recurso muy didáctico y recomienda su implementación en futuros cursos

Are Future Teachers Involved in Contributing to and Promoting the Reduction of Massive Waste Generation?

Massive waste generation linked to overconsumption is considered one of the most significant socio-ecological issues today, becoming a challenge for health and well-being and a barrier to achieving sustainability. Education is key to raising awareness and involving citizens in the adoption of responsible consumption habits, facilitating the recognition of the relationship between our daily activities and the production of waste. The aim of this exploratory study is to analyse the perceptions and commitments of future secondary school teachers (FTs) toward this issue and to explore the educational approaches they propose to address it in the classroom (n = 138). In this work, a mixed-methods approach was used based on quantitative and qualitative data collected through a questionnaire. The results show that FTs have difficulties in recognising the different factors involved in the problem of massive waste generation. However, they incorporate the health and ecological vision, which is close to the holistic vision of the One Health approach. The majority of them take personal responsibility for the problem, although they opt for low-effort options. Regarding the educational proposals they design, only a minority can do it following a commitment-oriented approach.This research was funded by AGENCIA ESTATAL DE INVESTIGACIÓN (Ministerio de Ciencia e Innovación, Gobierno de España), grant number PID2019-105705RA-I00/AEI/10.13039/501100011033 and The APC was funded by PID2019-105705RA-I00/AEI/10.13039/501100011033

3D model generated from UAV photogrammetry and semi-automated rock mass characterization

This work develops a rock mass characterization of a limestone quarry in northern Spain based on a 3D model obtained by using photographs taken from an unmanned aerial vehicle (UAV) flight and structure-from-motion algorithms. This methodology permits to obtain photogrammetric information in a rapid and low-cost way. Geological planar facets (stratification, faults) are related to the tectonic history of a geological formation and permit assessing slope stability. The spatial orientation of planar features is usually measured with a compass and clinometer, which requires experience and knowledge, it is space limited, and sometimes hazardous. Geological 3D models can mitigate these limitations. A 3D point cloud generated from a series of images obtained using an UAV is included in the open-access applications DSE and FACET, which serve to determine the main discontinuity planes within a limestone quarry. Comparison of the results from software analyses with data hand-measured directly in the field reveals the effectiveness of the use of UAV to develop a virtual outcrop model that permits to obtain accurate measurements. The resultant quarry 3D model has been included in Sketchfab, an open access platform that permits easy and quick access and availability for a wide audience. This study shows that the use of UAV combined with structure-from-motion algorithms is of great interest for geosciences as well as other related disciplines such as mining or civil engineering, and can facilitate decision-making for policy makers and authorities. In addition, it is a technique of great use to develop rock mass characterization in a low-cost, rapid, and easy way, and permits to reach areas with difficult accessibility. This way, this methodology can also be very useful for geosciences teaching purposes, as a complement to traditional field lectures, or to develop virtual field trips and laboratories

Calidad y durabilidad de áridos metamórficos empleados en capas de rodadura gallegas bajo el efecto de la sal y una climatología extrema

El uso del NaCl (sal común) en forma de salmuera está muy extendido durante el mantenimiento invernal de las carreteras españolas, pero este compuesto incide de forma negativa tanto en el medio ambiente como en las propias carreteras. Por este motivo, es necesario realizar un estudio detallado del efecto que tiene la sal cuando es esparcida sobre las carreteras en invierno. Además, esta sal puede permanecer en las superficies de las carreteras durante el verano, donde se pueden alcanzar temperaturas muy superiores a los 40º C. Por este motivo, es necesario considerar también estas condiciones en la evaluación de la durabilidad de una carretera. Por estos motivos, en esta tesis se ha estudiado la capa más superficial de una carretera y, por tanto, más expuesta a los efectos de la sal y agentes meteóricos (capa de rodadura). Estas capas están constituidas por mezclas asfálticas, cuyo mayor componente son los áridos de origen pétreo. Estos materiales son los principales responsables de la calidad y durabilidad de estas mezclas bituminosas por lo que es necesario analizar cómo se comportan bajo el efecto de la sal y en condiciones climatológicas adversas (invierno-verano). Los materiales estudiados fueron esquistos y anfibolitas explotadas en una cantera gallega, próxima a Santiago de Compostela. Esta cantera ha suministrado áridos y mezclas bituminosas a numerosas carreteras y autovías de la región, ya que dispone de su propia planta asfáltica..

Long-Term Behavior of the Micro-Texture of Aggregates Used on Roads Subjected to Extreme Climate Conditions and Winter Maintenance Operations

The micro-texture of fine and coarse aggregates used on roads is one of the main factors responsible for the skid resistance of asphalt pavements. However, the long-term behavior of this property regarding the effects of traffic and climate conditions has been poorly studied. Therefore, in this paper, two types of aggregates, schist and amphibolite, commonly used on roads that are subjected to winter maintenance actions and high temperatures in summer have been studied. The micro-texture of the aggregates has been characterized with an optical roughness tester, fluorescence microscopy and the Polished Stone Value test. The extreme climate conditions have been simulated in a laboratory with durability tests (freeze-thawing and thermal stress cycles) including the NaCl used as deicer during winter maintenance operations. Results have shown that the wearing mechanisms of the aggregates? surfaces are different regarding their composition and internal texture. On schist aggregates, weather conditions applied do not significantly deteriorate their micro-texture. However, the combined effect of traffic and extreme climate conditions with NaCl, double the decrease of the surface roughness measured when these aggregates are subjected to extreme climate conditions in the laboratory, improving, in some cases, their skid resistance. Conversely, the external factors considered have the same effect on the micro-texture of the analyzed amphibolite aggregate

Improvement of the production of aggregates from quarries located in complex geological settings: Touro quarry, A Coruña (Spain)

La cantera de Touro (A Coruña) es una explotación a cielo abierto de la que se extraen anfibolitas y esquistos para su uso como árido de machaqueo. Estos materiales geológicos han sufrido una evolución metamòrfica compleja, lo que dificulta su identificación y posterior separación en cantera. Por este motivo, es necesario buscar técnicas analíticas sencillas de campo y laboratorio que permitan identificar y caracterizar el material en los frentes y evaluar su calidad en relación a sus posteriores usos en obra. Con este objetivo, se identificaron las variedades litológicas presentes en los frentes de extracción y se estudió su dureza superficial, porosidad, expresada como la capacidad de absorción del agua, y velocidad de propagación de ondas P. A partir de los resultados obtenidos, se concluyó que la textura, tamaño de grano, porosidad y dureza superficial, son los mejores indicadores de la calidad de los materiales y se propone un sistema de sectorización de los frentes de explotación para un mejor aprovechamiento de los recursos geológicos y un control adecuado de la calidad del producto final en canteraTouro (A Coruna) is a quarry where amphibolite and schist are exploited as crushed aggregates. These materials formed in a complex metamorphic system and it is difficult to classify and separate them. For this reason, affordable techniques that can be used in quarry faces and in simple laboratories were searched to identify and characterize the stone materials. This characterization will help to evaluate "in situ" the quality of stone materials related to future uses. We have developed a petrological classification of the stone materials exploited in Touro. In order to differentiate the quality grades of the Touro quarry lithologies, the classification was completed by studying the stone surface hardness, porosity, expressed as water absorption capacity, and P-wave velocity propagation. On this basis, we concluded that texture, grain size, porosity and surface hardness are valuable "quarry faces"parameters to evaluate the quality of the stone materials. We also propose to separate the materials of the quarry faces by grades of quality to better control the final quarry produc