Evaluation of Mechanical Characteristics of Cement Mortar with Fine Recycled Concrete Aggregates (FRCA)

[EN] One of the growing demands in concrete manufacture is the availability of natural fine aggregates, which account for 35% to 45% of the total concrete. An alternative method of disposal of fine recycled concrete aggregates (FRCA) generated from demolition and construction waste (C&DW) is their usage in mortar and the development of recycled mortar. The main aim of this research work is to evaluate the viability of incorporating FRCA from urban C&DW for the manufacture of cement-based mortars. Simple processing techniques like washing and sieving are adopted to improve the FRCA quality. Physical and chemical characterization of ingredients is carried out. In total four mixes of 1:3 (cement: sand) mortar with partial replacement of normalized sand with FRCA (0%, 25%, 50%, and 100%) are evaluated for mechanical properties. Water to cement ratio for all four mortar mixes are determined by fixed consistency. Mechanical and physical properties like density, compressive strength, and flexural strength are studied for various curing periods, and the result is that the optimum usage of FRCA is 25% based on a 90-day curing period.SIReutiliza S.L. for offering the recycled and natural aggregate used in this study free of cost. Eduardo Torroja Institute for Construction Science and FCT for financial support

Utilización de Motores Gráficos de Videojuegos en Entornos de Aprendizaje Basado en Proyectos (ABP) / Utilização de motores gráficos de videojogos em ambientes de aprendizagem baseados em projectos (PBL)

El ABP es un método pedagógico que favorece el aprendizaje significativo, y en el que los alumnos trabajan autónomamente en la realización de un proyecto que plantea la resolución de problemas, reales y motivadores, abordando temáticas del currículo educativo. Una de sus características es la ausencia del marco tradicional de aprendizaje en el aula. El proyecto debe suponer un reto que conduzca al estudiante a involucrarse activamente en la construcción de su propio conocimiento, con una actividad lo suficientemente atractiva para captar su atención y esfuerzo, sin dejar de lado el aspecto colaborativo. Los Motores Gráficos para la realización de videojuegos (Unity3D) proporcionan la posibilidad de crear juegos de ordenador, paseos virtuales o aplicaciones 3D, sin coste, con una curva de aprendizaje simple. La capacidad de aplicar acciones mediante programación orientada a objetos, unido a la posibilidad de simular comportamientos siguiendo las leyes de la física (motores de físicas), proporcionan características idóneas a este software para ser usado en el ABP. En el presente artículo se describen, analizan y, en su caso, se evalúan, tres entornos donde profesores del Área de Expresión Gráfica de la ULE, ya están aplicando el ABP, usando como herramienta de trabajo un motor gráfico (Unity3D). Cronológicamente, y debido también a las características de la propia tarea, se inició este proceso con la tutorización de trabajos fin de grado o máster (TFG y TFM). El profesor actúa como orientador y es el estudiante el que elige la temática dentro de sus preferencias o expectativas profesionales. Posteriormente, se ha aplicado la metodología en el ámbito de la asignatura de Expresión Gráfica II. El alumno propone un proyecto de su interés, relacionado con la especialidad de sus estudios y, en el que, además de trabajar competencias propias de la asignatura, comienza a adquirir otras transversales de otras materias. Por último, la tercera experiencia, que está en fase de diseño y autorización, corresponde al nivel de Educación Secundaria en los denominados estudios de Bachiller de Investigación/Excelencia. Los estudiantes adquirirán habilidades en ingeniería, colaborando en un proyecto conjunto con sus pares y realizando otro trabajo individual de su preferencia

Performance study of graphene oxide as an antierosion coating for ornamental and heritage dolostone

9 figures, 2 tables.-- Supplementary information available.Concern for the perpetuation of stone monuments is deeply ingrained in humans; however, despite the attempts made in this field, there is still a great deal of effort needed to bring about advancements in the conservation of ornamental stone. Erosive agents, such as rain, extreme temperatures, and chemical and biological agents, threaten our stone heritage and gradually wear away buildings, sculptures, and other monuments found all around the world. Limestone and dolostone have been widely used throughout history, given their ease of extraction and workability. Nevertheless, these properties make them particularly vulnerable to the aforementioned erosive agents, for which the main solution at present is costly and time-consuming restoration. Given the scarcity of effective and durable agents to prevent the deterioration of ornamental and heritage stones, and as graphene oxide (GO) has recently shown impressive effectiveness for this task, this work will further explore the viability of GO as a protective coating for monumental dolostone. For this purpose, GO is sprayed over dolostone surfaces by water dispersion with no adjuvants. The coating performance is assessed in terms of thermal stress, optical inspection (structured light 3D scanner), colorimetry, leachate analysis, and electron microscopy. The main results show that spray-coated GO over stone surfaces creates a highly protective and durable barrier without altering their aesthetic qualities.This research received funding from the University of León (ULE-PoC 2018) and Fundación General de la ULE y de la Empresa (FGULEM) under projects 2019/00149/001 and 2020. This research was also funded through an awarded MICINN project (PID2020-120439RA-I00). The authors are also thankful to the “Applied innovation against climate change and other aggressions on stone monuments (PRESERVARTE)” project of the Regional Ministry of Culture and Tourism of Castilla y León, which will be used to complement this research in the future.Peer reviewe

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Constructionist Learning Tool for Acquiring Skills in Understanding Standardised Engineering Drawings of Mechanical Assemblies in Mobile Devices

The purpose of Graphic Design is to transfer information about design into reality and concerns the analysis, design and representation of mechanical components and assemblies. For the correct rendering of mechanical components, this discipline requires a command of, and the ability to, manage techniques and systems for graphical representation and standardisation; 3D models in a virtual environment enable engineering students to develop graphical skills and spatial awareness. The objective of the present study is the development of an application for smart devices (mobile phones and tablets), based on the constructionist theory of learning, which will enable first year engineering degree students to acquire the technical drawing knowledge and skills necessary to render mechanical assemblies. The mobile application tested and designed in this work is called ARPAID. It is a learning tool aimed at teaching students about the representation of mechanical assemblies as part of an engineering Graphic Design course. Teaching material and a process for evaluation have been designed. A detailed description is given of a classroom activity accompanied by a tabulation and analysis of the results obtained. This mobile application, when used in a Graphic Design course, promotes a more rapid understanding of spatial relationships and problems, fosters students’ learning and motivation, and develops higher order skills. Results from before and after the use of the application will be presented and do indeed show significant improvements in student performance

Impact of Design Parameters on the Ratio of Compressive to Split Tensile Strength of Self-Compacting Concrete with Recycled Aggregate

Most concrete studies are concentrated on mechanical properties especially strength properties either directly or indirectly (fresh and durability properties). Hence, the ratio of split tensile strength to compressive strength plays a vital role in defining the concrete properties. In this review, the impact of design parameters on the strength ratio of various grades of Self-Compacting Concrete (SCC) with recycled aggregate is assessed. The design parameters considered for the study are Water to Cement (W/C) ratio, Water to Binder (W/B) ratio, Total Aggregates to Cement (TA/C) ratio, Fine Aggregate to Coarse Aggregate (FA/CA) ratio, Water to Solid (W/S) ratio in percentage, superplasticizer (SP) content (kg/cu.m), replacement percentage of recycled coarse aggregates (RCA), replacement percentage of recycled fine aggregates (RFA), fresh density and loading area of the specimen. It is observed that the strength ratio of SCC with recycled aggregates is affected by design parameters

Satisfaction Level of Engineering Students in Face-to-Face and Online Modalities under COVID-19&mdash;Case: School of Engineering of the University of Le&oacute;n, Spain

University education in times of COVID-19 was forced to seek alternative teaching/learning methods to the traditional ones, having to abruptly migrate to the online modality, changes that have repercussions on student satisfaction. That is why this study aims to compare the level of student satisfaction in face-to-face and &ldquo;forced&rdquo; online modalities under COVID-19. A quantitative, cross-sectional methodology was applied to two groups of students: Under a face-to-face modality (n = 116) and under an online modality (n = 120), to which a questionnaire was applied under a Likert scale, with four dimensions: Course design structure, content, resources, and instructor. Non-parametric statistics, specifically the Mann&ndash;Whitney U-test, were used to compare the groups. The results showed that there are significant differences in the level of satisfaction of students in the face-to-face and online &ldquo;forced&rdquo; modalities (p = 0.01984 &lt; 0.05), and the dimensions of the level of satisfaction that presented significant differences were course design structure (p = 0.04523 &lt; 0.05) and content (p = 0.00841 &lt; 0.05). The research shows that students in the face-to-face modality express a higher level of satisfaction, which is reflected in the dimension design structure of the course, specifically in its workload indicator, as well as in the dimension content, in its indicators, overlapping with other courses and materials

Satisfaction Level of Engineering Students in Face-to-Face and Online Modalities under COVID-19—Case: School of Engineering of the University of León, Spain

University education in times of COVID-19 was forced to seek alternative teaching/learning methods to the traditional ones, having to abruptly migrate to the online modality, changes that have repercussions on student satisfaction. That is why this study aims to compare the level of student satisfaction in face-to-face and “forced” online modalities under COVID-19. A quantitative, cross-sectional methodology was applied to two groups of students: Under a face-to-face modality (n = 116) and under an online modality (n = 120), to which a questionnaire was applied under a Likert scale, with four dimensions: Course design structure, content, resources, and instructor. Non-parametric statistics, specifically the Mann–Whitney U-test, were used to compare the groups. The results showed that there are significant differences in the level of satisfaction of students in the face-to-face and online “forced” modalities (p = 0.01984 p = 0.04523 p = 0.00841 < 0.05). The research shows that students in the face-to-face modality express a higher level of satisfaction, which is reflected in the dimension design structure of the course, specifically in its workload indicator, as well as in the dimension content, in its indicators, overlapping with other courses and materials

Responsible heritage protection actions

2 figures,1 table.-- Conference paper presented at the EURECA-PRO Conference - 2022 , held in León (Spain) from October 19 to October 21, 2022.-- Editorial policy for use: https://www.springernature.com/gp/open-research/policies/accepted-manuscript-termsIn recent decades, interest in maintaining and conserving cultural assets has grown and there has been greater investment in the conservation of historical heritage. Developing a good methodology for action is key to guaranteeing adequate preservation of cultural assets. With this in mind, the Spanish Historical Heritage Institute convened a conference in 2002 to try to define basic criteria to guide the different phases of the intervention process in stone materials in all stages of stone conservation: cleaning, consolidation and protection. Carrying out efficient protection of monuments in the traditional way focuses efforts only on how it affects the property, but not on the collateral impact it may have on the environment, or how the effects of climate change may alter its functionality. Thus, a more multidisciplinary test design is needed, with a mandatory laboratory simulation phase under simulated rainfall that represents the increased environmental aggressiveness expected in the near future due to climate change. Hence, water becomes a means to simulate these future conditions, but also a way to explore the effects on rivers and groundwater near the points where the monuments will be treated. Since fresh water is one of the resources that is expected to become scarce in the short term, we intend to carry out responsible tests that take into account both aspects: saving water use and water pollution. Combining the conservation of monuments and environmental responsibility, it will be shown how it is possible to carry out research to achieve a natural product that serves as a sustainable coating for monuments of stone material that is durable but that reduces the environmental impact both in the selection of the product and in the experimental phase, as well as in its operation after application.This research received funding from the Universidad de León (ULE-PoC 2018) and “Fundación General de la ULE y de la Empresa (FGULEM)” under project 2019/00149/001, from the “Consejería de Educación-Desafíos 2020” and the “Consejería de Turismo-PRESERVARTE project” of the Region of Castilla y León, and the granted MICINN project (PID2020-120439RA-I00).Peer reviewe