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Mechanical behavior of concrete with recycled aggregates and expanded polystyrene, focused on prefabricated panels
No full textThe urgent need to reduce the use of natural resources and energy consumption by the construction industry, as well as provide a solution to the accumulation of residues and waste generated in the construction sector, to clean up the environment, is of concern to scientists and researchers around the world. The aim of this study is to evaluate the viability of concrete with low resistance requirements, intended to be used in non-load-bearing prefabricated panels, in which the natural coarse aggregate has been replaced by recycled coarse aggregate in different percentages (25%, 50%, 75% and 100%), incorporating in all dosages, one third of the replacement, by expanded polystyrene. To do this, their mechanical and physical properties have been studied: compressive strength, flexural, diametral compression tensile, absorption, durability and density. The recycled coarse aggregates (brick masonry, concrete blocks and reinforced concrete structural elements) were obtained through a selective process of the waste generated in demolition works in the city of Guayaquil (Ecuador). The results show that as the percentage of recycled aggregates is reduced, the compressive strength and other mechanical properties increase, as well as its density, approaching more and more to that of the control concrete. The behavior of the best mixture, with 25% replacement with coarse recycled aggregates and expanded polystyrene, meets the structural requirements of a prefabricated wall panel, in addition to reducing the environmental impact generated by the use of recycled coarse aggregates
Stress, fear, and anxiety among construction workers: a systematic review
No full textObjectives: The aim of this review was to assess the possible risk factors arising from working conditions, that could have an impact on the stress, fear, and anxiety of construction workers. Methods: A systematic review was conducted following the PRISMA format in the Pubmed, Cochrane, Web of Science, Scopus, and PsycInfo electronic databases on February 3, 2023, using the following key words: anxiety, stress, fear, and construction workers. Methodological quality was assessed using the critical appraisal tools of the Joanna Briggs Institute. Results: A total of 35 studies were included. The results showed a number of conditioning factors for stress, anxiety, and fear among construction workers such as age, inappropriate safety equipment, safety culture, high workload and long working hours, physical pain, low social support from direct supervisor or co-workers, lack of organizational justice and lack of reward, financial situation, maladaptive coping strategies, and characteristics of the pandemic. Conclusions: There are a number of risk factors related to working conditions, organizations, and individuals that can affect the levels of stress, anxiety, and fear among construction workers, such as age, work hardship, safety culture and, especially, the long hours that construction professionals work. This may lead to an increase in the number of occupational accidents and higher associated fatality rates. Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022367724, identifier: CRD42022367724. Copyright © 2023 Gómez-Salgado, Camacho-Vega, Gómez-Salgado, García-Iglesias, Fagundo-Rivera, Allande-Cussó, Martín-Pereira and Ruiz-Frutos
Consideración de la ventilación natural mediante modelos de simulación en transitorio utilizando TRNFlow
No full textThe building sector is a major contributor to the environmental impact in the European Union due to energy consumed, extraction of resources and greenhouse gas emissions. Particularly, the existing building stock represents a greater challenge than new constructions, since up to 85% of the buildings existing in 2050 have already been built. The extensive lifespan of buildings mean that construction assemblies remain standing for long periods of time, which accounts for most of the embodied environmental impact and affects its energy performance during the use stage. Also, because the façade surfaces generally cover most of the building envelope, they have strong potential to reduce existing buildings environmental impacts and energy consumption, when undertaking major refurbishments. This paper aims to compare the environmental performance of different refurbishment alternatives for façade assemblies typically used in existing buildings in the Mediterranean region in Spain. For this purpose, a three-step methodology based on a life cycle approach was applied: (I) Identification of existing façade assemblies and their related refurbishment alternatives, (II) Bill of Materials, and (III) Environmental, cost and energetic impact of each façade and their refurbishment alternatives were analysed with the Life Cycle Assessment and Life Cycle Cost methodologies and U-values calculation, respectively. The results were used to draw conclusions to help construction sector practitioners, such as building designers and contractors, to make decisions during the design and construction stages in major renovation projects. They could also be used to select the optimum façade refurbishment alternatives, aiming at nearly zero-energy buildings. © Published under licence by IOP Publishing Ltd
Analysis of the effectiveness of using Kahoot! In university degrees in building engineering
No full textGamification is increasingly used for better content assimilation. However, it is hardly used in theoretical and technical courses related to building and architecture. This study focuses on assessing the use of gamification with Kahoot! to arouse students’ interest and to ease content assimilation. Experimentation was undertaken during the 2020/2021 and 2021/2022 academic years. All students enrolled in the course participated in experimentation: 67 and 65 students, respectively. Gamification sessions took place in the middle and at the end of each academic year (the week before partial exams). Students were also surveyed to assess their degree of satisfaction with gamification sessions. The results showed that gamification dynamics improved students’ performance in exams, obtaining a lower percentage of failures and increasing higher marks. Cluster analysis results also showed that students’ performance in Kahoot! is not a clear indicative of their performance in exams, so it is useful as a self-assessment tool. Moreover, most students positively assessed gamification sessions for better content assimilation. This study stresses the implementation potential of Kahoot! in teaching dynamics in university degrees in architecture and building engineering. © Article’s contents are provided on an Attribution-Non Commercial 4.0 Creative commons International License. Readers are allowed to copy, distribute and communicate article’s contents, provided the author’s and JOTSE journal’s names are included. It must not be used for commercial purposes. To see the complete licence contents, please visit https://creativecommons.org/licenses/by-nc/4.0/
Film grammar and 3D animation for science dissemination
No full textPrestar especial atención al lenguaje audiovisual empleado en las producciones destinadas a la difusión del conocimiento científico, juega un papel importante en los procesos de transferencia del conocimiento y es crucial para despertar el interés por la ciencia. En la actualidad, nuestra cultura visual está fuertemente influenciada por el material audiovisual creado a través de la industria del entretenimiento, entre las que se encuentran la potente industria del videojuego y del cine, actores de un proceso de influencias mutuas repletas de afecciones recíprocas. En este trabajo se aborda la realización de material audiovisual destinado a la divulgación de contenido científico, haciendo uso de tecnologías gráficas avanzadas como el modelado y la animación 3D. El uso de esta tecnología se pone al servicio de una gramática visual heredada de la industria cinematográfica. La conjunción de ambos elementos se ejemplifica haciendo un análisis de la producción audiovisual de divulgación científica titulada La célula. Unidad de vida
Scaled concrete beams containing maximum levels of coarse recycled aggregate: Structural verifications for precast-concrete building applications
No full textThe use of Recycled aggregate (RA) enhances concrete sustainability. If used on an industrial-scale, structural verification, and testing will be required to confirm that RA concrete can meet relevant industrial standards and the requirements of manufacturers, especially in the precast-concrete industry. In this paper, an experimental campaign with the participation of a precast-concrete manufacturer is reported. The objective is to test a self-compacting concrete (SCC) mix, designed for structural applications, that contains maximum amounts of 100% coarse RA, in order to establish its compliance with the habitual requirements of precast-concrete manufacturers. Thus, scaled beams (12 × 24 × 180 and 24 × 24 × 130 cm) were subjected to bending, shear-bending, shear, and long-term-deflection tests. In addition, the performance of that SCC mix in the bending and shear-bending tests was compared with the performance of an SCC mix of similar compressive strength containing 0% coarse RA. In the failure tests, the experimental results were between 1.5 and 3 times higher than the required values. The elastic behavior of both SCC mixes was also very similar in those tests, regardless of the amount of coarse RA, due to the robust design of the water and superplasticizer content of the SCC, which balanced the decreased flowability and the lower compressive strength of SCC that resulted from the additions of coarse RA. The SCC mix with 100% RA showed a lower load-bearing capacity after failure and narrow compliance margins with the deflection limits of the long-term-deflection test. Even though the SCC mix with 100% RA met all the standard technical specifications of the precast-concrete manufacturer, reference should always be made to the serviceability limit states that are applicable at the time of the structural design phase. © 2023 The Authors. Structural Concrete published by John Wiley & Sons Ltd on behalf of International Federation for Structural Concrete
Validity of Machine Learning in Assessing Large Texts Through Sustainability Indicators
No full textAs machine learning becomes more widely used in policy and environmental impact settings, concerns about accuracy and fairness arise. These concerns have piqued the interest of researchers, who have advanced new approaches and theoretical insights to enhance data gathering, treatment and models’ training. Nonetheless, few works have looked at the trade-offs between appropriateness and accuracy in indicator evaluation to comprehend how these constraints and approaches may better redound into policymaking and have a more significant impact across culture and sustainability matters for urban governance. This empirical study fulfils this void by researching indicators’ accuracy and utilizing algorithmic models to test the benefits of large text-based analysis. Here we describe applied work in which we find affinity and occurrence in indicators trade-offs that result be significant in practice to evaluate large texts. In the study, objectivity and fairness are kept substantially without sacrificing accuracy, explicitly focusing on improving the processing of indicators to be truthfully assessed. This observation is robust when cross-referring indicators and unique words. The empirical results advance a novel form of large text analysis through machine intelligence and refute a widely held belief that artificial intelligence text processing necessitates either accepting a significant reduction in accuracy or fairness. © 2023, The Author(s)
Validation and implementation of a platform for monitoring ergonomic risks in construction
No full textThe present research aims to validate and implement a mobile, unobtrusive and privacy-preserving platform for real-time ergonomic risk alert and training, enabling the design of workplace interventions tailored to the needs and fitness levels of a specific ageing workforce. For the implementation and validation of the system a BSN (Body Sensor Network) sensor suit has been developed, non-intrusive for the worker that continuously monitors wirelessly all the ergonomic parameters of the construction worker during his full working day and collects and analyses in real time the values captured by the sensors, giving both the worker and the medical or health service information about his condition and fitness during work making it possible to help and advise him for the improvement of his health both at work and in private life
Variation in the viscoelastic properties of polydimethylsiloxane (PDMS) with the temperature at ultrasonic frequencies
No full textPolydimethylsiloxane (PDMS) is an organic silicone with a viscoelastic behavior suitable for use in engineering. This material presents substantial changes in its properties depending on the temperature and the flow rate: at high temperatures or high flow rates, it behaves as a viscous liquid; whereas, at low temperatures or low flow rates, it behaves as an elastic solid. The lack of accurate information about the modifications in PDMS under thermal changes affects the design of transducers (both sensors and actuators) based on this material and also their calibration. In this study, 10:1 base-agent mixing ratio was analyzed in a 20 °C to 50 °C temperature range to assess the ultrasonic P-wave properties (velocity, attenuation, and variation of both with the frequency) and hence complex elastic modulii of this material under a temperature dependent environment. P-wave velocity and attenuation were extracted for every temperature step in a 3–7 MHz frequency range which is the typical range for medical applications. Acoustic dispersion of PDMS properties such as velocity and attenuation in a pulse-echo set up were analyzed to also compute attenuation coefficient, temperature and frequency dependent models and complex modulus. © 202
Reusing Ceramic Waste as a Precursor in Alkali-Activated Cements: A Review
No full textConcrete and ceramic products are among the most widely used materials in the construction sector. The production of ceramic materials has significantly grown in recent years. Concrete is one of the most widely used materials worldwide and most of its carbon dioxide (CO2) emissions are attributed to Portland cement (PC) production. This review analyzed previous research works into the use of ceramic waste (CW) as a precursor in alkali-activated (AA) cements. The physico-chemical properties of different CW materials were analyzed, and the properties and environmental impact of three main categories of AA CW cements were explored: those developed solely with CW; hybrid cements combining CW with traditional binders (PC, calcium hydroxide or calcium aluminate cement); combinations of CW with other precursors (i.e., blast furnace slag, fly ash, fluid catalytic cracking residue, etc.). The results evidenced that CW can be successfully employed as a precursor in AA cements, particularly in the context of prefabricated products where thermal curing is a prevalent procedure. When enhanced mechanical strength is requisite, it is feasible to attain improvements by employing hybrid systems or by combining CW with other precursors, such as blast furnace slag. This new alternative reuse option allows progress to be made toward sustainable development by reducing not only CO2 emissions and embodied energy compared to PC but also PC consumption and CW accumulation in landfills. © 2023 by the authors