1,721,041 research outputs found
Thermal energy storage characterization of cement-based systems containing microencapsulated-PCMs
No full textThis work reports a detailed experimental study that is aimed at investigating the Thermal Energy Storage (TES) performance of cementitious systems containing Microencapsulated Phase Change Materials (MPCMs). New spherical-shaped test specimens for TES measurements were produced following an innovative casting technique, developed at the Institut für Werkstoffe im Bauwesen – TU Darmstadt. Three water-to-cement ratios and three MPCMs volume fractions, leading to a total of nine different mixtures, were investigated. The thermal experiments were accompanied by mechanical tests to observe the effect MPCMs have on the resulting strengths in both compression and bending. The analysis and discussion of the TES results are employed for calibrating an enthalpy-based model. The experimental data have been applied to evaluate the corresponding temperature-based material parameters like specific heat, conductivity, or more in general, the energy storage capacity of a system under transient heat conduction conditions.Fil: Mankel, Christoph. Universitat Technische Darmstadt; AlemaniaFil: Caggiano, Antonio. Universitat Technische Darmstadt; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; ArgentinaFil: Ukrainczyk, Neven. Universitat Technische Darmstadt; AlemaniaFil: Koenders, Eddie. Universitat Technische Darmstadt; Alemani
A mesoscale approach for modeling capillary water absorption and transport phenomena in cementitious materials
Full text linkThis paper proposes a mesoscale approach for simulating moisture transport by capillary action in partly-saturated porous cementitious composites. The modeling approach explicitly accounts for moisture transport through a mesostructure composed of coarse aggregates, surrounding cementitious mortar and interfaces. These latter, namely interface transition zones (ITZs), allow to describe the interaction between aggregates and mortar, and may cause an alternative path for the internal moisture movements. Basic morphology effects of the ITZs are simulated using a ribbon approach. Random spatial distribution of cement particles are stacked in the meso-geometry. Aggregate particles are introduced as randomly perturbed polygons and the moisture transport is modeled as a diffusion problem and solved by means of the finite element method. The proposed constitutive models are based on a proper description of the permeability and pore size distribution which strongly affect the local moisture content. Numerical results at both macro- and mesoscale levels demonstrate the soundness and capability of the proposed approach. The integrated modeling results actually demonstrate the potential of the mesoscale approach and shows the role of the ITZs as an internal interconnected network.Fil: Caggiano, Antonio. Universitat Technische Darmstadt; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; ArgentinaFil: Said Schicchi, Diego. Leibniz-Institut Für Werkstofforientierte Technologien; Alemania. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Mankel, Christoph. Universitat Technische Darmstadt; AlemaniaFil: Ukrainczyk, Neven. Universitat Technische Darmstadt; AlemaniaFil: Koenders, Eduardus A. B.. Universitat Technische Darmstadt; Alemani
Numerical Phase-Field Model Validation for Dissolution of Minerals
Full text linkModelling of a mineral dissolution front propagation is of interest in a wide range of scientific and engineering fields. The dissolution of minerals often involves complex physico-chemical processes at the solid–liquid interface (at nano-scale), which at the micro-to-meso-scale can be simplified to the problem of continuously moving boundaries. In this work, we studied the diffusion-controlled congruent dissolution of minerals from a meso-scale phase transition perspective. The dynamic evolution of the solid–liquid interface, during the dissolution process, is numerically simulated by employing the Finite Element Method (FEM) and using the phase–field (PF) approach, the latter implemented in the open-source Multiphysics Object Oriented Simulation Environment (MOOSE). The parameterization of the PF numerical approach is discussed in detail and validated against the experimental results for a congruent dissolution case of NaCl (taken from literature) as well as on analytical models for simple geometries. In addition, the effect of the shape of a dissolving mineral particle was analysed, thus demonstrating that the PF approach is suitable for simulating the mesoscopic morphological evolution of arbitrary geometries. Finally, the comparison of the PF method with experimental results demonstrated the importance of the dissolution rate mechanisms, which can be controlled by the interface reaction rate or by the diffusive transport mechanism
Environmental benchmarks for the European cement industry
No full textThe urgent need to address climate change has pushed Europe to the forefront of environmental legislation initiatives, such as the Environment Action Program (EAP) within the European Green Deal and the disclosure of Environmental Product Declarations (EPDs) in the construction sector. The cement industry plays a vital role in this transition because it is one of the biggest contributors to greenhouse gas emissions worldwide. EPDs have managed to articulate the environmental information flow across different stakeholders, allowing them to incorporate sustainability design practices at the manufacturing, construction, and design levels. However, current EPDs are deterministically disclosed and lack benchmarks, hindering effective comparison and impeding sustainable material development. To address this challenge, the present research introduces a novel Life Cycle Assessment (LCA)-based probabilistic analysis to develop clinker and cement benchmarks. The proposed method incorporates data from industry reports, environmental databases, and EPDs, to generate the stochastic benchmarks. Moreover, a wide range of environmental performance indicators at a national level in Europe are covered, offering a holistic perspective beyond climate change. The results highlight the benefits of using country-specific environmental benchmarks, reducing the standard deviation of results by 2 to 7 times compared to background datasets. The reduction of clinker content proved to reduce 7 to 9 kg CO2eq/t for every 1% reduction in all countries. However, it also increased other indicators depending on the mineral component used as a replacement, underscoring the need for holistic analysis. The research also exposes discrepancies between EPDs and industry-related data, accentuating the need for stochastic information disclosure to enhance reliability and facilitate decision-making by stakeholders. Another significant contribution of this research is the development of an extensive open-access database, providing a reference for future developments regarding sustainable cement and concrete.Fil: Sambataro, Luciano. Universitat Technische Darmstadt; AlemaniaFil: Bre, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; ArgentinaFil: Ukrainczyk, Neven. Universitat Technische Darmstadt; AlemaniaFil: Koenders, Eduardus A. B.. Universitat Technische Darmstadt; Alemani
Dataset: Environmental benchmarks for European Cement Industry
No full text<p>This dataset contains the information relative to the article "Environemntal benchmarks for European cement industry".</p>
<p><a title="Persistent link using digital object identifier" href="https://doi.org/10.1016/j.spc.2024.01.020" target="_blank" rel="noopener">Reference paper</a></p>
<p><a href="https://www.researchgate.net/publication/377796848_Environmental_benchmarks_for_the_European_cement_industry" target="_blank" rel="noopener">ResearchGate link</a></p>
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Acid Neutralization Capacity of Metakaolin‐based Geopolymers
No full textA titration method is used to analyse the acid neutralization/consumption capacity (ANC) of cement binders, which involves plotting the steady‐state pH against the amount of acid added to a diluted suspension of hardened cement samples. Despite ANC being employed for several decades, there is no reported application of ANC for metakaolin‐based geopolymers. This study compares the resistance of metakaolin geopolymers to acetic acid and hydrochloric acid with that of Calcium Aluminate Cement (CAC) and Portland Cement (PC). The proposed ANC test setup involves small acid dosage steps using an auto‐titrator, resulting in a high‐resolution titration curve. The effect of binder chemical composition on acid resistance is evaluated through cumulative and differential ANC analysis, providing a new rapid approach to evaluate the durability of geopolymers in low pH environments
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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