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Test methods for chloride diffusivity of blended cement pastes: a review by RILEM TC 298-EBD
No full textThe use of supplementary cementitious materials (SCM) is an important part of the roadmap for reducing CO2 emissions and extending the service life of reinforced concrete structures. To accelerate the adoption of SCMs, the RILEM Technical Committee 298-EBD evaluates scaled-down cement paste test methods to assess the effect of SCM on resistance to chloride and sulfate ingress and reactivity, which are critical to concrete durability. This review focuses on methods for measuring chloride diffusivity and is divided into four sections: diffusivity models and parameters, diffusion test methods (including NMR and chloride measurements), migration test methods and implications for future research. Key insights highlight the complexities of multi-species ionic and molecular diffusion/migration, including various binding interactions, and compares the different measurement methodologies. The review also addresses the test scale and aggregate effects, noting the pros and cons of testing at the paste, mortar, and concrete scales. The review underscores the need for further investigation into testing protocols and the influence of SCM on chloride diffusion, emphasizing that comprehensive testing across different scales provides complementary information for assessing durability performance
Assessment of the Application of Scaling Concepts for Blast Effects Analysis
No full textBlast testing finds its implementation in several applications, e.g. for the purpose of investigation into accidental or intentional explosions, or for an assessment of the level of protection provided by a certain structural configuration. Analytical and/or semi-empirical methods are generally limited to preliminary assessments prior to blast testing. Applications of numerical simulations with hydrocodes coupled with finite element methods (FEM) can only reduce the amount of blast testing required, as these necessitate fulfillment of the fundamental prerequisites of model verification and that of model validation.
Field tests are implemented for contact detonations as well as near-field blast scenarios and shock tube tests for far-field blast scenarios. However, these can be extremely resource intensive. Reliable small-scale experiments are a promising alternative.
The concepts of dimensional analysis and similarity based on Buckingham’s Π-theorem (1914) have been applied in different fields. For applications to the phenomenon of shock wave propagation, Hopkinson-Cranz or cube-root scaling is a well-established concept. When it comes to scaling the structural response, research has predominantly focused on structures made of metallic materials. Scaled investigations with concrete or reinforced concrete (RC) structures remain limited. The lack of even the most basic guidelines (far from any ‘standardized scaling methods’ for blast tests) show that scaling as a method is not yet established in blast effects analysis.
In this preliminary study, we present a systematic approach and evaluation of scaling of blast effects analysis for RC slabs in order to develop guidelines for resource efficient testing methods. We study the blast scenario at two different scales. The focus of these investigations has been on evaluation of scaling of dynamics using pressure sensors, acceleration sensors and fiber optic sensing cables for distributed acoustic sensing (DAS). Further, the resulting plastic behavior upon blast is characterized by distributed strain sensing (DSS) along the same cables
Software and data repository: Can simple exchange heuristics guide us in predicting magnetic properties of solids?
No full textSoftware and data for the publication "Can simple exchange heuristics guide us in predicting magnetic properties of solids?" Release that corresponds to the first preprint version of the article. Full Changelog: https://github.com/DigiMatChem/paper-exchange-heuristics-in-magnetic-materials/commits/v1.0.
Towards solution-driven recycling of gypsum
No full textGypsum (CaSO₄·2H₂O) is a crucial mineral across sectors such as construction, agriculture, and biomedicine. Despite its potentially full recyclability, a shortage looms due to limited mining in Europe and decreasing production of flue gas desulfurization (FGD) gypsum, a byproduct of coal power plants. With current EU consumption at 24 MT/a (17 MT mined, 7 MT FGD), a deficit of 10-35 MT/a is projected by the 2030s as CaSO₄ becomes a critical raw material [1]. Meanwhile, substantial CaSO₄ waste is produced in various industries (e.g., phosphogypsum, red gypsum), but its recycling remains limited (10% in Germany, 5% in the EU) due to contamination and separation challenges.
This contribution introduces a sustainable, efficient wet-chemical method for converting gypsum to bassanite (CaSO₄·0.5H₂O), and thus recycling gypsum, under mild conditions (T 4 M) [2]. The optimal conversion conditions (T > 80°C, c[NaCl] > 4 M) enable rapid (<5 min) and reversible transformation. Upon cooling, gypsum re-forms, offering a temperature-dependent control over phase transition. Unlike conventional thermal dehydration (150-200 °C), this approach promotes the dissolution of gypsum, allowing contaminants to be separated via selective precipitation or adsorption. Additionally, the wet-chemical process facilitates the physical removal of impurities from gypsum matrices, making it advantageous for recycling gypsum waste from sources such as demolition or urban mining, where it is often mixed with other materials
Historical Plaster Formulations and Their Influence on Crystallographic Microstructure
No full textHistorical plaster formulations offer valuable insights into advanced engineering in pre-modern cultures. This study examines two such gypsum-based recipes: Gach-e Koshteh from 14th-century Iran and Gesso Sottile from 15th-century Italy, both of which have unique characteristics and were essential for artistic and architectural decoration. By replicating these recipes in a laboratory setting, we demonstrate how traditional masters manipulated gypsum microstructure without additives to optimize the surface and mechanical properties of plaster for specific functional and artistic purposes.
The Koshteh recipe involves intensive kneading during plaster hydration, which retards setting and produces a platelet-like crystal morphology with alignment of the {010} faces, resulting in a hydrophilic surface ideal for water-based wall paintings. Sottile, in contrast, relies on slow recrystallization in excess water, generating loosely packed, needle-like crystals with reduced wettability—suitable for oil-based painting and gilding.
Using wide-angle X-ray scattering (WAXS), atomic force microscopy (AFM), and scanning electron microscopy (SEM), we reveal that the Koshteh recipe yields a denser, better-packed plaster with enhanced wettability, while the Sottile recipe forms larger, more loosely arranged crystals and a more hydrophobic surface. These findings underscore the ingenuity of historical materials engineering and offer valuable insights for modern conservation and sustainable restoration practices
Total Focusing im Virtuellen Wellenkonzept: 3D-Defektrekonstruktion mit räumlich strukturierter Erwärmung
No full textDie klassische aktive thermografische Prüfung von Industriegütern hat sich bisher meist auf die Erstellung von zweidimensionalen Fehlerlandkarten beschränkt. Während dies für die Erkennung von oberflächennahen Defekten bereits das gewünschte Ergebnis ist, wird für tiefliegende Defekte immer mehr eine 3D-Rekonstruktion der Defektgeometrie angestrebt. Dieser allgemeine Trend ist auch bei vielen anderen ZfP-Methoden (Radiographie, Ultraschallprüfung) zu beobachten, wo die Entwicklung von 2D zu 3D-Rekonstruktionsmethoden teilweise bereits weit fortgeschritten ist (CT, UT Phased-Array).
Die Erzielung einer vollständigen 3D-Defektrekonstruktion in der aktiven thermografischen Prüfung leidet stark unter der diffusiven Natur der thermischen Prozesse. Eine mögliche Lösung zur Bewältigung der Hemmnisse thermischer Diffusion ist die Anwendung des virtuellen Wellenkonzepts, welches durch die Lösung eines inversen Problems die Extraktion der Diffusionseigenschaften aus den thermografischen Daten im Post-Processing ermöglicht. Was übrig bleibt, folgt der Physik propagierender Wellen und ermöglicht die Anwendung bekannter Algorithmen aus der Ultraschallprüfung. Zwar lassen sich die nachteiligen physikalischen Eigenschaften der Wärmeleitung nie gänzlich überwinden, was sich weiterhin in der Qualität der gewonnenen Daten widerspiegelt, jedoch bietet die thermografische Prüfung insgesamt inhärente Vorteile in Bezug auf die Anzahl kohärenter Sender- und Empfängerpostionen.
In dieser Arbeit stellen wir unsere Fortschritte bei der 3D-Rekonstruktion tiefliegender Defekte durch räumlich strukturierte Lasererwärmung in Verbindung mit der Anwendung der Total Focussing-Methode (TFM) im virtuellen Wellenbereich vor. Experimentell kombinieren wir entweder mehrere Einzelpunkterwärmungen für die Rekonstruktion von Abschnitten des zu untersuchenden Objekts oder 2D-strukturierte Anregungsmuster für eine vollständige 3D-Volumenrekonstruktion
Analytical practices, use and needs of standard and reference materials in the German-speaking metabolomics community: results of an online survey
No full textIntroduction
Since the early 2000s, metabolomics has grown rapidly, becoming integral to fields like life sciences, health, and environmental research. This expansion has led to the formation of national and international societies, such as Germany’s DGMet, to tackle emerging challenges. One of DGMet’s goals is to improve measurement quality by assessing community needs for harmonization and standardization. A recent survey within the German-speaking community aimed to identify current practices and gaps in the use of chemical standards and reference materials, to guide future standardization efforts and collaborative initiatives.
Methods
An online survey was conducted between June 2023 and April 2024. The survey consisted of 38 key questions and was open to research institutions from Germany, Austria, and Switzerland.
Results
The survey was accessed by 68 laboratories, with 23 institutes providing complete or partial responses (34% response rate), which is comparable to rates reported in similar surveys within the metabolomics and lipidomics communities. Respondents were mainly experienced researchers from Germany, focusing mainly on health-related (“red”) metabolomics, as indicated by 78% of the respondents, followed by microbial (“grey”, 48%) and plant (“green”, 39%) metabolomics (multiple answers possible). The use of targeted methods was reported more frequently (91%) than that of non-targeted methods (78%), whereas metabolite fractions studied were equally split between polar, midpolar and lipid fractions (83% each). Human (74%), mouse (61%) and Arabidopsis (30%) were the most frequently studied organisms. Most participants used synthetic chemical standards for instrument qualification (83%), calibration (78%), and metabolite identification (74%), while matrix reference materials were mainly applied for quality control (52%) and method validation (44%). There was a strong demand for more standards, especially for metabolite identification and quantification, with cost being a major barrier, particularly for isotopically labelled standards and certified reference materials.
Conclusions
Valuable insights into the use of standards and reference materials within the German-speaking metabolomics community were obtained. Moving forward, the community should address critical gaps in metabolomics standardization. To achieve this, it must share its knowledge, articulate its needs clearly, and actively engage in joint efforts with national metrology institutes and international standardization initiatives
A silica-based protective system modified with rock powder for the preservation of tuff stone
No full textTuffs are lightweight and porous pyroclastic rocks composed of a volcanic ash matrix containing pumice and rock fragments, quartz, sanidine and other individual crystals, zeolites, and clay minerals. Due to their low density and high porosity, tuff stones are easy to work with and transport. They have been used as construction material in many historical buildings in Germany. However, most tuff stones exhibit poor resistance to weathering due to their morphology and porosity. If the physico-chemical degradation of the stones is already well advanced, ensuring the safety of the buildings often requires extensive stone replacement. However, this contradicts the fundamental principle of conservation, which prioritises the preservation of the original material. In a recently completed research project, a silica-based protective system modified with rock powder was developed for the preservation of tuff stone. Suitable colloidal silica dispersions and modified rock powders customised produced from tuff waste were used. The protective system was optimised to reduce the capillary water absorption of tuff while maintaining its water vapour diffusion properties, to build a durable protective system-tuff bond, and to achieve a visual and tactile resemblance to tuff. The protective system was developed at laboratory scale. It was subsequently applied to a test area at a restoration site in Berlin-Zehlendorf, Germany, to assess its performance under outdoor conditions. By applying the new protective system, the historic building structure is better preserved, tuff stone resources are saved, and tuff waste is effectively recycled
Peering inside the black box by learning the relevance of many-body functions in neural network potentials
No full textMachine learned potentials based on artificial neural networks are becoming apopular tool to define an effective energy model for complex systems, either incorporating electronic structure effects at the atomistic resolution, or effectively renormalizing part of the atomistic degrees of freedom at a coarsegrained resolution. One main criticism regarding neural network potentials is that their inferred energy is less interpretable than in traditional approaches, which use simpler and more transparent functional forms. Here we address this problem by extending tools recently proposed in the nascent field of explainable artificial intelligence to coarse-grained potentials based on graph neural networks.With these tools, neural network potentials can be practically decomposed into n-body interactions, providing a human understandable interpretation without compromising predictive power. We demonstrate the approach on three different coarse-grained systems including two fluids (methane and water) and the protein NTL9. The obtained interpretations suggest that well-trained neural network potentials learn physical interactions, which are consistent with fundamental principles
Sodium-ion battery research @ BAM (I): investigating the thermal runaway behaviour of commercial sodium-ion battery cells
No full textCommercially available sodium-ion battery (SIB) cells, with energy densities comparable to lithium-ion battery (LIB) cells based on LiFePO4, were investigated regarding their safety behaviour under thermal abuse conditions. Tests were carried out in an inert atmosphere. The SIB-cells went into thermal runaway (TR), intriguingly, even at a rather low state of charge of 30%. The TR-event was coupled with a pronounced jelly roll ejection, challenging the interpretation of the TR-diagrams. These findings highlight the necessity of incorporating SIB-cells into the ongoing safety classification discussions for LIB-cells