bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fibre reinforced ultra‐high performance concrete – Rheology, fibre bond strength and flexural strength
Authors: Schleiting Maximilian , Wetzel Alexander , Link Janna , Middendorf Bernhard 
Published: December 2023

AbstractUltra‐high performance concrete (UHPC) is characterised by a high compressive strength, high durability, and a dense microstructure. The latter causes UHPC to fail in a brittle and sometimes explosive manner. For this reason, UHPC is reinforced with microfibre reinforcement. On the one hand, these lead to increased tensile and bending loads being able to be absorbed, but above all to ductile post‐fracture behaviour. The fibres used are mostly steel fibres.An essential aspect of the fibre reinforcement is the bond strength between UHPC and metallic fibre. The bond is divided into chemical‐adhesive bond, form bond and friction bond. Depending on the shape, material and surface condition of the fibre, the individual types of bond have different effects on the concrete. To quantify these effects, fibre pull‐out tests are often carried out. These provide information about the bond strength between the fibre and the concrete. However, results of various studies show that the bond strength does not automatically correlate with the actual influence on the resulting tensile and flexural strengths of concrete components.
LIBS‐ConSort: Development of a sensor‐based sorting method for construction and demolition waste
Authors: Klewe Tim , Völker Tobias , Landmann Mirko , Kruschwitz Sabine 
Published: December 2023

AbstractA joint project of partners from industry and research institutions approaches the challenge of construction and demolition waste (CDW) sorting by investigating and testing the combination of laser‐induced breakdown spectroscopy (LIBS) with near‐infrared (NIR) spectroscopy and visual imaging. Joint processing of information (data fusion) is expected to significantly improve the sorting quality of various materials like concrete, main masonry building materials, organic components, etc., and may enable the detection and separation of impurities such as SO3‐cotaining building materials (gypsum, aerated concrete, etc.)Focusing on Berlin as an example, the entire value chain will be analyzed to minimize economic / technological barriers and obstacles at the cluster level and to sustainably increase recovery and recycling rates.The objective of this paper is to present current progress and results of the test stand development combining LIBS with NIR spectroscopy and visual imaging. In the future, this laboratory prototype will serve as a fully automated measurement setup to allow real‐time classification of CDW on a conveyor belt.
Electrokinetic and Microstructural Peculiarities of the Portland Cement Hydration with Microadditives
Authors: Shumeiko Vita , Shabanova Halyna , Logvinkov Sergii , Korohodska Alla , Pitak Yaroslav 
Published: December 2023

AbstractThe results of given studies included a comparison of changes in temperature, redox potential, OH‐ions concentration and pH values in the Portland cement‐water‐additive system depending on the hydration time and features of hydration processes in the microstructure of the cement stone. The studied additives were selected taking into account the prospects for their use in the complex modifiers compositions for cement‐containing building materials. The results of electrokinetic measurements are presented and regularities and features of the influence of each studied additives on the processes of hydration structure and phase formation in Portland cement paste in the early stages of hardening are determined. The microstructure and fracture surfaces of cement stone samples formed during cement paste hardening with the optimal content of additives and features of hydration processes of cement stone were studied. The features of the mutual arrangement of individual phases in crystalline hydrate aggregates of cement stone, as well as the nature of the porosity of its microstructure, were investigated.
Application of slags for the production of resource‐efficient paving stones
Authors: Shams Taban , Dittrich Sebastian 
Published: December 2023

AbstractIn a recent research project under the lead of the Fraunhofer Institute for Building Physics IBP, gravel and sand within a mixture of paving stones were replaced with LD converter slag and blast furnace slag for 50 wt. % and 100 wt. % to produce resource‐efficient concrete components. For this purpose, first, the dry processing of the slags including metal separation and crushing was carried out. In the next step, the particle size distributions of slags using sieve analysis were determined. Finally, the mix designs were set based on the optimum combination of different size fractions of slags. This combination was determined in a way to lead to an almost identical grading curve as that of the original formulation. Splitting tensile strengths of the obtained samples were measured after 14 days of curing under a humidity of 95%. Several paving stone specimens containing slags showed higher splitting tensile strengths than that of the reference sample. Similar results were observed for industrially produced paving stones which demonstrates the successful transfer of the laboratory mixes to the industrial plant.
Damage identification based on XFEM: inverse analysis and experimental validation
Authors: Nguyen‐Tuan Long , Alkam Feras , Lahmer Tom 
Published: December 2023

AbstractModel‐based inverse analyses emerge as an alternative means to reconstruct buried objects in structures. In this paper, we introduced an inverse analysis using XFEM and adjoint method to identify the cracks, which is based on laboratory experimental data. XFEM model allows precisely reproducing the crack forms in the structures, whilst adjoint state with level set for inverse problem allows calculating the gradient of complex geometrical structures and avoiding the local minima traps. Besides proposing a modification XFEM to model reinforced concrete behaviors, we also establish the adjoint formulas for inverse analysis based on the measured displacement and strain in the experiments. Finally, the preliminary results are verified with experimental data.
Produkt‐ und Technologieentwicklung für Bauteile aus eindimensional gradiertem Beton
Authors: Weisheit Sandro , Zier Hans‐Werner 
Published: December 2023

KurzfassungDer Schall‐ und Wärmeschutz von Wohn‐ und Industriegebäuden ist für den Menschen ein wesentlicher Faktor für eine hohe Lebens‐ und Arbeitsqualität. Die aktuellen Systeme in diesen Bereichen bestehen vorwiegend aus mehreren Lagen, welche aufwendig in mehreren Arbeitsschritten in der Produktion oder nachträglich an den Gebäuden installiert werden müssen.Aus diesem Grund wurde im Rahmen eines vom Bundesministerium für Bildung und Forschung [BMBF] geförderten Verbundprojektes ein Verfahren entwickelt, mit welchem es möglich ist Betonelemente herzustellen, welche über dem Bauteilquerschnitt sowohl lastabtragende als auch wärme‐ bzw. schalldämmende Eigenschaften besitzen. Im gegenständigen Bericht werden ausgewählte Ergebnisse zur Entwicklung der Betonrezeptur und der Herstellungstechnologie im Labor‐ und Technikumsmaßstab vorgestellt. Dabei wird vor allem auf die für diesen speziellen Fall benötigte Verdichtungstechnologie im Detail eingegangen.
Fracture toughness on compact tension specimen as a quality parameter for cement stone
Authors: Gierth Anne Zora , Syring Simon , Mielke Tommy , Lupascu Doru C. 
Published: December 2023

AbstractA series of tests of compression strength and fracture toughness of hardened cement paste (cement stone) was carried out. The compression strength was tested on cubes with side lengths of 10, 20, 30 and 40 mm. Fracture toughness was measured on compact tension (CT) specimens with dimensions commonly used in metallurgy; two different thicknesses were used (h x l x b: 50 x 48 x 3 mm3 and 50 x 48 x 8 mm3). A particularly stiff piezo‐controlled test frame was used as testing device. The different thicknesses of the specimens allow the investigation of a possible size effect in toughness. In a Weibull statistical evaluation, the scatter of the strength results is compared with the scatter of the measured toughnesses. It could be shown that the fracture toughness results are as reliable as the strength results and the method is a useful addition to the research on fracture of binders.
Influence of silanes on the hydration of cement by separating the cement into its individual phases
Authors: Kaltenbach Jonas , Schwotzer Matthias , Süßmuth Julia , Arévalo Galván Beatriz , Gerdes Andreas 
Published: December 2023

AbstractCementitious materials can be treated with organosilicon compounds (silanes) to achieve a water‐repellent effect. However, the influence of silanes on cement hydration is still not fully understood. For this reason, we studied the hydration of the main Portland cement phase (C3S ‐ tricalcium silicate) and the interaction with iBTES (isobutyltriethoxysilane), iOTES (isooctyltriethxysilane) and nOTES (n‐octyltriethoxysilane) by isothermal calorimetry and in‐situ X‐ray diffraction (XRD). The results show that C3S hydration is initially retarded and subsequently accelerated by iBTES and iOTES. In addition to the hydration process, the crystal growth of the portlandites (calcium hydroxide) is also affected by the silanes. The XRD results indicate that the portlandites grow significantly more plate‐like. In this context, the influence of the silanes on the portlandite crystallization was therefore also recorded in a special experimental setup. From the scanning electron microscope images it can be shown that all portlandite crystals grown in the presence of silanes have a platelike morphology. This is due to the fact that the hexagonal surfaces of the portlandite are covered by silanes and thus the growth direction of the crystals is affected. The modified portlandite crystals indicate that silanes also influence the microstructure of the cement paste and therefore its chemical and mechanical properties.
Fire resistance of gypsum drywall partitions with polyurethane foam filling
Authors: Kania Tomasz , Wieteska Marcin 
Published: December 2023

AbstractGypsum drywall systems have gained their popularity, among other reasons, due to the excellent fire‐resistant properties. The use of different variants of the structures filled with insulating material (most often mineral wool) makes it possible to shape the parameters of fire resistance according to the requirements. The use of polyurethane foam for filling spaces inside drywall systems has become increasingly popular. This is especially applicable to the performance of thermal insulation of wooden roof slopes. The advantages of polyurethane foams over mineral wool include good adhesion to the substrate, lower specific weight, lower thermal conductivity and shorter time to make a tight filling layer. Its undoubted disadvantage is lower fire resistance. The paper presents a research on the fire resistance of gypsum drywall systems with self‐extinguishing polyurethane foam filling. The fire resistance time of the structures was measured in accordance with EN1363‐1 using a standard temperature‐time curve. The tests simulated a fire on the outside of a service shaft with a layer of polyurethane foam on its interior side, and a fire in an attic room with self‐extinguishing polyurethane foam thermal insulation between wooden rafters, and an interior enclosure made of two layers of gypsum board on a steel frame. The tests made it possible to determine the times of meeting the fire resistance criteria of partitions with polyurethane filling.
Influences of Accelerators on Compressive Strength Development of Composite Cements
Authors: Herrmann Jens , Rickert Jörg 
Published: December 2023

AbstractLow‐clinker composite cements often have the disadvantage of lower early compressive strength. Hardening accelerators can increase the early compressive strength of Portland cement at the expense of reduced late strength. The extent to which different hardening accelerators influence the compressive strength development of low‐clinker composite cements containing granulated blast furnace slag and limestone was systematically investigated using compressive strength test, ultrasound transmission experiments and heat flow calorimetry.The results show that the accelerator must always be adapted to the particular composite cement in order to increase the early compressive strength. Synergetic effects of cement constituents besides clinker can partly compensate for the reduced late strength of accelerated systems.
Quellverhalten von Portland‐ und Hochofenzementstein bei unterschiedlichen Temperaturen
Authors: Wagemann Falk , Schmidt‐Döhl Frank , Rahimi Amir 
Published: December 2023

KurzfassungZementgebundene Baustoffe quellen bei permanenter Wasserlagerung, d. h., sie erfahren eine zeitabhängige Volumenzunahme. Wesentlich für das Quellverhalten zementgebundener Baustoffe ist der volumetrische Anteil an Zementstein. Für Bereiche, in denen Betonbauteile permanent einer Wasserumgebung ausgesetzt sind, wie zum Beispiel bei Gründungen im Grundwasser, kann das Quellverhalten ggf. die Tragwirkung verbessern, da sich Bauteile im Boden infolge des Quelldruckes verspannen. Dieser Beitrag untersucht das Quellverhalten von Zementstein aus CEM I und CEM III/B mit w/z‐Werten von 0,3 und 0,5 bei 10 °C und 20 °C betrachtet. Zusätzlich wurden im Rahmen der Untersuchungen Zementsuspensionen verpresst, um Filtrationseffekte abzubilden. Neben dem Quellmaß zu verschiedenen Zeitpunkten (1, 3, 5, 7, 14, 28 und 56 Tage) wurde der Hydratationsgrad und Gehalt an Calciumhydroxid mit Hilfe der Thermogravimetrie und die Porosität mittels Quecksilberdruckporosimetrie als Materialkennwerte bestimmt. Die Untersuchungsmethoden erlauben einen Rückschluss von Porosität und Hydratphasenausbildung auf das Quellverhalten der untersuchten Zementsteine zu ziehen. Bei beiden Zementarten führen niedrigere Lagerungstemperaturen zu höheren Quellmaßen.
Automatisierte Analyse natürlicher Gesteinskörnungen mit Betonschädigungspotenzial anhand hyperspektraler Informationen
Authors: Linß Elske , Anding Katharina , Hunhold Patrick , Polte Galina , Garten Daniel , Weisheit Sandro , Walz Jurij 
Published: December 2023

KurzfassungEs wird ein Verfahren zur automatischen optischen Prüfung natürlicher Gesteinskörnungen vorgestellt, bei dem hyperspektrale Bildgebung und Algorithmen in Form von Klassifikatoren aus dem Machine Learning und dem Deep Learning eingesetzt werden. Ziel der Untersuchungen ist es, eine Auswahl der in der Betonherstellung benötigten Gesteinskörnungen anhand ihrer spektralen Eigenschaften mit Hilfe von Hyperspektralbildern zuverlässig und automatisch zu klassifizieren. Dazu wurden Spektren und Hyperspektralbilder verschiedener Gesteine mittels Laborspektrometer und Hyperspektralkamera in verschiedenen ausgewählten spektralen Wellenlängenbereichen aufgenommen und mit Klassifikatoren aus dem Bereich der künstlichen Intelligenz (KI) ausgewertet. Zur Klassifizierung der dimensionsreduzierten Hyperspektralbilder wurden vortrainierte Deep‐Learning‐Modelle verwendet. Des Weiteren wurde eine kaskadierte Erkennungsroutine entworfen, die eine zweite Klassifikationsstufe für die mittels Deep‐Learning schlecht erkannten Objekte zur Verbesserung der Erkennungsperformance ermöglicht. Im Ergebnis konnte nachgewiesen werden, dass eine Klassifikation in vorgegebenen Gesteinskategorien anhand der Spektral‐ und Bildinformationen möglich ist und bereits mit rund 91 % hohe Erkennungsraten für die Klassifizierung in die drei Klassen “unkritisch”, “kritisch 1” und “kritisch 2” erzielt werden können.
Frosteinfluss auf den Chloridtransport in Beton ‐ Kennwerte
Authors: Langer Christoph , Kapteina Gesa 
Published: December 2023

KurzfassungIm Winter wird überwiegend das Salz NaCl zur Aufrechterhaltung der Verkehrssicherheit auf Straßen und andere Infrastrukturbauwerke gestreut. Die in der Eisschmelze vorhandenen Chloridionen dringen in den Stahlbeton überwiegend durch die Transportprozesse Diffusion und Konvektion ein. Durch die Exposition Frost (XF) kann es zur Koppelung der Transportprozesse kommen und den Chlorideintrag in Hinblick auf die eingetragene Menge und Tiefe erhöhen. Betone, die bereits im CDF‐Test mit NaCl beaufschlagt wurden, werden zu verschiedenen Zeitpunkten im Migrationstest auf die Widerstandsfähigkeit gegenüber erneutem Ioneneindringen (Bromidionen, RBM‐Versuch) getestet. Dadurch kann der Einfluss der Frost‐Tausalz‐Wechsel (FTSW) des CDF‐Versuches auf das Bromideindringen im anschließenden Migrationsversuch (RBM) untersucht werden. Die Quantifizierung der Chlorid‐ und Bromidgehalte erfolgt mit der Laser‐Induzierten Breakdown Spektroskopie (LIBS). Ergänzende Untersuchungen wie die Fluoreszenzmikroskopie liefern weitere Erkenntnisse, die auf das Wirken von Frost in der Konvektionszone zurückzuführen sind. Durch die Kombination der Laborversuche CDF‐ und Migrationsversuch (RBM) können unter Einbezug der LIBS‐Analyse Kennwerte ermittelt werden, die den Frosteinfluss auf den Chloridtransport in Beton quantifizierbar machen.
Acid Neutralization Capacity of Metakaolin‐based Geopolymers
Authors: Ukrainczyk Neven , Koenders Eddie 
Published: December 2023

AbstractA 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.
Schnellprüfverfahren für den Carbonatisierungswiderstand von dampfgehärteten Baustoffen: Erste Vorarbeiten
Authors: Felten Christian , Vollpracht Anya , Winkels Bernd , Nebel Holger , Matschei Thomas 
Published: December 2023

AbstractDie Einflussfaktoren auf den Carbonatisierungswiderstand des 11Å‐Tobermorits in dampfgehärteten Baustoffen sind bislang nicht systematisch untersucht worden. In der Vergangenheit haben Forschungen gezeigt, dass ein geringer Carbonatisierungswiderstand mit einem auffällig hohen Trockenschwindwert einhergeht. Daher wurde durch das DIBt ein Grenzwert für das Schwinden von Porenbetonen von 0,4 mm/m eingeführt. Es ist jedoch nicht systematisch untersucht, ob ein geringer Carbonatisierungswiderstand per se mit niedrigen Schwindwerten beim Trocknungsschwinden einhergehen. In einem von der DFG geförderten Forschungsprojekt werden unterschiedliche potentielle Einflussfaktoren auf die Carbonatisierung von Porenbeton untersucht, wofür Modellporenbetone hergestellt wurden, die sich im Sulfatgehalt unterscheiden. Für eine möglichst hohe Vergleichbarkeit werden die äußeren Einflussfaktoren wie die Luft‐ und Materialfeuchtigkeit, Temperatur und Kohlendioxidkonzentration konstant gehalten.Im Rahmen dieser Untersuchungen wurden kleinformatige Prismen extrahiert, an denen die Festigkeitsentwicklung mit zunehmender Carbonatisierung unter ansonsten gleichen Bedingungen untersucht wurde. Die spezifische Oberfläche dieser Prüfkörper wurde mit dem BET‐Verfahren vor und nach der Carbonatisierung charakterisiert, um Rückschlüsse auf die Veränderung der Mikrostruktur zu ziehen. Zudem wurde an aus den Prismen extrahierten Pulverproben die Phasen nach der Carbonatisierung mineralogisch analysiert.
CO2 and H2 Activation on Zinc‐Doped Copper Clusters
Authors: Zamora Bárbara , Nyulászi László , Höltzl Tibor 
Published: December 2023

AbstractHere we systematically investigate the CO2 and H2 activation and dissociation on small CunZn0/+ (n=3–6) clusters using Density Functional Theory. We show that Cu6Zn is a superatom, displaying an increased HOMO‐LUMO gap and is inert towards CO2 or H2 activation or dissociation. While other neutral clusters weakly activate CO2, the cationic clusters preferentially bind the CO2 in monodentate nonactivated way. Notably, Cu4Zn allows for the dissociation of activated CO2, whereas larger clusters destabilize all activated CO2 binding modes. Conversely, H2 dissociation is favored on all clusters examined, except for Cu6Zn. Cu3Zn+ and Cu4Zn, favor the formation of formate through the H2 dissociation pathway rather than CO2 dissociation. These findings suggest the potential of these clusters as synthetic targets and underscore their significance in the realm of CO2 hydrogenation.
Suppression of Photocyclization of an Inverse Type Diarylethene Derivative by Inclusion into β‐Cyclodextrin
Authors: Suganuma Misato , Kitagawa Daichi , Hamatani Shota , Sotome Hikaru , Ito Syoji , Miyasaka Hiroshi , Kobatake Seiya 
Published: December 2023

AbstractDiarylethene derivatives are one of the promising compounds for practical applications including optical memory, display, sensor, and photoactuator. In this work, we newly designed and synthesized an inverse type diarylethene derivative bearing sodium carbonate groups at the p‐position of the lateral phenyl ring and investigated the photochromic behavior in the presence and absence of cyclodextrins (CDs) (αCD, βCD, and γCD). Interestingly, only in the presence of βCD, the photocyclization reactivity decreased. From the results of job‐plots, NOESY spectra, and quantum chemical calculations, it was suggested that the distinctive interaction between the diarylethene and βCD leads to the restriction of molecular geometrical change, resulting in the suppression of the photocyclization reactivity. These results provide information on the rational designing of inverse type diarylethenes with advanced properties.
Insularization drives physiological condition of Amazonian dung beetles
Authors: de Cerqueira Leonardo Vilas‐Bôas M. P. , González Tokman Daniel , Correa César M. A. , Storck‐Tonon Danielle , Cupello Mario , Peres Carlos A. , Salomão Renato Portela 
Published: December 2023

AbstractThe fragmentation and degradation of otherwise continuous natural landscapes pose serious threats to the health of animal populations, consequently impairing their fitness and survival. While most fragmentation ecology studies focus on habitat remnants embedded withinn terrestrial matrices, the effects of true insularization remains poorly understood. Land‐bridge islands created by major dams leads to habitat loss and fragmentation, negatively affecting terrestrial biodiversity. To assess the effects of insularization, we conducted a study on the key aspects of dung beetle physiological condition and body size throughout the Balbina Hydroelectric Reservoir located in the Central Amazon. We assessed these traits at the population and assemblage levels, collecting dung beetles from both forest islands and continuous forest areas while analyzing various landscape variables. We show that landscapes with higher forest cover positively affected dung beetle body size. Interestingly, dung beetle responses to insularization were species‐dependent; larger islands tended to host larger individuals of Deltochilum aspericole, while in Canthon triangularis, smaller islands showed larger body sizes. However, individuals from the mainland were larger than those from the islands. Moreover, the proportion of closed‐canopy forest in the landscapes also impacted physiological attributes. It negatively affected the body size of Deltochilum aspericole and the lipid mass of Dichotomius boreus, but positively affected the lipid mass of Canthon triangularis. These findings contribute to a better understanding of how habitat fragmentation in aquatic matrices affects the size structure and physiology of insect assemblages. This is essential in formulating effective conservation strategies for preserving biodiversity loss in tropical forest regions and mitigating the consequences of hydropower infrastructure.