bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the Efficiency of Task Completion and Time Management for Surgical Junior Doctors during their Surgical Foundations Rotations/Placements
Authors: Maduka Godsfavour C. , Farooq Muhammad U. , Maduka Divinegrace C. , Lazdina Laura G. , Karim Seiver , Maduka Hugh C. C.
Published: December 2023

Task completion and time management for surgical junior doctors during their surgical foundation trainings and placements were investigated amidst techniques for improvement and efficient service delivery in the big health facility setting in East and North Herts NHS Trusts by us, a group of medical scientists. The factors reducing and impeding efficient service delivery were presented which included lack of organisational equipment and availability leading to delayed job completion and patient output.
Introduction: Patient safety and the quality of patient-centred care provided are of utmost importance. Quality improvement projects in surgery are vital as we can highlight and rectify issues that may arise through them. We determined that a critical problem lies in the inefficiency of job performance among surgical junior doctors due to a lack of equipment organisation and availability. This inefficiency results in a delay in job completion and potentially poor patient outcomes. Surgical junior doctors are becoming increasingly frustrated at the lack of availability and organisation of equipment required to perform urgent and non-urgent patient care during their shifts. Through our detailed research, we aimed to improve the efficiency of surgical junior doctors’ task completion by reducing the time required for completion of tasks through the production of surgical equipment packs to improve equipment availability and accessibility to facilitate efficient urgent and non- urgent patient care.
Methodology: We collected data via analysis and evaluation of responses from initial and post- implementation surveys sent to surgical junior doctors working across a range of specialities and different NHS trusts around the country.
Results: The initial survey demonstrated that most of the time taken for task completion was spent on sourcing/gathering equipment. The post-introduction of surgical equipment packs survey indicated that over 80% of the responders found them helpful in carrying out practical jobs. More than 60% of responders reported that 0-10 minutes are needed to complete practical employment with the help of surgical equipment packs. Comparatively, only 30% could complete practical tasks within 20 minutes before implementation.
Conclusion: Results showed that surgical have improved equipment accessibility and, overall, improved task completion efficiency. 80% of responders would continue using surgical equipment packs to improve efficiency in ward-based practical jobs.
Categories: Quality Improvement, Surgery, Surgical Equipment
GLP-1 Receptor Agonists and Colorectal Cancer Risk in Drug-Naive Patients With Type 2 Diabetes, With and Without Overweight/Obesity
Authors: Wang Lindsey , Wang William , Kaelber David C. , Xu Rong , Berger Nathan A.
Published: December 2023

This cohort study compares glucagon-like peptide 1 receptor agonists (GLP-1RAs) with 7 non–GLP-1RA antidiabetics among drug-naive patients with type 2 diabetes.
CRK and NCK adaptors may functionally overlap in zebrafish neurodevelopment, as indicated by common binding partners and overlapping expression patterns
Authors: Stergas Helaina R. , Dillon‐Martin Maeve , Dumas Caroline M. , Hansen Nicole A. , Carasi‐Schwartz Francesca J. , D'Amico Alex R. , Finnegan Kylie M. , Juch Uatchet , Kane Keeley R. , Kaplan Isabel E. , Masengarb Madeline L. , Melero Marina E. , Meyer Lauren E. , Sacher Conrad R. , Scriven Evan A. , Ebert Alicia M. , Ballif Bryan A.
Published: December 2023

CRK adaptor proteins are important for signal transduction mechanisms driving cell proliferation and positioning during vertebrate central nervous system development. Zebrafish lacking both CRK family members exhibit small, disorganized retinas with 50% penetrance. The goal of this study was to determine whether another adaptor protein might functionally compensate for the loss of CRK adaptors. Expression patterns in developing zebrafish, and bioinformatic analyses of the motifs recognized by their SH2 and SH3 domains, suggest NCK adaptors are well‐positioned to compensate for loss of CRK adaptors. In support of this hypothesis, proteomic analyses found CRK and NCK adaptors share overlapping interacting partners including known regulators of cell adhesion and migration, suggesting their functional intersection in neurodevelopment.
Analysis of Microstructure, Texture Evolution, and the Mechanism of Grain Refinement of Commercially Pure Titanium During Cold Rolling: Experiment and Simulation
Authors: Sun Yuxing , Yang Xirong , Liu Xiaoyan , Qiang Meng , Yue Xu , Chen Wei
Published: December 2023

A comprehensive understanding of the microstructures and texture evolutions during the rolling process is of great significance for the preparations of high‐quality commercially pure titanium (CP‐Ti) sheets. Therefore, in the present work, the effects of rolling reductions on the microstructures and textures of CP‐Ti are investigated by optical microscope, electron backscatter diffraction, and X‐ray diffraction. A crystal plasticity finite element model (CPFEM) is developed to accurately predict the rolling deformation behaviors of CP‐Ti sheets. The results show that the slip and twinning including , compression twins and extension twins are prone to plastic deformations during the whole rolling process. The c‐axes of grains gradually tilt toward the transverse direction and the grains gradually deviate from the original //rolling direction (RD) to //RD. As a result, the mixed textures of and are developed in the specimen. The grain refinements are closely linked with the developments of and twins. In addition, the twin fractions and texture evolutions are well predicted by the CPFEM model. These results documented in this work should not only help to elucidate the microstructures and texture evolutions of CP‐Ti, but also shed important light on improving its properties.
Impact of Thermal Annealing on the Interaction Between Monolayer MoS2 and Au
Authors: Lough Stephanie , Thompson Jesse E. , Smalley Darian , Rao Rahul , Ishigami Masahiro
Published: December 2023

Herein, the impact of thermal annealing on the interaction between monolayer MoS2 and Au using Raman spectroscopy is investigated. It is found that MoS2 has two main modes of interactions with the underlying Au being either weakly coupled or strongly coupled. The regions strongly coupled to Au are hybridized to Au, minimally strained, and electron doped. The weakly coupled regions are found to be slightly hole doped with tensile strain of 1.0%. The overall areal coverage of the strongly coupled regions is not increased by thermal annealing, and the variability in the degree of hybridization increases at annealing temperatures above 100 °C. The data also show that monolayer MoS2 starts to decouple from Au around 100 °C, becoming fully decoupled above 200–250 °C, suggesting that monolayer MoS2 produced by Au‐assisted mechanical exfoliation may be more easily transferred off Au at elevated temperatures.
Three‐Component 1,4‐Addition through Ugi‐Type Reaction, an Oxidative Dearomatization Strategy
Authors: Chen Zhihao , Liu Yuqing , Gao Xing , Sun Yuanyuan , Lei Lingyu , Zhao Xia , Lu Kui
Published: December 2023

A three‐component 1,4‐addition variant of the Ugi reaction involving carboxylic acids, isocyanides, and cyclic α,β‐unsaturated imines is presented in this study. The cyclic α,β‐unsaturated imines were conveniently prepared through the oxidative dearomatization of N‐substituted anilines. The reaction proceeded successfully to produce a sole diastereomer, and the relative configuration was determined through 2D NMR and X‐ray diffraction analysis.
Discovery and Development of Cyclic Peptide Proteasome Stimulators
Authors: Nelson Samantha , Harris Timothy J. , Muli Christine S. , Maresh Marianne E. , Baker Braden , Smith Chloe , Neumann Chris , Trader Darci J. , Parkinson Elizabeth I.
Published: December 2023

The proteasome degrades proteins, which is essential for cellular homeostasis. Ubiquitin independent proteolysis degrades highly disordered and misfolded proteins. A decline of proteasomal activity has been associated with multiple neurodegenerative diseases due to the accumulation of misfolded proteins. In this work, cyclic peptide proteasome stimulators (CyPPSs) that enhance the clearance of misfolded proteins were discovered. In the initial screen of predicted natural products (pNPs), several cyclic peptides were found to stimulate the 20S core particle (20S CP). Development of a robust structural activity relationship led to the identification of potent, cell permeable CyPPSs. In vitro assays revealed that CyPPSs stimulate degradation of highly disordered and misfolded proteins without affecting ordered proteins. Furthermore, using a novel flow‐based assay for proteasome activity, several CyPPSs were found to stimulate the 20S CP in cellulo. Overall, this work describes the development of CyPPSs as chemical tools capable of stimulating the proteasome and provides strong support for proteasome stimulation as a therapeutic strategy for neurodegenerative diseases.
Effect of Sulfotyrosine and Negatively Charged Amino Acid of Leech‐Derived Peptides on Binding and Inhibitory Activity Against Thrombin
Authors: Chen Tzu‐Yin , Shyur Eileen , Ma Tzu‐Hsuan , Wijeyewickrema Lakshmi , Lin Sheng‐Wei , Kao Mu‐Rong , Liang Pi‐Hui , Shie Jiun‐Jie , Chuang Er‐Yuan , Liou Jing‐Ping , Hsieh Yves S. Y.
Published: December 2023

Hirudins, natural sulfo(glyco)proteins, are clinical anticoagulants that directly inhibit thrombin, a key coagulation factor. Their potent thrombin inhibition primarily results from antagonistic interactions with both the catalytic and non‐catalytic sites of thrombin. Hirudins often feature sulfate moieties on Tyr residues in their anionic C‐terminus region, enabling strong interactions with thrombin exosite‐I and effectively blocking its engagement with fibrinogen. Although sulfotyrosines have been identified in various hirudin variants, the precise relationship between sulfotyrosine and the number of negatively charged amino acids within the anionic‐rich C‐terminus peptide domain for the binding of thrombin has remained elusive. By using Fmoc‐SPPS, hirudin dodecapeptides homologous to the C‐terminus of hirudin variants from various leech species were successfully synthesized, and the effect of sulfotyrosine and the number of negatively charged amino acids on hirudin‐thrombin interactions was investigated. Our findings did not reveal any synergistic effect between an increasing number of sulfotyrosines or negatively charged amino acids and their inhibitory activity on thrombin or fibrinolysis in the assays, despite a higher binding level toward thrombin in the sulfated dodecapeptide Hnip_Hirudin was observed in SPR analysis.
Der Einfluss von Zusatzmitteln auf das Recycling von calciumsulfatbasierten Bindemitteln Teil I (Ausgangsstoff gezüchtete Kristalle)
Authors: Pritzel Christian , Zeitoun Edrees Abu , Trettin Reinhard , Killian Manuela S.
Published: December 2023

Kurzfassung

Durch die Energiewende in Deutschland werden die verschiedenen Kraftwerksnebenprodukte, unter anderem REA‐Gips, mehr und mehr verschwinden. Aus diesem Grunde rückt das Recycling von Gips zunehmend in den Fokus der Wissenschaft. Bisher wurde der Einfluss von Additiven auf das Recycling von Gips nur begrenzt untersucht. Mit den vorgestellten Untersuchungen soll ein Beitrag zu dieser Diskussion geliefert werden. Dazu wurden Gipskristalle auch in Anwesenheit von Additiven per Diffusionsynthese aus Natriumsulfat und Calciumchlorid hergestellt. Diese wurden anschließend zu Halbhydrat umgesetzt und dieses wieder hydratisiert. Beide Vorgänge wurden mit verschiedenen Methoden untersucht. Mit Hilfe der Elektronenmikroskopie konnten die Morphologien sowohl der Gipskristalle als auch des gebildeten Halbhydrates bestimmt werden. Die Wärmeflusskalorimetrie hat dazu beigetragen den Hydratationsverlauf des Halbhydrates zu verfolgen. Es konnte gezeigt werden, dass einige Additive im System verbleiben und im Recyclingprodukt zu neuen Herausforderungen führen können.
Resting time effect on the rheological behaviour of glass beads and cement suspension: The role of PCE size and ionic strength
Authors: Ji Yanliang , Mezhov Alexander , Becker Simon , von Klitzing Regine , Wolfram Schmidt , Stephan Dietmar
Published: December 2023

Studies have shown that in an aqueous suspension of inert glass beads, the yield stress is increased as a function of resting time. This study investigates this unexpected phenomenon, focusing on solid surface potentials, PCE size in ionic solutions, and their possible relations to rheological behaviour with resting time. Results indicated that PCE in artificial pore solution will result in a higher yield stress with time. PCE with lower anionic charges and molecular weight can significantly increase the yield stress after 2 h of resting. The absolute value of the zeta potential grows to a certain degree after resting phase. Dynamic light scattering (DLS) results showed that the size of PCE molecules in ionic solutions increases over time, suggesting an enhanced depletion force or bridging force among glass bead particles, which could be the reasons for the increase in yield stress over time. Furthermore, the possible impacts of the depletion force or bridging force resulting from the PCE size change on the rheological properties of cement suspension are discussed.
Multiphase granular suspension flow of fresh concrete during pumping in complex geometries
Authors: Mikhalev Daniil , Kluwe Moritz Niklas , Schwarze Rüdiger , Mechtcherine Viktor
Published: December 2023

During the pumping process of multiphase granular suspensions, such as concrete, through pipe systems, many parameters can influence the material's ability to flow. To understand the hydrodynamics and particle mechanics in granular, non‐Newtonian suspensions under nonlinear flow conditions, the authors have been working on a joint project within the Priority Program SPP 2005 “Opus Fluidum Futurum ‐ Rheology of Reactive, Multiscale, Multiphase Construction Materials” funded by the German Research Foundation (DFG). Based on the results obtained, it is possible to describe the relationships between concrete composition and the rheological properties of the fresh mixture for pumping applications. The effects of particle geometry and flow conditions on flow‐induced particle migration (FIPM), subsequently the formation of a lubricating layer (LL), and eventually on pumping pressure were also shown. While the behavior of concrete and other complex, multiscale suspensions in generic flows (Couette, Poiseuille) is still part of current research and only partially understood, the behavior in complex geometries is even less explored so far. Here, additional effects based on the curvature of streamlines and mass inertia of the particle phase come into play. In the framework of the project, these effects have been investigated experimentally and numerically. Various experimental approaches have been developed to observe the behavior of particles within their carrier fluid in an opaque, dense, and enclosed moving system, yielding insightful results. Currently, models are being developed and experimentally validated to describe particle migration quantitatively, allowing conclusions about the local rheological behavior to be drawn. This information is essential to predict the flow behavior necessary for modern processes such as 3D printing and energy‐optimized pumping.
Tool developments for additive manufacturing processes with anchor for the modern flow production
Authors: Lindner Marco , Gliniorz Ralf , Männel Mike , Garbe Daniel , Funke Henrik , Gelbrich Sandra , Berger Maik
Published: December 2023

In modern flow production, the focus is on the continuous digitally controlled tools within the context of the digital twin. Spray extrusion, especially in combination with a thin layer of shotcrete and ribbed supporting structures, for example for facade elements, leads to very efficient components with high load‐bearing capacity and high quality surfaces. The developed combined spray extrusion nozzle offers the possibility of both: spraying and extruding, adapting mortar and concrete. In addition, automated integration of anchors is the focus of flow production, for which anchors and tooling systems have been developed. Based on the determination of characteristic values, the practicability and the increase in productivity could and will be proven. This data forms the basis of a digital twin in preparation for Industry 4.0. This increase in productivity in additive manufacturing leads to positive economic effects, applications of high strength lightweight structures in construction are becoming more attractive and enable the series implementation of free form modular constructions.
Clinker‐efficient cements and their application ‐ today and tomorrow
Authors: Müller Christoph
Published: December 2023

The concrete standard DIN 1045‐2 currently provides fixed limit formulations for the respective exposure class. The tests of cements in concrete with regard to durability (carbonation, chloride penetration, frost and freeze‐thaw salt resistance) are now carried out within approvals procedures in a limit composition for the exposure class under consideration. Test results of clinker‐efficient cements are shown against the assessment background of the German Institute for Building Technology (DIBt) e. g. for carbonation: This test is currently to be carried out with a water‐cement ratio of w/c = 0.50. While, for example, a CEM III/A or a CEM II/C‐M (S‐LL) fit well into the assessment background in this test with the required limit composition, the depth of carbonation of a cement is 20 percent clinker, 30 percent blast furnace slag and 50 percent unburned limestone clearly outside. If the water‐cement ratio is reduced to w/c = 0.40, the result is already in the upper range of the evaluation background. A further reduction to w/c = 0.35 leads to a result in the range of the reference cements. A further significant reduction in the clinker content in cements with a high proportion of unburnt limestone would therefore be possible if the concretes are composed accordingly.
Entwicklung eines alkalisch aktivierten Bindemittels für das Extrusionsverfahren
Authors: Kruppa Henning , Kalthoff Matthias , Vollpracht Anya , Matschei Thomas
Published: December 2023

Kurzfassung

Ein Hauptfokus der derzeitigen Forschung im Bauwesen liegt in der Untersuchung und Entwicklung von nachhaltigen Herstellungsmethoden und Baumaterialen. Ein hohes Potential weisen neue Fertigungsmethoden wie die Extrusion von Textilbeton auf, da somit leichte und lastpfadgerechete Bauteile hergestellt werden können. Allerdings werden hierbei derzeit häufig Betone mit hohen Bindemittelanteilen und CO2‐Fußabdruck verwendet. Eine nachhaltige Alternative zu dem konventionellen Betonen stellen alkalisch aktivierte Materialen (AAM) dar. Die chemische Zusammensetzung, Reaktivität und das rheologische Verhalten unterscheiden sich jedoch meist stark von zementbasierten Systemen, wodurch ein hoher Forschungsbedarf besteht. Im Rahmen dieser Arbeit wurde ein innovatives AAM unter Verwendung von Basalt‐ und Hüttensandmehl synthetisiert. Für eine genauere Charakterisierung des AAM wurden der Erstarrungszeitpunkt und die Wärmeentwicklung mit einem isothermen Wärmeflusskalorimeter für unterschiedliche Bindemittelzusammensetzungen untersucht. Die Eignung als Bindemittel für die Extrusion wurde ebenfalls systematisch getestet. Um eine fehlerfreie Extrusion zu gewährleisten, muss der Frischbeton im Extruder förderbar sein und eine hohe Grünstandsfestigkeit aufweisen, so dass eine maßhaltige, fehlstellen‐ und schalungsfreie Herstellung der Bauteile gewährleistet ist. Für die rheologische Beschreibung der neu entwickelten AAM für den Extrusionsprozess wurde ein innovativer Kugelpenetrationstest eingesetzt, mit dem die Extrudierbarkeit vorhergesagt werden konnte.

Die Ergebnisse zeigen, dass die AAM zielsicher für den Extrusionsprozess entwickelt und die Eignung vor den eigentlichen Prozess vorhergesagt werden können. Zusätzlich konnte gezeigt werden, dass AAM aus industriellen Nebenprodukten für diesen Prozess geeignet sind und dadurch der CO2‐Ausstoß minimiert werden kann.
Crack Resistance of Concrete Using Granulated BlastFurnace Slag Sand under Flexural Stress
Authors: Hashimoto Ryota , Onoue Kozo
Published: December 2023

Granulated blast‐furnace slag sand (BFS) has the potential to be used as an alternative to fine aggregates in concrete production. The interface between the cement paste and the aggregate in concrete is densified when BFS is used, due to the hydrates that are generated by its latent hydraulicity. This fact suggests that the crack resistance of concrete, which is closely related to the conditions at the aggregate interface, would be enhanced by the use of BFS. The fracture energy (GF) of concrete under flexural stress is here measured to evaluate the crack resistance of concrete made using BFS. BFS samples from three different steel mills in Japan are used as the fine aggregates for concrete production, and mountain sand is used as a natural sand for comparison. Compressive strength, static modulus of elasticity, and fracture energy tests are conducted at the material ages of 28 and 91 days. The GF of the BFS concretes increase with increasing compressive strength; on the other hand, the GF of the concrete made using mountain sand decrease. Thus, it is concluded that BFS concrete has superior properties to concrete made using natural sand in terms of the crack resistance under flexural stress, especially in high‐strength regions for large material ages.
Moisture transport properties of concrete with SCMs – descriptions, test methods and some applications
Authors: Nilsson Lars‐Olof
Published: December 2023

Moisture transport properties of concrete are rarely determined, simply because it is difficult and time‐consuming. Most studies in literature are limited to cement paste and mortar. Translation of these properties to concrete are not straight‐forward. Recently, however, a few measurements are done, also on concretes with supplementary cementitious materials.

An overview is given on various ways of theoretically describing the moisture transport properties of concrete, with different “moisture transport coefficients” and their interrelations. Methods of determining those properties are shown and their advantages and drawbacks are discussed. Available data in literature are summarized and compared. A recently developed test method, the tin‐can method, is described. New results are shown for concretes with SCMs. The method's possibilities to be used for short‐term tests of aging concrete are discussed.

A few important applications where the moisture transport properties are decisive are presented: applying moisture‐sensitive flooring materials on concrete floor slabs and carbonation‐initiated reinforcement corrosion under varying climatic conditions.
Physicochemical Properties of Portland Cement/Calcium Aluminate Cement/Calcium Sulfate Ternary Binder Exposed to Deep Seafloor
Authors: Kobayashi Mari , Takahashi Keisuke , Kawabata Yuichiro , Bier Thomas A.
Published: December 2023

Cementitious materials employed in deep‐sea marine engineering must have excellent durability. In this study, the durability of a ternary binder‐based paste composed of Portland cement, calcium aluminate cement, and anhydrite was investigated after deep‐sea exposure at a depth of 3515 m for 438 days. The recovered paste specimen showed significant expansion. However, the hydrate phases in the ternary binder exhibited no changes with the exception of the formation of Friedel's and Kuzel's salts. One reason for this was the transformation from unstable monosulfate to stable ettringite under low‐temperature seawater conditions. However, the additional ettringite formation could lead to significant expansion of the paste specimen.
Influence of Calcium Carbonate Flour on Hydration, Strength, and Rheology of fast setting CSA based mortars
Authors: Crcoroska Katarzyna , Kupiński Marcin , Stobieniecka Karolina , Kotwica Łukasz
Published: December 2023

Calcium Sulfoaluminate cements (CSA) are a more sustainable alternative to Portland Cement (PC). On top of that, they can outperform PC in mortars application. The addition of calcium carbonate to such a system is beneficial as it improves workability, accelerates the setting time, and stabilizes the ettringite in the hardened mortar. In this paper, we are investigating the influence of fine calcium carbonate flour on CSA‐C$‐based mortars. The hydration course was traced by the means of isothermal microcalorimetry. It was observed that with the addition of fine calcium carbonates the heat release due to the hydration of CSA started earlier and resulted in the higher hydration peak. Higher hydration degree was able to partially compensate for additional water used to maintain workability. The rheological properties were measured with the rotational viscometer. The results were compared to the mortars of the same composition where fine calcium carbonate was replaced with the ground quartz sand of similar particle size distribution. Surprisingly, no differences in rheology and mechanical parameters between these flours were found.
The facilitated synthesis of core‐multi‐shell silica nanoparticles and its performance onto cementitious based system in comparison with commercial silica nanoparticles
Authors: Tran Cuong , Pritzel Christian , Kowald Torsten , Trettin Reinhard
Published: December 2023

The implementation of nanoparticles in cementitious systems have been studied for long time, however the knowledge about the influence of nanosized part (e.g. silica nanoparticles) has still to be fulfilled. The enhancement of cementitious matrix, specifically in the ultra‐high‐performance‐concrete (UHPC) system, has always been focused by researchers in various means of investigation and the application of silica nanoparticle plays a significant role as one of the attempts.

Different methods have been applied for synthesizing silica nanoparticles (including the core multi‐shell silica nanoparticle) within this study to simplify the process. Moreover, the comparison of two types of silica nanoparticle (synthesized and commercial) has been done in mean of character and effect to the cementitious systems by appropriate methods, to be named as: size distributions examination, microscopic methods, investigation of mechanical properties, phases composition, etc. In order to hamper crack propagation at the nanoscale, a brand‐new and simple synthesized core multi‐shell silica nanoparticle with a high specific surface area was able for the first time be applied to the scope of cementitious matrices with an impressive impact on the properties of the investigated UHPC systems. This silica nanoparticle performs double functions: as nanoscopic shock absorber and as an additive to achieve a homogeneous nanoscale elastomer distribution and thus generates positive influence not only on the properties of UHPC, but also on future solutions for materials and environmental issues. With deep and meticulous study in the future, this type of complex nanoparticle is promising great applications to give a hand to find the solution for raw materials and therefore being closer to the aim of greener construction industry.
Einfluss von Aktivatoren auf die Hydratation von hüttensandsubstituierten Zementsystemen
Authors: Alexandru Pîrvan Adrian , Schröder Miriam , Schwendinger Michael , Yammine‐Malesys Joumana , Lothenbach Barbara , Winnefeld Frank
Published: December 2023

Kurzfassung

Hüttensand ist ein leistungsfähiger Zusatzstoff für Zement und Beton, der vor allem zu späten Prüfterminen einen erheblichen Festigkeitsbeitrag leisten kann. Die Festigkeit von Mischungen von Portlandzement mit Hüttensand zu frühen Zeiten (z.B. nach 1 oder 2 Tagen) ist oft jedoch eher gering, kann aber durch den Einsatz von Beschleunigern verbessert werden. Dieser Einfluss der Aktivatoren auf die mechanischen Eigenschaften ist zwar bekannt, aber es ist nicht viel über die zugrunde liegenden Mechanismen bekannt. Diese Studie konzentriert sich auf zwei solcher Aktivatoren, (i) Calciumformiat und (ii) ein Gemisch aus Natriummetasilikat und Kalkhydrat, sowie ihre Auswirkungen auf den Hydratationsmechanismus von hüttensandhaltigem Portlandzement. Es wurde festgestellt, dass eine Mischung aus beiden Aktivatoren die Druckfestigkeit sowohl im frühen als auch im späten Alter positiv beeinflusst. Vor allem Calciumformiat hat hier einen positiven Einfluss, da es nicht nur den Zement beschleunigt, sondern auch die Auflösung des Hüttensandes.
Fast set GGBS Binder
Authors: Blessing Ludo Vannes
Published: December 2023

To reduce CO2 emission producing Ordinary Portland cement (every ton of Portland cement accounts for roughly 850 kg CO2) the use of supplementary cementing materials (SCM's) are becoming todays standard in the cement and construction industry.

Although some SCMs are used on their own, most of them are used in combination with Portland cement clinker.

Aim was to accelerate the setting time of a pure GGBS binder and improve its early strength development. From different publications we learned that fast setting cements contain C11A7. CAF2 similar to the phases calculated from our Type II GGBS.
Preventing Alkali‐Silica Reaction in Concrete
Authors: Ideker Jason H. , Drimalas Thano , Folliard Kevin J. , Ghanizadeh Ardalan , Parashar Anuj , Chopperla Krishna Siva Teja , Snyder April , Thomas Michael D.A.
Published: December 2023

Alkali‐silica reaction continues to be a challenging durability issue for portland cement‐based concrete. While myriad of preventive options is known to reduce the risk of ASR, changes in availability and consistency of materials make either prescriptive or performance‐based approaches difficult to develop and then quickly adapt. In general, the research community has supported industry with practical solutions based on empirically derived relationships, mostly from accelerated test methods and to a lesser extent realistic exposure/field structures. It is time to increase the level of science behind our approach. The research team represented in this talk is investigating a new methodology that combines the alkali availability needed to initiate ASR (aggregate specific) with the available alkali from the total cementitious blend. The relationship between reactivity of a supplementary cementitious material and the ASR expansion is also explored. This keynote lecture will: 1) Explore performance‐based testing versus prescriptive approaches and why a hybrid approach should be considered ASR prevention; 2) Evaluate the relationship between accelerated laboratory tests, outdoor exposure blocks and field structures; 3) Examine the use of “non‐traditional” supplementary cementitious materials and/or chemical admixtures to prevent alkali‐silica reaction; 4) Propose future research needs and; 5) Make recommendations for how best to prevent alkali‐silica reactivity following the proposed approach.
Effect of the pH on the interaction of hydrotalcite with dyes from textile wastewater
Authors: Behringer Martin , Hilbig Harald , Helmreich Brigitte , Machner Alisa
Published: December 2023

The increase in textile fibre production volume is expected to result in a corresponding rise in untreated wastewater, highlighting the need for effective and affordable wastewater treatment methods. This study explored the potential of hydrotalcite, a product in cement hydration, which can be used as a low‐cost adsorbent, in treating wastewater containing Reactive Blue 19 or Acid Green 1 dyes. The effect of pH on the decolourization properties was studied using HCl, HNO3, H2SO4, NaOH, KOH, Ca(OH)2, and Ba(OH)2. The results showed that both dyes had significantly different decolourization properties with hydrotalcite in acidic and basic dye solutions, with acidic environments enhancing dye uptake. The ions present in the dye solution have no significant impact on the decolourization properties. Zeta potential analysis supported these findings, with acidic dye solutions exhibiting higher zeta potential. An intercalation of dye molecules into the layered structure of the hydrotalcite could not be detected. The study shows that hydrotalcite is most effective as an adsorbent in acidic environments.
Zur kolloidalen Natur von AKR‐Produkten
Authors: Giebson Colin , Ludwig Horst‐Michael
Published: December 2023

Kurzfassung

Von den Produkten einer Alkali‐Kieselsäure‐Reaktion (AKR) wird angenommen, dass sie Wasser aufnehmen und sich infolgedessen ein Quelldruck in Gesteinskörnern und im Zementstein aufbaut, der Dehnungen verursacht und schließlich zur Rissbildung im Beton führt. Neuere Untersuchungen haben jedoch gezeigt, dass AKR‐Produkte oft eine kristalline Struktur haben und weniger Wasser aufnehmen als erwartet. Darüber hinaus sind gemessene Quelldrücke oft überraschend gering. Offensichtlich ist die Natur der AKR‐Produkte noch nicht in ausreichendem Umfang verstanden worden.

Ergebnisse eigener Untersuchungen zeigten, dass AKR‐Produkte als kolloidale Systeme betrachtet werden können. Um zu klären, ob und inwieweit AKR‐Produkte kolloidale Eigenschaften aufweisen, wurden 10 AKR‐Produkte mit unterschiedlicher Zusammensetzung und unterschiedlichem Wassergehalt bei zwei Temperaturen (40 und 60 °C) synthetisiert. Die AKR‐Produkte wurden über einen Zeitraum von 1,5 Jahren unter anderem mittels der Rasterelektronenmikroskopie, der Nanopartikelanalyse sowie mittels eines Osmosezellenversuchs untersucht. Die Ergebnisse zeigen insbesondere, dass AKR‐Produkte Partikel kolloidaler Größe (50‐600 nm) enthalten. Dadurch kann es im Beton zum DONNAN‐Effekt kommen, der zur Osmose führt und damit eine Erklärung für den AKR‐Quellvorgang liefert.
Bewertung der Innenhydrophobierung als neuartige AKR‐Vermeidungsstrategie bei Betonfahrbahndecken
Authors: Fladt Matthias , Weise Frank
Published: December 2023

Kurzfassung

Zur Vermeidung von AKR‐Schäden an Betonfahrbahndecken im deutschen Autobahnnetz wurden mit dem ARS 04/2013 verbindliche Eignungsprüfungen zum Ausschluss alkaliempfindlicher Gesteinskörnungen bei Neubau‐ und Erhaltungsmaßnahmen eingeführt. Das hatte eine signifikante Reduzierung geeigneter Gesteinskörnungen zur Folge. Deshalb wird geprüft, ob durch die Zugabe eines Hydrophobierungsmittels während der Betonherstellung grenzwertig alkaliempfindliche Gesteinskörnungen nutzbar gemacht werden können. In diesem Beitrag wird der Einfluss der Dosierung eines Compounds mit Hydrophobierungsmittel (HM) auf die Frisch‐ und Festbetoneigenschaften eines Waschbetons mit einer reaktiven Grauwacke dargestellt. Es zeigt sich, dass aufgrund des Antagonismus die zunehmende Dosierung des HM‐Compounds eine signifikante Erhöhung der Zugabe des Luftporenbildners auf Wurzelharzbasis erfordert. Der AKR‐Schädigungsprozess wird ab einer Dosierung des HM‐Compounds von 0,75 M.‐%, bezogen auf den Zementgehalt, hinreichend vermindert. Die mechanischen Eigenschaften des hydrophobierten Waschbetons verschlechtern sich im betrachteten Dosierungsbereich des HM‐Compounds nur geringfügig. Auch der Frost‐Tausalz‐Widerstand vermindert sich, ohne den normativen Grenzwert für die Abwitterung zu überschreiten.
Entwicklung eines chemischen Schnelltestverfahrens mit Gesteinsmehl zur Detektion alkalireaktiver Gesteinskörnung
Authors: Hartmut Gyde , Schmidt‐Döhl Frank , Püstow Anna
Published: December 2023

Die Alkalikieselsäure Reaktion (AKR) führt zu schweren bis irreparablen Schäden in Bauwerken und kann nur durch präventives Testen der Gesteinskörnung vermieden werden, allerdings haben die angewandten Testverfahren noch Potential zur Optimierung, welches auf schnellere und präzisere Verfahren hoffen lässt. Am Institut für Baustoffe, Bauphysik und Bauchemie der Technischen Universität Hamburg wird ein neues Testverfahren entwickelt, welches den chemischen Testverfahren ähnelt. Anders als bei den üblichen chemischen Verfahren wird die Reaktivität der Gesteinskörnung nicht von dem Masseverlust oder Konzentration einzelner Komponenten bestimmt. In diesem Ansatz wird die Reaktivität der Gesteinskörnung aus der Veränderung chemischer Parameter, die infolge der Lösung von Gesteinsmehl in hochkonzentrierter heißer Lauge hervorgerufen werden, abgeleitet. Während des Versuchs werden der pH‐Wert, das Redoxpotential und die elektrische Leitfähigkeit aufgezeichnet. Die Zeitverläufe dieser Parameter haben mathematisch quantifizierbare Eigenschaften, wie Geschwindigkeitskonstanten, stationäre Zustände oder Extrempunkte anhand derer die Reaktivität der Gesteinskörnung gefolgert werden soll. Dies basiert auf der Annahme, dass sich das Lösungsverhalten verschieden reaktiver Materialien unterscheidet. Die bisherigen Ergebnisse zeigen sich wiederholende Ergebnisse und eine Differenzierbarkeit der quantifizierbaren Punkte bezüglich der jeweiligen Proben.
Effect of cement composition and the storage conditions on the morphology of ASR products in concrete
Authors: Krüger Miriam E. , Heisig Anne , Heinz Detlef , Machner Alisa
Published: December 2023

Under natural conditions, the alkali silica reaction (ASR) is a slow degradation process in concrete. Therefore, accelerated laboratory test methods are used to estimate the alkali‐reactivity of aggregates and concrete performance regarding a damaging ASR. In this study, concrete cubes were stored in a fog chamber at 40 °C/100% RH and at outdoor conditions in Munich climate for up to 9 years. Opaline sandstone/flint (25 vol.%) was used as reactive aggregate. 15 wt.% of OPC was replaced by fly ash and compared with the reference mix with 100 wt.% OPC. The cracks widths of the cubes were measured regularly. To investigate the effect of accelerating test conditions on the morphology of reaction products, the concrete microstructure, pore solution composition and ARS products formed under accelerated and field conditions were investigated. The present study shows that accelerated test methods consider only partial aspects of the complex mechanisms of ASR in concretes containing pozzolanic fly ash. Storage conditions have a direct effect on the morphology of the ASR products, the porosity and the pore solution composition of the concrete. When testing blended binders under accelerating conditions, opposing mechanisms are achieved and the chemical and physical processes can be changed significantly.
A multi‐DOE approach to investigate the effect of different factors on the properties of ternary binders
Authors: Qorllari Anxhelina , Bier Thomas A.
Published: December 2023

The Design of Experiment (DOE) is a widely recognized approach to designing and analyzing experiments. It is a statistical method utilized to simultaneously examine the impact of multiple factors on the results. In this study, two different DOE methods, including mixture and factorial design were employed to evaluate the influence of various factors on the performance of ternary binders. To assess the effect of each component such as Portland cement (PC), calcium aluminate cement (CAC) and sulphate (CŜHx) on the workability and strength of ternary binders, mixture design was utilized. A two‐stage factorial design was implemented to investigate the impact of various factors on the fresh and hard properties of ternary binders. In the first stage the influence of composition, supplementary cementitious material (SCM) and cement replacement ratio were examined. In the second stage the impact of composition, CAC and CŜHx type were analyzed. Principal Component Analysis was also employed to analyse the continuous data obtained from the XRD patterns. The study results indicated that increased CAC and CŜHx content in the mixture enhances the workability of the pastes. High compressive strengths were found to be a result of increased cement content in the mixture and low SCM substitution.
Analyse des Frost‐Tausalz‐Widerstands zementgebundener Baustoffe mittels 3D‐Laserscanning
Authors: Haynack Alexander , Timothy Jithender J. , Kränkel Thomas , Gehlen Christoph , Thiel Charlotte
Published: December 2023

Kurzfassung

Eine Herausforderung performancebasierter Prüfverfahren zur Bewertung der Dauerhaftigkeit ist die Beschleunigung natürlicher Mechanismen. Dies ist notwendig, um innerhalb kurzer Zeit die Langzeit‐Leistungsfähigkeit ermitteln zu können. Die Bestimmung der Frost‐Tausalzbeständigkeit von Beton kann durch den CDF‐Test erfolgen, welcher für Betone mit ausreichendem Frost‐Tausalz‐Widerstand sehr gut funktioniert. Bei Proben mit einer unzureichenden bzw. unbekannten Performance können erhöhte Randabwitterungen auftreten, welche durch das Ablösen des seitlichen Abdichtbands entstehen. Der zunehmende Randeinfluss führt so zu einer Verfälschung der Ergebnisse und zu einer Unterschätzung der tatsächlichen Performance des Bauteils. In diesem Beitrag werden Mörtel‐ und Betonprobekörper mit unterschiedlichen Abwitterungsraten in Anlehnung an das CDF‐Verfahren untersucht. Zusätzlich wird die Oberflächenschädigung der Proben anhand einer neuartigen Messmethode mittels hochauflösendem 3D‐Laserscanning ausgewertet. Die Ergebnisse zeigen, dass die Randeffekte mit der Laserscan‐Methode umgangen und vergleichbare Ergebnisse zu den CDF‐Untersuchungen erzielt werden können. Somit können Betone ohne Randeinflüsse charakterisiert und eine präzise Prognose der Langzeitbeständigkeit getroffen werden.
Frostwiderstand in Labor und Praxis ‐ Aktuelle Erkenntnisse aus Forschung und Bauwerksbegutachtung
Authors: Spörel Frank
Published: December 2023

Kurzfassung

Die Übertragbarkeit von Laborprüfergebnissen auf das Verhalten in der Praxis über die gesamte vorgesehene Nutzungsdauer ist mit Unwägbarkeiten behaftet. In der derzeit ruhenden DAfStb‐AG Praxisfrost wurden seinerzeit Monitoring‐Kampagnen zur Erfassung der tatsächlichen Frostbeanspruchung an Bauwerken begonnen und im Verkehrswasserbau bis dato weitergeführt. Die Temperaturbeanspruchung sowie die Feuchteverteilung wurden für ein Schleusenbauwerk über nahezu die gesamte Nutzungsdauer kontinuierlich in unterschiedlichem Abstand zur Betonoberfläche erfasst. So liegen nun für das Schleusenbauwerk für dessen gesamte bisherige Nutzungsdauer von derzeit etwa 20 Jahren Erkenntnisse zur tatsächlichen Frostbeanspruchung vor. In Verbindung mit der am Bauwerk eingetretenen frostbedingten Schädigung des Betons sowie den Ergebnissen von Bohrkernuntersuchungen und Untersuchungen an gesondert hergestellten Laborprüfkörpern in unterschiedlichem Prüfalter und bei unterschiedlichen Lagerungsbedingungen besteht nun erstmals die Möglichkeit einer ganzheitlichen Betrachtung. Die Erkenntnisse zu Einwirkungen und Widerstand bei Bauwerksbeton und Laborprüfkörpern werden vor dem Hintergrund der eingetretenen Bauwerksschäden diskutiert und können als Grundlage für weiterführende Betrachtungen dienen.
Wissensbasierte Digitalisierung von betontechnologischen Materialdaten
Authors: Meng Birgit , Dehn Frank , Unger Jörg F. , Shepherd David Alós , Tamsen Erik , Pirskawetz Stephan
Published: December 2023

Kurzfassung

Die sprunghaft zunehmende Wichtigkeit von FAIR‐ und Open‐Data für die Qualitätssicherung, aber auch für die Nachnutzbarkeit von Daten und den Erkenntnisfortschritt führt zu enormem Handlungsbedarf in Forschung und Entwicklung. Damit verbunden laufen derzeit vielfältige, ambitionierte Aktionen, z. B. bezüglich der Erstellung von Ontologien und Wissensgraphen. Das Knowhow entwickelt sich rasant, die Ansätze zur Implementation entstehen in verschiedenen Fachwelten bzw. mit unterschiedlichen Zielsetzungen parallel, so dass recht heterogene Herangehensweisen resultieren.

Diese Veröffentlichung fokussiert auf Arbeiten, die derzeit als möglichst ganzheitlicher Ansatz für Materialdaten im Rahmen der Digitalisierungsinitiative „Plattform MaterialDigital“ vorangetrieben werden. Die Autoren bearbeiten baustoffbezogene Aspekte im Verbundprojekt „LeBeDigital ‐ Lebenszyklus von Beton”. Zielsetzung ist die digitale Beschreibung des Materialverhaltens von Beton über den kompletten Herstellungsprozess eines Fertigteils mit einer Integration von Daten und Modellen innerhalb eines Workflows zur probabilistischen Material‐ und Prozessoptimierung. Es wird über die Vorgehensweise und die dabei gewonnenen Erfahrungen berichtet, nicht ohne den Blick auf die oft unterschätzte Komplexität der Thematik zu lenken.
Influence of air cooled and granulated blast furnace slag on the thermal resistance of cyclic high‐temperature concrete
Authors: Feldrappe Volkert , Ehrenberg Andreas , Iravani Ahmad , Anders Steffen
Published: December 2023

Concrete is the most widely used building material. Particularly in industrial floors or air ducts in steel and foundry industries, it is often exposed to high continuous or cyclical temperatures. In these applications, high temperature resistance of the concrete is essential to ensure high bearing capacity and durability. In addition to the temperature level, the composition of the concrete is also important regarding long‐term stability of the exposed concrete members.

This study investigates the effect of slag cements as well as granulated and air‐cooled blast furnace slag as industrial aggregates on the hot and residual strength of concretes exposed to temperatures up to 700 °C. In addition, the material parameters determined were transferred to the component level to calculate the bearing capacity of model walls. It was shown that the hot and residual strength, as well as the bearing capacity at the component level, are high when concretes are made from these materials. The characteristics are comparable to those of concrete made with thermally stable but relatively expensive basalt and even significantly better when quartzitic aggregates were used. The results allow suggestions to be made for additions to current fire resistance design codes.
Probabilistic service life prediction of cracked concrete using numerical and engineering models
Authors: L. Schultheiß Annika , Patel Ravi A. , Dehn Frank
Published: December 2023

Chloride ingress induced depassivation of reinforcing steel leading to corrosion is a major durability concern for concrete structures. The influence of the presence of cracks commonly occurring in concrete structures on chloride ingress should be accounted to improve the accuracy of service life predictions. This study investigates the depassivation probability of the reinforcement in both cracked and uncracked concrete using both analytical and 1D numerical models. The probabilistic service life prediction is realized using the Monte Carlo simulation to incorporate the uncertainty and variability in the input variables. For uncracked concrete the result of the numerical model agreed well with the fib chloride model. For cracked concrete, the numerical simulation suggests that the optimal engineering approach to account for cracks in a service life analysis is the adaptation of crack depth. Although, the approach could lead to an overestimation of chloride concentration because the 1D numerical simulation did not consider lateral diffusion in cracked concrete.