scholarly journals Experimental Study of Slag Changes during the Very Early Stages of Its Alkaline Activation

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 231
Author(s):  
Vlastimil Bílek ◽  
Petr Hrubý ◽  
Valeriia Iliushchenko ◽  
Jan Koplík ◽  
Jakub Kříkala ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Pore Solution ◽  
Isothermal Calorimetry ◽  
Hydration Kinetics ◽  
Alkaline Activation ◽  
Early Stages ◽  
Setting Times ◽  
Oscillatory Rheology ◽  
Activated Slag

The very early stages of alkaline activation of slag control its rheology and setting, but also affect its hydration, which occurs later. Simultaneously, these parameters are dictated by the nature and dose of the alkaline activator. Therefore, we investigated and compared the changes in slag particles (SEM, BET, laser diffraction), as well as in the pore solution composition (ICP–OES), pH, and conductivity, of alkali-activated slag (AAS) pastes containing the three most common sodium activators (waterglass, hydroxide, and carbonate) and water during the first 24 h of its activation. To ensure the best possible comparability of the pastes, a fairly nontraditional mixture design was adopted, based on the same concentration of Na+ (4 mol/dm3) and the same volume fraction of slag in the paste (0.50). The results were correlated with the pastes’ hydration kinetics (isothermal calorimetry), structural build-up (oscillatory rheology), and setting times (Vicat). Great differences were observed in most of these properties, in the formation of hydration products, and in the composition of the pore solution for each activator. The results emphasize the role of the anionic groups in the activators and of the pH, which help predict the sample’s behavior based on its calorimetric curve, and offer data for further comparisons and for the modelling of AAS hydration for specific activators.

scholarly journals Contribution of Recycled Alumina Waste to Cement Strength and Microstructure Development

2018 ◽  
Vol 10 (3) ◽  
pp. 70
Author(s):  
Suzan Ibrahim ◽  
Ayman Hagrass ◽  
Tawfik Boulos ◽  
Samir Youssef ◽  
Fouad El-Hosiny ◽  
...  
Keyword(s):  
High Speed ◽  
Hydration Product ◽  
Strength Development ◽  
Oil Well ◽  
Hydration Kinetics ◽  
Rapid Repair ◽  
Setting Times ◽  
Cement Strength ◽  
Kinetics Of

The role of alumina waste as a reactive pozzolan for the local Portland cement has been thoroughly investigated. The results showed that the initial and final setting times of the hardened blended pastes were reduced significantly by increasing the amount of the added alumina. In addition, the compressive strength and the hydraulic property measures of the hardened blends showed progressive improvement reaching approximately 42% and 23% after the early ages of hydration (1 and 3 days), respectively. According to such conditions, these cement blends could be applied in many concrete applications, such as high speed construction, rapid repair, frost prevention, tunneling, shoring, gas and oil well cementing, that require concrete to have rapid setting and strength development abilities.The improvement of the physico-mechanical characteristics and the hydration kinetics of the hardened blended pastes with the recycled alumina were explained after the microstructure study included the examinations of hydration product morphology and type, the thermal gravimetric (TG), the differential scanning calometry (DSC) and the differential thermo-gravimetric (DTG) thermographs analyses. The scanning electron microscope (SEM) was used to examine the microstructure and morphology of hydration products.

Injecting Knowledge

2017 ◽  
Author(s):  
Lucia Dacome
Keyword(s):  
Eighteenth Century ◽  
Blood Vessels ◽  
Comparative Perspective ◽  
Anatomical Models ◽  
Early Stages ◽  
The Creation ◽  
Cabinet Of Curiosities

Chapter 7 furthers the analysis of the role of anatomical models as cultural currencies capable of transferring value. It does so by expanding the investigation of the early stages of anatomical modelling to include a new setting. In particular, it follows the journey of the Palermitan anatomist and modeller Giuseppe Salerno and his anatomical ‘skeleton’—a specimen that represented the body’s complex web of blood vessels and was presented as the result of anatomical injections. Although Salerno was headed towards Bologna, a major centre of anatomical modelling, he ended his journey in Naples after the nobleman Raimondo di Sangro purchased the skeleton for his own cabinet of curiosities. This chapter considers the creation and viewing of an anatomical display in di Sangro’s Neapolitan Palace from a comparative perspective that highlights how geography and locality played an important part in shaping the culture of mid-eighteenth-century anatomical modelling.

Limited Influence? The Role of the Party of European Socialists in Shaping Social Democracy in Central and Eastern Europe

2011 ◽  
Vol 46 (1) ◽  
pp. 32-55 ◽  
Author(s):  
Michael Holmes ◽  
Simon Lightfoot
Keyword(s):  
Eastern Europe ◽  
Central And Eastern Europe ◽  
Social Democracy ◽  
Social Democratic ◽  
Academic Literature ◽  
Early Stages ◽  
European Norm ◽  
Democratic Parties ◽  
Social Democratic Parties

AbstractThis article looks at the role of the Party of European Socialists (PES) in its attempts to shape social democratic parties in Central and Eastern Europe (CEE) towards a West European norm. It discusses how existing views in the academic literature on the role of transnational parties are inadequate. We argue that the PES did not play a key role in encouraging the establishment and development of parties in the CEE states from the 2004 enlargement in the early stages of accession. We contend that the overall influence of party federations has been limited, and that these limitations were as much in evidence before enlargement took place as they were afterwards.

scholarly journals Microstructure and magnetic properties of Nd-Fe-B-(Re, Ti) alloys

Nukleonika ◽  
2015 ◽  
Vol 60 (1) ◽  
pp. 29-33
Author(s):  
Mariusz Hasiak
Keyword(s):  
Magnetic Properties ◽  
Phase Composition ◽  
Volume Fraction ◽  
Magnetic Characteristics ◽  
Ti Alloys ◽  
Wide Range ◽  
Magnetically Hard ◽  
Ti Addition ◽  
Microstructure And Magnetic Properties

Abstract The microstructure and magnetic properties of nanocomposite hard magnetic Nd-Fe-B-(Re, Ti) materials with different Nd and Fe contents are studied. The role of Re and Ti addition in phase composition and volume fraction of the Nd-Fe-B phase is determined. All samples are annealed at the same temperature of 993 K for 10 min. Mössbauer spectroscopy shows that the addition of 4 at.% of Re to the Nd8Fe78B14 alloy leads to creation of an ineligible amount of the magnetically hard Nd2Fe14B phase. Moreover, the microstructure and magnetic characteristics recorded in a wide range of temperatures for the Nd8Fe79−xB13Mx (x = 4; M = Re or Ti) alloys are also analyzed.

The role of digital artefacts in early stages of distributed innovation processes

2021 ◽  
Vol 50 (10) ◽  
pp. 104349
Author(s):  
Markus C. Becker ◽  
Francesco Rullani ◽  
Francesco Zirpoli
Keyword(s):  
Early Stages ◽  
Innovation Processes

scholarly journals Effect of the matrix subsystem on hydrostatic parameters of a novel 1–3-type piezo-composite

2015 ◽  
Vol 08 (05) ◽  
pp. 1550049 ◽  
Author(s):  
Vitaly Yu. Topolov ◽  
Christopher R. Bowen ◽  
Paolo Bisegna ◽  
Anatoly E. Panich
Keyword(s):  
Elastic Properties ◽  
Electromechanical Coupling ◽  
Volume Fraction ◽  
Electromechanical Coupling Factor ◽  
Ferroelectric Ceramic ◽  
Coupling Factor ◽  
Polyurethane Composite ◽  
The Matrix ◽  
Type Composite

The influence of the aspect ratio and volume fraction of ferroelectric ceramic inclusions in a 0–3 matrix on the hydrostatic parameters of a three-component 1–3-type composite is studied to demonstrate the important role of the elastic properties of the two-component matrix on the composite performance. Differences in the elastic properties of the 0–3 matrix and single-crystal rods lead to a considerable dependence of the hydrostatic response of the composite on the anisotropy of the matrix elastic properties. The performance of a 1–0–3 0.92 Pb ( Zn 1/3 Nb 2/3) O 3–0.08 PbTiO 3 SC/modified PbTiO 3 ceramic/polyurethane composite suggests that this composite system is of interest for hydroacoustic applications due to its high hydrostatic piezoelectric coefficients [Formula: see text] and [Formula: see text], squared figure of merit [Formula: see text], and electromechanical coupling factor [Formula: see text].

scholarly journals A Gnotobiotic Model to Examine Plant and Microbiome Contributions to Survival under Arsenic Stress

2020 ◽  
Vol 9 (1) ◽  
pp. 45
Author(s):  
María del Carmen Molina ◽  
James F. White ◽  
Sara García-Salgado ◽  
M. Ángeles Quijano ◽  
Natalia González-Benítez
Keyword(s):  
Seedling Growth ◽  
Endophytic Bacteria ◽  
Root Hairs ◽  
Resistant Bacteria ◽  
Relative Importance ◽  
Early Stages ◽  
Bacterial Interaction ◽  
Arsenic Stress ◽  
Free Media

So far, the relative importance of the plant and its microbiome in the development of early stages of plant seedling growth under arsenic stress has not been studied. To test the role of endophytic bacteria in increasing plant success under arsenic stress, gnotobiotic seeds of J. montana were inoculated with two endophytic bacteria: Pantoea conspicua MC-K1 (PGPB and As resistant bacteria) and Arthrobacter sp. MC-D3A (non-helper and non-As resistant bacteria) and an endobacteria mixture. In holobiotic seedlings (with seed-vectored microbes intact), neither the capacity of germination nor development of roots and lateral hairs was affected at 125 μM As(V). However, in gnotobiotic seedlings, the plants are negatively impacted by absence of a microbiome and presence of arsenic, resulting in reduced growth of roots and root hairs. The inoculation of a single PGPB (P. conspicua-MCK1) shows a tendency to the recovery of the plant, both in arsenic enriched and arsenic-free media, while the inoculation with Arthrobacter sp. does not help in the recovery of the plants. Inoculation with a bacterial mixture allows recovery of plants in arsenic free media; however, plants did not recover under arsenic stress, probably because of a bacterial interaction in the mixture.

scholarly journals The role of graphene/graphene oxide in cement hydration

2021 ◽  
Vol 10 (1) ◽  
pp. 768-778
Author(s):  
Shaoqiang Meng ◽  
Xiaowei Ouyang ◽  
Jiyang Fu ◽  
Yanfei Niu ◽  
Yuwei Ma
Keyword(s):  
Graphene Oxide ◽  
Cement Paste ◽  
Cement Hydration ◽  
Isothermal Calorimetry ◽  
High Mobility ◽  
Nucleation And Growth ◽  
Early Hydration ◽  
Mobility Of Ions ◽  
Cement Surface

Abstract Graphene (G) and graphene oxide (GO) have been shown to significantly improve the mechanical properties of cement-based materials. In this study, the effect of the G/GO on cement hydration was investigated. First, the zeta potential of G/GO in simulated solutions was tested, and the interaction between G/GO’s surface and Ca2+ was explored. Subsequently, scanning electron microscopy was used to observe the morphology of C–S–H nucleation and growth on the cement surface in the cement paste containing G/GO. Furthermore, XRD and TGA analyses were carried out on the hydration products of the sample. At last, isothermal calorimetry was applied to investigate the influence of G/GO on the early hydration of cement. The results showed that the addition of G/GO significantly accelerates C–S–H nucleation and growth on the cement surface. It is indicated that the high mobility ions derived by G/GO in the cement paste dominate the reason for the accelerated hydration of cement. The presence of G, especially GO, facilitates the mobility of ions, especially Ca2+, thus enhances the interaction between the cement surface and the ions. This strong interaction promotes the C–S–H nucleation and growth, and therefore, the hydration of the cement.

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