Rheology of an alkali-activated Fe-rich slag suspension: Identifying the impact of the activator chemistry and slag particle interactions

2021 ◽  
Vol 561 ◽  
pp. 120747
Author(s):  
Glenn Beersaerts ◽  
Anja Vananroye ◽  
Dimitrios Sakellariou ◽  
Christian Clasen ◽  
Yiannis Pontikes
Keyword(s):  
Particle Interactions ◽  
Slag Particle ◽  
The Impact ◽  
Alkali Activated

Engineering the Interaction Forces to Optimize CMP Performance

2002 ◽  
Vol 732 ◽  
Author(s):  
G. B. Basim ◽  
I. Vakarelski ◽  
P. Singh ◽  
B. M. Moudgil
Keyword(s):  
Material Removal ◽  
Surface Deformation ◽  
Defect Density ◽  
Removal Rate ◽  
Particle Interactions ◽  
Interaction Forces ◽  
High Performing ◽  
Optimal Material ◽  
Slurry Stability ◽  
The Impact

AbstractThe main objective of Chemical Mechanical Polishing (CMP) process is to planarize the metal or dielectric layers deposited on the wafer surfaces in microelectronics device manufacturing. In CMP, slurries containing submicrometer size particles and chemicals are used to achieve planarization. An effective polishing requires an optimal material removal rate with minimal surface deformation. Therefore, it is important to control the particle-substrate interactions that are responsible for the material removal and the particle-particle interactions, which control the slurry stability and consequently the defect density. This paper discusses the impact of interaction forces on polishing, and underlines the scientific guidelines to formulate consistently high performing CMP slurries.

scholarly journals MICROSCOPICAL AND MICROMECHANICAL FEATURES OF HIGH PERFORMANCE CONCRETE CONTAINING LOW LEVELS OF FLY ASH

2019 ◽  
Vol 21 ◽  
pp. 10-15
Author(s):  
Vladimír Hrbek ◽  
Zdeněk Prošek ◽  
Roman Chylík ◽  
Lukáš Vráblík
Keyword(s):  
Fly Ash ◽  
High Performance ◽  
Chemical Resistance ◽  
High Performance Concrete ◽  
Micro Structure ◽  
Mass Percentage ◽  
Slow Development ◽  
Low Levels ◽  
The Impact ◽  
Alkali Activated

Alkali activated fly ash is a widely used admixture to the concrete. Due to the pozzolanic activity, the fly ash can replace up to 60 mass percentage. The impact of fly ash on the concrete depend on the level of it content, i.e. in small levels it improves the macro-mechanical properties and durability as well as chemical resistance. On the other side, fly ash admixture negatively influence the set time and cause slow development of strength. Therefore, the effect of small fly ash admixture levels on the micro-structure of high performance concrete (HPC) is discussed in this study.

scholarly journals Life Cycle Assessment of alkali activated materials: preliminary investigation for pavement applications

2021 ◽  
Vol 6 ◽  
pp. 124-130
Author(s):  
Francesca Lolli ◽  
Kimberly E. Kurtis
Keyword(s):  
Global Warming ◽  
Global Warming Potential ◽  
Capital Investment ◽  
Mechanical Performance ◽  
Preliminary Investigation ◽  
Raw Material ◽  
Cement Concrete ◽  
Usual Practice ◽  
The Impact ◽  
Alkali Activated

The capital investment in the US for construction and maintenance of the infrastructure road network is $150 billion/year. Investments in OECD countries will likely stabilize, while other countries will face an exponential growth of investments for infrastructures driven by the development of metropolitan cities. Continued “business-as-usual” practice for portland and asphalt cement concrete pavement construction ignores the increasing warning calls for the identification of more sustainable and less energy intensive paving materials. Alkali activated materials concrete (AAM) have been studied with growing interest during the last three decades. AAM show promising results in terms of mechanical performance, while also having a global warming potential impact 30-80% less than that of portland cement concrete. The global warming potential of AAM is closely dependent on the: 1) activating solution used to activate the raw material and 2) origin of the raw material. Specifically, the impact of the transport for both of these components is ~ 10% of its global warming potential. Hence, to increase the adoption of AAM for pavements, it is fundamental to analyze the existing literature to clarify the link between environmental impact and mechanical performance, identifying opportunities for applications that are tailored to the local availability of raw material.

Characterization of Carbonatation Rate of Alkali-Activated Blast Furnace Slag in Various Environments

2021 ◽  
Vol 325 ◽  
pp. 40-46
Author(s):  
Richard Dvořák ◽  
Petr Hrubý ◽  
Libor Topolář
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Destructive Testing ◽  
Time Intervals ◽  
Impact Echo ◽  
The Impact ◽  
Non Destructive ◽  
Furnace Slag ◽  
Alkali Activated

Carbonatation represents one of the potential degradation processes whose can negatively affect the service life of constructions based on the inorganic binders. The carbonatation depth of the constructions when exposed to various environments is significantly dependent on the existing conditions. The most crucial parameters are the partial pressure of carbon dioxide and humidity. There were selected four environments for the deposition of samples made of the alkali-activated blast furnace slag mortars (exterior, interior, water and CO2 chamber) in this study. These types of environments guarantee the variation of desired parameters influencing the carbonatation rate. The progress of carbonatation was evaluated with a selected technique in time intervals of 28; 56 and 84 days of the sample's exposition to the selected environments. The characterization was done using the destructive techniques (compressive and flexural strength, phenolphthalein method) as well as the non-destructive one like the Impact-Echo or the Ultrasound time passage measurement. The combination of these techniques allows to determine and evaluate the progress of carbonation without the destructive testing of the samples which is necessary for the real applications of these materials.

Removal Phosphorous from High Phosphorous Converter Steel Making Slag by Hydrometallurgical Process

2012 ◽  
Vol 581-582 ◽  
pp. 940-943 ◽  
Author(s):  
Wen Tang Xia ◽  
Xue Jiao Zhou ◽  
Jian Guo Yin ◽  
Yi Feng Gao ◽  
Wen Qiang Yang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Steel Slag ◽  
Converter Steel ◽  
Content Increase ◽  
Solid Ratio ◽  
Slag Particle ◽  
High Efficient ◽  
Hydrometallurgical Method ◽  
The Impact

Removing phosphorus from high phosphorus converter steel slag by hydrometallurgical method was studied in this paper. The influence of different dephosphorizting agents on the effect of phosphorus slag was investigated, and high efficient dephosphorizating agent was found. The effects of reaction time, liquid to solid ratio, stirring speed, reaction temperature and dephosphorizing agent concentration on the impact of dephosphorization were studied. The results showed that on the conditions of the reaction time 40 min, slag particle size <0.147 mm, liquid to solid ratio of 4:1, stirring speed 400 rpm, the reaction temperature 25 °C, and dephosphorizing agent concentration 5 mol/L, the optimum dephosphorization results were achieved. The dephosphorization ratio can reach 70%, and the phosphorus content in steel slag decreased from 1.03% to 0.46%, the total iron content increase from 30.676% to above 44%.

NDT Monitoring of Alkali-Activated Material Carbonation

2020 ◽  
Vol 868 ◽  
pp. 45-50
Author(s):  
Iveta Plšková ◽  
Michal Matysík ◽  
Libor Topolář ◽  
Petr Hrubý
Keyword(s):  
Portland Cement ◽  
Raw Materials ◽  
Ultrasound Velocity ◽  
Degradation Process ◽  
Dominant Frequency ◽  
Impact Echo ◽  
The Impact ◽  
Non Destructive ◽  
Impact Echo Method ◽  
Alkali Activated

Production of Portland cement is relatively environmentally demanding (high CO2 emissions, extraction of raw materials for its production). Alkali-activated materials are an alternative to conventional Portland cement in the production of concrete. For alkali-activated binder concretes, their ability to withstand corrosive environments and their ability to protect steel reinforcement must be assessed. It is also necessary to know the suitability of non-destructive methods for monitoring the degradation process of these concretes. The paper deals with the carbonation monitoring of concrete with alkali-activated binder (slag) by the impact-echo method. Slag activated by sodium hydroxide (NaOH) was used as a binder. The specimens were tested by the non-destructive method (Impact-echo, ultrasound velocity). We focused on the shift of the dominant frequency obtained by the Impact-echo method.

scholarly journals Incorporating grain-scale processes in macroscopic sediment transport models

2021 ◽  
Author(s):  
Bernhard Vowinckel
Keyword(s):  
Sediment Transport ◽  
Learning Strategies ◽  
Multiple Scales ◽  
Particle Interactions ◽  
Transport Models ◽  
Particle Level ◽  
Continuum Scale ◽  
Engineering Practices ◽  
The Impact ◽  
The Continuum

AbstractSediment transport simulations face the challenge of accounting for vastly different scales in space and time that cannot be tackled by a unifying approach. Instead, processes are subdivided into a microscale at the particle level, a mesoscale of a large finite number of particles, and a macroscale that computes the sediment motion by means of advection–diffusion equations. The different processes occurring at different scales are simulated using different computational approaches. However, modeling sediment transport at multiple scales with high fidelity requires proper closure arguments that interconnect the different processes. Ultimately, we will need efficient macroscale models that can readily be utilized for engineering practices covering, e.g., entire river reaches or even estuaries. In recent years, highly resolved simulations have become a valuable tool to provide these closure arguments for sediment transport models on the continuum scale. In this paper, we will review the most relevant approaches to simulate sediment transport at different scales and discuss the perspectives of four most promising modeling techniques that can help to improve sediment transport modeling. On the grain scale, these enhancements include the impact of mechanical properties of cohesion and biocohesion as well as the shape of non-spherical sediment grains on fluid–particle and particle–particle interactions. On larger scales, we review constitutive equations for the macroscopic rheological behavior of sediment beds that may decouple the relevant scales for fluid and sediment motion. Furthermore, we discuss machine learning strategies as an efficient means to derive scaling arguments across multiple scales.

Dual role of friction in granular flows: attenuation versus enhancement of instabilities

2013 ◽  
Vol 729 ◽  
pp. 484-495 ◽  
Author(s):  
Peter P. Mitrano ◽  
Steven R. Dahl ◽  
Andrew M. Hilger ◽  
Christopher J. Ewasko ◽  
Christine M. Hrenya
Keyword(s):  
Cooling System ◽  
Translational Motion ◽  
Granular Flows ◽  
Md Simulations ◽  
Particle Interactions ◽  
Frictional Dissipation ◽  
Inelastic Dissipation ◽  
The Stability ◽  
The Impact

AbstractFlow instabilities driven by the dissipative nature of particle–particle interactions have been well documented in granular flows. The bulk of previous studies on such instabilities have considered the impact of inelastic dissipation only and shown that instabilities are enhanced with increased dissipation. The impact of frictional dissipation on the stability of grains in a homogeneous cooling system is studied in this work using molecular dynamics (MD) simulations and kinetic-theory-based predictions. Surprisingly, both MD simulations and theory indicate that high levels of friction actually attenuate instabilities relative to the frictionless case, whereas moderate levels enhance instabilities compared to frictionless systems, as expected. The mechanism responsible for this behaviour is identified as the coupling between rotational and translational motion. These results have implications not only for granular materials, but also more generally to flows with dissipative interactions between constituent particles – cohesive systems with agglomeration, multiphase flows with viscous dissipation, etc.

scholarly journals Some observations considering undrained shear strength, liquidity index, and fluid/solid ratio of mono-mineralic clays with water–ethanol mixtures

2018 ◽  
Vol 55 (7) ◽  
pp. 1048-1053 ◽  
Author(s):  
Giovanni Spagnoli ◽  
Helge Stanjek ◽  
Asuri Sridharan
Keyword(s):  
Pore Space ◽  
Regression Line ◽  
Liquid Limit ◽  
Particle Interactions ◽  
Solid Ratio ◽  
Liquidity Index ◽  
The Impact ◽  
First Time ◽  
The Relationship ◽  
Undrained Shear

The mechanical properties of clays are influenced by the characteristics of the fluid in the pore space. The liquid limit reacts differently to the permittivity, ε, of the fluid: for smectites the slopes are positive, for kaolinite and illite they are negative and smaller. This dissimilarity can be explained by the structural differences between swelling smectites with solvated interlayer cations and nonswelling clay minerals such as kaolinite and illite. Undrained shear strengths, cu, of Ca–smectite, but not Na–smectite, correlate with the actual fluid ratio. Regressing cu against the liquidity index, IL, yields two different regression lines for Na–smectite and Ca–smectite. For the first time it is shown that normalizing cu to the ε of the pore fluid results in a single regression line for both smectitic clay types. As kaolinites and illites possess significantly less exchangeable cations than smectites, this yields significantly smaller ranges for Atterberg limits and reduces the impact of ε on almost pure particle–particle interactions. In addition, the much larger particle sizes of the kaolinite and illite may dominate the undrained shear strengths, as normalization of cu to ε did not change the relationship to either the actual water content or the liquidity index.

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