Effect of the Interfacial Transition Zone on the Migration Behavior of Cations under the Accelerated Lithium Migration Technique

2011 ◽  
Vol 250-253 ◽  
pp. 3743-3747
Author(s):  
Chih Chien Liu ◽  
Wei Chien Wang
Keyword(s):  
Regression Analysis ◽  
Steady State ◽  
Transition Zone ◽  
Interfacial Transition Zone ◽  
Combined Effect ◽  
Migration Behavior ◽  
Volume Fractions ◽  
The Matrix ◽  
Lithium Migration ◽  
Migration Technique

This paper researches the effect of the interfacial transition zone (ITZ) on the migration behavior of cations under the Accelerated Lithium Migration Technique (ALMT). Cylindrical mortars with different aggregate volume fractions (Vf) and w/c=0.5 were used. The result shows that when Vf≤ 20 %, the Li+steady state migration coefficient (Ds) is influenced by the dilution and tortuosity effects of the aggregate. The combined effect of ITZ and percolation occurs at Vf= 30 %, and the effects increase with the increase in Vf. Based on the experimental and regression analysis results, when the assumed thickness of ITZ = 20 μm, the approximate Dsof ITZ and percolated ITZ are 46.4 and 52.6 times the matrix migration coefficient.

On the Relationship between Deteriorated Level of ASR Damaged Concrete and Lithium Migration from Acceleration Lithium Migration Technique Test

2010 ◽  
Vol 163-167 ◽  
pp. 3812-3819
Author(s):  
Wei Chien Wang ◽  
Chih Chien Liu ◽  
Chau Lee
Keyword(s):  
Steady State ◽  
Linear Relationship ◽  
Current Density ◽  
Lithium Ion ◽  
Sodium Ion ◽  
Electrochemical Technique ◽  
The Relationship ◽  
Lithium Migration ◽  
Migration Technique

This research is to study the effect of deteriorated level on the ions migration in inhibiting the concrete damaged by ASR using electrochemical technique. Cylindrical concrete specimens made by reactive sandstone with 10 cm diameter and 5 cm height were prepared at the ages of 7, 14, 28, 90, and 180 days curing in a 38°C and 100% R.H. storage environment. The accelerated lithium migration technique (ALMT) was performed using LiOH H2O and Ca(OH)2 as electrolytes for anode and cathode, respectively. 9 A/m2 current density was used to drive lithium ion into and remove sodium ion out of the concrete. The results show that the rates of ions migration increase with increasing the deteriorated level of specimen. Furthermore, a linear relationship exists between the non-steady state migration coefficient of Li+ and the deteriorated level of specimen.

Influence of Aggregate Volume Ratio of Mortar on the Migration of Cations Using the Accelerated Lithium Migration Technique

2011 ◽  
Vol 230-232 ◽  
pp. 400-404
Author(s):  
Wei Chien Wang ◽  
Chih Chien Liu ◽  
Chau Lee
Keyword(s):  
Steady State ◽  
Current Density ◽  
Linear Correlation ◽  
Volume Ratio ◽  
Constant Current ◽  
Constant Current Density ◽  
Pass Through ◽  
And Migration ◽  
Lithium Migration ◽  
Migration Technique

This study utilizes mortar specimens, to design 3 different a/c ratios of 2.25, 2.75, and 3.25. The aggregate volume ratios (Vf) are 46 %, 52 %, and 57 %, respectively, while the w/c ratio is 0.5, and undergoing a 9, 12, and 15 A/m2 constant current density Accelerated Lithium Migration Technique after curing for 3 months. Results show that, on specimens applied with the same current density, the time of Li+ to pass through the specimen, and steady state flux and migration coefficient all exhibit a positive linear correlation with Vf. At the same time, the non-steady state migration coefficient for Li+ have a negative linear correlation with Vf.

Microstructural Analysis of Paste and Interfacial Transition Zone in Cement Mortars Modified with Water-Soluble Polymers

2011 ◽  
Vol 466 ◽  
pp. 21-28 ◽  
Author(s):  
Elke Knapen ◽  
Dionys Van Gemert
Keyword(s):  
Transition Zone ◽  
Cement Mortar ◽  
Microstructural Analysis ◽  
Interfacial Transition Zone ◽  
Water Soluble ◽  
Water Soluble Polymers ◽  
Soluble Polymers ◽  
Cement Mortars ◽  
The Matrix ◽  
Mixing Water

The presence of water-soluble polymers affects the microstructure of polymermodified cement mortar. Such effects are studied by means of SEM investigation. Polyvinyl alcohol-acetate (PVAA), Methylcellulose (MC) and Hydroxyethylcellulose (HEC) are applied in a 1 % polymer-cement ratio. The polymers provide an improved dispersion of the cement particles in the mixing water. The tendency of certain water-soluble polymers to retard the flocculation of the cement particles minimizes the formation of a water-rich layer around the aggregate surfaces. They also provide a more uniform distribution of unhydrated cement particles in the matrix, without significant depletion near aggregate surfaces. Both effects enable to reduce the interfacial transition zone (ITZ). The polymers also provide a more cohesive microstructure, with a reduced amount of microcracks.

scholarly journals Nanomechanical characteristics of interfacial transition zone in nano-engineered concrete

Engineering ◽  
2021 ◽  
Author(s):  
Xinyue Wang ◽  
Sufen Dong ◽  
Zhenming Li ◽  
Baoguo Han ◽  
Jinping Ou
Keyword(s):  
Transition Zone ◽  
Interfacial Transition Zone

Design of a Multifunctional Aircraft Skin With Energy Harvesting via Entropy Generation Minimization

Aerospace ◽  
2006 ◽  
Author(s):  
K. Ahlers ◽  
K. P. Hallinan ◽  
B. Sanders ◽  
R. McCarty
Keyword(s):  
Energy Harvesting ◽  
Entropy Generation ◽  
Waste Heat ◽  
Skin Layer ◽  
Skin Thickness ◽  
Power Devices ◽  
Volume Fractions ◽  
Entropy Generation Minimization ◽  
The Matrix ◽  
Aircraft Skin

The Entropy Generation Minimization (EGM) approach is applied to the design of a new integrated radar aircraft skin, which both meets requisite aircraft structural needs and provides a pathway for the waste heat from structurally integrated power devices. Thermoelectric (TE) devices, sandwiched between a heterogeneous skin layer and the radar devices for the purpose of harvesting waste heat rejected to the ambient, are considered in the analysis. A heterogeneous skin layer is designed using the EGM approach, which is then applied to the overall mission of the aircraft to determine the optimal skin thickness and volume fractions of the matrix and inclusions in the composite skin.

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