Assessment of Ionic Diffusivity in Cementitious Materials Using Electrical Conductivity

2016 ◽  
Vol 42 (3) ◽  
pp. 209-215 ◽  
Author(s):  
João Marcos M. Vaillant
Keyword(s):  
Electrical Conductivity ◽  
Cementitious Materials ◽  
Ionic Diffusivity

scholarly journals Evaluation of Methods to Correct the Effect of Temperature on Electrical Conductivity of Mortar

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Milena Rangelov ◽  
Somayeh Nassiri
Keyword(s):  
Electrical Conductivity ◽  
Cementitious Materials ◽  
Temperature Correction ◽  
Supplementary Cementitious Materials ◽  
Embedded Sensors ◽  
Degree Of Saturation ◽  
Effect Of Temperature ◽  
Temperature Range ◽  
Durability Assessment ◽  
Higher Temperature

Nondestructive methods to obtain the electrical conductivity (σ) or resistivity (ρ) of concrete are gaining popularity for durability evaluation. However, these methods are susceptible to the effects of curing and conditioning, primarily temperature and degree of saturation. Before σ of concrete at varied temperatures can be used for durability assessment, appropriate corrections must be made to account for the effect of temperature (T). In this study, two existing and one new temperature correction methods were evaluated for 12 mortar mixtures varying in water-to-cementitious material ratio (w/cm) and the content and types of supplementary cementitious materials (SCM). Mortar specimens instrumented with embedded sensors were cured in sealed conditions for 11–13 months. After this period, the sealed specimens were subjected to stepwise temperature change in 5–50°C range while σ was recorded using the embedded sensors. Linear, bilinear, and Arrhenius temperature correction (LTC, BLTC, and ATC, respectively) were fitted to the obtained σ-T datasets and were evaluated for fitness. LTC provided an acceptable fit to the σ-T data (R2 > 0.81) but was found the most suitable in 5–30°C temperature range. BLTC was defined as a combination of two distinct LTC below and above the reference temperature at 23°C and had a better fit to the data (R2 > 0.96). Lastly, ATC showed the best fit among the tested methods (R2 > 0.98) and was found applicable for the full tested temperature range. Comparison of correction coefficients among the mixtures indicated that increase in w/cm results in less sensitivity of σ to temperature. Mixtures with SCM generally exhibit higher temperature sensitivity compared to the corresponding plain mixture. Since the variations in correction coefficients were not substantial (less 18% variation among 10 of 12 mixtures), a single value of activation energy of conduction (Ec) at 32 kJ/mol was identified as the general recommendation for all the tested mixtures.

Modern Electrical Measurement of Alkali Activated Slag Mortars with Increased Electrical Conductivity

2016 ◽  
Vol 861 ◽  
pp. 64-71 ◽  
Author(s):  
Miroslav Lunak ◽  
Ivo Kusak
Keyword(s):  
Electrical Conductivity ◽  
Construction Materials ◽  
Electrical Measurement ◽  
Cementitious Materials ◽  
Test Methods ◽  
Electrical Impedance Spectroscopy ◽  
Promising Alternative ◽  
Dopant Atoms ◽  
Activated Slag ◽  
Coaxial Probe

Slag mortars belong to the new promising alternative construction materials. Conventional cementitious materials are harder to measure by electrical test methods. It is being researched if the dopant atoms in the form of powder improve the mechanical properties. This article describes how the test slag mortars with addition of carbon by electrical impedance spectroscopy measurement methods and their extensions in the form of using ZNC vector analyzer with a coaxial probe from Speag. Impedance spectra of samples were obtained in the 40 Hz to 1 MHz. Declines of impedance by adding more carbon were expected and confirmed. Electrical conductivity and permittivity were measured by vector analyzer for the 100 MHz to 3 GHz. The permittivity was varied from 4 to 20, depending on the addition of carbon, the conductivity of the samples from 1/2600 to 0.3 S·m-1.

scholarly journals The Effect of Complex Modification on the Impedance of Cement Matrices

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 557
Author(s):  
Grigory Yakovlev ◽  
Černý Vít ◽  
Irina Polyanskikh ◽  
Anastasiya Gordina ◽  
Igor Pudov ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Negative Impact ◽  
Calcium Nitrate ◽  
Control Sample ◽  
Multiwall Carbon Nanotubes ◽  
Strength Loss ◽  
Cementitious Materials ◽  
Strength Properties ◽  
Cement Matrix

The research results presented in this article were obtained by joint scientific research on creatingcement materials with reduced impedance. It is known that functional additives added to impart electrically conductive properties have a negative impact on physical and mechanical characteristics of the material. This study suggests using the multiwall carbon nanotubes in the amount of 7% from binder mass as a functional additive. The results obtained prove that the addition of this amount of the modifier does not lead to a significant decrease of strength characteristics. Calcium nitrate in the amount of 1–7% was added in order to level the strength loss and to ensure the effective stable electrical conductivity. The multifunctionality of using this salt has been proven, which is manifested in the anti-frost and anticorrosive effects as well in enhancement of electrical conductivity. The optimal composition of the additive with 7% of carbon nanotubes and 3% of calcium nitrate ensures a reduced electrical impedance of cement matrix. The electrical conductivity was 2440 Ohm, while the decrease of strength properties was within 10% in comparison tothe control sample. The nature of changes in the microstructure were studied to determine the influence of complex modifications that showed significant changes in the morphology of the hydration products. The optimum electrical characteristics of cementitious materials are provided due to the uniform distribution of carbon nanotubes and the formation of a network of interconnected micropores filled with the solution of calcium nitrate that provides additional and stable electrical conductivity over time.

Experimental and Computer Simulation Results for the Electrical Conductivity of Portland Cement Paste

1991 ◽  
Vol 245 ◽  
Author(s):  
B.J. Christensen ◽  
T.O. Mason ◽  
H.M. Jennings ◽  
D.P. Bentz ◽  
E.J. Garboczi
Keyword(s):  
Electrical Conductivity ◽  
Computer Simulation ◽  
Portland Cement ◽  
Cement Paste ◽  
Quantitative Agreement ◽  
Einstein Relation ◽  
Simulation And Experiment ◽  
Simulation Results ◽  
Ionic Diffusivity ◽  
Portland Cement Paste

ABSTRACTThe electrical conductivity of portland cement paste is an important transport property, especially since, when properly normalized by the pore fluid conductivity, it is equivalent to the normalized ionic diffusivity of the material via the Nernst-Einstein relation. This paper presents experimental and computer simulation results for σ/σo, where σ is the conductivity of the bulk paste as determined from impedance spectroscopy, and σo is the conductivity of the pore solution. Comparison between simulation and experiment is carried out for an 0.5 water:cement ratio white cement paste as a function of capillary porosity. The quantitative agreement between theory and experiment is reasonable.

Influence of chemical composition and inorganic admixtures on the electrical conductivity of hydrating cement pastes

1989 ◽  
Vol 4 (1) ◽  
pp. 215-223 ◽  
Author(s):  
M. Perez-Pena ◽  
D. M. Roy ◽  
F. D. Tamás
Keyword(s):  
Electrical Conductivity ◽  
Cementitious Materials ◽  
Heat Of Hydration ◽  
Chemical Compositions ◽  
Chemical Parameters ◽  
Cement Pastes ◽  
Rate Of Development ◽  
Wide Range ◽  
Physical And Chemical Parameters ◽  
Physical And Chemical

Electrical conductivity of cementitious materials with a wide range of chemical compositions has been studied during the first 24 h of hydration. Relationships between heat of hydration and electrical conductivity curves are discussed. Results are tentatively explained in terms of some physical and chemical parameters. Further evidence that the electrical conductivity of hydrating cement pastes is related to the hydration mechanisms operating in these systems was obtained. The order in which the cations of inorganic admixtures (chlorides and hydroxides) were found to increase the peak and rate of development of the electrical conductivity is the same order that they have been found to increase the heat liberated upon hydration of systems containing these admixtures.

A Novel Experimental Setup to Measure the Changes in Electrical Conductivity of Hydrating Cementitious Materials

1987 ◽  
Vol 114 ◽  
Author(s):  
J. Majling ◽  
P. Moses ◽  
M. Perez-Pena ◽  
D. M. Roy
Keyword(s):  
Electrical Conductivity ◽  
Capillary Forces ◽  
Cementitious Materials ◽  
Experimental Setup ◽  
Porous Bodies ◽  
Loose Powder

One of the alternative ways to fabricate shaped bodies from cementious materials would be to press the loose powder of materials (in steel dies, or isostatically) and to infiltrate them with liquids using the natural capillary forces of porous bodies [1,2].

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

Macromolecular structures of biological specimens are not obscured by controlled osmium impregnation

1983 ◽  
Vol 41 ◽  
pp. 606-607
Author(s):  
Klaus-Ruediger Peters ◽  
Samuel A. Green
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Critical Point ◽  
Metal Films ◽  
High Magnification ◽  
Osmium Impregnation ◽  
Instrumental Resolution ◽  
20 Nm ◽  
Continuous Metal

High magnification imaging of macromolecules on metal coated biological specimens is limited only by wet preparation procedures since recently obtained instrumental resolution allows visualization of topographic structures as smal l as 1-2 nm. Details of such dimensions may be visualized if continuous metal films with a thickness of 2 nm or less are applied. Such thin films give sufficient contrast in TEM as well as in SEM (SE-I image mode). The requisite increase in electrical conductivity for SEM of biological specimens is achieved through the use of ligand mediated wet osmiuum impregnation of the specimen before critical point (CP) drying. A commonly used ligand is thiocarbohvdrazide (TCH), first introduced to TEM for en block staining of lipids and glvcomacromolecules with osmium black. Now TCH is also used for SEM. However, after ligand mediated osinification nonspecific osmium black precipitates were often found obscuring surface details with large diffuse aggregates or with dense particular deposits, 2-20 nm in size. Thus, only low magnification work was considered possible after TCH appl ication.

Total Body Electrical Conductivity Measurements in the Neonate

1991 ◽  
Vol 18 (3) ◽  
pp. 611-627 ◽  
Author(s):  
Marta L. Fiorotto ◽  
William J. Klish
Keyword(s):  
Electrical Conductivity ◽  
Conductivity Measurements ◽  
Total Body
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