Experimental Examination of Electrical Characteristics for Portland Cement Mortar Frost Damage Evaluation

Electrical measurements are promising for evaluation of frost damage of concrete, but the index is still controversial. In this paper, to propose an efficient index, various electrical characteristics were examined to correlate them with the mechanical property degradation of meso-scale mortar samples due to combined effects of sodium chloride and freeze–thaw cycles (FTCs). While the electrical responses of specimens were measured during FTCs, the mechanical properties were obtained from three-point bending tests after FTCs. Typical microstructural change after the damage was also analyzed by using a water absorption test. The results showed that no clear degradation tendency was observed for electrical resistivity at the lowest temperature, the activation energy or the freezing/thawing point change with the FTCs. The reduction in electrical resistivity at reference temperature has a consistent tendency with that of elastic modulus and flexural strength, thus can be an efficient index for quantitative frost damage evaluation. The change due to salt-frost damage is mainly due to the increase of connectivity rather than porosity.

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Silicon Surface Chemical Treatments in Oxide/Nitride Dielectric Stack Properties

MRS Proceedings ◽

10.1557/proc-716-b7.8 ◽

2002 ◽

Vol 716 ◽

Author(s):

D. Jacques ◽

S. Petitdidier ◽

J.L. Regolini ◽

K. Barla

Keyword(s):

Oxygen Content ◽

Oxide Thickness ◽

Morphological Data ◽

Electrical Characteristics ◽

Electrical Measurements ◽

Chemical Cleaning ◽

Force Microscopy ◽

Chemical Treatments ◽

Atomic Force ◽

Interfacial Oxygen

AbstractOxide/Nitride dielectric stack is widely used as the standard dielectric for DRAM capacitors. The influence of the chemical cleaning prior to the stack formation has been studied in this work. As a result, morphological data such as stack surface roughness (Atomic Force Microscopy) and silicon nitride (SiN) incubation time for growth are comparable for all the studied cases on <Si>. However, Tof-SIMS exhibits different oxygen content at the Si/stack interface following the different chemical treatments. Electrical measurements show comparable C-V and I-V results, for the same Equivalent Oxide Thickness (same capacitance at strong accumulation i.e.-3V) while the different studied interfaces bring different interface states density with lower values for higher interfacial oxygen content. For DRAM applications, a clear improvement in electrical characteristics is obtained under low interfacial oxygen content conditions. Results are compared in embedded-DRAM cells for which we developed an industrially compatible dielectric deposition sequence to obtain minimum leakage current with maximum specific capacitance and no particular linking constraints.

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Investigation of the Deformation Twins on the Bending Cross Section of TA2 Titanium Sheet

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.837.41 ◽

2020 ◽

Vol 837 ◽

pp. 41-45

Author(s):

Shuai Sun ◽

Kai Hua Liu

Keyword(s):

Electron Backscatter Diffraction ◽

Testing Machine ◽

Pure Titanium ◽

Titanium Sheet ◽

Bending Tests ◽

Three Point Bending ◽

Deformation Twins ◽

Ebsd Technique ◽

Backscatter Diffraction ◽

Deformation Area

In order to determine the evolution features of deformation twins for TA2 commercial pure titanium (cp-TA2), the TA2 samples were bent under different bending angles in three-point bending tests via a universal testing machine. The electron backscatter diffraction (EBSD) technique was applied to identify the grain boundaries (GBs) and twin boundaries (TBs) in the bending areas. The results reveal that the type of deformation area would effect the evolution of different deformation twins. It is inferred that the state of stress would promote the multiplication of the same type of deformation twins.

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Electromechanical Response of Smart Ultra-High Performance Concrete under External Loads Corresponding to Different Electrical Measurements

Sensors ◽

10.3390/s21041281 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1281

Author(s):

Min Kyoung Kim ◽

Huy Viet Le ◽

Dong Joo Kim

Keyword(s):

Electrical Resistivity ◽

High Performance ◽

High Performance Concrete ◽

Steel Slag ◽

Measurement Methods ◽

Electrical Measurements ◽

Ultra High Performance Concrete ◽

Ac Measurement ◽

External Loads ◽

Functional Fillers

This study investigated the electromechanical response of smart ultra-high-performance concretes (smart UHPCs), containing fine steel slag aggregates (FSSAs) and steel fibers as functional fillers, under external loads corresponding to different measurement methods. Regardless of different measurement methods of electrical resistance, the smart UHPCs under compression showed a clear reduction in their electrical resistivity. However, under tension, their electrical resistivity measured from direct current (DC) measurement decreased, whereas that from alternating current (AC) measurement increased. This was because the electrical resistivity, from DC measurement, of smart UHPCs was primarily dependent on fiber crack bridging, whereas that from AC measurement was dependent on tunneling effects.

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A Study of the Flexural Behavior of Fiber-Reinforced Concretes Exposed to Moderate Temperatures

Materials ◽

10.3390/ma14133522 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3522

Author(s):

Marta Caballero-Jorna ◽

Marta Roig-Flores ◽

Pedro Serna

Keyword(s):

Steel Fiber ◽

Flexural Behavior ◽

Polypropylene Fibers ◽

Fiber Reinforced ◽

Insulation System ◽

Bending Tests ◽

Synthetic Fibers ◽

Three Point Bending ◽

Lower Performance ◽

Cracked Specimens

The use of synthetic fibers in fiber-reinforced concretes (FRCs) is often avoided due to the mistrust of lower performance at changing temperatures. This work examines the effect of moderate temperatures on the flexural strengths of FRCs. Two types of polypropylene fibers were tested, and one steel fiber was employed as a reference. Three-point bending tests were carried out following an adapted methodology based on the standard EN 14651. This adapted procedure included an insulation system that allowed the assessment of FRC flexural behavior after being exposed for two months at temperatures of 5, 20, 35 and 50 °C. In addition, the interaction of temperature with a pre-cracked state was also analyzed. To do this, several specimens were pre-cracked to 0.5 mm after 28 days and conditioned in their respective temperature until testing. The findings suggest that this range of moderate temperatures did not degrade the behavior of FRCs to a great extent since the analysis of variances showed that temperature is not always a significant factor; however, it did have an influence on the pre-cracked specimens at 35 and 50 °C.

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Utilization of Dacite as Alternative Aggregate in Asphalt Mixture

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.509.209 ◽

2012 ◽

Vol 509 ◽

pp. 209-214

Author(s):

Shao Peng Wu ◽

Pan Pan ◽

Ming Yu Chen

Keyword(s):

Asphalt Mixture ◽

Asphalt Mixtures ◽

Major Objective ◽

Widespread Application ◽

Bending Tests ◽

Three Point Bending ◽

Large Numbers ◽

Asphalt Content ◽

The Cost ◽

Cost Of Construction

With the widespread application of asphalt mixture, current demand from transportation managers for construction and maintenance of their pavement network consumes large numbers of aggregates. If agencies excessively favor to some certain kinds of excellent aggregates, the cost of construction could be considerably expensive. The major objective of this study is to determine the feasibility of utilizing dacite in asphalt mixtures. By means of Marshall, freeze-thaw, rutting and three-point bending tests, the performances of dacite and basalt asphalt mixture are compared. The results of the testing illustrate that dacite asphalt mixture is more susceptible to gradation and asphalt content than basalt asphalt mixture. Meanwhile it is showed that the performances of dacite asphalt mixture can be improved greatly with the involvement of additives including active mineral powder and cement. Furthermore, it is validated that dacite can be used as alternative aggregate in asphalt mixture.

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