Investigation of Fracture and Electrical Resistivity Parameters of Cementitious Composite for their Utilization in Deterioration Models

2013 ◽  
Vol 577-578 ◽  
pp. 265-268 ◽  
Author(s):  
Václav Veselý ◽  
Petr Konečný ◽  
Petr Lehner ◽  
Přemysl Pařenica ◽  
Jan Hurta ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Crack Length ◽  
Fracture Process ◽  
Bending Test ◽  
Resistivity Measurements ◽  
Structural Durability ◽  
Notch Length ◽  
Fracture Tests ◽  
Length Changes ◽  
Concrete Resistivity

The paper is focusing on the investigation of the effective crack length obtained from bending test on concrete notched beams with the complementary measurements of electrical resistivity of the tested concrete. The electrical resistivity measurements are performed on several stages of the fracture process along the specimen ligament for each tested notched beam. Gained results of the concrete resistivity during the fracture process, i.e. its dependence on the crack length or opening, provide information which should be taken into account in structural durability analyses. The fracture tests are conducted for a set of specimens differing in the notch length. Changes of the concrete resistivity with increasing effective crack length are observed and discussed.

Investigation of Selected Physical Parameters of Cementitious Composite during Sequential Fracture Test

2014 ◽  
Vol 969 ◽  
pp. 228-233 ◽  
Author(s):  
Petr Konečný ◽  
Václav Veselý ◽  
Petr Lehner ◽  
Daniel Pieszka ◽  
Libor Žídek
Keyword(s):  
Crack Length ◽  
Concrete Specimen ◽  
Bending Test ◽  
Physical Parameters ◽  
Fracture Test ◽  
Notch Length ◽  
Fracture Tests ◽  
Length Changes ◽  
Pass Through ◽  
Ultrasound Pulse

The paper is focusing on the investigation of the effective crack length obtained from bending test on concrete notched beams with the complementary measurements of ultrasound passing time through the tested concrete specimen. The ultrasound passing time measurements are performed on several stages of the fracture process along the specimen ligament for each tested notched beam. Gained results of the time of ultrasound pulse needed to pass through specimens' failure zone, i.e. its dependence on the crack length or opening, provide information which may help to identify the process of crack formation without the visible indications. The fracture tests are conducted for a set of specimens differing in the notch length. Changes of the ultrasound passing times with increasing effective crack length are observed and discussed.

scholarly journals Electrical Resistivity Measurements of Reinforced Concrete Slabs with Delamination Defects

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7113
Author(s):  
Kevin Paolo V. Robles ◽  
Dong-Won Kim ◽  
Jurng-Jae Yee ◽  
Jin-Wook Lee ◽  
Seong-Hoon Kee
Keyword(s):  
Electrical Resistivity ◽  
Reinforced Concrete ◽  
Concrete Slab ◽  
Experimental Studies ◽  
Element Model ◽  
Concrete Slabs ◽  
Reinforced Concrete Slab ◽  
Resistivity Measurements ◽  
Reinforced Concrete Slabs ◽  
Concrete Resistivity

The main objectives of this research are to evaluate the effects of delamination defects on the measurement of electrical resistivity of reinforced concrete slabs through analytical and experimental studies in the laboratory, and to propose a practical guide for electrical resistivity measurements on concrete with delamination defects. First, a 3D finite element model was developed to simulate the variation of electric potential field in concrete over delamination defects with various depths and lateral sizes. Second, for experimental studies, two reinforced concrete slab specimens (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)) with artificial delamination defects of various dimensions and depths were fabricated. Third, the electrical resistivity of concrete over delamination defects in the numerical simulation models and the two concrete slab specimens were evaluated by using a 4-point Wenner probe in accordance with AASHTO (American Association of State Highway and Transportation Office) T-358. It was demonstrated from analytical and experimental studies in this study that shallow (50 mm depth) and deep (250 mm depth) delamination defects resulted in higher and lower electrical resistivity (ER) values, respectively, as compared to measurements performed on solid concrete locations. Furthermore, the increase in size of shallow defects resulted in an increase in concrete resistivity, whereas the increase in sizes of deep delamination defects yielded opposite results. In addition, measurements done directly above the steel reinforcements significantly lowered ER values. Lastly, it was observed from experimental studies that the effect of delamination defects on the values of electrical resistivity decreases as the saturation level of concrete increases.

In-situ electrical-resistivity measurements in the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 68-69
Author(s):  
W. E. King
Keyword(s):  
Electrical Resistivity ◽  
Electron Microscope ◽  
High Voltage ◽  
Resistivity Measurements ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Wide Range ◽  
Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

scholarly journals Electrical Resistivity Measurements and Soundings on Glaciers: Introductory Remarks

1967 ◽  
Vol 6 (47) ◽  
pp. 599-606 ◽  
Author(s):  
Hans Röthlisberger
Keyword(s):  
Electrical Resistivity ◽  
Resistivity Measurements ◽  
Resistivity Method

A brief description of the resistivity method is given, stressing the points which are of particular importance when working on glaciers. The literature is briefly reviewed.

Effect of Concrete Mixture Composition on Acoustic Emission and Fracture Parameters Obtained from Three-Point Bending Test

2015 ◽  
Vol 1100 ◽  
pp. 152-155
Author(s):  
Libor Topolář ◽  
Hana Šimonová ◽  
Petr Misák
Keyword(s):  
Acoustic Emission ◽  
Bending Test ◽  
Mixture Composition ◽  
Three Point Bending ◽  
Concrete Mixtures ◽  
Fracture Parameters ◽  
Fracture Tests ◽  
Stress Behaviour ◽  
Bending Fracture ◽  
Fracture Processes

This paper reports the analysis of acoustic emission signals captured during three-point bending fracture tests of concrete specimens with different mixture composition. Acoustic emission is an experimental tool well suited for monitoring fracture processes in material. The typical acoustic emission patterns were identified in the acoustic emission records for three different concrete mixtures to further describe the under-the-stress behaviour and failure development. An understanding of microstructure–performance relationships is the key to true understanding of material behaviour. The acoustic emission results are accompanied by fracture parameters determined via evaluation of load versus deflection diagrams recorded during three-point bending fracture tests.

STUDY OF THE DEPENDENCE OF HIGH Tc ON VARIOUS SINTERING TEMPERATURES FOR Bi-Pb-Sr-Ca-Cu-O SUPERCONDUCTORS

1991 ◽  
Vol 05 (24n25) ◽  
pp. 1635-1638
Author(s):  
S.M. M.R. NAQVI ◽  
A.A. QIDWAI ◽  
S.M. ZIA-UL-HAQUE ◽  
FIROZ AHMAD ◽  
S.D.H. RIZVI ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Liquid Nitrogen ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
Resistivity Measurements ◽  
Zero Resistance

Bi1.7-Pb0.3-Sr2-Ca2-Cu3-Ox superconducting samples were prepared at 855°C, 862 C, 870 C, and 882 C sintering temperatures respectively. All samples were sintered for 120 hours. The samples were then quenched in liquid nitrogen. The electrical resistivity measurements showed that the samples sintered at 870° C had the best Tc. For these samples the Tc onset was around 120 K and the zero resistance was obtained at 108 K. X-ray diffraction studies showed that the samples were multiphased.

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