Contact electrical resistivity between cement and carbon fiber: Its decrease with increasing bond strength and its increase during fiber pull-out

1995 ◽  
Vol 25 (7) ◽  
pp. 1391-1396 ◽  
Author(s):  
Xuli Fu ◽  
D.D.L. Chung
Keyword(s):  
Electrical Resistivity ◽  
Carbon Fiber ◽  
Bond Strength ◽  
Pull Out

Study on Conductive Mechanism of Carbon Fiber Filled Cement-Based Composites

2011 ◽  
Vol 415-417 ◽  
pp. 1435-1438
Author(s):  
Xue Li Nan ◽  
Xiao Min Li
Keyword(s):  
Electrical Resistivity ◽  
Carbon Fiber ◽  
Cement Paste ◽  
Ionic Conduction ◽  
Strong Electrolyte ◽  
Pull Out ◽  
Fiber Bridging ◽  
Interface Contact ◽  
Conductive Mechanism ◽  
Conductive Properties

In order to investigate conductive mechanism of carbon fiber filled cement-based composites, the conductive properties of cement paste, carbon fiber filled cement-based composites containing different contents of carbon fibers or aggregates were studied. Experimental results indicate that the electrical resistance of the plain cement paste obviously increases with hydration time, which results from the ionic conduction in strong electrolyte solution. The electrical resistivity of the carbon fiber filled cement-based composites decreases with the increase of fiber content. Both contacting conduction and ionic conduction are in charge of the electrical conduction in these composites. The electrical resistivity of the carbon fiber filled cement-based composites decreases under compression, which is due to the improvement of interface contact between matrix and fibers and the increase of fiber bridging probability. The fiber pull-out and breaking under tension lead to an increase in electrical resistivity of these composites. Aggregates block fiber dispersion and contact. This causes an increase in electrical resistivity of the composites.

Interfaces Studied by Electromechanical Pull-Out Testing

1996 ◽  
Vol 458 ◽  
Author(s):  
Xuli Fu ◽  
D. D. L. Chung
Keyword(s):  
Electrical Resistivity ◽  
Bond Strength ◽  
Shear Bond Strength ◽  
Steel Fiber ◽  
Contact Resistivity ◽  
Matrix Interface ◽  
Preparation Conditions ◽  
Pull Out ◽  
Fiber Matrix Interface

ABSTRACTThe experimental technique of electromechanical pull-out testing is introduced to study the interface between fiber and matrix. The technique involves measuring both the contact electrical resistivity and the shear bond strength of a fiber-matrix interface. Samples that are identically prepared differ in contact resistivity and bond strength, which correlate. The correlation allows determination of even small differences in bond strength due to differences in sample preparation conditions. It also gives information on the structure of the interface and allows the bond strength to be nondestructively determined by measuring the contact resistivity. The technique is demonstrated for the interface between steel fiber and cement.

Experimental Research on Interfacial Bond Performance in Rock Anchor with High-Performance Grouting Medium

2012 ◽  
Vol 517 ◽  
pp. 932-938 ◽  
Author(s):  
Zhi Fang ◽  
Hong Qiao Zhang
Keyword(s):  
Rock Mass ◽  
Bond Strength ◽  
High Performance ◽  
Interfacial Bond ◽  
Interfacial Bond Strength ◽  
Bond Performance ◽  
Pull Out ◽  
Steel Bar ◽  
Reactive Powder ◽  
Ground Anchor

There exist the problems such as low bond strength and bad durability in the ordinary grouting slurry of the ground anchor system at present. The high-performance grouting mediums RPC (Reactive Powder Concrete) and DSP (Densified Systems containing homogeneously arranged ultrafine Particles) would become the potential replacement of grouting medium in ground anchor resulting from their high compressive strength, durability and toughness. Based on a series of pull-out tests on ground anchors with different high-performance grouting medium of RPC and DSP , different bond length in the construction field, the bond performance on the interfaces between anchor bolt (deformed steel bar) and grouted medium as well as between grouted medium and rock mass was studied. The results indicate that the interfacial bond strength between RPC or DSP and deformed steel bolt ranges within 23-31Mpa, far greater than that (about 2-3MPa) between the ordinary cementitious grout and deformed steel bar. Even though the interfacial bond strength between the grouted medium and rock mass of limestone was not obtained in the test since the failure mode was pull-out of those steel bar rather than the interface shear failure between grouted medium and rock mass, the bond stress on the interface reached 6.2-8.38 MPa, also far greater than the bond strength (about 0.1-3MPa) between the ordinary cementitious slurry and rocks.

Structural Health Monitoring for Carbon Fiber/Carbon Nanotube (CNT)/Epoxy Composite Sensor

2006 ◽  
Vol 321-323 ◽  
pp. 290-293 ◽  
Author(s):  
Sang Il Lee ◽  
Dong Jin Yoon
Keyword(s):  
Electrical Resistivity ◽  
Carbon Nanotube ◽  
Carbon Fiber ◽  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Epoxy Composite ◽  
Structural Safety ◽  
Structural Health ◽  
Nanotube Composites ◽  
Carbon Fiber Epoxy

Structural health monitoring for carbon nanotube (CNT)/carbon fiber/epoxy composite was verified by the measurement of electrical resistivity. This study has focused on the preparation of carbon nanotube composite sensors and their application for structural health monitoring. The change of the electrical resistance was measured by a digital multimeter under tensile loads. Although a carbon fiber was broken, the electrical connection was still kept by distributed CNT particles in the model composites. As the number of carbon fiber breakages increased, electrical resistivity was stepwise increased. The CNT composites were well responded with fiber damages during the electro-micromechnical test. Carbon nanotube composites can be useful sensors for structural health monitoring to diagnose a structural safety and to prevent a collapse.

Size Effect on the Bond Behavior of Grouted Reinforcing Bars Embedded in Light-weight Concrete

2021 ◽  
Author(s):  
Aamer Abbas ◽  
◽  
Yaqoob Yaqoob ◽  
Ola Hussein ◽  
Ibrahim Al-Ani ◽  
...  
Keyword(s):  
Bond Strength ◽  
Concrete Specimen ◽  
Light Weight ◽  
Reinforcing Bars ◽  
Conventional Concrete ◽  
Bond Behavior ◽  
Pull Out ◽  
Specimen Width ◽  
Light Weight Concrete ◽  
The Relationship

This study presents experimentally the bond behavior of light-weight concrete specimens with grouted reinforcing bars in comparison with conventional concrete specimens. A total of (9) pull-out specimens were studied; (3) specimens of conventional concrete, (3) specimens of light-weight concrete, and other (3) specimens of grouted light-weight concrete. Two variables are adopted in this investigation: specimen width and type of concrete (conventional concrete, light-weight concrete and grouted light-weight concrete). The study contains a discussion of the general behavior of the specimens in addition to the study of the ultimate bond capacity, maximum bond stresses and the relationship between the stress and the slip for different pull-out specimens. Results show that bond strength is highest for the largest specimen size (bond strength of grouted light-weight concrete specimen with specimen width 400 mm is higher than that of the specimen with (200 mm) width by about (13.13%)). Also, bond strength is highest for the grouted light-weight concrete specimen (bond strength of grouted light-weight concrete specimen is higher than conventional concrete specimen by (11.11%)).

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