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.

scholarly journals Improving the Interfacial Bond Properties of the Carbon Fiber Coated with a Nano-SiO2 Particle in a Cement Paste Matrix

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Gwang-Hee Heo ◽  
Jong-Gun Park ◽  
Ki-Chang Song ◽  
Jong-Ho Park ◽  
Hyung-Min Jun ◽  
...  
Keyword(s):  
Surface Modification ◽  
Carbon Fiber ◽  
Cement Paste ◽  
Bond Properties ◽  
Interfacial Bond ◽  
Sio2 Particle ◽  
Nano Sio2 ◽  
Pull Out ◽  
Modification Method ◽  
Sio2 Particles

To improve the interfacial bond properties of the carbon fiber coated with a nano-SiO2 particle in a cement paste matrix, the present study proposed a method of coating nano-SiO2 particles on the surface of the carbon fiber by the chemical reaction of a silane coupling agent (glycidoxypropyltrimethoxysilane, GPTMS) and colloidal nano-SiO2 sol in an alkaline environment. To verify whether a nano-SiO2 particle was effectively modified on the surface of the carbon fiber, the surface morphology, chemical composition, and chemical structure were characterized and analyzed by several techniques such as the scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), and Fourier-transform infrared spectroscopy (FT-IR). Nano-SiO2 particles were entirely covered and uniformly distributed on the surface of the carbon fiber, resulting in the formation of a thin layer of nano-SiO2 particles. A thin layer of nano-SiO2 particles reacted with Ca(OH)2 to form a calcium-silicate-hydrate (C-S-H) gel, which is most helpful to increase the form between the fiber and the matrix. In addition, a pull-out test of the tow carbon fibers was performed to verify the effect of the new surface modification method on the interfacial bond properties of the carbon fiber embedded in the cement paste matrix. The experimental results showed that the frictional bond strength of the carbon fiber coated with a nano-SiO2 particle was significantly increased compared to the plain carbon fiber. These results were expected to improve the interfacial bonding force of hardened cement paste from the formation of the C-S-H gel produced through the chemical reaction of nano-SiO2 particles coated on the surface of the carbon fiber with Ca(OH)2. In particular, it was confirmed that the carbon fiber-reinforced cement paste (CFRCP) specimens coated with a nano-SiO2 particle and silica fume which replaced 10 wt.% of cement by mass showed the highest pull-out resistance performance at 28 days of age. The new surface modification method developed in this study can be very beneficial and helpful in improving the interfacial bond properties of CFRCP.

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.

Plain para-aramid/phenolic multiwall carbon nanotubes prepreg/multistiched preform composites: Experimental characterization of mode-I toughness

2018 ◽  
Vol 53 (13) ◽  
pp. 1847-1864 ◽  
Author(s):  
K Bilisik ◽  
E Sapanci
Keyword(s):  
Fracture Toughness ◽  
Multiwall Carbon Nanotubes ◽  
Beam Theory ◽  
Mode I ◽  
Multiwall Carbon Nanotube ◽  
Axial Filament ◽  
Pull Out ◽  
Fiber Bridging ◽  
Nanotube Composites ◽  
Multiwall Carbon

The fracture toughness (mode-I) properties of nanostitched para-aramid/phenolic multiwall carbon nanotube prepreg composites were investigated. The fracture toughness (GIC) of the stitching and nanostitched composites showed 42-fold and 41-fold (beam theory), 18-fold and 21-fold (modified beam theory) increase compared to the control, respectively. The prepreg para-aramid stitching yarn and nanostitched yarn were dominant parameters. The toughness resistance to arrest crack growth in the nanostitched composite was primarily due to nanostitching fiber bridging and pull-out, and was secondarily due to nanotubes and biaxial fiber bridging and pull-out. The failed surfaces of the nanostitched and stitching composites had tensile filament failures in the aramid stitching fibers where filament/matrix/nanotube debonding and axial filament fibrillar splitting were found. The results indicated that stitching yarn and the nanotubes arrested the crack propagation. Therefore, the nanostitched and stitched para-aramid/phenolic composites displayed a better damage resistance performance compared to those of the control or nanotube composites.

Effect of Cellulose Functionalization on Thermal and Mechanical Properties of Epoxy Resin

2017 ◽  
Vol 757 ◽  
pp. 62-67 ◽  
Author(s):  
Kritsanachai Leelachai ◽  
Supissara Ruksanak ◽  
Tarakol Hongkeab ◽  
Supakeat Kambutong ◽  
Raymond A. Pearson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Diglycidyl Ether ◽  
Cellulose Content ◽  
Thermal And Mechanical Properties ◽  
Chemical Surface ◽  
Pull Out ◽  
Fiber Bridging ◽  
Surface Modified ◽  
Modified Epoxy

In this study, diglycidyl ether of bisphenol A (DGEBA) cured cycloaliphatic polyamine was modified with functionalized celluloses for improved thermal and mechanical properties. Three different types of surface-modified cellulose, polyacrylamide-g-cellulose (PGC), aminopropoxysilane-g-cellulose (SGC), and carboxymethyl cellulose (CMC), were investigated and used as reinforcing agents in epoxy resins. The storage modulus of these modified epoxy systems was found to significantly increase with addition of cellulose fillers (up to 1 wt. % cellulose content). An improved fracture toughness (KIC) was also observed with increasing cellulose loading content with PGC and SGC. Among the surface-modified celluloses, epoxy modified with SGC was found to have the highest fracture toughness followed by PGC and CMC at 1.0 wt.% cellulose addition due to the chemical surface compatibility. The toughening mechanisms of the cellulose/epoxy composites, measured by scanning electron microscopy (SEM), revealed that fiber-debonding, fiber-bridging, and fiber-pull out were responsible for increased toughness.

scholarly journals Influence of Carbon Fiber Incorporation on Electrical Conductivity of Cement Composites

2020 ◽  
Vol 10 (24) ◽  
pp. 8993
Author(s):  
Ilhwan You ◽  
Seung-Jung Lee ◽  
Goangseup Zi ◽  
Daehyun Lim
Keyword(s):  
Electrical Conductivity ◽  
Electrical Resistivity ◽  
Carbon Fiber ◽  
Percolation Threshold ◽  
Cement Composite ◽  
Electrode Spacing ◽  
Cement Composites ◽  
Different Types ◽  
The Difference

This study investigated the effects of carbon fiber (CF) length, electrode spacing, and probe configuration on the electrical conductivity of cement composites. Accordingly, 57 different types of samples were prepared, considering three different CF lengths, five different CF contents, three different electrode spacings, and two different probe configurations. This research found that the influence of CF length on the electrical resistivity of cement composite depends electrode spacing. For the cement composite with wide electrode spacing of 40 mm, its resistivity decreased as increasing CF length as in the previous study. However, when the electrode spacing is 10 mm, which is narrow (10 mm), the resistivity of the cement composite rather increased with increasing CF length. The results implied that when an electrode is designed for the cement composite incorporating CF, the CF length should be short compared to the electrode spacing. The percolation threshold of CF measured by the two-probe configuration was 2% or more. This is higher than that measured by the four-probe configuration (1%). At a lower CF content than 2%, the two-probe configuration gave higher resistivity of the cement composite than the four-probe configuration. However, the difference coming from the different probe configurations was marginal as increasing the CF content.

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