This paper concentrates on conductive composites with conductive fillers and their use for strain sensing based on piezoresistivity. Percolation curves of resistivity were summarized and validated as the basic for the design of such conductive composites-made piezoresistivity-based strain sensors, with percolation zoon and percolation slope as the key. A detailed comparison between cement-based and resin-based conductive composites with fibrous and particulate fillers were made and discussed in this work for further understanding the design of such sensors based on percolation curves. Magnetic field was introduced as an extrinsic factor for the design of the percolation curves and further for the design of such sensors’ piezoresistivity curves, which was proved to be quite an effective way. Concluded speaking, when making more full use of the designability of percolation curves, we can make better strain sensors used for structural health monitoring.
This paper investigates a scouring sensor using electrical properties of carbon nanotubes(CNTs)-filled cement-based composite. First, for specimens filled with different amount of CNTs, the electrical behavior and the principle which it followed were studied. The effect of the different magnetic field intensity on the arrangement of CNTs in the base was presented. Furthermore, the environment effects (temperature and humidity) on sensors and its causes were revealed. Also, the design of the temperature and humidity self-compensation sensor based on separated electrode was proposed. Finally, by comparison of the sensitivity of the scouring electrode and the stability of the reference electrode, the optimal scheme of the electrode was determined.
This paper investigates properties about electrical resistivity and piezoresistivity of multi-wall carbon nanotubes (MWCNTs)-filled epoxy-based composite and its further use for strain sensing. The MWCNTs dispersed epoxy resin, using MWCNTs in the amount of 1.5~3.0 vol.%, was first prepared by combined high-speed stirring and sonication methods. Then, the MWCNTs dispersed epoxy resin was cast into an aluminum mold to form specimens measuring 10×10×36 mm. After curing, DC electrical resistance measurements were performed along the longitudinal axis using the four-probe method, in which copper nets served as electrical contacts. The percolation threshold zone of resistivity was got as MWCNTs in the amount of 2.00–2.50 vol.%. Further compressive testing of these specimens was conducted with four-probe method for resistance measurements at the same time. Testing results show that the electrical resistivity of the composites changes with the strain’s development, namely piezoresistivity. While for practical strain sensing use, signals of electric resistance and current in the acquisition circuits were both studied. Results show that the signal of current, compared with that of resistance, had better linear relationship with the compressive strain, better stability and longer effective section to reflect the whole deformation process of the specimens under pressure. Further works about the effects of low magnetic field on the electrical resistivity and piezoresistivity of Ni-CNTs filled epoxy-based composites were presented briefly at the end of the paper.
The ductility of high strength nano-TiO2 reinforced cement-based composites were experimentally studied and compared
with that of plain cement-based composite and cement-based composite containing silica fume by stress-strain
relationship. The results showed that the ductility of high strength cement-based composite containing nano-TiO2 were
better than that of plain cement-based composite and cement-based composite containing silica fume, which
demonstrated that it is an available and effective way to improve ductility of high strength cement-based composite by
means of mixing nanophase materials into cement-based composite. The origin of nanoparticles improving ductility of
high strengthen cement-based composite was also preliminary interpreted.
Cement-based composite filled with nanophase carbon black (CCN) was found the promising strain sensor material
candidate. Experimental results showed that temperature had obviously influence on the initial resistivity of CCN, but
nearly no effect on the strain-sensing property of CCN. Resistivity of CCN decreases linearly upon compressive strain,
and the strain gauge factors measured under various temperatures were all about 55. Strain sensor was made with CCN
and applied in concrete beam for strain monitoring, the results monitored by CCN sensor agreed well with that of strain
gauge. The results of this paper suggested CCN sensor a practicable strain sensor.
Cement-based composites filled with carbon black of 120nm size were prepared, the composites contained 15% amount of CB was in the percolation threshold, and it showed good strain sensing ability, the resistivity of composites changed linearly with applied strain, suggesting that this kind of composites was a promising candidate for strain sensor used in concrete structures. Water ratio has obviously influences on the initial resistivity of the composites. Epoxy encapsulated was found a practicable way to insulate the composites from water, and make the resistance measurement practicable. Strain senser was maken with the composite contained 15% amount of CB, and applied in concrete column for strain monitoring, the results showed that the strain of the concrete column could be monitored by this kind of sensor.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.