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Smart Structures and Systems Volume 18, Number 2, August 2016 , pages 217-231 DOI: https://doi.org/10.12989/sss.2016.18.2.217 |
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Percolation threshold and piezoresistive response of multi-wall carbon nanotube/cement composites |
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I.W. Nam, H. Souri and H.K. Lee
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| Abstract | ||
| The present work aims to develop piezoresistive sensors of excellent piezoresistive response attributable to change in nanoscale structures of multi-wall carbon nanotube (MWNT) embedded in cement. MWNT was distributed in a cement matrix by means of polymer wrapping method in tandem with the ultrasonication process. DC conductivity of the prepared samples exhibited the electrical percolation behavior and therefore the dispersion method adopted in this study was deemed effective. The integrity of piezoresistive response of the sensors was assessed in terms of stability, the maximum electrical resistance change rate, and sensitivity. A composite sensor with MWNT 0.2 wt.% showed the lowest stability and sensitivity, while the maximum electrical resistance change rate exhibited by this sample was the highest (96 %) among others and even higher than those found in the literature. This observation was presumably attributed by the percolation threshold and the tunneling effect. As a result of the MWNT content (0.2 wt.%) of the sensor being near the percolation threshold (0.25 wt.%), MWNTs were close to each other to trigger tunneling in response of external loading. The sensor with MWNT 0.2 wt.% was able to maintain the repeatable sensing capability while sustaining a vehicular loading on road, demonstrating the feasibility in traffic flow sensing application. | ||
| Key Words | ||
| piezoresistive sensor; multi-wall carbon nanotube; cement composite; percolation threshold; sensitivity and stability | ||
| Address | ||
| I.W. Nam: Infrastructure Research Center, K-water Institute, 125, 1689 beon-gil, Youseongdae-ro, Yuseong-gu, Daejeon 34045, Republic of Korea H. Souri: Center of Advanced Composite Materials (CACM), Department of Mechanical Engineering, The University of Auckland, Khyber pass road, New market, Auckland 1010, New Zealand H.K. Lee: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea | ||