Carbon nanotube (CNT)/cement composites with different concentration levels of multi-walled CNT (MWNT) and water/cement ratios are fabricated. By comparing the responses of electrical resistance of these CNT/cement composites to compressive stress, the effects of MWNT concentration level and water/cement ratio on the piezoresistive sensitivity of composites are investigated. Experimental results indicate that the piezoresistive sensitivities of CNT/cement composites with 0.05, 0.1, and 1 wt% of MWNT first increase and then decrease with the increase of CNT concentration levels. Water/cement ratio is another factor that affects the composite properties, the electrical resistance of CNT/cement composite with 0.6 water/cement ratio is more sensitive to compressive stress than that of composite with 0.45 water/cement ratio. The piezoresistive sensitivity is heavily dependent on the conductive network in the composites, which in turn is influenced by the CNT concentration level and water/cement ratio.
Bibliographical noteFunding Information:
The authors thank the funding supported from the US National Science Foundation (CMMI-0856477), Federal Highway Administration (FHWA) of US Department of Transportation (DTFH61-10-C-00011), the Northland Advanced Transportation Systems Research Laboratory (NATSRL) of the University of Minnesota Duluth, and ITS of the University of Minnesota. This study is also partially supported by National Science Foundation of China (grant no. 50808055), the Ministry of Science and Technology of China (grant no. 2006BAJ03B05), and Natural Scientific Research Innovation Foundation in Harbin Institute of Technology (grant no. HIT. NSRIF. 2009096).
- CNT concentration level
- CNT/cement composites
- water/cement ratio