Fabrication and piezoresistivity of self-sensing Ni nanowire/cement composites

Nickel nanowires were obtained using the porous alumina template by the alternating current electro-deposition method. For the first time, the Ni nanowire/cement composites were fabricated by using the as-obtained nanowires as the conductive filler, and the polycarboxylate superplasticizer as the dispersant. The microstructures of Ni nanowires and Ni nanowires/cement composites were studied by SEM, TEM and XRD. Besides, the percolation threshold and piezoresistivity of Ni nanowires/cement composites were investigated by the four-pole method. The results indicate that the diameter of as-obtained Ni nanowires is about 65 nm and the aspect ratio is about 50. Also, the polycarboxylate superplasticizer can effectively improve the dispersion of Ni nanowires. In addition, the resistivity of cement-based composites displays the typical features of percolation phenomena with the increase of Ni nanowires content, the percolation threshold is concluded to be 0.5vol%. Furthermore, the measured gage factor of Ni nanowires/cement composites with 1.0vol% Ni nanowires is 509.2, far higher than the value of 2.0 for the resistance-strain gauge. The Ni nanowires/cement composites are promising for the application as the stress sensor in the concrete structures.