Improving conductivity and self-sensing properties of magnetically aligned electroless nickel coated glass fiber cement

Abstract

The nickel coated glass fiber (Ni-GF) cement (NGFC) holds promise for self-sensing concrete structure due to its improved conductivity and corrosion resistance. This paper is aimed at evaluating the conductivity and self-sensing properties of preferentially orientated NGFC, which was prepared by the magnetic field (MF) induction. The microstructure of electroless Ni-GFs and their arrangement characteristic in cement were observed by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The anisotropic conductivity and self-sensing properties of as-prepared composites were measured by four-electrode method. The results indicate that the Ni-GFs with uniform nickel coating layer in the as-fabricated composite have an excellent alignment effect under the MF induction. When the Ni-GF content is 2.62 vol%, the composite exhibits maximum anisotropy. The order of the electrical resistivity and percolation thresholds of NGFC is: parallel to MF < without MF < perpendicular to MF. Under the cyclic compression load, the NGFC parallel to MF shows the optimum self-sensing properties. With the increase of loading amplitude and decrease of loading rate, the maximum sensitivities of the as-prepared composite at all directions almost increase linearly. Under the failure compression load, the conductivity of as-prepared composites parallel to MF show a steadier and higher self-sensing response.