Aligning conductive particles using magnetic field for enhanced piezoresistivity of cementitious composites

The electrical and mechanical properties of the cement-based composites with magneto-aligned nickel powder are investigated in this study. The microstructure of the conductive pattern is examined by scanning electron microscope (SEM) and X-ray computed tomography (CT) scanning. It demonstrates that with the intervention of magnetic field, the electrical resistivity drops significantly and percolation threshold of the composites reaches at a lower filler concentration. The problems of high filler usage, low flowability and strength exists in the composites with randomly dispersed nickel particles can be addressed using the proposed method. Additionally, investigation on the influence of magnetic field intensity and duration shows that by adjusting these key parameters, the piezoresistive performance of the cementitious composites can be lifted. Under the superior piezoresistivity, giant gauge factor of the cement sensors is achieved which demonstrates an ability of stress/strain monitoring with high sensitivity.