Effect of characteristics of assembly unit of CNT/NCB composite fillers on properties of smart cement-based materials

Electrostatic self-assembled CNT/NCB composite fillers with high CNT aspect ratio and large NCB size is incorporated into cement-based materials to develop smart cement-based composites. The mechanical, electrical and piezoresistive properties of the cement-based materials with CNT/NCB composite fillers are investigated. Percolation equation is used to describe electrically conductive property. Electrochemical impedance spectroscopy and equivalent circuits are used to explore the conductive and mechanical mechanism. The research results show that cement-based materials with CNT/NCB composite fillers at low content present acceptable mechanical property, high conductive property and stable and sensitive piezoresistive property. The fractional change of electrical resistivity, stress and strain sensitivity of cement-based materials with 1.41 vol.% CNT/NCB composite fillers can reach 13.4%, 3.12%/MPa and 521, respectively. It is concluded that high CNT aspect ratio and large NCB size in CNT/NCB composite fillers are beneficial for improving the properties of smart cement-based composites.