Multifunctionality of cement based composite with electrostatic self-assembled CNT/NCB composite filler

In this paper, electrostatic self-assembled carbon nanotube (CNT)/nanocarbon black (NCB) composite is employed as filler for developing multifunctional cement-based composites. The performances of the composites with different content of filler are investigated. The electrochemical impedance spectroscopy and equivalent circuit are used to explore the conductive and mechanical mechanisms of the composites. Experimental results indicate that the compressive strength and elasticity modulus of the composites sharply decrease when the filler content exceeds 0.77 vol.%. The percolation threshold zone of the electrical conductivity of the composites ranges from 0.39 vol.% to 1.52 vol.%. The piezoresistive properties of the composites with 2.40 vol.% filler are stable and sensitive, and the maximum fractional change of electrical resistivity is 25.4% when the stress amplitude is 10 MPa. The composites feature sensitive and linear thermal resistance effect when the filler content is 0.77 vol.%. Electromagnetic shielding effectiveness of the composites with 2.40 vol.% filler at 18 GHz is 5.0 dB, which is 2.2 times of that of the control samples. The composites exhibit high absorbing electromagnetic wave performances in the frequency range of 2-18 GHz, and the minimum reflectivity reaches −23.08 dB with 0.77 vol.% filler.