Electrical properties of carbon nanotubes filled cementitious composites

Twelve types of multi-walled carbon nanotubes (MWCNTs) at contents of 0.1%, 0.5% and 0.8% were incorporated into cementitious composites. A new method to calculate the electrical resistivity of these composites was proposed. The effects of MWCNT types and contents on electrical resistivity and electrochemical impedance spectroscopy (EIS) of cementitious composites were investigated. The equivalent circuit model of cementitious composites with different types of MWCNTs was established. Experimental results showed the proposed calculation method of electrical resistivity is accurate because it can eliminate the contact resistance between electrodes and cement matrix. The introduction of different types of MWCNTs at suitable contents all can decrease the electrical resistivity of cementitious composites. The maximal relative/absolute decrease of 63.8%/125.42 Omega . m is achieved by incorporating 0.8% of nickel-coated MWCNTs. The topological structure of AC-EIS can be changed when 0.8% long-length and large-diameter untreated MWCNTs is introduced into cementitious composites. The equivalent circuit model of MWCNTs filled cementitious composites is R-s(Q1(R1W1))(Q2(R2W2))(Q3R3). Based on this established model, the AC-EIS calculated values can well match with the AC-EIS measured values of cementitious composites incorporating different types of MWCNTs.