Relationship between Alternated Current Impedance Spectrum and Microstructure of Graphene Enhanced Concrete

Abstract

This study presented experimental research on the alternating current (AC) impedance spectrum of graphene-enhanced cement matrix composites with dosage amounts of 0.1%, 0.2%, 0.4%, 0.8%, 1.6%, and 3.2%, respectively. The electrical properties were compared and analyzed with the Nyquist diagram, Bode diagram, and phase angle diagram. The microscopic pore structure was studied using mercury intrusion porosimetry (MIP) to establish the relationship between the pore structure parameters, the equivalent circuit fitting parameters of the AC impedance spectrum, and the mechanical properties. This study found that the incorporated graphene decreases the arc diameter of the impedance spectrum and causes the slope of the straight lines of the low-frequency region to drop. For the Bode curves, within low frequencies (1 Hz and 10 Hz), the impedance gradually increases as the graphene dosage increases. However, when the frequency is between 100 KHz and 1000 KHz, the impedance drops with an increase in the amount of graphene. According to the MIP test results, the proper incorporations of graphene increase the proportion of pores below 0.1 μm, which leads to a denser micro-structure and higher strength.