Evaluation of the effects of sonication energy on the dispersion of carbon black nanoparticles (CBN) and properties of self-sensing cementitious composites

Good dispersion of nanomaterials within cementitious matrices provides cementitious nanocomposites with stable and replicable properties. Improved dispersion also increases the number of conductive paths and improves the material's mechanical properties. Despite this, there has been no previous research investigating the effects of variation of sonication energy on the electromechanical properties of self-sensing mortars. Thus, the aim of this study was to carry out a combined evaluation of the electromechanical and rheological behavior of cementitious sensors, supported by a comprehensive analysis of the dispersion quality of nanosuspensions using four different techniques: Dynamic Light Scattering (DLS), Zeta Potential, Ultraviolet–visible Spectroscopy (UV-VIS) and Field Emission Gun – Scanning Electron Microscope (FEG-SEM). The electromechanical and rheological behavior of the Cement Composite Nanomodified Sensors (CCNSs) performed best in the sonication energy range of 120 J/mL to 240 J/mL. The zeta potential, UV-VIS absorption and DLS measurements used to analyze the nanosuspensions enabled a satisfactory assessment of the degree of CBN dispersion. All results suggested that sonication energies of around 240 J/mL were responsible for producing nanosuspensions with the most efficient dispersions. Sonication energies of this magnitude were also able to optimize the electromechanical and rheological characteristics of the CCNSs. The main contributions originated from this work are related to the combined evaluation of the mechanical, electrical, and rheological behavior of mortars produced with CBN, the analysis of the quality of the CBN dispersion provided by different sonication energy levels and identification of the optimum sonication energy for the production of CCNS containing CBN.