Effect of Power Ultrasound Assisted Mixing on Graphene Oxide in Cement Paste: Dispersion, Microstructure and Mechanical Properties

Dispersed graphene oxide incorporated into cement paste easily reaggregates in an alkaline environment, which is detrimental to the microstructure evolution and mechanical properties. In this study, a novel power ultrasound (PUS) assisted mixing technology was developed for optimizing the dispersion of graphene oxide in cement paste. X-ray computed tomography (X-CT) and Scanning electron microscopy-energy disperse spectroscopy (SEM-EDS) were used to characterize the distribution of graphene oxide. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and mercury intrusion porosimetry (MIP) were adopted to analyze the evolution of the hydration products. The results indicated that PUS-assisted mixing process improved the bonding ability between the Ca2+ and -COO- groups of graphene oxide. Moreover, applying PUS-assisted mixing decreased the average equivalent diameter of graphene oxide agglomerates by 9.9% at 1 day, alongside flexural and compressive strength increments of 26.6% and 3.2%, respectively at 1 day and 22.7% and 12.6%, respectively at 28 days compared with the reference group. The present research can provide a novel approach for the preparation of nanocarbon cement-based materials.