In this work, graphene nanoplatelets (GNPs) were dispersed uniformly in aqueous solution using methylcellulose (MC) as a dispersing agent via ultrasonic processing. Homogenous GNP suspensions were incorporated into the cement matrix to investigate the effect of GNPs on the mechanical behavior of cement paste. The optimum concentration ratio of GNPs to MC was confirmed as 1:7 by ultraviolet visible spectroscopy (UV-Vis), and the optical microscope and transmission electron microscopy (TEM) images displayed remarkable dispersing performance. The GNP–cement composite exhibited better mechanical properties with the help of surface-modified GNPs. The flexural strength of cement paste increased up to 15%–24% with 0.05 wt % GNPs (by weight of cement). Meanwhile, the compressive strength of the GNP–cement composite increased up to 3%–8%. The X-ray diffraction (XRD) and thermal analysis (TG/DTG) demonstrated that the GNPs could accelerate the degree of hydration and increase the amount of hydration products, especially at an early age. Meanwhile, the lower porosity and finer pore size distribution of GNP–cement composite were detected by mercury intrusion porosimetry (MIP). In addition, scanning electron microscope (SEM) analysis showed the introduction of GNPs could impede the development of cracks and preserve the completeness of the matrix through the plicate morphology and tortuous behavior of GNPs.

Preparation of homogeneously dispersed graphene has significant impact on its applications. In this research paper, graphene nanoplatelets (GNPs) were uniformly dispersed in an aqueous solution by means of sonication with methylcellulose (MC) as a dispersant. The dispersing performance of GNP suspension was characterized by a variety of techniques, including standing test, optical microscope study, UV-Vis absorbance, adsorption isotherm of MC on GNPs. Meanwhile, the microstructure of GNPs was represented using transmission electron microscope (TEM). Results demonstrated that the best dispersion was achieved with MC addition of 0.7 g/L; it is meaning that the optimum concentration ratio of GNPs to MC is 1:7. The TEM micrographs showed that the agglomeration of layers was broken up and the thickness of GNPs was weakened by introducing MC. In addition, the dispersing mechanism was also discussed. The surface of GNPs was coated by the MC molecules, the steric hindrance was formed on account of hydrophobic and hydrophilic groups of surfactant to overcome the Van der waals attractive force between the layers of GNPs effectively, the homogeneous GNP suspension is achieved.

In this work, graphene nanoplatelets (GNPs) were dispersed uniformly in aqueous solution using Methylcellulose (MC) as dispersing agent by ultrasonic processing. And the homogenous GNP suspensions were incorporated to cement matrix to investigate the effect of GNPs on the mechanical behavior of cement paste. The optimum concentration ratio of GNPs to MC was confirmed as 1:7 by ultraviolet visible spectroscopy (UV-vis), the optical microscope and transmission electron microscopy (TEM) images displayed the remarkable dispersing performance. The GNP-cement composite showed higher mechanical properties with the help of surface-modified GNPs. The flexural strength of cement paste increased up to 15%-24% with 0.05wt% GNPs (by weight of cement). Meanwhile, the compressive strength of the GNP-cement composite increased up to 3%-8%. The X-ray diffraction (XRD) and thermal analysis (TG/DSC) demonstrated that the GNPs could accelerate the degree of hydration and increase the amount of hydration products, especially at the early age. Meanwhile, the lower porosity and finer pore size distribution of GNP-cement composite were detected by mercury intrusion porosimetry (MIP). In addition, scanning electron microscope (SEM) analysis showed the introduction of GNPs could impede the development of cracks and keep completeness of the matrix by the plicate morphology and tortuous behavior of GNPs.