Enhanced Dispersion of Graphene Nanoplatelets in Cementitious Materials with an Improved Stirring and Mixing Approach

Carbon nano additives (CNA) enable the development of functionalized cement composites. However, a homogeneous dispersion of CNA in cement composites is always a challenging task. Herein, a practical stirring and mixing scheme was developed to promote the dispersion of CNA in cement composites. As an example, graphene nanoplatelets (GNP) was selected as a presentative CNA and incorporated into the cement with three different stirring methods and two different mixing schemes. The dispersion efficiency was measured by UV–Vis tests. The micro-structure of the cement composites with GNP prepared by different stirring and mixing schemes was characterized by scanning Electron Microscope (SEM). Mercury intrusion porosimetry (MIP) was employed to measure the pore size distributions (PSDs). The results showed that GNP in water and cement suspension can be homogeneously dispersed under direct ultrasonic stirrings (DUS) than indirect ultrasonic stirrings (IUS). The combined use of DUS and the spraying mixing method can greatly reduce the GNP agglomerations in the cement matrix. The improved stirring and mixing method enhanced compactness for the GNP-modified cement composites. This research provides an effective and practical dispersion scheme of CNA in cement-based materials with promising applicability to the development of advanced building materials.