Mechanical and transport properties of graphene-mortar composites: Influence of particle size and dispersing agent

Abstract

This study investigates the influence of different types of graphene nanoplatelets (GNPs) and various dispersion agents on the mechanical and transport properties, and microstructure of mortar specimens. The GNPs utilized exhibit variations in lateral size (25 µm and <2 µm) and specific surface area (120 m²/g and 300 m²/g). Prior to their incorporation into mortar mixtures, these GNPs underwent dispersion in water through surfactant-assisted sonication. The dispersion agents considered for this purpose included Sodium Dodecylbenzene Sulfonate (SDBS), an anionic surfactant, Pluronic F127, an ionic surfactant, and a combination of both surfactants. To evaluate the impact of sonication duration and surfactant type on the dispersion performance, several tests were conducted, including dynamic light scattering (DLS), UV–vis spectroscopy, and visual observations on the aqueous suspensions. The compressive strength tests were performed to assess the mechanical properties of GNP-mortar composites. These tests involved the fabrication of GNP-mortar composites using two types of GNPs at concentrations of 0.05% and 0.1% by weight of cement, with the application of different surfactants. Furthermore, porosity and sorptivity tests were conducted to assess the volume of permeable voids and the capillary water absorption properties of the developed GNP-mortar composites. The influence of GNP addition on the hydration process was examined through thermogravimetric analysis. Microstructural evaluations of GNP-reinforced cementitious composites were carried out using scanning electron microscopy (SEM) imaging. Results indicate that up to 36% increase in compressive strength, 53% decrease in permeable porosity, and 79% decrease in sorptivity can be achieved with the addition of GNPs in mortar composites. The utilization of GNPs with a larger particle size and SDBS generally results in higher enhancements compared to employing GNPs with a smaller particle size and Pluronic F-127.