Impact of Graphene on Microstructure and Compressive Strength of Cement Mortars Utilizing Two Different Dispersion Methods

Carbon-based nanomaterials are currently used to reinforce cement-based composite materials based on their superior properties. This study investigates the mechanical property (compressive strength) of cement mortars incorporated with pristine graphene. The dosages of graphene materials used were 0.01%, 0.02%, 0.03%, and 0.04% by weight of cement. Moreover, this study compares two dispersion techniques: ultrasonication with surfactant coating and mechanical blending with surfactant coating to promote the use of graphene in cement mortars. A commonly used polycarboxylate superplasticizer Sika-Viscocrete Ultra 2100, was used as a dispersant agent (surfactant) of graphene with a surfactant to graphene weight ratio of 9 to 1. Dynamic Light Scattering analysis was used to assess graphene aqueous suspensions and obtain the optimum surfactant to graphene weight ratio. The 28-day compressive strength of the cement mortars containing pristine graphene with 0.03% by weight of cement was enhanced by 38% and 33.6% for ultrasonication with surfactant coating and mechanical blending with surfactant coating employed as dispersion techniques of graphene, respectively, compared to the control samples. However, the mechanical blending with surfactant coating is more convenient in terms of practicality and cost than ultrasonication with surfactant coating. The workability of cement mortars incorporated with pristine graphene at these dosages was investigated. Results show that graphene, at these dosages, did not impact the workability of cement mortars. Finally, a Scanning Electron Microscope was utilized to characterize graphene and to assess the microstructure of the cement mortars incorporated with graphen