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

Abstract

Carbon-based nanomaterials are currently used to reinforce cement-based composite materials based on their superior properties. However, the mechanical performance of the cement-based composite materials can be improved by achieving an effective dispersion of nanomaterials in the cement matrix. Hence, this study investigates the effect of the surfactant coating method with or without the help of ultrasonication to promote the use of graphene in cement mortars. The dosages of graphene materials used were 0.01%, 0.02%, 0.03%, and 0.04% by weight of cement. A commonly used polycarboxylate superplasticizer (PCE) was used as a dispersant agent of graphene with a surfactant-to-graphene weight ratio of 9∶1. Dynamic light scattering (DLS) analysis was utilized to assess graphene aqueous suspensions and obtain the optimum surfactant-to-graphene weight ratio. In addition, compressive strength tests and scanning electron microscopic (SEM) micrographs were employed to verify the embedment and dispersion of graphene in the cement matrix. As a result, the 28-day compressive strength of the cement mortars containing graphene with 0.03% by weight of cement was enhanced by 17.5% and 13.7% for ultrasonication with surfactant coating and mechanical blending with surfactant coating employed as dispersion methods of graphene, respectively, compared to the control specimens. However, mechanical blending with surfactant coating is more convenient than ultrasonication with surfactant coating in terms of practicality and cost.