Polycarboxylate Based Superplasticizers as Dispersant Agents for Exfoliated Graphene Nanoplatelets Reinforcing Cement Based Materials

Abstract

Graphene nanoplatelets (GNPs) are considered one of the most advanced nanomaterials that hold the promise of providing multifunctional characteristics to the cementitious matrix. To effectively employ the GNPs as a nanoreinforcement, their uniform dispersion within the matrix must be achieved. The present study investigates the efficiency of four different polycarboxylate based superplasticizers, which are fully compatible with cement-based materials, to be exploited as GNPs dispersant agents. Exfoliated GNPs were selected that had a quite small diameter/lateral size of ~5 µm. The dispersing efficiency of the superplasticizers was investigated experimentally by measuring the electrical resistivity of the resulting nanocomposites. A discussion explaining the dispersing mechanism of these types of surfactants is provided. The use of a superplasticizer in conjunction with ultrasonic energy application was found to be necessary to properly disperse the GNPs. The results prove that the polycarboxylate based superplasticizers can be employed to promote the GNPs uniform distribution in cementitious materials. The polycarboxylate ester superplasticizer showed poor results, while the polycarboxylate polymer superplasticizers were found to be more effective to uniformly disperse the GNPs