Preparation and properties of graphene/carbon nanotube hybrid reinforced mortar composites

The successful application of multi-wall carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) in mortar composites depends on their dispersion properties. In this study, MWCNTs and GNPs were modified by the surfactant polycarboxylate ether (PC). One-dimensional MWCNTs and two-dimensional GNPs led to the MWCNTs forming a bridge between adjacent GNP sheets, effectively avoiding restacking of GNPs and agglomeration of MWCNTs, which resulted in greater dispersion. An excellent synergetic effect was generated between MWCNTs and GNPs, enhancing various physical and chemical properties. Hybrid GNP/MWCNT structures improved the mechanical properties of mortar composites (compressive strength and tensile strength) and volume stability (drying shrinkage). Scanning electron microscope images clearly showed that hybrid GNPs/MWCNTs were compatible for use in mortar composites. The hybrid weight ratio of GN11-PC (GNPs:MWCNTs = 1:1) led to optimal compressive strength, greater than that obtained upon addition of GNPs or MWCNTs individually. The compressive strength of the mortar composites containing 0.05 wt% GN11-PC (by weight of cement) aged for 28 d increased by 61% in comparison with the blank sample, and the tensile strength increased by 47.1%, while shrinkage decreased by 6.9%.