Extra-Low Dosage Graphene Oxide Cementitious Nanocomposites: A Nano- to Macroscale Approach

The impact of extra-low dosage (0.01% by weight of cement) Graphene Oxide (GO) on theproperties of fresh and hardened nanocomposites was assessed. The use of a minimum amount of 2-Dnanofiller would minimize costs and sustainability issues, therefore encouraging the market uptake ofnanoengineered cement-based materials. GO was characterized by X-ray Photoelectron Spectroscopy(XPS), Fourier-transform infrared spectroscopy (FTIR), Atomic Force Microscopy (AFM), X-rayDiffraction (XRD), and Raman spectroscopy. GO consisted of stacked sheets up to 600 nm 800 nmwide and 2 nm thick, oxygen content 31 at%. The impact of GO on the fresh admixtures was evaluatedby rheology, flowability, and workability measurements. GO-modified samples were characterized bydensity measurements, Scanning Electron Microscopy (SEM) analysis, and compression and bendingtests. Permeability was investigated using the boiling-water saturation technique, salt pondingtest, and Initial Surface Absorption Test (ISAT). At 28 days, GO-nanocomposite exhibited increaseddensity (+14%), improved compressive and flexural strength (+29% and +13%, respectively), anddecreased permeability compared to the control sample. The strengthening effect dominated overthe adverse effects associated with the worsening of the fresh properties; reduced permeability wasmainly attributed to the refining of the pore network induced by the presence of GO.