Gesso para a construção civil reforçado com nanocargas de óxido de grafeno

Abstract

The use of gypsum in building construction has shown significant growth, being a lowcost and easy-to-handle material. Graphene oxide (GO), a material derived from graphite powder, has been extensively studied in the scientific community and applied in the building construction as a filler in cementitious materials, creating more resistant composites. Among the methods for obtaining GO, the modified Hummers method stands out, because of its accessible precursor raw material (graphite), high yield, and water processability, making it more suitable for using in composites. We proposed the reinforcement of casting plaster, used for making blocks, by nanofillers of graphene oxide (OG) - obtained from graphite by the modified Hummers method - in the percentages 0.005%, 0.01%, 0.03 %, 0.05% and 0.10% by mass, aiming at improvements in their mechanical and physical properties. In the morphological and structural analysis of graphene oxide, the following characterization techniques were used: X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The same characterization techniques were used on the reference gypsum (without OG addition) and on the OG-reinforced gypsum composites. The physical and mechanical properties (surface hardness, compressive strength, and flexural strength) of the reference gypsum and composites were obtained from the parameters and tests proposed in NBR's 13207, 12127, 12128, 12129 and 13279. The workability of gypsum paste is reduced with the gradual addition of OG (% by mass). The graphene oxide reinforced gypsum shows optimum improvement in the mechanical properties at 0.01 wt.%, with a 13.40% increase in compressive strength in the water/gypsum ratio 0.65, and increases, in the water/gypsum ratio 0.50, of 8.90% in compressive strength, 3.50% in hardness and 22.60% in flexural strength. However, with further gradual increase in the amount of GO, the resistance is gradually reduced to lower values as compared to the reference plaster.