Gypsum Casting Plaster Reinforced with Graphene Oxide Nanofillers

Abstract

Casting plaster, mainly used in building construction for the manufacture of partition wall blocks, panelboards/drywalls, coatings, and casting molds, was reinforced with graphene oxide (GO) nanofillers. The composites were studied with the aim of improving their mechanical and physical properties and understanding their structural interaction mechanisms. The GO aqueous dispersion was obtained from graphite, via the modified Hummers method, and the plaster nanocomposites were prepared by gradually adding small aliquots of GO dispersion to the water mixing used for the molding of block samples. Its structural properties and behaviors were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The physical and mechanical (compressive strength) properties of the reference gypsum and composites were measured. Heat calorimetry showed a faster setting time with the gradual wt.% addition of GO, reducing the workability of the gypsum paste. So, setting retardants and plasticizer were added to the mixture and their properties were compared with that of pure gypsum/GO composites. Graphene oxide–reinforced gypsum showed a maximum significant 13% improvement, as compared to the reference plaster, in the compressive strength at 0.01 wt.% GO loading. However, further wt.% increase of GO led to a gradual reduction in the mechanical resistance. This reduction agrees with a cluster phase separation and unproper formation of gypsum crystals visualized by optical and SEM microscopies, together with an increase in the macroscopic porosity. Our study showed GO can improve the mechanical properties of plaster and can be produced in a stable aqueous dispersion, being readily used during the plaster mixing procedure. Overall, this novel technique for using graphene oxide as a nanofiller in gypsum composites is promising and can become an effective and viable method.