Effect of graphene-based additives on mechanical strength and microstructure of gypsum plaster

Abstract

In this study, graphene-based materials such as graphene oxide, reduced graphene oxide, and boron-doped reduced graphene oxide were synthesized, and their effects on the microstructure and mechanical properties of gypsum plaster were investigated. The graphene oxide (GO) sample was synthesized by modified Hummers’ method, and reduced graphene oxide (rGO) was obtained with the thermal reduction of GO. Boron doped reduced graphene oxide (B-rGO) was prepared via the impregnation method. The synthesized graphene-based materials were characterized using H 2 -TPR, TGA-DTA, XRD, FT-IR, SEM-EDS, TEM, Raman, and N 2 adsorption-desorption analysis. Analysis results confirmed that 450 o C was a sufficient temperature under an H 2 atmosphere to reduce GO and preserve rGO structure. XRD results revealed the presence of multilayer graphene structure in the rGO and B 2 O 3 crystals in the B-rGO sample. Multilayer graphene formation was also determined from the I 2D /I G ratio (0.1) of Raman analysis. Mechanical strength studies showed that while GO had a negative effect on both bending and compressive strength of gypsum plaster, rGO enhanced its bending and compressive strength. The addition of 0.1 wt% rGO added gypsum plaster increased the bending strength by 15.1% and compressive strength by 3.70%. SEM, He Pycnometry, and N 2 adsorption-desorption analyses revealed that rGO addition significantly changed the microstructure of gypsum plaster. The addition of B-rGO positively affected the compressive strength of the plaster and the highest increase was obtained as 8.6%; however, no significant change was observed in the microstructure of gypsum. • Electron microscopy images represented graphene nanosheets and graphene layers • X-ray diffraction results revealed the B 2 O 3 crystals in the boron-doped sample • Reduced graphene oxide increased the bending and compressive strength • Boron doped reduced graphene oxide enhanced the compressive strength • Reduced graphene oxide decreased the porosity of the gypsum