Enhanced chemical resistance to sulphuric acid attack by reinforcing Graphene Oxide in Ordinary and Portland Pozzolana cement mortars

Concrete when exposed to aggressive environmental conditions cause significant damage to the structures which substantially reduces its durability properties. The addition of nanofillers can improve hydration properties and hence improve fresh, hardened, and durability properties. In this study, two types of cements such as Ordinary Portland Cement (OPC) and Portland Pozzolana fly ash-based cement (PPC) were reinforced with Graphene Oxide (GO) to check the chemical resistance towards 5% Sulphuric acid exposure. Initial investigations such as surface characteristics and pore size measurements were analyzed through Brunauer- Emmett- Teller (BET) analysis. The resistance to Sulphuric acid attack is assessed through the change in dimensions, mass, visual observations, un-effected depth by microscopic observations, and loss in flexural strength of acid-exposed specimens. The further obtained reaction products were characterized through Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction Analysis (XRD), Fourier Transform Infrared-ray Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA) investigations. The addition of GO improved hydration and formed dense microstructure which enhanced the resistance to acid attack by measuring the change in length, cross-section, and weight loss after the acid attack. 0.04% GO addition improved 24.5% and 1.7% flexural strength after the acid attack. The formation of flower-like crystals by the addition of GO improved better resistance to acid attack confirmed through FESEM morphology. The results obtained showed GO has the potential in improving porosity characteristics by enhancing hydration characteristics. GO helped in enhancing flexural strength and improved microstructure after 28 days of acid exposure in OPC and PPC composites. The overall results showed improved resistance characteristics to Sulphuric acid attack by reinforcing optimum GO content in enhancing hydration and microstructure in OPC and PPC composites.