Enhanced impermeability of cementitious composite by different content of graphene oxide nanoparticles

Graphene oxide (GO) as a high-performance nanoparticle is among the most commonly used nanomaterials for improving concrete properties. This study is aimed to examine the effect of different amount of GO (0%, 0.025%, 0.05%, 0.1% and 0.2% by weight of cement) on the concrete permeability. According to some standards for water permeability assessment of concrete, concrete permeability is just measured in one direction and at constant pressure. Therefore, the impact of different hydrostatic pressures (up to 0.95 MPa) and direction of testing on the permeability of GO-reinforced concrete was also investigated. Moreover, a regression approach was used to investigate the relationship between GO content, permeability characteristics, and microstructural parameters of cement composites. The measured parameters during this study include primary and secondary water sorptivity, volumetric water absorption, porosity, penetrated water volume and depth, penetrated water flow rate, permeability coefficient, and compressive strength. The concrete permeability and pore distribution were examined by "cylindrical chamber" and the mercury intrusion porosimetry (MIP) method, respectively. Experimental results showed that even a small amount of GO can effectively prevent further water penetration into the concrete, both in the direction of concrete placement and the perpendicular to it. In addition, as the dosage of GO increases, the cumulative water penetration volume increase rate decreases up to 54% as the applied hydrostatic pressure rises. Furthermore, the change rate of primary and secondary water sorptivity coefficients increases linearly with the increment of GO dosage. Moreover, the contribution of the initial linear part of water sorptivity in the overall process in mortar specimens increases from 42% to 60% with increasing GO content. Additionally, the decrease in permeability coefficient was also observed 75%–94% in reinforced concrete samples. Finally, a linear correlation with high determination coefficient exists between the change rate of penetrated water volume and the volume of capillary pores in the concrete structure.