Study on the microscale structure and sulfate attack resistance of cement mortars containing graphene oxide nanoplatelets

Abstract

This study investigates the corrosion resistance of cement-based materials modified with GO (graphene oxide) against sulfate, employing a series of experiments. The results demonstrate that the inclusion of GO enhances the corrosion resistance of cement in terms of mechanical properties, sulfate ion diffusion, and microstructural characteristics. The internal pore network structural parameters of the composite were analyzed using X-ray microcomputed tomography processing techniques at a microscopic scale. The permeability of the composites was numerically simulated using hydrodynamic equations, such as the Hagen-Poiseuille and Kozeny-Carman equations. The additional amount of GO in the composite cement was varied as follows: 0%, 0.01%, 0.03%, 0.05%, and 0.1%, with 0% serving as the reference specimen. In the flexural and compressive strength tests, the strength of the GO-modified specimens exhibited varied improvements after 180 days of exposure to a sodium sulfate solution. The flexural and compressive corrosion resistance coefficients were optimized by 12.34% and 11.07%, respectively, with the addition of 0.03% GO. The diffusion coefficients of sulfate ions were consistently observed at a level of 10-6 mm2/s and decreased over time. Furthermore, the presence of GO hindered the transport of sulfate ions. The gas permeability test results indicated that the GO-modified cement mortar exhibited lower porosity and permeability compared to the reference mortar. The pore network structure model revealed that the reference specimen possessed a connected porosity of 8%, an average porosity of 10%, and a wide distribution of pore and throat radii. In contrast, the 0.03% GO composite cement specimens exhibited a connected porosity of 5.3% and an average porosity of 8%. Through simulations using the Kozeny-Carman equation, it was determined that the reference specimen had higher permeability and faster internal flow rates.