Efeitos da incorporação de óxido de grafeno rico em grupo carbonila nas propriedades termomecânicas de concretos de alto desempenho

Abstract

The use of High-Performance Concrete (HPC), primarily characterized by its high compressive strength and durability, has grown significantly. However, due to their lower porosity, HPCs present a greater potential for fragmentation or explosive spalling when exposed to high temperatures. In recent years, nanomaterials have been incorporated into concrete to enhance its properties. Among these, graphene oxide has shown significant potential due to its large specific surface area, high mechanical strength, and good chemical stability. In this context, the present study evaluated the effects of incorporating carbonyl-rich graphene oxide (CGO) on the thermomechanical properties of C55-grade HPC subjected to elevated temperatures (300°C, 600°C, and 900°C) and ambient temperature (AT). For this purpose, two types of HPC were produced: a reference mix (C-REF) and a mix containing CGO at a concentration of 0.02% by cement weight (C-CGO). Tests were conducted to assess compressive and tensile strength, ultrasonic pulse velocity (UPV), static and dynamic modulus of elasticity, mass loss, specific mass, void index, water absorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal conductivity.The study demonstrated that the addition of CGO led to an increase of approximately 27% in compressive strength, 16.5% in tensile strength, and a 31.5% increase in modulus of elasticity at ambient temperature, acting as a reinforcement in the material's structure. Regarding residual properties after high-temperature exposure, the C-CGO mix showed superior performance compared to C-REF, with improvements of approximately 26% in compressive strength, 13% in tensile strength, and 60% in modulus of elasticity. Thermal conductivity results for C-CGO at ambient temperature and after exposure to elevated temperatures were lower than those of C-REF, highlighting the potential of this nanomaterial for the development of more thermally insulating concrete. These findings indicate that CGO incorporation can enhance both the mechanical performance and thermal resistance of high-performance concretes subjected to elevated temperatures.